Background :As a material binder (commonly mixed with something called a binder) for making electrodes for lithium-ion and lithium-polymer batteries. The reason adhesives are used as electrode materials in lithium-ion batteries is to bond the slurry to the fluid collector foil and to prevent the electrode material from peeling off the fluid collector foil after drying (to increase peel strength).In addition, there is now a strong trend towards the use of substances that can reduce environmental impact, from so-called solvent-based electrodes using organic solvents NMP and PVDF as binders, to the trend of using water and binders as solvents for pastes using water-based electrodes using certain rubber-based or acrylic based materials. Here, I will explain what is SBR (styrene butadiene rubber), which is the representative water-based adhesive.The Definination of SBR:SBR is an abbreviation of the scientific name styrene butadiene rubber. SBR is a versatile rubber that accounts for about 80% of synthetic rubber production. The physical properties of SBR include the following, but basically it is a material with an excellent balance between strength, chemical resistance, etc. In many cases, it is used as a water-based adhesive for lithium-ion batteries.The general physical characteristics of SBR:SBR Features (Advantages)(1) High strength, elasticity, wear resistance, heat resistance, acid resistance, alkali resistance, insulation;(2) The proportion of impurities in the manufacturing process is low and the purity is high;(3) easy to vulcanize;(4) Price stability.SBR Features (Disadvantages)(1) The tolerance to gas phosphorus and other oils, benzene, toluene and other organic solvents, organic acids is relatively low. However, when used as an electrode for lithium-ion batteries, the material is strongly compressed after formation, so it is unlikely to react with organic solvents as electrolytes, so there is no particular problem. The specific use of SBR in lithium-ion batteriesSBR (Styrene-butadiene rubber) is used as a representative water-based adhesive in lithium-ion batteries. In water-based electrodes, when SBR is used as a binder, CMC (carboxymethyl cellulose) is basically used as a thickener. Taking the positive electrode as an example, the composition of the water electrode is mainly active substances: conductive additives: binders: thickeners (CMC), and the solid content ratio is 80~90% : 0~10% : 0~10% : 0~ 0~ usually accounts for about 10%.If it is a negative electrode, the composition of the water-based electrode is mainly the active substance: binder: thickener (CMC), and the solid content ratio is 80~90% : 0~10% : 0~10%. The basic manufacturing process for electrodes using water-based adhesives (SBR) is as follows:Solvent-based systems primarily use PVdF as a binder and NMP as a viscosity regulator (diluent), while water-based systems, as the name suggests, use water and CMC (carboxylic acid) as a viscosity regulator. Each battery manufacturer optimizes the electrode material composition, mixing procedure, mixing time, coating conditions, etc., but in most cases the process flow is basically as follows.

Enhancing Battery Performance through Ethanol-Induced Phase Inversion StrategyRecently, The team of Prof. Fokko M. Mulder of Delft University of Technology in the Netherlands published A paper entitled "A phase inversion strategy for low-tortuosity and Low-Tortuosity" in Cell Reports Physical Science ultrahigh-mass-loading nickel-rich layered oxide electrodes ". This paper reports a strategy of phase conversion induced by ethanol, which is an effective method for the preparation of high quality supported nickel-rich layered oxide (LiNi0.8Mn0.1Co0.1O2 [NMC811]) electrodes. The ethanol-induced phase change electrode is obviously superior to the conventional NMC cells at 1 C discharge. The non-solvent-induced binder structure improves pore connectivity, reduces the bending coefficient, and rapid solvent removal reduces adhesive migration during drying, enabling ultra-high active mass loads of up to 60 mg/cm2 (12 mAh/cm2). In addition, the high compatibility of this phase conversion process with the roll-to-roll coating devices currently used in industry makes it highly industrial feasible, which has important implications for the development of high energy density batteries. EPI Technology: A Game-Changing Strategy for High-Performance ElectrodesThis work develops a new strategy based on EPI technology for manufacturing high-performance nickel-rich layered oxide electrodes with high-quality loads. Using EPI technology, NMCC811 electrodes with a high active mass load (35 mg/cm2) were designed to perform better than conventional NMC811 electrodes during fast charging, with an improvement of 50% at 0.5C and 120% at 1C. Unlike conventional electrodes, EPI electrodes can be made into ultra-thick electrodes (60 mg/cm2, 12 mAh/cm2) without delamination or cracking problems. The EPI electrode showed a higher weight capacity and a similar capacity retention rate over long cycles than conventional electrodes, indicating that the processing does not affect the positive active material and can significantly improve magnification performance. Most importantly, the introduction of EPI technology only requires the addition of a phase conversion treatment step to the conventional battery manufacturing process, in line with existing industrial production lines, which provides an important technical basis for the preparation of future batteries with high energy and power density.

There are three main routes for solid-state battery electrolyte materials, which are polymers, oxides and sulfides. Each of the three products has advantages and disadvantages, and different companies choose different paths, but at present, no one can fully achieve the balance of technology and mass production costs.1: European and American companies mainly use polymer routesThe advantage of the polymer is that its conductivity is similar to that of a liquid electrolyte. However, the shortcomings are also obvious, the mechanical strength is insufficient, and there is still the problem of lithium dendrite piercing. In other words, the internal conduction problem of polymer solid-state batteries still exists, and safety cannot be effectively guaranteed. At present, European and American companies mainly use the polymer route.2: Japanese and Korean enterprises adopt the sulfide routeThe sulfide has high conductivity, close to the liquid electrolyte, and the interface is relatively stable, with both strength and processing properties, and high interface compatibility. However, the air stability of sulfur is poor, and when it is exposed to the air, it is easy to react with water and oxygen in the air to produce hydrogen sulfide toxic gas. Therefore, the synthesis, storage, transportation and post-treatment of sulphide electrolytes need to rely heavily on inert gases or drying chambers. As a result, the preparation process is extremely complicated and the cost is high. In addition, the sulfide electrolyte itself is also expensive. At present, mainly Japanese and South Korean companies adopt the sulfide route.3: Chinese enterprises are more likely to adopt the oxide routeIts advantages are high density, high mechanical strength, and it is not easy to puncture, so it can effectively improve safety. However, it is also its high density that causes the internal impedance to be too large, resulting in poor conductivity. "Its internal impedance is very large, and even affects the actual performance of internal charging and discharging, which is not as good as liquid products."In all the current solid electrolyte technology routes, the polymer is not so prominent, short board, while the industry maturity is higher.Long board, due to the high flexibility of polymer electrolyte material, easy processing, the price is only slightly higher than the liquid; The production is compatible with the existing battery process, the equipment cost is not different, and the mass production cost is low. In terms of performance, the polymer material has good contact with the positive and negative electrode material interface, which is conducive to the extension of battery cycle life.

Safety and high energy density, solid state battery advantagesThe rapid development of the new energy vehicle industry, but frequent safety accidents, energy density bottleneck, is the core problem to be solved. Solid state batteries replace flammable electrolyte with solid state electrolyte, which can realize the intrinsic safety of the battery, while compatible with better performance of positive and negative electrode materials, which can greatly improve the energy density of lithium batteries, with high safety and high energy density, and become the inevitable choice to comprehensively improve the performance of lithium batteries.Under the guidance of many forces, the industrialization process has acceleratedAll-solid-state batteries have comprehensive performance, but there are problems such as high cost and poor solid-solid interface conductivity, which limit their large-scale commercial application. Semi-solid state battery as a transition technology, has been in the NiO, Dongfeng Lantu, SAIC Zhiji and other brands on the batch. In addition, the rapid development of the eVTOL industry, its battery energy density, safety, rate performance and other higher requirements, the existing battery technology can not meet its requirements, solid state batteries are expected to meet the batch application in eVTOL, industrial development is expected to benefit. Major countries in the world have actively laid out the solid-state battery industry, and major overseas companies such as Solid Power, Toyota, Samsung SDI, etc., have chosen the sulfide route as the direction of solid-state battery technology, and mainly develop all-solid-state batteries. Domestic enterprises such as Weilan, Qingtao, etc., have chosen the oxide route, and first developed and produced semi-solid batteries. Under the joint promotion of car enterprises and battery factories at home and abroad, the industrialization process is expected to continue to accelerate.Material system upgrade, create new opportunities for industryThe transformation process of lithium battery technology to solid state battery will drive the upgrading of the material system, mainly including: 1) solid electrolyte: solid state battery replaces the electrolyte and diaphragm with solid electrolyte; Zirconium, lanthanum and other materials in the oxide system are expected to benefit; Under the sulfide system, germanium may welcome new opportunities; 2) Positive and negative electrode materials: the positive electrode will be more widely used in high-nickel ternary, and gradually change to lithium-rich manganese base; The negative electrode will evolve to the silicon base negative electrode and the lithium gold negative electrode. 3) Porous copper foil: Compared with traditional electrolytic copper foil, porous copper foil can improve the lithium-ion transmission efficiency of solid-state batteries, improve the cycle, further enhance the safety of solid-state batteries, and more suitable for solid-state batteries; 4) aluminum-plastic film: Soft laminated film can improve the flexibility of solid-state batteries, or the most suitable assembly method for solid-state batteries, is expected to drive the demand for aluminum-plastic film.

Slurry preparation process challenges(1) Water-based positive slurry. NMP is the only solvent for positive PVDF adhesives. NMP is toxic and carcinogenic, consumes more energy than water by evaporation, and requires solvent recovery systems in industrial applications. Therefore, it is urgent to develop the positive slurry of water system.(2) Continuously stir. Coating is a continuous process, but the traditional mixing process is an intermittent process. The continuous mixing process reduces process time and energy consumption and improves process control, resulting in a more consistent slurry.(3) Increase solid content. The solid content of the negative slurry is usually ~ 50%, and the positive NMP slurry is generally ~ 70%. If solid content can be increased while maintaining the processing properties of the coating process, material and energy costs will be reduced. The ultimate limit is the solvent-free coating process.(4) Thicker electrodes. Thick electrodes reduce the amount of metal foil and diaphragm in the battery and increase the energy density. However, due to the longer electron and ion conduction pathways in the electrodes, thick electrodes will reduce the magnification performance of the battery. In addition, it is also difficult to produce thick coatings with good mechanical properties in industry.(5) Synchronous double-sided coating. The coating drying oven is usually horizontal, and the wet coating is generally on the upper part of the metal foil. Current double-sided coating is done by drying one side before recoating the other side, which adds additional manufacturing time and passes the A-side coating through the oven twice. At the same time, double-sided coating requires a drying oven with a pole sheet floating.(6) porosity gradient electrode. The two-layer electrode model calculated an optimal porosity of 10% near the fluid collector and 50% on the coated surface instead of a uniform 30%. In production, this requires a continuous double-layer coating or formwork technique.Rheological challenge of electrode pasteThe use of rheology as a predictive tool in the manufacturing process has three main challenges that need to be addressed:(1) The differences between laboratory scale and industrial processes can be large, and the relationship between these amplification process changes and key properties (such as rheology) is unclear, it is necessary to use industry-relevant formulations, weight percentages and equipment (mixers and coators) in the study, and to characterize the rheology of the electrode paste. Rheology can detect subtle but important changes within a slurry batch during mixing and coating. For example, poor mixing can result in an uneven distribution of free carbon black in the slurry, resulting in changes in viscosity and viscoelasticity throughout the batch.(2) Reveal the interactions between the components in the electrode slurry, what is their relationship to the formulation and mixing process? How do they affect flow characteristics?(3) Quantitative understanding of optimal rheology in manufacturing and process control. Hydrodynamic modeling is a means of understanding coating flows and potential problems, such as unstable flows, stock buildup in dead zones, and defects such as pinholes, blisters, cracking, and delamination.Electrode coating challenges(1) Many of the limitations of current coating techniques are related to the use of liquid pastes. Usually in these slurries, 30%-60% of the mass is solvent, which needs to be removed from the electrode and leaves too much porosity in the dry electrode layer, so it needs to be calendered to be dense. In addition, higher water surface tension results in higher capillary forces during drying and poor collector wetting, resulting in cracking and delamination of the coating, especially for thick (>100 μm) electrodes. Dry or low-solvent electrode processes can avoid these problems, but also have their own challenges: ensuring adequate mixing of the dry powder, preparation of the dry powder mixture into a film of a specified width and thickness, and ensuring that the electrode film can adhere to the fluid collector.(2) The electrode of the wet process has a spatially-uniform distribution of components and pore structure, and the optimal composition, thickness and porosity of the current electrode are obtained through repeated tests under the constraints of the slurry coating process. Relaxing these restrictions and providing greater flexibility could enable the design of higher performance electrodes.(3) Optimization and control of electrode structure parameters. Electrode thickness is one of the key structural parameters that affect the energy density of lithium-ion batteries. Thicker slurry coated electrodes lead to slow transmission of lithium ions due to longer transmission path. Thick electrodes are also prone to cracking and delamination. Therefore, to increase electrode thickness, there are many challenges to overcome. Porosity is another key parameter that can have both positive and negative effects on lithium-ion battery performance. Currently, electrode porosity is mainly controlled through the calendering process, and thicker electrodes require additional processes to control the necessary porosity to ensure good performance. Tortuosity, that is, the ratio of the actual length of the lithium ion transport path to the linear distance between the starting point and the end point, is a structural parameter describing the difficulty of lithium ion transport within the electrode. For electrodes with higher mass loads, the challenge is the need to develop new electrode structure strategies to achieve low electrode tortuosity by controlling the shape, size, and distribution of the electrode holes without sacrificing other electrode properties.(4) The main challenge of the dry electrode process is to reduce the content of inactive materials to a level comparable to that of wet coating, while some processes involve degreasing steps and high temperature sintering, making the process more expensive and potentially difficult to scale up.Electrode drying process challenges(1) Create an efficient drying model that correlates dynamic measurements of drying conditions with the final characteristics of the electrode to enable a more controlled drying process. Examples include computational fluid dynamics models at the continuous level, convection heat and mass transfer models at the air-porous material interface, theoretical models of drying of two-component colloidal suspensions, and one-dimensional models of particle coatings including Brownian diffusion, sedimentation and evaporation.(2) The drying kinetics of the wet electrode film is particularly complex, and in order to better control the electrode structure and its corresponding electron and ion transport characteristics, we need to understand the process of electrode structure formation. Drying is the basis for forming the electrode structure, so it is necessary to develop advanced metrological tools to understand the physical processes that occur during drying, to measure and analyze the effect of solvent evaporation on defects, such as crack formation. The adhesive distribution can be characterized by energy spectrum EDX, Raman spectrum, Fourier transform infrared spectroscopy (FTIR) and multispot diffusion wave spectroscopy (MSDWS). Solvent evaporation can be measured by thermogravimetric analysis and quartz crystal microbalances (QCM). The surface temperature and drying stress during solvent evaporation can be measured by infrared (IR) thermography. Active materials can be characterized by SEM, X-ray CT, and fluorescent-based imaging/microscopy.Electrode calender process challengesDuring the calendering process, the particle structure of the active material (AM) and the carbon colloidal phase (CBD) are compressed and rearranged, and the intergranular porosity is reduced. The compaction of the pore structure of the electrode particles will in turn affect the electron ion transport performance and the battery performance.(1) In the manufacturing process, the mechanical properties of the electrode are affected by the material composition, process parameters (such as roller temperature, speed) and electrode thickness. Due to the complex effects of these characteristics and parameters on the electrode rolling deformation, it is necessary to characterize the mechanical properties of the electrode, such as hardness, elastic deformation, and adhesion between the electrode and the collector. In order to obtain further understanding of the mechanism, a large number of systematic studies between parameters and material properties are needed, such as numerical simulation and experimental studies to obtain the dynamic mechanical response of calender to porous carbon gel phase.(2) Capturing particle plastic deformation and fracture at high calendering levels is challenging, and a deeper understanding of interparticle forces is still needed to establish nonlinear constitutive behavior and study microstructure evolution within the electrode in high fidelity.

Due to its advantages of high energy density, long cycle life, low self-discharge rate, and no memory effect, lithium-ion batteries stand out from many energy storage technologies and become the most important part of the electrochemical energy storage field at present. In recent years, the application scenarios of lithium-ion batteries have expanded rapidly, from portable electronic products to electric vehicles, home energy storage, industrial energy storage, etc., lithium-ion batteries have penetrated into all aspects of society, which also puts higher requirements on the safety and energy density of lithium-ion batteries.Traditional lithium-ion batteries mainly rely on organic liquid electrolyte to conduct lithium ions, and the flammable and volatile characteristics of the electrolyte lead to thermal runaway, fire, explosion and other safety risks in the case of overheating, short circuit, overcharge, and mechanical damage. New energy vehicle safety accidents occur from time to time, and ensuring the safe operation of new energy vehicles is the primary task of the current development of the industry. In recent years, through the innovation of battery system structure, the safety of power battery operation has been improved to a certain extent. Facing the future, the development of battery structure innovation to material system innovation is an inevitable trend of power batteries.Therefore, the development of high safety and high energy density energy storage technology to make up for the shortage of liquid lithium-ion batteries is an important development direction of lithium-ion batteries in the future.The use of solid electrolytes to replace liquid electrolytes and the development of all-solid-state lithium batteries can solve the energy density bottleneck and safety risks faced by the current liquid ion batteries, and become the most potential next-generation lithium-ion battery follow-up technology. As shown in Figure 1, the structure and working principle of the all-solid lithium battery is similar to that of the liquid lithium ion battery, but the solid electrolyte has high thermal stability and chemical stability, and will not leak, burn or explode, thereby reducing the risk of thermal runaway and improving the intrinsic safety of the battery. At the same time, the solid electrolyte has a high Young's modulus, which can effectively inhibit the growth of lithium dendrites, and is expected to realize the application of metal lithium anode, which greatly improves the energy density of the battery. In addition, the packaging of all-solid-state batteries is easier. The use of bipolar stacking technology in solid-state batteries can reduce the use of inactive materials such as pole ears and leads, and the battery module does not require a cooling system, which is expected to further improve the volume and mass energy density of the system.

As an important instrument for the measurement of adiabatic thermal runaway of batteries, the core technical index of the battery adiabatic calorimeter is the self-exothermic detection sensitivity of the sample, that is, the ability to identify the weak exothermic heat of the sample. This index directly determines the measurement accuracy of the instrument for the characteristic temperature points such as the initial temperature of the battery self-exothermic heat. In order to achieve high detection sensitivity, the instrument is required to have ideal structural design, accurate temperature measurement technology and efficient temperature control algorithm, so as to achieve excellent adiabatic performance.At present, there is a lack of measurement and calibration specifications for the whole battery adiabatic calorimeter in the industry, so there is no unified, scientific and reasonable method to verify the core indicators of the instrument, which is not conducive to objectively evaluating the performance of the instrument and regulating the instrument standards, and the data measured by the instrument with poor adiabatic performance will directly affect the relevant enterprises to carry out the safety design of the battery system, and have a negative impact on the development of the lithium battery related industries.Some manufacturers and users use lithium batteries with empirical data as standard samples for instrument evaluation. There are some problems in this method: (1) The same batch of batteries may have slight differences in internal structure and materials, and the consistency of thermal runaway experimental data cannot be guaranteed, which will introduce additional uncertainty; (2) The thermal runaway process of some lithium batteries is severe, causing obvious pollution and even damage to instruments and equipment, and at the same time, high requirements for the test site.

Carbon nanotubes (CNTS) are perfect 1D cylinders composed of one (single-walled carbon nanotube, SWCNT) or multiple graphene sheets (multi-walled carbon nanotube, MWCNT) rolled up and have become the focus of research due to their unique geometry and excellent properties. Both experimental and theoretical analyses show that single-walled carbon nanotubes (SWCNT) and multi-walled carbon nanotubes (MWCNT) have high mechanical strength, high aspect ratio (> 1000), high thermal conductivity, high melting point and low density (1.2-2.6 g/cc). In addition, CNT has a larger surface area (approximately 1000 m²/g), showing excellent hydrogen storage capacity, significant biological properties, and higher corrosion resistance. CNTS also have unique electrical conductivity, and depending on their structure (diameter and helicity), they can exhibit the electronic properties of metals or semiconductors. It is precisely because of its excellent physical and chemical properties that carbon nanotubes have initially blossomed in the field of new materials, gradually realizing industrialization, and are also widely used in the lithium battery industry, attracting more and more attention from the industry.Domestic carbon nanotubes as a conductive agent used in power batteries, its market with the rapid growth of the power battery industry, the scale has reached billions of yuan per year, there are a number of domestic and foreign companies and listed companies have been involved in the field of carbon nanotubes conductive, such as Dow Technology, German nano, Cabot and other companies. With the expansion of the application scale of new technologies such as high-nickel positive lithium batteries, silicon-based negative batteries and solid-state batteries, the market for carbon nanotubes will also grow explosively, and it will become an annual market of 10 billion in the field of lithium batteries alone.In addition to excellent electrical conductivity, carbon nanotubes also have a huge potential market for development such as ultra-high mechanical and thermal properties. The 1996 Nobel Prize winner in Chemistry, the Honourable Richard E. Smalley (the discoverer of fullerenes), once said: "Carbon nanotubes are the strongest, toughest and hardest molecules that can be made, and are the best molecular conductors of heat and electricity." It sounds like this is the good prediction and desire of scientists, but this is the original intention of Juyuan Material Technology (Zunyi) Co., Ltd. to intervene in the carbon nanotube industry, and it is also the goal of industrialization. The application of lithium battery conductive agent is only the "tip of the iceberg" of the industrialization of carbon nanotubes, and it is the first step for capital and traditional chemical new material enterprises to understand carbon nanotubes. Carbon nanotubes in the touch screen, transistors, biomedical, solar photovoltaic cells, tires, fuel cells, drug delivery, hydrogen storage, polymer materials, capacitors, composite materials and other fields will have a broader market, will continue to break through more than 10 billion of the market, become a 100 billion market industry.The huge carbon nanotube application market requires sufficient carbon nanotube production capacity to support and a sustainable supply of low-cost high-quality carbon nanotubes in order to open a huge downstream potential application market. The early tonnage production of carbon nanotubes was achieved by fixed bed/moving bed equipment, and the continuous addition of catalysts and hydrocarbon raw materials and the continuous output of carbon nanotube products in a horizontally placed tube furnace through a sophisticated device can realize the production of the first generation of carbon nanotube plants with tons to tens of tons per year in a single device. Up to now, there is still some market space for some special types of carbon nanotubes, or some special raw materials for carbon nanotube production, using fixed bed/moving bed first-generation carbon nanotube factories.In order to achieve larger scale carbon nanotube production, the second-generation carbon nanotube factory with fluidized bed reactor solves the larger scale production problem to a certain extent, and the annual production capacity of a single reactor can reach 100 tons to hundreds of tons. At present, the large-scale production of carbon nanotubes in China, many production companies are basically based on fluidized bed reactors. With the emergence of larger production requirements, fluidized bed reactors have the following characteristics: 1. They cannot be scaled up; 2, easy carbon deposition, coking plugging reactor; 3, the boiler shutdown and cleaning of the reactor is difficult, the time-consuming period is long and other problems, which seriously restricts the expansion of the single production capacity of the fluidized bed reactor. At present, the inner diameter of the fluidized bed reactor in the industry is basically 500mm\600mm\800mm, and it is difficult to further expand.

At present, the need of high-endurance new energy vehicles forces the energy density of batteries to become higher and higher, and the use of thick electrodes with high load density active materials is one of the most practical strategies. However, their long cycle use process is accompanied by serious attenuation of electrochemical performance, power performance is not satisfied, and the capacity retention rate is getting worse and worse. So what exactly is causing the bottleneck of poor performance?Kyu-Young Park et al. explored the key processes that restrict battery decay by designing thick electrodes with different area degrees.1. Experimental designUsing NCM622: carbon black: PVDF 97:1.5:1.5 ratio and NMP mixed into pulp, after coating, drying and roller pressing, two kinds of electrodynamic half cells (2032) with different surface densities (20 and 28mg/cm-2) were prepared, and the pressure was between 2.8 and 2.9, in order to ensure better porosity. The charge and discharge cycle of the multi-channel device was carried out with the charge and discharge interval of 2.8-4.3V and the rate 1C was about 150mA/g. EIS, chemical composition and morphology were analyzed after every 20 cycles.2. Results and discussionThe following is the cross-section diagram of the electrodes of two thickths, respectively 70 and 100μm(standard electrode, thick electrode), the rest of the porosity, 1C current density and other design parameters are basically the same, and then the 1C cycle test is carried out. It is found in Figure c that although the capacity of the thick electrode of 100μm is only 40% higher than that of 70μm, but after 100 battery cycles, The thick electrode has a capacity retention rate of only 36%, while the standard electrode has a capacity retention rate of 76%. Even taking into account the volume specific capacity, the thick electrode after attenuation in Figure c is still much lower than the electrode. Interestingly, in Figure c, even in the initial cycle process, the circulation curves of the thick electrode and the standard electrode are close, and the attenuation degree is similar. Thick electrodes are getting worse.In illustrating the poor electrochemical performance observed, the authors note that thick electrodes may be subject to kinetic limitations caused by how fast or slow charge carriers migrate, which in electrochemical processes is either controlled by lithium-ion transport or by the transport of electrons that accumulate along the electrode. And, in each case, assuming that the main source of supply of electrons and lithium ions to the electrode is carried out from the electrode/collector interface and the electrode/electrolyte interface, in each case there will be a clear spatial distribution of both after the reaction.3. ConclusionBy using batteries designed with different electrode thickness, the authors verify that lithium ion diffusion is the limiting factor of charge transfer, but not electron transfer. This is also the reason why SOC at different locations is uneven, voltage drop IR increases, particle breakage and even battery diving under charge and discharge in batteries designed with thick electrodes. The electrode plate is designed according to the ion transport characteristics to avoid the phenomenon of excessive local current density, so as to improve the battery life