关键词: 锂离子电池, 循环性能, 吡啶；, 固体电解质界面

Abstract: Li-ion battery using graphite anode and LiPFO₄ cathode (Gr.||LFP) has been widespread in energy storage. To match the warranty period of energy storage systems, the lifespan of this kind of Li-ion battery, not only under room temperature but also under relatively high temperature, is critical. Exploration of functional electrolyte additive provides an efficient approach to address this issue. This study reports the usage of pyridine (Py) as a new electrolyte functional additive for Gr.||LFP. In the first cycle, it was found that Py can be reduced before ethylene carbonate and vinylene carbonate, forming a dense and homogeneous solid electrolyte interface (SEI) layer containing rich N and F elements. Owing to the merits of the SEI layer, the parasitic reaction which occurs at graphite anode and consumes active lithium ion during cycling were suppressed. With the dosage of 0.5 wt% Py additive in the electrolyte, the Gr.||LFP pouch cell with a capacity of 3.2 Ah exhibited remarkable enhanced cycling stability and high-temperature storage capability. Under 25℃and 0.5 P experimental condition, the capacity retention of the pouch cell reached 95.64% after 500 cycles, and which still maintained 82.75% of the initial capacity after 1000 cycles while under 45°C and 1 P conditions. After the 30-day storage at 45°C and 60°C, the capacity retention rates were 87.38% and 80.56%, respectively, significantly higher than those of the pouch cells with the blank control electrolyte. This work identifies Py as a highly promising electrolyte additive in stabilizing the graphite-based anode of Li-ion battery under both room temperature and high temperature.

Key words: Lithium-ion batteries, Cyclability, Pyridine, Solid electrolyte interface(SEI)