美国马里兰大学化学和生物分子Chunsheng Wang团队设计了一种碳酸盐电解质中先进锂金属电池的富无机固体电解质界面相。 该研究成果发表在2020年11月09日出版的《德国应用化学》。

在碳酸盐岩电解质中,锂（Li）金属阳极表面形成的有机-无机固体电解质界面相（SEI）与Li紧密结合，并经历与Li相同的体积变化，在沉积/溶出循环过程中会发生连续的开裂/再生。

在该文中，研究人员在锂金属表面设计中了一种富含无机物的SEI，通过在二甲基亚砜（DMSO）中溶解4M浓度的LiNO3作为基于碳酸氟乙烯（FEC）的电解质的添加剂来降低其与Li金属的结合能。由于NO3^-的聚集结构及其参与了初始Li⁺溶剂化鞘层，因此在生成的SEI中富含Li2O、Li3N和LixOy颗粒。此外，由于PF6^-的还原，形成了均匀分布的LiF。富含无机物的SEI与Li的弱键合（高界面能）能有效地促进Li沿SEI/Li界面的扩散，阻止Li枝晶穿过SEI。因此，研究人员设计的碳酸盐电解液可使锂阳极获得99.55%的高锂沉积/溶出CE（1 mA cm-2，1.0 mAh cm‐2）。同时，电解液也使Li | LiNi 0.8 Co 0.1 Mn 0.1 O 2（NMC811）全电池（2.5 mAh cm‐2）在200次循环后仍能保持75%的初始容量，突出的CE为99.83%。

该文提出的策略为进一步优化锂离子电池用碳酸盐电解液提供了一种实用的解决方案。

附：英文原文

Title: Inorganic‐rich Solid Electrolyte Interphase for Advanced Lithium Metal Batteries in Carbonate Electrolytes

Author: Sufu Liu, Xiao Ji, Nan Piao, Ji Chen, Nico Eidson, Jijian Xu, Pengfei Wang, Long Chen, Jiaxun Zhang, Tao Deng, Singyuk Hou, Ting Jin, Hongli Wan, Jingru Li, Jiangping Tu, Chunsheng Wang

Issue&Volume: 09 November 2020

Abstract: In carbonate electrolytes, the organic‐inorganic solid electrolyte interphase (SEI) formed on the lithium (Li) metal anode surface is strongly bonded to Li and experiences the same volume change as Li, thus it undergoes continuous cracking/reformation during plating/stripping cycles. Here, an inorganic‐rich SEI is designed on a Li metal surface to reduce its bonding energy with Li metal by dissolving 4 M concentrated LiNO  3  in dimethyl sulfoxide (DMSO) as an additive for a fluoroethylene carbonate (FEC) based electrolyte. Due to the aggregate structure of NO  3  ‐  ions and its participation in the primary Li  +  solvation sheath, abundant Li  2  O, Li  3  N, and LiN  x  O  y  grains are formed in the resulting SEI, in addition to the uniform LiF distribution from the reduction of PF  6  ‐  ions. The inorganic‐rich SEI’s weak bonding (high interface energy) to Li can effectively promote Li diffusion along the SEI/Li interface and prevent Li dendrite penetration into the SEI. As a result, our designed carbonate electrolyte enables a Li anode to achieve a high Li plating/stripping CE of 99.55% (1 mA cm  ‐2  , 1.0 mAh cm  ‐2  ) and the electrolyte also enables a Li||LiNi  0.8  Co  0.1  Mn  0.1  O  2  (NMC811) full cell (2.5 mAh cm‐2) to retain 75% of its initial capacity after 200 cycles with an outstanding CE of 99.83%. The concentrated additive strategy presented here provides a drop‐in practical solution to further optimize carbonate electrolytes for beyond Li‐ion batteries.

DOI: 10.1002/anie.202012005

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202012005