Gradient‐Modified Li‐Rich Manganese‐Based Oxides Cathodes with Breakthrough of Kinetic Limitation for High‐Performance All‐Solid‐State Lithium Metal Batteries

ABSTRACT The Li‐rich manganese‐based oxides (LRMO) with high operating voltage and large reversible capacities can demonstrate comprehensive advantages of intrinsic safety and high energy density when employed in all‐solid‐state lithium batteries (ASSLBs). However, severe interfacial incompatibility with solid electrolytes (SEs) arising from unstable lattice oxygen and sluggish Li + ionic transport hinders their practical application. In this contribution, the gradient‐modified structure containing S, Zr co‐doping near‐surface and amorphous Zr(SO 4 ) 2 coating is simultaneously established onto LRMO cathode by a one‐step mechano‐fusion process. The synergistic co‐functionalization stabilizes the oxygen framework, enhances charge transport, and suppresses oxygen dimerization under high potential. Besides, the amorphous Zr(SO 4 ) 2 coating evenly adhering onto LRMO bulk ensures long‐term intimate contact with SEs to guarantee electrochemical activities and restrains interfacial parasitic reactions. Consequently, the optimized A‐LRMO cathode exhibits a high discharge capacity of 292 mAh/g at 0.1 C and 81.8% capacity retention after 2000 cycles at 1 C. Pouch cells delivered an areal capacity of 8.5 mAh/cm 2 with >99.6% Coulombic efficiency. This gradient‐modification strategy offers an effective pathway to improve interfacial stability and accelerate the practical application of LRMO‐based ASSLBs.