Liu Yongchao, Hong Liu, Jiang Rui, Wang Yueda, Patel Sawankumar V, Feng Xuyong, Xiang Hongfa
School of Materials Science and Engineering, Anhui Provincial Key Laboratory of Advanced Functional Materials and Devices, Hefei University of Technology, Hefei, Anhui 230009, P. R. China.
Engineering Research Center of High Performance Copper Alloy Materials and Processing, Ministry of Education, Hefei, Anhui 230009, P. R. China.
ACS Appl Mater Interfaces. 2021 Dec 8;13(48):57430-57441. doi: 10.1021/acsami.1c18783. Epub 2021 Nov 29.
A lithium metal anode and high nickel ternary cathode are considered viable candidates for high energy density lithium metal batteries (LMBs). However, unstable electrode-electrolyte interfaces and structure degradation of high nickel ternary cathode materials lead to serious capacity decay, consequently hindering their practical applications in LMBs. Herein, we introduced ,-bis(trimethylsilyl) trifluoro acetamide (BTA) as a multifunctional additive for removing trace water and hydrofluoric acid (HF) from the electrolyte and inhibiting corrosive HF from disrupting the electrode-electrolyte interface layers. Furthermore, the BTA additive containing multiple functional groups (C-F, Si-O, Si-N, and C═N) promotes the formation of LiF-rich, Si- and N-containing solid electrolyte interfacial films on a lithium metal anode and LiNiMnCoO (NMC811) cathode surfaces, thereby improving the electrode-electrolytes interfacial stability and mitigating the capacity decay caused by structural degradation of the layered cathode. Using the BTA additive had tremendous benefits through modification of both anode and cathode surface layers. This was demonstrated using a Li||NMC811 metal battery with the BTA electrolyte, which exhibits remarkable cycling and rate performances (122.9 mA h g at 10 C) and delivers a discharge capacity of 162 mA h g after 100 cycles at 45 °C. Likewise, this study establishes a cost-effective approach of using a single additive to improve the electrochemical performance of LMBs.
锂金属负极和高镍三元正极被认为是高能量密度锂金属电池（LMBs）的可行候选材料。然而，不稳定的电极-电解质界面和高镍三元正极材料的结构退化导致严重的容量衰减，从而阻碍了它们在LMBs中的实际应用。在此，我们引入了双（三甲基硅基）三氟乙酰胺（BTA）作为一种多功能添加剂，用于从电解质中去除痕量水和氢氟酸（HF），并抑制腐蚀性HF破坏电极-电解质界面层。此外，含有多个官能团（C-F、Si-O、Si-N和C═N）的BTA添加剂促进了富含LiF、含Si和N的固体电解质界面膜在锂金属负极和LiNiMnCoO（NMC811）正极表面的形成，从而提高了电极-电解质界面稳定性，并减轻了由层状正极结构退化引起的容量衰减。使用BTA添加剂通过修饰阳极和阴极表面层带来了巨大的好处。这在使用含BTA电解质的Li||NMC811金属电池中得到了证明，该电池表现出卓越的循环和倍率性能（在10C下为122.9 mA h g），并在45°C下100次循环后提供162 mA h g的放电容量。同样，本研究建立了一种使用单一添加剂来提高LMBs电化学性能的经济有效方法。
