The side voltage of the lithium battery refers to the voltage of the aluminum layer between the positive ear of the soft-pack battery and the aluminum-plastic film.In theory, the aluminum layer between the positive electrode and the aluminum-plastic film is insulated, that is, their voltage should be 0In fact, during the processing of the aluminum-plastic film, the PP layer of the inner layer will be locally damaged, resulting in local conduction (including electronic channels and ion channels) between them, forming a microbattery, and thus a potential difference (voltage).The side voltage standard varies from manufacturer to manufacturer, but most of the industry is set below 1.0V, and the standard voltage is based on the dissolution potential of aluminum lithium alloy!Why control the side voltage?Because if the inner PP film of the aluminum-plastic film is damaged, the capacity will be corroded.The conditions for corrosion must have two points: 1, the electronic path, the negative electrode and the aluminum layer of the aluminum-plastic film form the electronic path; 2, the ion path, the aluminum layer of the aluminum-plastic film and the electrolyte form an ion path; Without either one, corrosion doesn't work.After the two conditions are established, the lithium ion will react with the aluminum layer of the aluminum-plastic film to generate lithium aluminum alloy; Lithium aluminum alloy is a powdery substance, resulting in aluminum-plastic film penetration; That is, we often see some black spots inside the aluminum-plastic film; These dark spots will become more and more obvious with time and the number of charges and discharges.How to choose?The current statistical detection methods are:1, test the resistance between the aluminum plastic film and the negative ear, greater than 5M ohms is relatively safe, some companies define the relatively low, look at the final PPm of bad products we endure, you can measure some data and then define their own standards can also; This resistance test is mainly to pick out the electronic path;2, test the current between the positive electrode and the aluminum film, you can use the DC source test, it is generally believed that the current is greater than 0.001mA, it is defective, need to be picked out;3. Test the voltage between the positive electrode and the aluminum film, which is generally considered to be greater than 1V for defective products.You can test 1 and 2, or 1 and 3 together.

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

Lithium-ion battery (LIBs) has become one of the widely used electrochemical energy storage systems due to its high energy density, high operating voltage and no memory effect, and its commonly used graphite negative electrode is difficult to fully meet the increasing market demand due to its relatively low capacity (372 mAh g-1). Over the past few decades, researchers have proposed a variety of new anode materials, which generally exhibit the advantages of ideal potential range, higher capacity, excellent magnification performance, and long cycle life, but have the disadvantage of large initial active lithium loss (ALL). Therefore, how to eliminate ALL before full battery assembly is critical to achieving high-performance LIBs. In the course of development in recent years, new anode materials for the next generation of LIBs have gradually begun to be commercialized, so the research of pre-lithium technology, which is crucial to the elimination of ALL, has become an important research direction.Causes of loss of high initial active lithium in negative electrodeThe high initial ALL of the negative electrode occurs in the first few cycles and the coulomb efficiency is low (CE < 100%), which indicates that some Li+ remains in the negative electrode, resulting in a decrease in the amount of Li+ that can be cycled in the LIBs. When matched with the positive electrode, the reduced recyclable Li+ will inevitably lead to a reduction in the energy density of the entire battery. Figure 1 shows the typical intercalation/insertion, conversion and alloying lithium storage mechanisms of negative electrode materials, which mainly exhibit relatively low potential and much higher capacity than commercial graphite and Li4Ti5O12, but the first loop coulomb efficiency of these materials is usually less than 80%, resulting in a low coulomb efficiency mechanism. The causes of initial negative ALL can usually be divided into the formation of SEI, the loss of active material and the appearance of dead lithium.Effect of negative active lithium lossIn practical applications of LIBs, some of the recyclable Li+ is consumed to form SEI on the negative surface, resulting in a lower first turn of CE, which in turn leads to a rapid capacity decay of the battery. As shown in Figure 2, the reversible capacity of the electrode is not reduced during this process, and when additional lithium sources are added to the system, the specific capacity of the battery will be restored to the ideal situation. The introduction of additional lithium sources will offset the specific energy gain brought by the pre-embedded lithium, and the effect of higher initial ALL on the specific capacity loss of the whole battery can be elaborated through theoretical calculation and analysis, and the specific energy based on the total mass of the negative electrode, the positive electrode and the lithium source can be obtainedFigure  shows the effect of different additional lithium sources on contrast energy. The specific capacity function of R with respect to the lithium source (cls) is shown for different negative lithium sources with initial CE of 50%, 70% and 90%, respectively. It can be seen that with the increase of cls, the R factor increases, while the decrease of CE will lead to a lower R factor. It can also be seen that when cls is greater than cc, it is necessary to use lithium sources to effectively improve the energy density. The analysis of these results can add more detailed parameters for different systems.A lithium source is added to the negative electrodeInitial ALL is caused by irreversible electrochemical processes on the negative electrode, so the most direct strategy for eliminating initial ALL is to prepare the pre-embedded lithium negative electrode by electrochemical and/or chemical strategies prior to pairing with the positive electrode. The positive electrode strategies can be divided into three categories: the half cell electrochemical method (HC-EM), the short circuit electrochemical method (SC-EM) and the chemical method (CM) as shown in the figure. After the negative electrode is pre-embedded with lithium, the initial ALL problems can be solved well, and the Coulomb efficiency of the entire battery first circle can be effectively improved.

China Blue Sky is fully charged and invites you to join us at CIBF 2024. China Blue Sky brings electrolytes, PVDF series products, and new technologies to meet new energy and new momentum with you. Address: Booth T167, Hall N4, Chongqing International Expo Center, No. 66 Yuelai Avenue, Yubei District, Chongqing. Enter through Gate 10 and you will see the China Blue Sky booth straight ahead.01-- Industrial Layout, Deep Insight China Blue Sky has been deeply involved in fluorine chemical industry for more than 70 years, with a deep layout in the lithium battery materials industry. Production bases for electrolytes, lithium hexafluorophosphate, additives, and PVDF are established in Zhejiang, Hubei, Hunan, Shaanxi, Sichuan, and other areas, with core raw materials self-sufficient. The 200,000-ton electrolyte project (Phase I) in Sichuan, established by China Blue Sky, is about to be put into operation. Stay tuned! 02-- Leading Research, Passionate Pursuit The lithium battery research platform of China Blue Sky has gathered superior resources, establishing electrolyte research platform and PVDF research platform with remarkable achievements. The electrolyte research platform has formed a complete set of R&D technology system, including additive invention and development, raw material synthesis process development, R&D analysis, high-performance electrolyte formulation development, electrolyte application research, and technical support. With a focus on the invention and development of high-performance electrolyte additives and the improvement of raw material quality and cost reduction. The PVDF research platform covers comprehensive research results in the fields of LFP, NCM, and separators in lithium battery applications, with independent intellectual property rights and "internationally leading" technical certification. Continuously ensuring stable quality through high automation, breakthrough in tri-system copolymerization technology, and continuous improvement in metal tube control level. Keeping up with trends, creating high-purity new materials, and accelerating the launch of non-PFAS lithium battery products. 03-- Advanced ManufacturingPersistence Efficient manufacturing: intelligent and efficient electrolyte factory. Reliable quality: full-process quality control. Adhering to customer focus, implementing quality leadership strategy, conducting "whole life cycle" and "whole value chain" quality management of products, providing customers with high-quality products and services, achieving customer satisfaction, and striving to exceed customer expectations. Integrated management system 04-- High-Quality Products, Strength Revealed The product system includes secondary and primary electrolytes covering multiple material systems and applications. The product system includes: lithium iron phosphate electrolyte, lithium cobaltate electrolyte, ternary material electrolyte, special product series, and secondary electrolyte. 

The "China International Battery Technology Exchange/Exhibition (CIBF)" is an international professional technical exchange/exhibition in the battery industry organized by the China Chemical and Physical Power Industry Association.It is one of the most influential new energy exhibitions globally, building a high-end platform for exchange for 15 consecutive times. CIBF is held every two years in Shenzhen and, to drive industry development, the organizers have added CIBF roadshows between the main events.CIBF2024 will be held in Chongqing International Expo Center for the first time, from April 27th to 29th, 2024. With 14 exhibition halls covering nearly 180,000+ square meters, it is expected to attract over 200,000 visitors.About company Jiangxi Black Cat Carbon Black Co., Ltd. (referred to as "Black Cat Co., Ltd."), is a leading domestic producer of carbon black. Founded in 2001, the company is headquartered in Jingdezhen, Jiangxi, with over ten production bases nationwide. It is the first listed company in China with state-owned assets, specializing in single carbon black as its main product (stock abbreviation: Black Cat Co., Ltd., stock code: 002068). The company's main product, carbon black, has been the top-selling product in China's carbon black industry for twenty consecutive years.In recent years, Black Cat Co., Ltd. has focused on independent innovation, industrial transformation and upgrading, and the development of new materials. Since 2021, driven by cost reduction and fast charging trends, the company has stimulated the domestic substitution and high-end development of conductive carbon black. The independently developed conductive carbon black achieved mass production in September 2022 and can be applied in the fields of lithium-ion batteries, sodium-ion batteries, and other energy storage batteries.After over a year of market promotion and customer verification, the product has passed validation tests in multiple lithium battery companies and completed factory audits, entering the stage of bulk procurement. Currently, there are two 5,000 tons/year conductive carbon black production lines in Wuhai, Inner Mongolia, with a total capacity of 10,000 tons/year. The company plans to invest in a new production facility in Leping in the second quarter of 2024, with a capacity of 20,000 tons of conductive carbon black, totaling a capacity of 30,000 tons.The company has collaborated with renowned domestic universities such as Fudan University, South China University of Technology, Beijing University of Chemical Technology, Qingdao University of Science and Technology, and academic teams to conduct research and development, mastering the mechanism of high-end conductive carbon black. It has also partnered with leading downstream companies to conduct application research and development. In the future, Black Cat Co., Ltd. will continue to promote the layout of carbon-based new materials, accelerate new product research and development, and application promotion, continuously expanding the product matrix, and contributing to the new energy field!