Gradient-morph LiCoO2 single crystals with stabilized energy density above 3400 W h L−1

摘要: The cycling stability of LiCoO2 under high voltages (>4.5 V) was plagued by hybrid anion- and cation-redox (HACR) induced oxygen escape uncontrolled phase collapse. With DEMS in situ XANES mapping at the NSLS-II, we demonstrate that triggers irreversible transformations into “bad” surface phases rapidly propagate inward. Enabling HACR but stopping global migration is key to a stable high-energy cathode. Therefore, developed ∼10 μm single crystals with bulk smoothly transitioning Co-free LiMn0.75Ni0.25O2 surface. By means initial electrochemical formation, semi-coherent LiMn1.5Ni0.5O4 spinel-like shell established operando little loss integrally wrap bulk. Then obtained gradient-morph prevent percolating out particle achieved enhanced reversibility voltages. cathode undergoes substantially stabilized when charged above 4.6 V, hence cyclic volumetric energy density >3400 W h L−1 has been pouch full-cell coupled commercial graphite anode lean electrolyte (2 g A h−1), exhibiting up 2906 even after 300 cycles.