储量丰富的钠使钠离子电池在大规模储能领域得到广泛应用，但是钠离子电池的循环性能还需进一步改善。在1 mol/L NaClO₄/EC/PC电解液中加入0.5%五氟乙氧基环三磷腈（FPN）添加剂，可以有效地调控P2-Na_xCo_0.7Mn_0.3O₂（x≈1.0）钠离子正极材料的界面稳定性，提高钠离子电池的循环稳定性。电化学和物化表征分析测试结果表明，FPN添加剂的加入可以在P2-Na_xCo_0.7Mn_0.3O₂（x≈1.0）正极材料表面形成一层富含NaF的致密正极电解质中间相（CEI），该CEI层可以明显降低电池的阻抗，抑制电解液的持续分解，使得电池在1 C倍率下循环200圈之后还可以保持92%的容量保持率，而没有添加FPN添加剂的基础电解液在1 C倍率下循环200圈之后的容量保持率只有75%。

Sodium ion battery (SIB) is promising for application on the large-scale energy storage field thanks to the abundant sodium resource in the globe.However,the application of SIB is still limited to its relatively poor cycle performance.It is found that addition of electrolyte additive is a simple and efficient method to improve SIB's cycle performance.In this work,0.5% of pentafluoroethoxy cyclotriphosphazene (FPN,also called 1,3,5,2,4,6-triazatriphosphorine) is added into a 1 mol·L^-1 NaClO₄/EC/PC electrolyte as an additive to regulate the performance of the cathode electrolyte interphase (CEI) of a P2-Na_xCo_0.7Mn_0.3O₂(x≈1.0) cathode material,thus improving the cycle stability of SIB.Electrochemical and physicochemical characterization results show that the addition of FPN additive can help to form a thin,uniform,and NaF-rich CEI layer on the surface of P2-Na_xCo_0.7Mn_0.3O₂(x≈1.0) cathode material,which can greatly reduce the impedance of SIB,suppress the continuous decomposition of electrolyte on the cathode and help to stabilize the structure of cathode material.As a result,the SIB with FPN can maintain 92% capacity retention rate after 200 cycles at 1 C rate,comparing with the 75% of the SIB without FPN additive.

禇艳丽(1992-),女,硕士研究生,研究方向为二次电池界面,ylchu2017@sinano.ac.cn