Effect of surface Sn doping on the electrochemical performance of Li-rich Mn-based materials
To meet the performance demands of lithium-ion batteries for long-distance electric vehicle travel,it is crucial to develop high-energy-density cathode materials.Li-rich Mn-based oxides(LRM)have garnered widespread attention as next-generation cathode materials for lithium-ion batteries due to their high reversible capacity of over 250 mA·h·g-1.The high capacity of LRM arises from the combined effect of oxygen anions and transition metal cations during the charge compensation.However,the structural degradation caused by oxygen release,transition metal ion migration,and surface reconstruction,severely affecting the material's cycling stability,voltage decay,and rate capability,thus limiting its commercialization.Numerous studies have shown that the performance degradation of Li-rich Mn-based cathodes originates from the collapse of the surface structure.In this study,large-sized Sn ions were used to modify the surface of the material,exploring the impact of Sn doping on the material's structure and electrochemical performance.Characterization techniques reveals that Sn successfully incorporated into the surface lattice,effectively inhibiting the irreversible migration of transition metal ions during cycling.Additionally,Sn induces the formation of a stable spinel phase on the surface,significantly enhancing the stability of surface oxygen and the interface,thereby greatly improving the electrochemical performance of the material.When discharged at 0.1 C,the specific capacity reaches 310 mA·h·g-1;after 150 cycles at 1 C,the capacity retention is 88％.This modification method provides an effective approach to improving the stability of lithium-rich manganese-based cathode materials.
lithium-ion batteriesLi-rich Mn-based cathode materialssurface Sn dopingcapacity retentionvoltage decay
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