Huang Junda, Liu Jiandong, He Jian, Wu Mingguang, Qi Shihan, Wang Huaping, Li Fang, Ma Jianmin
School of Physics and Electronics, Hunan University, Changsha, 410082, China.
Angew Chem Int Ed Engl. 2021 Sep 13;60(38):20717-20722. doi: 10.1002/anie.202107957. Epub 2021 Aug 15.
The safety and electrochemical performance of rechargeable lithium-metal batteries (LMBs) are primarily influenced by the additives in the organic liquid electrolytes. However, multi-functional additives are still rarely reported. Herein, we proposed heptafluorobutyric anhydride (HFA) as a qua-functional additive to optimize the composition and structure of the solid electrolyte interphase (SEI) at the electrode/electrolyte interface. The reduction/oxidation decomposition of the fluorine-rich HFA facilitate uniform inorganic-rich SEI and compact cathode electrolyte interphase (CEI) formation, which enables stable lithium plating during charge and suppresses the dissolution of transition-metal ions. Moreover, HFA optimizes the Li-ion solvation for stable Li plating/stripping and serves as the surfactant to enhance the wettability of the separator by the electrolyte to increase Li-ion flux. The symmetric Li∥Li cell with 1.0 wt % HFA electrolyte had an excellent cycling performance over 340 h at 1.0 mA cm with a capacity of 0.5 mAh cm while the Li∥NCM622 cell maintained high capacity retention after 250 cycles and outstanding rate performance even at 15 C.
可充电锂金属电池（LMBs）的安全性和电化学性能主要受有机液体电解质中添加剂的影响。然而，多功能添加剂仍然鲜有报道。在此，我们提出将七氟丁酸酐（HFA）作为一种四功能添加剂，以优化电极/电解质界面处固体电解质界面（SEI）的组成和结构。富含氟的HFA的还原/氧化分解有助于形成均匀的富含无机成分的SEI和致密的阴极电解质界面（CEI），从而在充电过程中实现稳定的锂电镀，并抑制过渡金属离子的溶解。此外，HFA优化了锂离子溶剂化以实现稳定的锂电镀/剥离，并作为表面活性剂增强电解质对隔膜的润湿性以增加锂离子通量。含1.0 wt % HFA电解质的对称Li∥Li电池在1.0 mA cm下具有超过340 h的优异循环性能，容量为0.5 mAh cm，而Li∥NCM622电池在250次循环后保持高容量保持率，即使在15 C时也具有出色的倍率性能。
