Wang Xianshu, Wang Shuwei, Wang Huirong, Tu Wenqiang, Zhao Yun, Li Song, Liu Qi, Wu Junru, Fu Yongzhu, Han Cuiping, Kang Feiyu, Li Baohua
Shenzhen Key Laboratory on Power Battery Safety and Shenzhen Geim Graphene Center, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China.
School of Materials Science and Engineering, Tsinghua University, Beijing, 100084, China.
Adv Mater. 2021 Dec;33(52):e2007945. doi: 10.1002/adma.202007945. Epub 2021 Oct 22.
Lithium (Li)-metal batteries (LMBs) with high-voltage cathodes and limited Li-metal anodes are crucial to realizing high-energy storage. However, functional electrolytes that are compatible with both high-voltage cathodes and Li anodes are required for their developments. In this study, the use of a moderate-concentration LiPF and LiNO dual-salt electrolyte composed of ester and ether co-solvents (fluoroethylene carbonate/dimethoxyethane, FEC/DME), which forms a unique Li solvation with aggregated dual anions, that is, PF and NO , is proposed to stabilize high-voltage LMBs. Mechanistic studies reveal that such a solvation sheath improves the Li plating/stripping kinetics and induces the generation of a solid electrolyte interphase (SEI) layer with gradient heterostructure and high Young's modulus on the anode, and a thin and robust cathode electrolyte interface (CEI) film. Therefore, this novel electrolyte enables colossal Li deposits with a high Coulombic efficiency (≈98.9%) for 450 cycles at 0.5 mA cm . The as-assembled LiǁLiNi Co Al O full batteries deliver an excellent lifespan and capacity retention at 4.3 V with a rigid negative-to-positive capacity ratio. This electrolyte system with a dual-anion-aggregated solvation structure provides insights into the interfacial chemistries through solvation regulation for high-voltage LMBs.
具有高压阴极和有限锂金属阳极的锂（Li）金属电池（LMBs）对于实现高能量存储至关重要。然而，其发展需要与高压阴极和锂阳极都兼容的功能性电解质。在本研究中，提出使用由酯和醚共溶剂（氟代碳酸乙烯酯/二甲氧基乙烷，FEC/DME）组成的中等浓度LiPF和LiNO双盐电解质，该电解质形成具有聚集双阴离子（即PF和NO）的独特锂溶剂化结构，以稳定高压LMBs。机理研究表明，这种溶剂化鞘改善了锂的电镀/剥离动力学，并在阳极上诱导生成具有梯度异质结构和高杨氏模量的固体电解质界面（SEI）层，以及一层薄而坚固的阴极电解质界面（CEI）膜。因此，这种新型电解质能够在0.5 mA cm下以高达98.9%的库仑效率实现450次循环的巨大锂沉积。所组装的LiǁLiNiCoAlO全电池在4.3 V下具有优异的寿命和容量保持率，且正负极容量比严格。这种具有双阴离子聚集溶剂化结构的电解质体系通过溶剂化调控为高压LMBs的界面化学提供了见解。
