期刊
ACS APPLIED MATERIALS & INTERFACES
卷 11, 期 38, 页码 34973-34988出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsami.9b11942
关键词
Concentrated Electrolyte; Activity; Solvation Structure; Li-ion Batteries; Electrode-electrolyte Interface; Ni-rich Positive Electrodes; NMC
资金
- BMW
- National Science Foundation [DMR-1419807, ACT-1548562]
- Office of Science of the U.S. Department of Energy [DE-AC02-05CH11231]
- Imperial-MIT Department of Materials Exchange Program
The interfacial (electro)chemical reactions between electrode and electrolyte dictate the cycling stability of Li-ion batteries. Previous experimental and computational results have shown that replacing Mn and Co with Ni in layered LiNixMnyCo1-x-yO2 (NMC) positive electrodes promotes the dehydrogenation of carbonate-based electrolytes on the oxide surface, which generates protic species to decompose LiPF6 in the electrolyte. In this study, we utilized this understanding to stabilize LiNi0.8Mn0.1Co0.1O2 (NMC811) by decreasing free-solvent activity in the electrolyte through controlling salt concentration and salt dissociativity. Infrared spectroscopy revealed that highly concentrated electrolytes with low free-solvent activity had no dehydrogenation of ethylene carbonate, which could be attributed to slow kinetics of dissociative adsorption of Li+-coordinated solvents on oxide surfaces. The increased stability of the concentrated electrolyte against solvent dehydrogenation gave rise to high capacity retention of NMC811 with capacities greater than 150 mA h g(-1) (77% retention) after 500 cycles without oxide-coating and Ni-concentration gradients or electrolyte additives.
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