The Effects of a Mixed Precipitant on the Morphology and Electrochemical Performance of LiNi0.5Mn1.5O4 Cathode Materials

Abstract

A series of LiNi0.5Mn1.5O4 (LNMO) samples were synthesized by adjusting the molar ratio of (NH4)2CO3 to Na2CO3 in a mixed precipitant for evaluating the effects of ammonia from (NH4)2CO3 as a complexing agent and Na2CO3 as a precipitant on the morphology and electrochemical performances of LNMO. In this research, a rapid precipitation method followed by hydrothermal treatment was used to prepare the precursors of LNMO, and different molar ratios (0:1, 1:2, 1:1, 2:1, 1:0) of (NH4)2CO3 to Na2CO3 were used for mixed precipitants. The test results revealed that the cathode material exhibits the best electrochemical performance when the molar ratio of (NH4)2CO3 to Na2CO3 is set at 1:2, displaying a specific discharge capacity of 129.4 mA h g−1 at 0.5 C and a capacity retention of 82.3% after 200 charge–discharge cycles. In addition, it still shows a high rate performance with a discharge capacity of 112.7 mA h g−1 at 10 C and 98.8 mA h g−1 at 20 C, which is attributed to an accurate Ni/Mn ratio, smaller primary particle sizes and a porous spherical morphology.

Keywords

• rapid precipitation
• hydrothermal treatment
• mixed precipitants
• spherical morphology