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Li-rich high-Mn oxides, xLi2MnO3·(1 − x)LiMO2 (x ≥ 0.5, M = Co, Ni, Mn…), have attracted extensive research interest due to their high specific capacity and low cost. However, slow Li2MnO3 activation and poor cycling stability have affected their electrochemical performance. Herein, to solve these problems, morphology regulation and LiAlF4 coating strategies have been synergistically applied to a Li-rich high-Mn material Li1.7Mn0.8Co0.1Ni0.1O2.7 (HM-811). This dual-strategy successfully promotes the activation process of the Li2MnO3 phase and thus improves the electrochemical performance of HM-811. Theoretical computation indicates that the LiAlF4 layer has a lower Li+ migration barrier than the HM-811 matrix, so it could boost the diffusion of Li+ ions and promote the activation of the Li2MnO3 phase. Benefiting from the morphology regulation and LiAlF4 coating, the HM-811 cathode shows a high initial charge capacity of >300 mA h g−1. In addition, the modified HM-811 could deliver superior electrochemical performance even at a low temperature of −20 °C. This work provides a new approach for developing high performance cathode materials for next-generation Li-ion batteries.

Li-rich high-Mn oxides, xLi2MnO3·(1 - x)LiMO2 (x ≥ 0.5, M = Co, Ni, Mn…), have attracted extensive research interest due to their high specific capacity and low cost. However, slow Li2MnO3 activation and poor cycling stability have affected their electrochemical performance. Herein, to solve these problems, morphology regulation and LiAlF4 coating strategies have been synergistically applied to a Li-rich high-Mn material Li1.7Mn0.8Co0.1Ni0.1O2.7 (HM-811). This dual-strategy successfully promotes the activation process of the Li2MnO3 phase and thus improves the electrochemical performance of HM-811. Theoretical computation indicates that the LiAlF4 layer has a lower Li+ migration barrier than the HM-811 matrix, so it could boost the diffusion of Li+ ions and promote the activation of the Li2MnO3 phase. Benefiting from the morphology regulation and LiAlF4 coating, the HM-811 cathode shows a high initial charge capacity of300 mA h g-1. In addition, the modified HM-811 could deliver superior electrochemical performance even at a low temperature of -20 °C. This work provides a new approach for developing high performance cathode materials for next-generation Li-ion batteries.

Layered lithium-rich transition-metal oxides (LRMs) have been considered as the most promising next-generation cathode materials for lithium-ion batteries. However, capacity fading, poor rate performance, and large voltage decays during cycles hinder their commercial application. Herein, a spinel membrane (SM) was first in situ constructed on the surface of the octahedral single crystal Li

Li-rich Mn-based oxides (LRMOs) are promising cathode materials for next-generation Li-ion batteries because of their high voltage, high capacity, and low cost. However, the low initial Coulombic efficiency (ICE), severe capacity fading and voltage dropping during cycling hinder their large-scale application of LRMOs. Hence, we propose a facile Metal-Organic Frameworks (MOF)-self-assembly coating strategy to modify LRMOs with CoxOy/C coating (LRMO@CoxOy/C). The CoxOy/C layer can alleviate the side-reaction between the electrolyte and cathode materials, and enhance both ion-diffusion and electrons-transportation speed throughout the surface of the electrode materials. In addition, the CoxOy/C layer suppresses the lattice oxygen release and improve structural stability of LRMOs during long-term cycling. Consequently, the LRMO@CoxOy/C cathode shows a high ICE of 91.5% and slow voltage dropping of only 2 mV/cycle at 0.2 C. After 300 cycles, it still delivers a high discharge capacity of 210.7 mAh·g−1 at 0.5 C with a capacity retention of ~80%. This work provides a novel approach to achieve next-generation high-energy density cathode materials.