Structural Modification and Electrochemical Performance of Al-doped LiNi0.5Co0.2Mn0.3O2 Materials
The ternary cathode material LiNi0.5Co0.2Mn0.3O2(NCM523)has attracted much attention due to its moderate price and high energy density.Nevertheless,the low cyclic stability of NCM523 has hindered its commercial application.In this work,a series of modified NCM523 cathode materials in which various amounts of Al atoms substituted for Mn atoms were prepared by a hybridized method combining co-precipitation and high-temperature sintering.The results showed that the appropriate dosage of Al could enhance the stability of the transition metal layer and sig-nificantly improve the poor cyclic stability of NCM523 material.The best electrochemical performance was obtained when an Al dosage of 7％mo-lar ratio(Al to Li)was adopted,as it provided a discharge specific capacity of 165.7 mAh·g-1 within the voltage range of 2.7-4.5 V at 0.1C current density,which deteriorated to 134.3 mAh·g-1 after 50 cycles,with 81.05％capacity retention.At the high-temperature(55 ℃)condi-tion,the sample with 7％Al/Li molar ratio still maintained the best electrochemical performance.
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