Achieving Ultra-High-Energy-Density\nLithium Batteries:\nElimination of Irreversible Anionic Redox through Controlled Cationic\nDisordering

Lithium-rich\nlayered oxides (LLOs) capable of supporting\nboth cationic\nand anionic redox chemistry are promising cathode materials. Yet,\ntheir initial charge to high voltages often trigger significant oxygen\nevolution, resulting in substantial capacity loss and structural instability.\nIn this study, we applied a straightforward low-potential activation\n(LOWPA) method alongside a relatively stable electrolyte to address\nthis issue. This approach enables precise control over the order-to-disorder\ntransformation of the transition metal layers in LLOs, producing an\nin-plane cation-disordered Li<sub>1.2</sub>Mn<sub>0.54</sub>Co<sub>0.13</sub>Ni<sub>0.13</sub>O<sub>2</sub> that averts irreversible\noxygen evolution at 4.8 V by stabilizing Mn–O<sub>2</sub> or\nMn–O<sub>3</sub> species within the Li/Mn-disordered nanopores.\nConsequently, an ultrahigh reversible capacity of 322 mAh g<sup>–1</sup> (equating to 1141 Wh kg<sup>–1</sup>), 91.5% initial Coulombic\nefficiency, and enhanced durability and rate capability are simultaneously\nachieved. As LOWPA does not alter any chemical composition of LLOs,\nit also offers a simple model for untangling the complex phenomena\nassociated with oxygen-redox chemistry.