Multi‐Level Modifications Enabling Chemomechanically Stable Ni‐Rich O3‐Layered Cathode toward Wide‐Temperature‐Tolerance Quasi‐Solid‐State Na‐Ion Batteries

Abstract

AbstractThe O3‐type Ni‐rich NaNixCoyMn1−x−yO2 (x ≥ 0.6) oxides are regarded as one of the most promising cathodes for high‐capacity Na‐ion batteries (NIBs), however, they still suffer from severe structural/morphological degradation induced by complicated phase transitions, as well as sluggish de‐/sodiation kinetics. For this, a multi‐level structural/compositional modification strategy, including “core–shell” design, bulk heteroatom doping, and surface coating, is purposefully explored to construct an advanced NaNi0.6Co0.2Mn0.2O2 cathode (denoted as T‐CSN6@A). The Ni‐rich core guarantees the high capacity, and the Mn‐rich surface region coupled with bulk Ti doping and surface Al2O3 coating reinforces the structural stability. This well‐designed architecture not only effectively inhibits the bulk and sur‐/interface structural fractures caused by repeated lattice volume variations upon cycling, but also dramatically boosts the de‐/sodiated kinetics, thus resulting in high chemomechanical stability and improved electronic/ionic transport for efficient sodium storage. When utilized as a competitive cathode, the T‐CSN6@A‐based quasi‐solid‐state NIBs are endowed with remarkable wide‐temperature‐tolerance Na‐storage behaviors within practicable working temperatures from −20 to 50 °C, along with an attractive material‐level energy density of ≈255 Wh Kg−1 at 25 °C. The feasible modification here provides a new avenue for advanced O3‐type Ni‐rich cathodes toward large‐scale industrialization of next‐generation NIBs.