Lithium-metal batteries (LMBs) are promising alternatives to state-of-the-art Lithium-ion batteries (LIBs) to achieve higher energy densities. However, the poor cyclability of LMBs resulting from Li metal anode (Li) irreversibility and concomitant electrolyte decompositions limits their practical applications. In this study, we reported a per-fluorinated salt, lithium tetrakis(perfluoro-tertbutyloxy)borate (abbreviated as ) as an electrolyte additive for Li-metal batteries, which contains 36 F atoms per molecule. This newly designed ionic additive tuned the chemical composition of the solid-electrolyte interphase (SEI) on Li by increasing the amount of LiF and Li-B-O inorganic species. DFT calculations and Molecular dynamics (MD) simulations indicated the preferential reduction of the anions at Li, which occurs with a lower free energy change than PF anions. The designed ionic additive enables the 4.6 V Li||LiNiMnCoO (NMC622) cell to achieve an average CE of 99.1 % and a high-capacity retention of > 50 % after 500 cycles. This experiment-simulation joint study illustrated an attractive approach to accelerating the design of electrolytes and interphases for LMBs.

中文翻译：

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一种富氟硼酸盐离子添加剂，可实现高电压锂金属电池

锂金属电池 (LMB) 是最先进的锂离子电池 (LIB) 的有前途的替代品，可实现更高的能量密度。然而，由于锂金属阳极（Li）的不可逆性和伴随的电解质分解而导致LMB的循环性能较差，限制了其实际应用。在这项研究中，我们报道了一种全氟化盐，四（全氟叔丁氧基）硼酸锂（缩写为 ）作为锂金属电池的电解质添加剂，其每个分子含有 36 个 F 原子。这种新设计的离子添加剂通过增加 LiF 和 Li-BO 无机物质的含量来调整 Li 上固体电解质界面 (SEI) 的化学组成。 DFT 计算和分子动力学 (MD) 模拟表明，Li 阴离子优先还原，其自由能变化比 PF 阴离子更低。设计的离子添加剂使 4.6 V Li||LiNiMnCoO (NMC622) 电池能够在 500 次循环后实现 99.1% 的平均 CE 和 > 50% 的高容量保持率。这项实验-模拟联合研究展示了一种加速 LMB 电解质和界面设计的有吸引力的方法。