LiFePO4锂离子电池的高倍率充放电性能

研究了正极材料、正极面密度、导电剂含量及电极结构对18650型LiFePO4锂离子电池高倍率充放电性能的影响。当D50为1.92μm,比表面积为11.4 m2/g,正极面密度为2.8 g/dm2,导电剂含量为4.0%时,电池具有较好的加工性能和倍率性能。相比于单极耳结构,双极耳结构电池的内阻减小了50%,为14 mΩ左右,且分布集中;5.00C充电和15.00C放电时的表面温升很小。在2.0～3.8 V充放电,优化后的20.00C、30.00C放电容量分别为1.00C时的96.6%、86.1%,1.00C充电、10.00C放电,第300次循环的容量保持率为86.3%。

High rate charge-discharge performance of LiFePO4 Li-ion battery

The effects of cathode materials,cathode surface density,conductive agent amount and electrode structure on high rate charge-discharge performance of 18650 type LiFePO4 Li-ion battery were studied.The battery with the D50 of 1.92 μm,specific surface area of 11.4 m2/g,cathode surface density of 2.8 g/dm2 and conductive agent amount of 4.0% had better processing performance and rate capability probably.The internal resistance of battery with the structure of bipolar reduced 50% to about 14 mΩ compared to the structure of unipolar,its distribution was centralized,the surface temperature rise was very small under the charge at 5.00 C and discharge at 15.00 C.After optimization,when charged-discharged in 2.0～3.8 V,the discharge capacity at 20.00 C and 30.00 C was 96.6%,86.1% of that at 1.00 C rate,respectively,the capacity retention rate was 86.3% at the 300th cycle of 1.00 C charge and 10.00 C discharge.