Bulk-surface dual modification via Mg/Zr doping and Li₃PO₄coating for suppressing phase transition and side reaction in 4.6 V LiCoO₂ AITranslate

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Chinese Library Classification Number:TM912[电气工程—电力电子与电力传动];TQ131.1[化学工程—无机化工]

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The rapid advancement of electronic devices has resulted in increasingly demanding performance requirements for highvoltage LiCoO₂(LCO)cathodes.However,LCO exhibits significant irreversible phase transitions and detrimental side reactions under high voltages.Herein,Mg/Zr co-doped and Li₃PO₄-coated LiCoO₂(denoted as MZP-LCO)was synthesized through an element self-diffusion reaction at a high temperature.Mg²⁺and Zr⁴⁺can partially replace Li+in the LCO structure,creating a homogeneous concentration distribution with a 60 nm thickness from the surface to the interior.Mg²⁺serves as a stabilizing"pillar"to suppress Co-O layer sliding during deep delithiation,enhancing the structural integrity of LCO,while Zr⁴⁺expands the Li+deintercalation channels,thereby increasing the capacity.Furthermore,a Li₃PO₄nano-coating layer forms in situ on the surface of the LCO,improving Li+transport efficiency and successfully inhibiting harmful side reactions at the electrode surface.The half-cell of MZP-LCO exhibits a capacity of 154.7 mAh·g^-1after 200 cycles at 0.5C within 3.0-4.6 V,and demonstrates superior rate capability,maintaining a capacity of 156.1 mAh·g^-1at 10C.The exceptional electrochemical performance can be attributed to the synergistic effects of the uniform Mg/Zr doping within the LCO and the Li₃PO₄coating nanolayer on the surface.These findings offer valuable insights for resolving the issues related to LCO cathode performance degradation at high voltages.