NaTiO_x-modified high-nickel layered oxide cathode for stable sodium-ion batteries

Abstract

The O3-type layered cathode with high Ni content has attracted much attention because of its high capacity and simple synthesis process. However, surface side reaction and O3–P3 phase transitions would occur during Na⁺ insertion/extraction, resulting in unsatisfying electrochemical performance. Herein, O3-Na[Ni_0.6Co_0.2Mn_0.2]O₂ (NNCM622) cathode is modified by a NaTiO_x coating layer in a wet chemistry method, which reduces the parasitic reaction and facilitates Na⁺ migration. Simultaneously, the partially doped Ti improves structural stability by restraining the irreversible multiple-phase transition. As a result, the modified NNCM622 cathode obtains a high specific capacity of 143.4 mAh g^–1 and an improved capacity retention of 69% after 300 cycles. Our work offers new prospects for stabilizing the NNCM622 cathode with a feasible coating strategy.

Keywords

cathode / high-nickel layered oxides / sodium-ion battery / surface modification

Author summay

Yingcong Liu, Xing Zhou, and Dongwei He contributed equally to this study.