LR41 battery

　　LFP battery cell specific energy is expected to exceed 200wh/kg

　　The biggest safety risk item of electric vehicles is the battery, which is mainly based on the following three aspects: material selection, battery cell design, and group technology and passive safety. Judging from the causes of new energy vehicle fires reported this year, electric vehicles account for the highest proportion of spontaneous combustion while standing, followed by spontaneous combustion during charging, spontaneous combustion while driving, and fire and explosion caused by collisions.

　　On December 16, Li Yuanheng·2019 Senior Engineer Lithium Battery & Electric Vehicle Annual Conference was held at the Hyatt Regency Shenzhen Airport. In the afternoon's special session on the three-power generation of passenger cars: the three-power upgrade under the electrification platform, Xu Xingwu, senior vice president of Guoxuan Hi-Tech and executive vice president of the General Institute of Engineering Research, delivered a speech on "Technical Challenges Facing Lithium-ion Power Batteries" , the speech focused on three major aspects: how to solve the safety of power batteries, how to improve the energy density of power batteries, and how to reduce battery costs.

　　Xu Xingwu pointed out in his speech that the electrical safety risks of power batteries mainly include three factors: material selection, cell design and group technology, and passive safety. Specifically:

　　1. Material selection. The selection of cathode materials in batteries is particularly critical and is also the main cause of safety hazards in power batteries.

　　At present, there are two main technical routes for selecting cathode materials for power batteries: ternary batteries and lithium iron phosphate. In terms of safety, figuratively speaking, ternary batteries burn like gunpowder, and lithium iron phosphate burns like coal. The lithium iron phosphate battery core material has low activity, stable structure, and does not release oxygen when overcharged. The safety of lithium iron phosphate batteries is significantly higher than that of ternary batteries.

　　Although ternary batteries are still the main installed base of new energy passenger cars, under the cost reduction requirements of subsidy reduction, a large number of models have switched some of their passenger car models back to the lithium iron phosphate technology route. Guoxuan Hi-Tech is also confident in the application prospects of lithium iron phosphate batteries in the fields of new energy passenger vehicles and special vehicles in the future.

　　Currently, Guoxuan High-tech has formulated a development strategy of "strengthening lithium iron and refining ternary batteries" to further explore the technical space of lithium iron phosphate batteries, while improving the company's technical level in the field of ternary batteries and achieving a diversified product layout.

　　Among them, the monomer specific energy of the lithium iron phosphate currently mass-produced by Guoxuan Hi-Tech reaches 190wh/kg, and the system energy density is 140wh/kg, which is equivalent to the ncm622 system and can be further improved in the future.

　　2. Battery core design. The following safety matters need to be paid attention to when designing the battery core: 1. Reasonable negative/positive electrode excess coefficient; 2. Ensure that the negative electrode piece covers the positive electrode piece; 3. Diaphragm selection; 4. Selection of electrolyte; 5. Case safety device design.

　　Xu Xingwu said that with the continuous advancement of material technology, the gram capacity of LFP materials in actual batteries can reach 150mAh/g. Combined with the advancement of battery technology, the specific energy of LFP cells can reach 190wh/kg, which is expected to be achieved this year. Breaking through 200wh/kg, the system reaches 160wh/kg.

　　3. In terms of group technology and passive safety. Inconsistent battery cells will cause individual strings of batteries to be overcharged, leading to safety accidents in electric vehicles.

　　In order to ensure battery safety, the battery pack safety design should be equipped with explosion-proof valves and fire-extinguishing functions to create a safety protection system.

　　In addition to improving battery safety, Xu Xingwu also talked about how to improve battery energy density and reduce costs in his speech.

　　In terms of improving energy density, there are mainly ways to increase the energy density of cathode materials, increase the energy density of negative electrodes, improve battery space utilization, and use lightweight and thin functional separators.

　　In terms of reducing battery costs, Xu Xingwu believes that battery companies should systematically think about cost reduction, including laying out upstream raw materials, structural parts to reduce costs, battery cell comprehensive cost reduction plans, improving battery efficiency and utilization, and multi-echelon power solutions on the same platform. , PACK optimization cost reduction, echelon utilization and other aspects.

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