backdropThe driving range has always been the main bottleneck restricting the development of new energy vehicles, which depends on the energy density of the battery. The energy density of the battery is basically determined by the material system of the positive and negative electrodes. At present, the lithium battery has undergone multiple iterations, and the main upgrade is the positive electrode material. The power battery bms has been upgraded from the initial lithium iron phosphate to 523 and 622 (three numbers represent the proportion of nickel, cobalt and manganese) in the ternary lithium battery, and then to the present 811, which is the high nickel ternary. It is expected to be further upgraded to lithium-rich manganese based materials in the future. The negative electrode material did not achieve a good breakthrough, mainly from graphite to silicon carbon negative electrode. The upper limit of the energy density of the silicon carbon negative electrode is 400Wh/kg, and if the metal lithium is directly used as the negative electrode, the energy density is expected to reach 2600-3500Wh/kg, achieving a qualitative leap. However, the lithium metal negative electrode cannot be used with the traditional liquid electrolyte, because in the process of lithium ion charging and discharging, the liquid electrolyte is easy to form lithium dendrites, and these small crystal spikes will puncture the middle diaphragm, resulting in a short circuit of the positive and negative electrodes, which will cause the rapid rise in the temperature of the battery pack and lead to spontaneous combustion. That is to say, although lithium metal is currently the theoretical energy density of the highest negative electrode material, but limited to the safety of liquid electrolyte, it cannot be applied, and if you want to use lithium metal, you need a solid electrolyte, its conductive properties and liquid electrolyte are roughly the same, but can resist the formation of lithium dendrites, so as to achieve a substantial increase in battery energy density. This is an important reason why solid-state batteries have become mainstream. Similarly, for safety reasons, the operating voltage of the electrolyte can only be maintained at about 4.2V, which also limits the further expansion of the positive electrode material, and if the solid electrolyte is used, then the more extreme and higher energy density of the positive electrode system can be applied.The biggest difference between solid-state batteries and existing lithium batteries is that the diaphragm of solid-state batteries will be canceled, and the electrolyte will be changed from liquid to solid. In addition to the two most important advantages of safety and energy density, solid batteries have also been greatly improved in terms of automotive lightweight, cycle life, charging speed and operating temperature range. In terms of safety and energy density, the solid electrolyte completely solves the risk of spontaneous combustion of the liquid electrolyte, and after the application of the positive and negative electrode materials that are not compatible with the liquid electrolyte and have higher performance, the battery energy density is expected to break through the 500Wh/kg threshold, and then make the electric vehicle driving range of more than 1000 kilometers. In terms of automotive lightweight, the diaphragm and electrolyte together account for nearly 40% of the volume and 25% of the mass of the battery, and after they are replaced by solid electrolytes, the thickness of the battery can be greatly reduced, and after the safety is improved, the temperature control components inside the battery can be omitted, and the volume utilization rate can be further improved. In terms of cycle life, due to overcoming the lithium dendrite phenomenon, the cycle performance of solid-state batteries can reach about 45,000 times in an ideal state. In addition, the solid-state battery only takes ten minutes to fully charge, and the operating temperature range is expanded to more than three times.  Semi-solid batteries are the transition routeHowever, solid-state batteries still have problems such as poor performance due to low ionic conductivity and high cost, so they are 5-10 years away from mass production. Solid-state battery electrolyte and electrode is a solid-state interface, it is difficult to form as close and sufficient contact as solid-liquid interface, which is not conducive to the transmission of lithium ions between positive and negative electrodes, affecting the battery performance, and by adding part of the electrolyte inside the solid state battery can improve the interface contact resistance, so the future technological development of solid state battery adopts a gradual transformation strategy. That is, the electrolyte content is gradually reduced, and finally solid electrolyte is used. According to the solid-liquid ratio of the electrolyte, the solid-state battery can be divided into semi-solid, quasi-solid and all-solid three, and the proportion of solid electrolyte increases in turn. Based on high safety, high compatibility with existing production lines and good economy, semi-solid batteries have become the best choice for the transition from liquid batteries to all-solid-state batteries, and it is expected that large-scale production can be achieved before 2025.In fact, semi-solid batteries do not help much to improve energy density, and the short-term driving factor is mainly the improvement of safety, especially in the risk test for external impact, external heating, internal short circuit and other problems, solid-state batteries perform far better than liquid batteries. In addition, the semi-solid battery is highly compatible with the traditional soft-pack battery production line in production and manufacturing, mainly on the basis of the original process to increase the in-situ solid-state process to achieve rapid switching, so the semi-solid state has the conditions for rapid volume in the short term, which is also the main reason why the semi-solid battery can be assembled to so many models this year. Incremental investment opportunity ElectrolyteThe electrolyte is still used in the semi-solid battery, which is mainly composed of solute lithium salt, organic solvents and additives, of which the solute lithium salt largely determines the operating temperature and safety of the lithium battery. At present, the mainstream electrolyte with LiPF6 (lithium hexafluorophosphate) as lithium salt may produce gas at high temperatures, which cannot meet the requirements of fast charging, while LiFSI (difluorosulfonimide) has the advantages of high conductivity, high chemical stability and high thermal stability. The electrolyte with LiFSI as lithium salt can better meet the development needs of solid state batteries with high energy density and wide operating temperature, so it is considered to be the next generation of lithium salt that is most likely to replace LiPF6. However, due to the complex production process, low yield and high cost of LiFSI, it has not been directly used as a solute lithium salt, but as a solute additive and LiPF6 mixed to improve the performance of the existing electrolyte. In the future, as technological progress drives down its cost, LiFSI is expected to gradually replace LiPF6, taking Tesla's newly launched high energy density battery 4680 battery as an example, the addition ratio of LiFSI increased from 3% to 15%, which is 5 times that of ordinary three-way batteries.There are various synthetic routes for LiFSI, of which the core intermediate difluorosulfonimide requires the use of sulfoxide chloride as a chlorinating agent, so sulfoxide chloride is the core raw material for LiFSI production and will benefit from the growth of LiFSI demand. However, due to the influence of the national environmental two and one capital restriction policy, the production capacity planning of sulfoxide chloride will hardly increase significantly. If sulfoxide chloride is very scarce in the future, its production capacity planning will only tilt to a few head enterprises with mature technology and less pollution in the production process. Electrolyte additivesIn addition, the supply chain of the semi-solid battery and the existing liquid battery is very high, and the positive and negative electrode materials have not changed fundamentally, mainly for the electrolyte to increase the in-situ solid-state process, which is simply to ensure a good interface contact between the electrode and the electrolyte through liquid injection first, and then gelate the electrolyte through external heating and other ways. Thus solving the problem of poor contact between solid and solid interfaces. In situ solid-state process requires additional special electrolyte additives for this process, of which the lithium additives are LiTFSI (lithium trifluoromethylsulfonimide), so LiTFSI manufacturers directly benefit. Negative electrodeSince the semi-solid battery still contains liquid components, it is still not possible to directly use metal lithium as a negative electrode, which means that some additional processing is needed to improve the electrical performance of the overall battery, and the commonly used is the negative pre-lithium treatment. The function of negative electrode prelithium is to offset the irreversible lithium loss caused by the formation of SEI film by replenishing lithium on the electrode material, so as to improve the total capacity and energy density of the battery, and the domestic companies that have laid out prelithium technology mainly have Guoxun High-tech and Yiwei Lithium Energy. Solid electrolyteIn addition to the electrolyte and the negative electrode, for the solid state battery industry, the most critical point is the development of solid electrolytes, the current mainstream technology path there are three main, respectively, polymers, oxides and sulfides, of which polymers belong to organic electrolytes, the last two belong to inorganic electrolytes.The development time of the polymer is the earliest, the advantage is that it is easy to process, can be compatible with the production equipment and process of the existing electrolyte, and has good mechanical properties and is relatively soft. However, its electrical conductivity is low, and it needs to be heated to 60 degrees to work normally; At the same time, due to the relatively poor high pressure resistance and thermal stability of this material, it can not adapt to the positive electrode system with higher energy density, so it does not meet the iterative trend of positive and negative electrode materials. At present, polymers are mainly made into composite materials with oxides to improve the overall performance of batteries.Just said, the solid state battery due to solid contact leads to low conductivity, and the conductivity of sulfide is the closest to the liquid electrolyte in the three technical routes, and its overall material is relatively soft, so the contact with the negative electrode is better, but there are still big difficulties in the process. First of all, its own production involves more complex sintering methods, resulting in its yield is generally low; Secondly, because the sulfide is easy to react with water and oxygen in the air to produce hydrogen sulfide highly toxic gas, it is also necessary to strictly control the production, such as the production requires an inert gas atmosphere, but this will increase the cost, and to synthesize the sulfide electrolyte requires the use of lithium sulfide precursor, and the cost of lithium sulfide precursor is also very expensive. Therefore, the production cost of sulfide electrolytes is much higher than the other two reasons, although technically sulfide is the most promising solid electrolyte for mass production, but considering the cost problem, there is still a long way to go from the real commercialization.In terms of global layout, the research and development of solid-state batteries is mainly concentrated in five countries and regions of China, Japan, Korea, the United States and Europe. China mainly takes the oxide route; Both Japan and South Korea are developing sulfide systems with national efforts. At present, Toyota of Japan is the company with the largest number of sulfide all-solid-state battery patents in the world, while the representative companies of South Korea mainly include LG Chemical, Samsung and PoSCO. In the United States, startups are the mainstay, and several routes are being promoted at the same time. Among the mainstream startups, Ionic Materials is based on polymer Solid system, Solid Power is based on sulfide system, and Quantum Scape is based on oxide system. Europe is the first region to promote the industrialization of polymer solid-state batteries, but based on the disadvantages of the above polymers, the final polymer did not form a trend, and now Europe has turned to investment, Volkswagen, BMW and Mercedes-Benz and other famous automakers have invested in the United States solid-state battery-related companies.Encapsulation mode BinderIn terms of process system, the adjustment of semi-solid batteries to the entire production line is relatively small, while the change of all-solid batteries will be relatively large, and one of the largest iterative direction is dry electrode technology. Unlike the traditional wet process used in lithium battery manufacturing, the dry electrode technology does not use solvents, and directly binds a small amount of PTFE binder and conductive agent to the positive and negative electrode powder, forming a thin electrode material strip through an extruder, and then laminates the electrode material strip onto the metal foil collector fluid to form the finished electrode.This technology is more suitable for the iterative trend of the next generation material system. For the negative electrode, because there is no need to add solvent and do not worry about the reaction between lithium metal and it, the pre-replenishment lithium technology can be implemented smoothly; For the positive electrode, it is easier to use higher energy density positive electrode materials such as ultra-high nickel. At the same time, because the solid binder PTFE used in dry electrode technology has elasticity, it can effectively solve the problem of separation from the electrode sheet caused by the expansion of the silicon-based negative electrode, and the cycle life will be several times increased. In terms of cost, compared with the wet process, the dry process completely skips the step of adding the solution, thus eliminating the complicated coating and pole sheet links, reducing the manufacturing cost, and also has a cost advantage in the input of drying equipment and the floor area of the factory.Dry electrode technology has been used in the all-solid state production mode announced by Samsung, and recently Tesla has made a breakthrough in this technology, the United States Patent and Trademark Office granted Tesla four patents in the field of battery dry electrode, 4680 battery also adopted this technology, and its cost advantage is expected to lay the foundation for the mass production of subsequent 4680 batteries. Since PTFE binders are critical to dry cell technology, producers of PTFE binders are expected to benefit.

On June 26, according to foreign media reports, due to unsatisfactory energy density and charging performance, and higher costs, Tesla is considering stopping the production of 4680 batteries at the Giga Texas factory in Texas. If the cost reduction does not achieve the expected effect by the end of the year, Tesla will abandon 4680 battery production and turn to external suppliers.Review the road to the Tesla 4680Four years ago, in 2020, Tesla launched a 4680 large cylindrical lithium-ion battery on its battery Day. Compared with the 2170 cylinder battery, the battery size is larger, the use of non-polar ear technology, the single capacity is higher, and the production cost of the battery can be effectively reduced.Look at a set of data: in the Q4 of 2023, Tesla's financial report shows that Tesla invested $3.969 billion (about 28.8 billion yuan) in research and development throughout the year. In Q4 alone, it spent $1.094 billion (about 7.95 billion yuan), an increase of 35% over the same period last year, which is the highest research and development investment in Tesla's history.By the Q1 of 2024, Tesla's earnings conference showed that the production efficiency of 4680 was only 18%-20% higher than that of Q4.This is the performance of the Tesla 4680 mass production efficiency encountered bottleneck.Reasons for abandoning 4680It is understood that the dry coating technology of the battery electrode that the 4680 battery initially promised to use and can greatly improve the production efficiency has not yet been successfully realized. In the nearly four years since the Tesla 4680 battery was released in 2020 to the present, Ningde Times, BYD and other companies have reduced the battery cost to 0.4 yuan /Wh. As a comparison, it is reported that the cost of manufacturing 4680 batteries may still be in the range of 0.8-1 yuan /Wh, which is more than twice the battery of Ningde era and BYD. In addition, the safety, cycle life and charging speed of the Tesla 4680 battery are weaker than mainstream batteries. The 4680 battery can no longer become Tesla's cost reduction and quality improvement in the short term.Tesla has freed up a lot of battery space On the one hand, Tesla hopes that through the new technology of 4680 large cylinder batteries, electric vehicle batteries can store more energy, last longer, and be cheaper, and eventually be used in Tesla's full range of electric vehicle products, including electric trucks and electric sports cars. On the other hand, Tesla also hopes that by using lithium iron phosphate materials, the 4680 cylinder battery will be applied to the energy storage field with broad market prospects and is expected to exceed automobile production in the future."Our long-term goal is to produce more than 1,000 GWH of batteries inside Tesla," Musk said in response to an investor's question. Today, assuming Tesla no longer produces 4680 batteries, about 1,000 GWH will become Tesla's demand for batteries. Japan's Panasonic, South Korea's LG New Energy, Samsung SDI, are producing or will soon produce 4680 batteries. There are also quite a number of enterprises in China that are producing or will soon produce 4680 batteries, including Ningde Times, Bic Battery, Billion Wei Lithium Energy, Zhongchuang New Aviation, Rupu Lanjun and so on. It can be expected that there will be more power battery companies that will soon enter the list of Tesla battery suppliers!

Backgrounds:In recent years, due to issues such as nuclear power plants, increased awareness of environmental issues, and electricity liberalization, we have begun to hear more and more frequently about how to save electricity and other power-related information. Among them, it is a typical term often seen in electricity-related fields.What is a Virtual Power Plant (VPP)?Virtual power plant (VPP) refers to power generation equipment such as renewable energy and fuel cells, storage battery equipment that efficiently stores and uses electricity, and consumers (demanders) such as homes and factories that consume electricity, and refers to centralized control, specific areas. It can be said to be a smart city concept that expands the scale of so-called smart homes. It is called a virtual power plant because it is like a virtual power plant in which all equipment, including power generation and storage, is controlled within a certain area.What are the benefits of VPP?Basically the same concept as the smart home (installing a household battery, etc.), and has the following advantages. For example, if electricity demand exceeds supply during a time when everyone uses a lot of electricity, such as during the day, demand response can be used to request power savings and reduce demand. On the other hand, during periods of abundant power supply, the generated power can be used more efficiently by storing it in storage batteries in the area, so that too much power is not wasted.Moreover, what makes it more attractive than smart homes is that it can introduce renewable energy sources, such as solar power plants and wind power plants, which can only be introduced using a certain amount of land, making it more renewable.Similarly, by integrating battery equipment over a considerable area of land, it can be said that it is conducive to improving the efficiency of electricity storage and taking safety measures in advance. Currently, VPP is in the early stages of demonstration testing, so there are many challenges to its widespread use, but it can be said that VPP is very attractive because of its potential to contribute to the environment and bring savings.

Analyzing the Performance and Design of the Tesla Model 3 Battery: A Study by Sandro Stock et al.Sandro Stock et al. from the School of Engineering and Design at the Technical University of Munich, Germany, disassembled and evaluated the electrochemical performance, battery design and chemical material system of the square hard-shell lithium iron phosphate battery used in the Tesla Model 3 to obtain the process-structure-performance relationship of the battery. The test analysis methods include weighing, geometric measurement, cross section analysis, material characterization by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX), electrolyte characterization, and electrochemical performance analysis of half and full cells.The Tesla Model 3 Battery: Capacity and Discharge TestingThe battery is obtained from the battery pack of the Tesla Model 3 produced in December 2020. The battery pack has a total energy of 55 kWh and consists of two 25 series 1 and two 28 series 1 battery modules, configured as a battery pack in 106 series 1. After removing the battery from the battery pack, charge and discharge the battery several times at C/20 to determine the battery capacity of 161.5Ah. After that, the battery is fully discharged using a constant current (CC) of 1A, followed by a constant voltage (CV) discharge at 2.65V, before the battery is transferred to a custom glove box for dismantling.Evolution of Tesla Model 3 Batteries: From 18650 Cylinder to Square LFPThe Model 3 initially featured the same 18650 cylinder NCA battery pack as the Model S/Model X. Later, Tesla introduced new battery iterations, including the 21,700 cylinder NCA batteries produced by Panasonic and others, which are used in the vast majority of performance and long-range Model 3s. There are also 21,700 cylindrical nickel-cobalt-manganese (NCM) batteries, which are used in Tesla cars produced in China and Berlin. In addition, Tesla has also begun using CATL's square lithium iron phosphate (LFP) battery in the standard version of the Model 3.Analyzing Battery Components through Disassembly and Microscopic ExaminationDuring the disassembly process, images were taken using the built-in microscope, and an example of the picture obtained was shown in Figure 2. After the battery is broken down into the shell, coil and top cover, the geometric dimensions of each component are recorded for graphic reconstruction using CAD. During the dismantling process, electrolyte residue was found at the bottom of the housing, which was removed and packaged for further analysis. The coils were then carefully dismantled and samples were taken every 50 cm. The electrode samples were washed with diethyl carbonate (DEC) to remove excess electrolytes or by-products, and dried before further examination of electrode parameters such as length, thickness, overlap and weight. When assembling a button cell, the electrode first removes the coating on one side of the electrode with acetone to obtain a single-coated pole piece.In summary, this paper disassembled and analyzed the 161.5Ah square flat coil hard shell LFP battery in the Tesla Model 3, decomposed the battery to the material level, and tracked the process steps and manufacturing characteristics. The specific energy of the battery was 163 Wh/kg and the volumetric energy density was 366 Wh/L. The cell presents a low void volume of 6.4% and a fluid collector thickness of 5µm for copper and 12µm for aluminum. The jelly roll core is connected to the top cover in a butterfly design to facilitate the welding process. Cross-sectional and microscopic analysis of the battery cover revealed the application of a variety of laser welding processes, providing high mechanical stability and air tightness. The coating of the electrodes showed a high degree of uniformity, with thickness fluctuations of less than 2μm. Scanning electron microscopy (SEM) images reveal bimodal particle distributions within the pure graphite anode and LFP cathode, where the positive electrode edges are covered with Al2O3 ceramic layers. Electrochemical analysis showed that the performance of the inherent electrolyte was better than that of the ordinary LP572 electrolyte.

Lithium-ion batteries have the advantages of high voltage, high capacity, high energy density and long life, so they are used in smart phone batteries, electric vehicle batteries, household batteries and so on. However, in recent years, the number of fire accidents caused by lithium-ion batteries such as smartphones has increased rapidly, and the safety (danger) of lithium-ion batteries has been recognized, and improving this safety is the subject of popularization of lithium-ion batteries. As the Internet of Things advances, the importance of lithium-ion batteries will increase, so increasing your knowledge of lithium-ion batteries will help you live a more comfortable life.In particular, it is well known that the performance of lithium-ion batteries tends to deteriorate under conditions that significantly deviate from normal use temperatures (such as high or low temperatures), and they can even operate under harsh conditions (such as high or low temperatures). The basic thing is that design can be done. The temperature at which a lithium-ion battery can be used is called the operating temperature range or simply the temperature range.(1) What is the upper limit of the operating temperature range of lithium-ion batteries?The upper limit of the operating temperature range of lithium-ion batteries is mainly determined at high temperatures where the capacity does not deteriorate, the internal resistance does not increase, and the battery does not explode and other dangerous temperatures. As described on this page about the high temperature characteristics of lithium-ion batteries, under normal circumstances, the chemical reaction of the negative electrode of lithium-ion batteries (SEI film growth) is the main cause of capacity degradation, internal resistance increase, etc.Since this deterioration is a chemical reaction, it follows a formula called Arrhenius's equation, which is characterized by a faster rate of deterioration at high temperatures. In other words, once deterioration occurs in a high temperature environment, it will appear in a form of deterioration that cannot be refreshed (resurrected). Therefore, in order to extend the life of lithium-ion batteries, be sure not to expose them to high temperatures.In addition, when the temperature exceeds the operating temperature range, the diaphragm, which is an integral part of the lithium-ion battery, begins to shrink, resulting in a short circuit caused by direct contact between the positive and negative electrodes. When a short circuit occurs, an exothermic reaction occurs, leading to further contraction of the diaphragm and the risk of further short circuits. This causes the temperature to rise rapidly, causing various exothermic reactions such as the reaction between the electrolyte and the negative electrode, the decomposition reaction of the electrolyte, and eventually leading to the risk of thermal runaway leading to rupture and fire. Although it depends on the positive electrode material, negative electrode material, electrolyte, etc., which constitutes the lithium-ion battery, the upper limit of the operating temperature range is often around 60 ° C due to the above reaction.(2) What is the lower limit of the operating temperature range of lithium-ion batteries?On the other hand, the lower limit of the operating temperature range of the lithium-ion battery is set to ensure that the output will not drop too much at low temperatures and prevent electrical deposition during rapid charging at low temperatures. As explained by the relationship between external temperature, capacity, and internal resistance, the internal resistance of all batteries, including lithium-ion batteries, increases at low temperatures. (In contrast, the ohmic resistance of a metal increases with decreasing temperature.)If the internal resistance of the battery increases, the output decreases, so if the battery is installed in the product, there is a risk that the product will not operate. In addition, when the lower limit of the operating temperature range is specified, the operating temperature range should be set to prevent this from happening, because rapid charging at low temperatures can lead to the phenomenon of negative electrodeposition, which significantly reduces the battery capacity and output has been set lower limits. Due to these factors, the lower limit of the temperature range for lithium-ion batteries is usually around -20 to 0°C, although this depends on the product.(3) How to expand the temperature range of lithium-ion batteriesSo, can we expand the temperature range (operating temperature range) of lithium-ion batteries by doing this? On the high temperature side, the main cause of degradation is the formation of sediment (SEI) due to the reaction between the negative electrode material and the electrolyte on the negative surface.In particular, by adding additives such as VC (vinylidene carbonate) and FEC to the electrolyte composition, and optimizing the ratio of other substances such as ethyl carbonate (EC) and diethyl carbonate (DEC), the performance of lithium-ion batteries can be improved. In some cases, degradation at high temperatures is greatly reduced. Therefore, electrolyte optimization is very important for extending the temperature range at high temperatures. (Of course, if the type, composition or electrode structure of the positive and negative materials is not suitable, there are also cases where the material deteriorates first, but in most cases, the main cause is the electrolyte.)In addition, it is best to use lithium titanate, because lithium titanate is a material that is not easy to cause electrodeposition at low temperatures, otherwise even the use of graphite negative electrode will reduce the available capacity of the negative electrode. One way to lower the lower end of your operating temperature range is to mix a small amount of a substance with a very low melting point (below freezing), such as PC (Propylene carbonate).However, if the PC component is too high, the SEI will not form well with the graphite negative and the battery performance will deteriorate significantly, so carefully consider the material composition before using this method. Ultimately, materials such as electrolytes, anode materials, and negative materials and their combinations need to be optimized, and various evaluations and considerations are made.(4) What are the temperature characteristics of lithium-ion batteries?Previously explained the temperature range of lithium-ion batteries, there is a similar term to the temperature range called temperature characteristics. The temperature characteristic of a lithium-ion battery is a vague term, similar to the term temperature range, which basically refers to "a wide operating temperature range" or "the temperature (high or low) when used in the end product." It is used as an indicator to show whether the required values for yield, capacity, etc., are being met. It can also be used as a general term to describe high temperature characteristics and low temperature characteristics. In addition to the operating temperature range, it is also necessary to understand the term temperature characteristics.

Ceramic materials are a broad category that includes a variety of inorganic nonmetallic materials obtained through high-temperature processing (such as sintering), usually in powder or granular form. A representative electrolyte in solid electrolyte is ceramic-based solid electrolyte, ceramic-based solid electrolyte has some beneficial inherent characteristics, such as non-flammability, large mechanical strength, wide electrochemical stability window, etc., they have unparalleled advantages in safety and service life, is one of the important directions of solid electrolyte research at home and abroad. Ceramic based solid electrolyte mainly includes oxide series and sulfide series, of which the oxide series mainly includes perovskite type, garnet type, LISICON (lithium superionic conductor) type, NASICON (sodium superionic conductor) type, sulfide series is mainly thiophosphate system. The representative material of perovskite solid electrolyte is LLTO (lithium lanthanum titanum oxide/lithium lanthanum titanate, Li0.33La0.56TiO3), and the representative material of garnet solid electrolyte is LLZO (lithium zirconium oxide/lithium lanthanum zirconate, Li7La3Zr2O12). The representative material of NASICON solid electrolyte is LATP (lithium aluminum titanium phosphate, Li1.3Al0.3Ti1.7(PO4)3), these three are the material types of the production line layout at present, and there are few reports about LISICON solid electrolyte. Although the solid electrolyte of sulfide in the phosphate thioate system has a high lithium ion conductivity, its stability is relatively poor, it may also release hydrogen sulfide gas when in use, and its mechanical properties are also relatively poor, so it may be mainly used in lithium-sulfur batteries. The introduction and application of Perovskite type LLTO solid electrolyteThe molecular formula of typical perovskite ceramics is ABO3, the A site is generally rare earth or alkaline earth element ion, the B site is A transition metal ion, and the A and B sites can be partially replaced by metal ions with similar radii to keep their crystal structure basically unchanged. Perovskite structure composite oxides are usually structurally stable, where Li+ is transported by vacancy transition mechanism, that is, Li+ directional transition to adjacent vacancy to generate lithium ion conductance.Currently, perovskite-structured LLtos (lithium lanthanum titanum oxide/lithium lanthanum titanate, Li0.33La0.56TiO3) have high crystal conductivity in crystalline solid electrolytes. In 1993, Inaguma et al. found that the room temperature ionic conductivity of LLTO single crystal body could reach 10-3S·cm-1, but its polycrystalline conductivity was two orders of magnitude smaller than that of monomer. The short-plate effect made the total conductivity of LLTO ceramics low, thus failing to meet the requirements of practical application in lithium batteries. The total conductivity should be improved by doping modification. In view of the problems existing in LLTO, the study of regulating crystal structure and improving electrochemical performance through doping modification of LLTO has been widely reported. At present, LLTO doping is divided into A-site doping, B-site doping and AB site co-doping. The use of rare earth elements in the sintering process can improve the LLTO-induced density and reduce the porosity, thus reducing the grain boundary impedance. The three-dimensional skeleton constructed by rare earth ions with large radius is conducive to ion diffusion and migration, and its doping can increase the LLTO cell volume, thereby expanding the ion transport channel and stabilizing the highly conductive cubic phase of LLTO. The introduction and application of Garnet type LLZO solid electrolyteThe general formula of garnet structure is A3B2(XO4)3, in which ABX coordinates with eight, six and four oxygen ions respectively to form dodecahedron, octahedron and tetrahedron, which together build a three-dimensional skeleton structure. At present, the most studied garnet solid electrolyte is LLZO (Lithium zirconium oxygen/lithium lanthanum zirconate, Li7La3Zr2O12), and its main raw materials are LiCO3, La(OH)3, ZrO2 and Al2O3.LLZO has two crystal structures: cubic phase (c-LLZO) and tetragonal phase (t-LLZO), and the most significant difference between the two structures is the occupation of Li, in the cubic phase Li partially occupies the gap position, while in the tetragonal phase Li occupies the gap position. Among them, c-LLZO has higher conductivity than t-LLZO, and its crystal skeleton network is composed of La3+, Zr2+ and O2- ions, and Li ions are distributed in the crystal grid. The shortest distance between Li ions in adjacent positions is the main reason for fast ion transport, and thus provides high ionic conductivity. At 25℃, the ionic conductivity of LLZO is 3×10-4S/cm, and the proportion of its grain boundary resistance to the total resistance is less than 50%. Therefore, the overall ionic conductivity of LLZO is in the same order of magnitude as the intracrystalline ionic conductivity, ensuring its high overall ionic conductivity as a solid electrolyte. LLZO solid electrolyte has great application potential in all-solid-state batteries, LLZO does not react with lithium metal, has low interface and grain impedance, and is relatively stable in air, and the strength and hardness of the densified ceramics sintered by LLZO heat treatment are relatively high. However, usually undoped LLZO has the advantages of stable electrochemical performance and wide electrochemical window, but the phase structure stability is poor, the vibration density is low, has a large grain boundary resistance and low room temperature ion conductivity, and will have a large interface resistance in the application of all-solid-state batteries. In addition, LLZO is exposed to air with moisture and CO2, and Li2CO3 will be generated on the surface due to the role of H+/Li+ exchange, resulting in gradual deterioration of performance. In order to enhance the chemical stability of LLZO system solid electrolyte in atmospheric environment, LLZO is mainly modified by doping different metal elements, the purpose is to stabilize the cubic phase structure, optimize the preparation route, reduce its interface resistance and grain boundary resistance, and improve its room temperature ionic conductivity.LLZO, as one of the most marketable solid electrolyte materials, has attracted the attention of many researchers, and through in-depth understanding of the crystal structure of LLZO and optimization of the structure of lithium-rich garnet by element doping, the lithium ion conductivity of LLZO has been improved by an order of magnitude. Although researchers have made a large number of attempts to build LLZ-based solid-state batteries and develop a series of effective strategies to solve the problem of positive /LLZO and negative /LLZO physical contact, up to now, there is indeed no mass-produced product that can significantly outperform traditional lithium-ion batteries in all aspects. The introduction and application of NASICON LATP solid electrolyteThe general formula of NASICON type material is M1xM2(2-x)(PO4)3, M1 and M2 can be a variety of different metal elements, A13+ doped NASICON type solid electrolyte LATP (lithium aluminum titanium phosphate, lithium titanium), Li1.3Al0.3Ti1.7(PO4)3) is one of the hot research objects of solid electrolyte in recent years.LATP has a complex crystal structure consisting of alternating layers of Li/Ti tetrahedrons and Al/PO4 octahedrons. The Li/Ti tetrahedrons form a three-dimensional frame by connecting shared vertices, while the Al/PO4 octahedrons fill the space between the tetrahedrons. This structure creates channels through which lithium ions can move. LATP can be synthesized by a variety of methods, including solid-state reactions, sol-gel methods, and hydrothermal methods. In one common method, lithium carbonate, alumina (Al2O3), titanium oxide (TiO2), and ammonium dihydrogen phosphate are mixed in stoichiometric proportions and heated in a reducing atmosphere at high temperatures (usually 900 to 1200 ° C) to form LATP ceramics. Some of the advantages of LATP include relatively high ionic conductivity, a wide electrochemical stability window, good mechanical stability, compatibility with lithium metal anodes, low reactivity with cathode materials, and a wide temperature range. In addition, LATP is not easy to form dendrites, which can improve the safety and cycle life of the battery. However, LATP is relatively expensive and has lower ionic conductivity than LLZO.

Basquevolt makes breakthrough in solid-state battery technology with successful production of 20Ah battery and plans for 80Ah batteries by end of year    Recently, Spanish solid state battery developer Basquevolt announced that the company's "A sample line" in Spain has successfully produced the first 20Ah battery, and is expected to be able to manufacture 80Ah batteries by the end of this year. Revolutionizing the Battery Industry: A Look at the State-of-the-Art Plant Producing High-Energy Lithium-Ion Batteries for Electric Vehicles    It is reported that the construction of the plant began in the summer of 2023, covering an area of 4,500 square meters, the plant has a process process that meets current lithium-ion battery industry standards, including the manufacture of patented electrolytes. The plant is now operational and equipped with state-of-the-art machinery for manufacturing batteries, enabling it to produce the first 20Ah batteries, with the first samples to be delivered to potential customers in the coming months. The company plans to expand the production process to 80Ah batteries in a few months, which means getting cells with enough energy density to make battery packs for electric vehicles.The Future of Electric Vehicles: Solid-State Batteries Leading the Way    Compared to traditional lithium-ion batteries (liquid), the technology developed by Basquevolt is already considered the "battery technology of the future" because solid-state batteries will allow the emergence of a "new generation of batteries" : with higher energy density (up to 50%), safer (non-flammable) and lower cost (approximately 30% less). "Our company's goal is to drive the true adoption of electric vehicles with 'Made in Europe' technology. The cost of electric vehicles is much higher than that of traditional internal combustion engine vehicles, and it is not enough to establish a regulatory framework to ban fuel vehicles, it must be made available to the billions of people who cannot currently afford electric vehicles, "said Francisco Carranza, CEO of Basquevolt.   Basquevolt: Leading the Charge in Solid-State Battery Technology in Europe    Basquevolt is a company focused on the development of solid-state battery technology, aiming to become the European leader in the next generation of solid-state lithium battery technology, based on the CIC energiGUNE patented composite electrolyte. In addition to producing 20Ah batteries, Basquevolt also plans to produce solid-state batteries at its 1GWh plant in Victoria-Gasteitz by the end of 2025, with the goal of reaching 10GWh production by 2027. The goal is supported by the founding shareholders of the Basque government, Iberdrola, CIE Automotive, Enagas, EIT InnoEnergy and CIC energiGUNE. 

Background Recently, there have been a lot of fire accidents caused by lithium-ion batteries, and I think the interest in lithium-ion batteries is increasing. However, there are certain aspects of lithium-ion batteries that are not well known, such as their composition, various safety features, and related terminology, which I have also described.1.What is the capacity retention rate?When secondary batteries such as lithium-ion batteries undergo cycle tests, floating charge tests, preservation tests and other battery evaluation tests, the battery will deteriorate, and its capacity will gradually decrease from the initial capacity [mAh or Ah]. The capacity retention rate is the ratio of the capacity at a point [mAh,Ah] to the initial capacity [mAh,Ah]×100, expressed as a percentage. 2.cycle test capacity retention rateAn example of the capacity retention rate of a lithium-ion battery during cycle testing is shown below. In simple terms, the cycle test is to evaluate the deterioration of the battery during repeated charging and discharging, and one of the evaluation items of the cycle test is the capacity retention rate. A battery that can maintain a high capacity retention rate even after multiple cycles is a good battery. The capacity retention rate of the battery depends not only on the number of cycles, but also on the charge and discharge rate during the cycle, the ambient temperature, etc.The reduction in the number of known cycle tests and the capacity maintenance rate can be obtained by the degradation coefficient Kc in the cycle test and the degradation coefficient Kf in the float test. Reduction of capacity maintenance rate = degradation coefficient Kc× number of root cycle tests + degradation coefficient Kf× route passage time. Here, the degradation coefficient Kc in the cycle test is strongly related to the DOD(depth of discharge) of the battery.In other words, the greater the DOD in the cyclic test, the greater the expansion and contraction of the active material due to charge and discharge, which tends to increase the contact resistance between the active materials and between the electrode foil and the active material. In addition, it should be noted that when conducting a cycle test, if the amount of electrolyte in the battery is too small, there will be a phenomenon called drying (liquid depletion), which is not good for the battery.

Enhancing Lithium-Ion Battery Technology: Strategies for Improving Energy Density and PerformanceWith the increasing demand for lithium-ion batteries, high energy density and high power density lithium-ion battery technology has become one of the research hotspots. Increasing electrode thickness, material modification and development of new materials can effectively improve the energy density of the battery, while the electrode microstructure parameters such as porosity, pore size and distribution, and curvature of the electrode are the key factors determining the performance of the electrode and the battery.Analyzing Pore Characteristics of Lithium-Ion Porous Electrodes: Methods and SignificanceFrom the current research of lithium-ion porous electrodes, it can be found that the actual porous electrode pores are affected by the accumulation effect and filling effect of particles, and the pore size and distribution are not uniform, and the zigzag degree is difficult to characterize. In order to characterize the pore characteristics of porous electrodes, researchers have devoted themselves to the development of efficient and fast methods for measuring the zigzag degree, such as the gas transmission resistance measurement method , the heat exchange method for hydrodynamic simulation of porous electrodes, the FIB-SEM reconstruction of 3D electrode structure measurement method, and the symmetric battery electrochemical impedance spectroscopy (EIS) test method. Among them, electrochemical impedance spectroscopy is easy to operate, and the test time is short. Because the electron transmission resistance of lithium-ion porous electrodes is usually small, the true curvature of porous electrodes can be obtained by electrochemical impedance spectroscopy. In addition, the measurement method of symmetrical battery electrochemical impedance spectroscopy can also be used to analyze the electrolyte wettability and the membrane curvature of the electrode plate, and has a certain guiding significance for the judgment of the production line electrolyte wettability time.Electrochemical impedance spectroscopy (EIS) was used to measure symmetrical cells assembled with negative electrode plates of different compaction. The ion resistance of each pole piece was obtained by fitting the EIS spectrum, and then the ion resistance value was substituted into the formula to obtain the McMullin number of the pole piece, as shown in Figure 5. It can be seen from the trend of the data that the ion resistance and McMullin number increase with the increase of the compaction density of the electrode sheet, indicating that the curvature of the graphite negative electrode sheet increases with the increase of the compaction.Effect of Compaction Density on Electrolyte Performance and Ion Transmission in Lithium-ion BatteriesWith the increase of compaction density, the contact between graphite particles and conductive particles is more dense, the performance of the absorbing electrolyte deteriorates, and the electrolyte is difficult to infiltrate, making the migration of lithium ions more difficult, increasing the ion transmission impedance, resulting in an increase in the curvature of the pole sheet.The Impact of Electrode Compaction Density on Battery PerformanceGenerally speaking, within the compaction range allowed by the material, the greater the electrode compaction density and the more active material contained per unit volume, the higher the capacity of the battery can be done. However, when the compaction of the pole plate is too high, the porosity is reduced, the greater the zigzag degree, the longer the lithium ion transmission path, which will seriously reduce the magnification performance and cycle performance of the battery. Especially for thick electrodes, low curvature is one of the key factors in the design of electrode structure. Therefore, compaction density is very important for battery design. We can preliminatively characterize the magnification performance of the pole sheet in the battery by testing the curvature of the pole sheet, so as to determine the appropriate design scheme of the pole sheet.