• • The engineered Co-free ultrahigh-Ni cathode operates at a charging cut-off voltage of 4.8 V, achieving an exceptional balance between capacity and cycle stability, breaking existing voltage constraints without compromising performance.
• • Pouch-type cells with graphite and Li metal anodes demonstrate excellent cyclability under demanding conditions, operating at high charging cut-off voltages of 4.5 V and 4.6 V, respectively.
• • The LiAlO2 nanoshell, deposited via atomic layer deposition, markedly enhances sur-/interfacial Li-ion migration kinetics, rendering low electron/ion-diffusion resistance.
• • The surface-to-bulk integrated modification prevents lattice stress-induced mechanical degradation and mitigates accumulation of by-products due to surface side-reactions, addressing chemo-mechanical and electrochemical degradation under high-voltage operation.