Solid-state synthesis of low-cost and high-energy-density sodium layered-tunnel oxide cathodes: Dynamic structural evolution, Na+/vacancy disordering, and prominent moisture stability
Publication Name
Nano Energy
Abstract
Manganese-based layered oxides show promise as cathode materials for sodium-ion batteries (SIBs). However, several challenges including sluggish Na+ kinetics, complex phase transitions, and poor air stability hinder their practical application. Herein, we proposed a dual-function strategy that not only precisely manipulates dynamic structural evolution from layered to tunnel structure, but also effectively suppresses Na+/vacancy and charge ordering by inhibiting electron delocalization. A series of Ti-substituted Na2/3Mn1-xTixO2 (x=0, 1/9, 2/9, 1/3) as proof of concept materials were designed to demonstrate the dual-function strategy. As a result, the optimized Na2/3Mn8/9Ti1/9O2 cathode material delivers a high specific capacity of 202.9 mAh g−1 at 0.1 C within 1.5−4.3 V, equivalent to 536.6 Wh kg−1 of energy density, and exhibits 71.0% of capacity retention after 300 cycles at 1 C. Meanwhile, a highly reversible P2/Tunnel-OP4/Tunnel phase transition process and interlocking effect between the layered and tunnel structure as well as prominent moisture stability even after soak water treatment are further confirmed by in-situ charge and discharge XRD and other advanced characterization techniques. Noting that the electrode assembled with water-solution binder still displays a high capacity retention of 85.4% after 400 cycles at 1 C. Our dual-function strategy provides valuable guidance for developing high energy density and water stable practical SIB cathode materials.
Open Access Status
This publication is not available as open access
Volume
125
Article Number
109528
Funding Number
202106370062
Funding Sponsor
China Scholarship Council