期刊
NANO ENERGY
卷 77, 期 -, 页码 -出版社
ELSEVIER
DOI: 10.1016/j.nanoen.2020.105167
关键词
Sodium-ion batteries; Cathode; Jahn-Teller effect; Sodium isomer; Electrochemistry
类别
资金
- US Department of Energy (DOE) [DEEE0008202]
- Vehicle Technology Office of the U.S. DOE through the Advanced Battery Materials Research (BMR) Program [DE-5C0012704]
- DOE Office of Science [DE -5C0012704]
Jahn-Teller distorted Mn(III) (t(2g)(3)e(g)(1)) ions play a key role in the performance of manganese-based layered oxides. Here we show that there is an obvious relationship between the Jahn-Teller distortion of a trivalent manganese and the electrochemistry in a pair of Na isomer, namely orthorhombic and hexagonal P2-type Na2/3Mn0.9Ti0.1O2 having the same composition. It is found that more reversible phase transformations, higher working voltage and faster Na diffusion correlated with Jahn-Teller effect are found for distorted P'2-Na2/3Mn0.9Ti0.1O2 upon Na+ ions extraction/insertion. Such Jahn-Teller distorted Mn assisted Na migration enables that the orthorhombic Na2/3Mn0.9Ti0.1O2 delivers a high specific capacity of 204.0 mA h g(-1) with a 2.7 V average working voltage, reaching 550 Wh Kg(-1) with both better cycle stability (a capacity retention of 82.3% after 100 cycles) and enhanced rate capability (97.8 mA h g(-1) cycled at 10C) in Na cell in contrast with undistorted Na2/3Mn0.9Ti0.1O2. This strategy for understanding the Jahn-Teller effect of P2-type compounds at orbital energy level grasps new insight into designing high energy density positive electrode materials for Na-ion batteries.
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