3.2v 300ah lifepo4 battery

3.2v 300ah lifepo4 battery technology needs to be tackled in three aspects

Continuous technological progress and improved product safety performance have always been the key to the development of the 3.2v 300ah lifepo4 battery industry, and are hot issues of concern within and outside the industry.

Continuous technological progress and improved product safety performance have always been the key to the development of the 3.2v 300ah lifepo4 battery industry, and are hot issues of concern within and outside the industry, and are also the focus of the China Battery Alliance's research. During the New Energy Lithium Battery Materials Industry Forum held recently, Wang Fang and other experts from the China Automotive Technology Research Center talked to the China Battery Alliance about her views on 3.2v 300ah lifepo4 battery technology and product safety issues.

The first 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 3.2v 300ah lifepo4 battery installed capacity reached 36.7 billion watt-hours. It is estimated that by 2020, the demand for power batteries will reach about 100 billion watt-hours.

A lithium battery expert believes that the problem with 3.2v 300ah lifepo4 battery technology is that the energy density is not enough. So far, the energy density of lithium iron phosphate installed batteries is basically 145Wh/Kg, and that of ternary batteries is 185Wh/kg. According to the data of pure electric passenger cars in 2017, among the 224 models, ternary batteries were installed in 199 models, accounting for 88.8% of the total models. At the same time, models with energy density between 120-150Wh/kg accounted for 27% of the total models. The technical maturity and safety of lithium iron phosphate batteries are relatively high.

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

In terms of packaging structure, the grouping efficiency of soft-pack batteries is higher than that of other packaging structures. The battery grouping rate increased from 0.63 to 0.74 from 2016 to 2018, including lithium iron phosphate and ternary batteries. In 2017, 145 models with single cell and battery pack system comparison data were counted. The average energy density of single cells is 173Wh/Kg. If the system is further subdivided, the average value of lithium iron phosphate single cells is 144Wh/Kg, and at the system level it is 117Wh/Kg, and the grouping rate can be as high as 81.5%.

The highest grouping rate of lithium iron phosphate batteries can reach 85%. The ternary monomer is 183Wh/Kg, and the system level is 115Wh/Kg, with a grouping rate of 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 the number of additional things in system integration, which has reduced the grouping rate of ternary batteries.

Regarding the competition among square, cylindrical, and soft packs, Wang Fang believes that the competition among square, soft pack, and cylindrical batteries is a good thing and can promote technological development. From monomers to systems, the grouping rate of cylindrical batteries does not have a particularly large advantage, and soft packs have a slight advantage. She counted more than 90 battery packs, only three of which are air-cooled, and the others are naturally cooled. This is completely different from the beginning of 2016. At the beginning of 2016, more passenger cars chose liquid cooling. In 2017, due to subsidies and other factors, fewer and fewer people chose liquid cooling and air cooling, and more chose natural cooling.

The above-mentioned lithium battery experts believe that 3.2v 300ah lifepo4 battery technology needs to increase research in three aspects, one is energy density performance, the second is safety, and the third is life.

The second is product safety issues.

For power batteries, the first thing to bear the brunt is safety issues, which are closely related to its energy density and power density, and the economical ones are life and low cost.

A battery expert said that product safety is a veto, followed by endurance, the third is acceleration, the fourth is full life, the fifth is convenience, the sixth is applicability, and the seventh is environmental friendliness. From the actual application of the whole vehicle, the performance of the whole vehicle includes acceleration performance, power, safety, economy and life. The most important of these is safety.

The national key new energy project layout proposed the concept of 300Wh/Kg, which is the product level, requiring the product to meet the 300Wh/Kg key indicators while meeting the use requirements of the whole vehicle and meet the basic requirements of battery safety and life.

She also explained the safety indicators from the perspective of test evaluation. She believes that battery safety accidents are initially caused by thermal runaway. The current evaluation is from materials, batteries, BMS, systems, to the realization of multi-level thermal characteristics and thermal safety, thermal runaway correspondence, to the thermal stability of materials, to the thermal safety of the battery throughout its life cycle, to the thermal management of BMS, and finally to the evaluation of the system thermal stability and the ability to control thermal runaway. Under different charging and discharging currents, the speed, power and heat generation of heat are different. It is necessary to understand the point where each battery has thermal runaway, the trend and possibility of thermal runaway, and the temperature range. It is necessary to understand the propagation path to another battery, the propagation speed, and the heat transfer. This is the most basic means of evaluation for designing thermal management.

Regarding the question of whether the battery is safe, battery experts believe that safety is a relative concept, while unsafety is absolute. How to improve the safety factor of the battery and reduce hidden dangers is a systematic project. To find the key point of thermal runaway, there must be enough time for people to escape. This is the safety concept of electric vehicles. There is only one safety regulation in the world, which is the safety of people, and property is not considered. How long will it take for people to escape? It is the time it takes to escape from the vehicle to a safe area while driving. The above-mentioned lithium battery expert holds the same view.

Finally, she revealed that the country is currently formulating national standards, which will be submitted to the WTO for international comments after review and will eventually become mandatory safety standards. In addition, the functional safety standards for electric vehicle management systems are also being formulated.

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