Al 3+ /Ta 5+ Co‐Doping Promotes Homogeneous Li + Transport Enabling High Performance Ni‐Rich Layered Oxide Cathodes

ABSTRACT Ni‐rich layered oxide cathodes with high energy density are regarded as one of the most promising cathode candidates for achieving next‐generation high‐energy lithium‐ion batteries (LIBs). However, increasing the Ni content introduces critical challenges, including undesirable phase transitions, sluggish Li + transport, and intergranular cracking, which hinder their large‐scale application. This work demonstrates an Al 3+ /Ta 5+ co‐doping strategy, enabling homogeneous Li + transport in a Ni‐rich cathode by forming LiNi 0.94 Ta 0.01 Al 0.05 O 2 (LNTAO) with refined grains and suppressed Li/Ni cation mixing. The achieved homogenization suppresses high‐voltage phase transitions and facilitates Li + intercalation/deintercalation during cycling. It also preserves the Ni valence state and Ni─O coordination environment, maintains grain‐boundary integrity, and suppresses interfacial side reactions during prolonged cycling. Enabled by these advantages, the cycle and rate performance of the Ni‐rich cathode are effectively enhanced. This Al 3+ /Ta 5+ co‐doping strategy provides fundamental materials‐design insights into enhancing the electrochemical performance of Ni‐rich layered cathodes through the homogenization of Li + transport.