The effect of dual-doping on the electrochemical performance of LiNi0.5Mn1.5O4 and its application in full‐cell lithium‐ion batteries

Abstract

Dual improvement on electrochemical kinetics and lifespan of LiNi0.5Mn1.5O4 (LNMO) cathode material is of great significance for realizing high-power and durable lithium-ion batteries (LIBs). To achieve this goal, the Mg2+−Cr3+ co-doping LNMO microspheres were prepared via the coprecipitation route. FTIR, Raman spectra and magnetic susceptibility verify that both the Mg2+ and Cr3+ doping are beneficial for the formation of disordered Fd3m phase leading to the improvement of electronic conductivity and decrease in electrochemical polarization and the charge transfer resistance (Rct). Meanwhile, the doping also reduces the content of Mn3+ in LNMO which can diminish the dissolution of Mn3+ resulting in the enhancement of cycling life. As a result, the Mg2+−Cr3+ co-doping sample (MC-LNMO) exhibits an improved electrochemical performance (EP). A discharge capacity (DC) of 110.7 mAh/g at 10C can be obtained for MC-LNMO which is higher than that of pure LNMO (only 53 mAh/g) and after 200 cycles the capacity fade is only 4.6% at 25 °C. To further evaluate the MC-LNMO electrode for practical application, in this study, the full cells were also fabricated using the MC-LNMO as cathode and Li4Ti5O12 (LTO) as anode. In the combination, the full device exhibits high energy density (ED) and long cycle life due to the large difference in the working potential of LNMO (4.7 V) and LTO (1.55 V) and their excellent lifespan. These findings provide a simple and scalable method to boost the EP of LNMO, which can be used to fabricate high-quality LIBs.