硫化物固态电解质Li10GeP2S12与锂金属间界面稳定性的改善研究

通过N-丁基-N-甲基哌啶双（氟磺酰）亚胺盐离子液体和双（氟磺酰）亚胺锂盐修饰了Li|Li₁₀GeP₂S₁₂界面，并研究了界面的改性效果.研究结果表明，在界面处原位生成一层致密的固体电解质界面膜（SEI），具有一定流变性的离子液体可渗透到Li₁₀GeP₂S₁₂晶粒内部；在0.1 mA/cm²的电流密度下，界面改性后的Li|Li₁₀GeP₂S₁₂|Li对称电池可稳定循环1500 h以上，极化电压仅为30 mV.在2.5~3.6 V电压范围内，Li|Li₁₀GeP₂S₁₂|LiFePO₄电池在0.2C倍率下充放电循环的首次放电比容量为148.1 mA·h/g，库仑效率为95.8%，经过30次循环后容量保持率为90.1%.

Improvement of Interface Stability Between Sulfide Solid Electrolyte Li10GeP2S12 and Lithium Metal

Sulfide solid electrolyte Li₁₀GeP₂S₁₂ exhibits extremely high ionic conductivity but relatively poor stability to lithium metal. After being modified by N-butyl-N-methylpiperidinium bis(fluorosulfonyl)imide together with lithium bis(fluorosulfonyl)imide, a thin and dense solid electrolyte interphase(SEI) was formed in situ at the Li|Li₁₀GeP₂S₁₂ interface. Besides, the ionic liquid with certain liquidity is able to penetrate into the interior grains of Li₁₀GeP₂S₁₂ to construct abundant lithium ion diffusion channels, which could alleviate the high impedance problem caused by the thermodynamically unstable interface. The modified Li|Li₁₀GeP₂S₁₂|Li symmetric cell attains a stable cycle life of over 1500 h with the polarization voltage of 30 mV at 0.1 mA/cm². In addition, the interface modified Li|Li₁₀GeP₂S₁₂|LiFePO₄ cell delivers an initial discharge capacity of 148.1 mA·h/g at 0.2C with the voltage range of 2.5-3.6 V and the first cycle Coulombic efficiency of 95.8%. The capacity retention is still 90.1% after 30 cycles, showing an improved cycling stability.