Reorganizing Helmholtz Adsorption Plane Enables Sodium Layered-Oxide Cathode Beyond High Oxidation Limits.

ABSTRACT

Sodium layered-oxides (Nax TMO2 ) sustain severe interfacial stability issues when subjected to battery applications. Particularly at high potential, the oxidation limits including transition metal dissolution and SEI reformation are intertwined upon the cathode, resulting in poor cycle ability. Herein, by rearranging the complex and structure of Helmholtz absorption plane adjacent to Nax TMO2 cathodes, the mechanism of constructing stable cathode/electrolyte interphase to push up oxidation limits is clarified. The strong absorbent fluorinated anions replace the solvents into the inner Helmholtz plane, thereby reorganizing the Helmholtz absorption structure and spontaneously inducing an anion-dominated interphase to envelop more active sites for layered oxides. More importantly, such multi-component cathode/electrolyte interphase proves effective for long-term durability of a series of manganese-based oxide cathodes, which achieves 1500-cycles lifetime against high oxidation voltage limit beyond 4.3 V. This work unravels the key role of breaking high-oxidation limits in attaining higher energy density of layered-oxide systems. This article is protected by copyright. All rights reserved.