Making 1000 Wh/kg LiNiO2 Cathode Nearly Strain-Free by Complex-Concentrated Doping

High-energy batteries require cathodes with greater capacity and specific energy. Ni-rich-layered oxides approach the performance limit of LiNiO2 (LNO), yet its practical use is hindered by severe chemomechanical degradation. Near 4.2 V, the H2-H3/H4 transition drives substantial c-axis contraction, volume shrinkage, O1 formation, oxygen loss, and rapid capacity decay. Here, we show that only 5% cobalt-free complex concentrated doping stabilizes LNO without sacrificing energy density. The modified LNO reduces c-axis strain from 7.4 to 2.1%, exhibits near-zero-strain behavior, and delivers 258 mAh•g–1 and 973 Wh•kg–1. In pouch cells, it retains 80% capacity after 1800 cycles and shows markedly improved thermal stability. These results demonstrate that complex-concentrated doping at low dopant loading can suppress strain and phase transformations at the full-Ni limit, providing a broadly applicable strategy for stabilizing high-energy intercalation electrodes while preserving their intrinsic capacity and specific energy during prolonged electrochemical cycling.