Li4V2Mn(PO4)4-stablized Li[Li0.2Mn0.54Ni0.13Co0.13]O2 cathode materials for lithium ion batteries
Li-rich Mn-based cathode materials are regarded as promising cathode materials for Li-ion batteries (LIBs) owing to their high electrochemical capacity and low cost. However, residual Li compounds on the surface and dissolution of metal ions cause severe degradation of the electrochemical performance, thereby hindering their practical applications. Li 4 V 2 Mn(PO 4 ) 4 is a composite cathode material with three-dimensional Li-ion diffusion channels and a stable structure at high operating voltages (>4.5 V). Herein, we modify the surface of Li[Li 0.2 Mn 0.54 Ni 0.13 Co 0.13 ]O 2 with Li 4 V 2 Mn(PO 4 ) 4 . The Li 4 V 2 Mn(PO 4 ) 4 coating layer can not only reduce the content of residual Li compounds on the surface but also restrain the dissolution of transition metals. Theoretical calculations illustrate that Li 4 V 2 Mn(PO 4 ) 4 reduces the Li-ion diffusion energy barrier and provides efficient diffusion pathways. Li[Li 0.2 Mn 0.54 Ni 0.13 Co 0.13 ]O 2 @Li 4 V 2 Mn(PO 4 ) 4 compounds deliver a discharge capacity of 300 mAh g −1 with a high initial coulombic efficiency (84.2%) and an excellent cycling stability (capacity retention of 78.1% after 200 cycles at 1C). Hence, the proposed modification strategy of phosphate-based materials could shed light on the structural design of surface-sensitive electrode materials for LIBs.
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