LR1130 battery.Power battery industry: two big mountains still need to be overcome: technology and safety

　　Continuous advancement of technology and improvement of product safety performance have always been the key to the development of the power battery industry. It is a hot issue both inside and outside the industry, and is also the focus of research by the China Battery Alliance. During the New Energy Lithium Battery Materials Industry Forum held recently, Wang Fang and other experts from the China Automotive Technology and Research Center shared her views with the China Battery Alliance on power battery technology and product safety issues.

　　One is technical issues. Data show that in 2017, the production and sales of domestic new energy vehicles reached 794,000 and 777,000 respectively, and the matching installed capacity of power batteries reached 36.7 billion watt-hours. It is expected that by 2020, the demand for power batteries will reach about 100 billion watt hours.

　　A lithium battery expert believes that the problem with power battery technology is insufficient energy density. So far, the energy density of lithium iron phosphate car batteries is basically 145Wh/Kg, and the ternary battery is 185Wh/kg. According to data on pure electric passenger cars in 2017, 199 of the 224 models were equipped with ternary batteries, accounting for 88.8% of the total models. At the same time, models with an energy density between 120-150 Wh/kg accounted for 199 models. to 27% of total vehicle models. Lithium iron phosphate batteries have relatively high technological maturity and safety.

　　In terms of the full life cycle performance of power batteries, the test evaluation is divided into three aspects: usable, controllable and disaster hazard evaluation.

　　In terms of packaging structure, the group efficiency of soft-pack batteries is higher than other packaging structures. The battery assembly rate increased from 0.63 to 0.74 from 2016 to 2018, including lithium iron phosphate and ternary batteries. In 2017, statistics were collected on 145 models comparing single cells and battery pack systems. The average energy density of single cells is 173Wh/Kg. When the system is further broken down, the average energy density of lithium iron phosphate single cells is 144Wh/Kg. , at the system level it is 117Wh/Kg, and the group rate can be as high as 81.5%.

　　The highest assembly rate of lithium iron phosphate batteries can reach 85%. The three-unit unit is 183Wh/Kg, the system level is 115Wh/Kg, and the grouping rate is 0.64. The safety of ternary batteries is poor, and the point of thermal runaway is much earlier than that of lithium iron phosphate. The emphasis on safety integration technology of ternary batteries has led to an increase in additional things in system integration, which has reduced the cost of ternary batteries. group rate.

　　Regarding the debate between square, cylindrical and soft-packed batteries, Wang Fang believes that competition among the three types of batteries, square, soft-packed and cylindrical, is a good thing and can promote technological development. From the single unit to the system, the grouping rate of cylinders does not have a particularly large advantage, while soft packages have a slight advantage. She counted more than 90 battery packs, and only three were air-cooled, while the others were naturally cooled. This was completely different from the beginning of 2016, when more passenger cars chose liquid cooling. In 2017, they were affected by subsidies and other factors. , fewer and fewer people choose liquid cooling and air cooling, and more and more people choose natural cooling.

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