The development of stable electrolytes for high-voltage lithium metal batteries (LMBs) is crucial for advancing battery technology. Diluted high-concentration electrolytes (DHCEs) have shown promise in enhancing interfacial stability, yet challenges persist due to the thermodynamic instability associated with conventional hydrofluoroether diluents and the interphase issues of monofluoroaromatic hydrocarbon diluents under high voltage conditions. In this study, we propose the incorporation of methyl 1,1,2,2,3,3,4,4,4-nonafluorobutyl ether (CNFE) as an additive to fluorobenzene (FB)-based DHCEs for high-voltage LMBs. CNFE with a molecular structure devoid of β-hydrogen guarantees the thermodynamic stability of FB-based DHCEs compared to conventional hydrofluoroether-based DHCEs. Moreover, CNFE promotes the formation of a LiF-rich and stable solid electrolyte interphase (SEI) and cathode electrolyte interphase (CEI). Consequently, a Li‖LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) cell demonstrates a remarkable capacity retention of 84.8% in the 700th cycle at a high cutoff voltage of 4.4 V.

中文翻译：

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九氟丁基醚提高高压锂金属电池中氟苯基稀释高浓度电解液的稳定性

开发用于高压锂金属电池（LMB）的稳定电解质对于推进电池技术至关重要。稀释的高浓度电解质（DHCE）在增强界面稳定性方面表现出了良好的前景，但由于传统氢氟醚稀释剂的热力学不稳定性以及单氟芳烃稀释剂在高电压条件下的相间问题，挑战仍然存在。在这项研究中，我们建议将甲基 1,1,2,2,3,3,4,4,4-九氟丁基醚 (CNFE) 作为添加剂添加到基于氟苯 (FB) 的 DHCE 中，用于高压 LMB。与传统的氢氟醚基 DHCE 相比，CNFE 的分子结构不含 β-氢，保证了 FB 基 DHCE 的热力学稳定性。此外，CNFE 促进了富含 LiF 且稳定的固体电解质界面（SEI）和阴极电解质界面（CEI）的形成。因此，Li‖LiNi _0.8 Co _0.1 Mn _0.1 O ₂ (NCM811) 电池在 4.4 V 的高截止电压下，在第 700 次循环中表现出 84.8% 的显着容量保持率。