磷酸铁锂吸湿规律及对电池性能的影响

Hygroscopicity of LiFePO_4 and its effects on the performance of battery

测定磷酸铁锂(LiFePO_4)粉体材料和所制备极片中的水分,得到LiFePO_4吸湿规律并分析原因。通过方形铝壳电池,研究水分对LiFePO_4正极锂离子电池首次充放电效率、负极片表面状态的影响。粒度、比表面积、残余碳酸锂(Li2CO3)含量及表面碳包覆层,对LiFePO_4材料的吸水性有较大影响。吸水量大且吸水速度快的LiFePO_4材料和极片,对环境水分更敏感,与10%湿度相比,在30%湿度下放置的正极片制备的电池,首次充放电效率低,首次充电过程中负极片表面有金属锂析出。

The water content of lithium iron phosphate（ LiFePO4 ） powder and as-prepared cathode were tested. The water absorbing property was obtained and the reason was analyzed. Using square aluminum shell Li-ion battery, the influence of the water content on the initial charge-discharge efficiency and the surface state of the anode were investigated. The particle size, specific surface area, residual lithium carbonate（ Li2CO3 ） content and the surface carbon layer had an important impact on the water absorbing property of LiFePO4 material. The cathode with high water absorption and fast water absorption was sensitive to the moisture of environment. Comparing with 10% humidity, as-prepared batteries at 30% humidity had the lower initial charge-discharge efficiency and there was lithium plating on the anode surface.