Excellent High‐Rate Electrochemical Performances of Microspherical High‐Voltage Spinel Cathodes Synthesized by a Polyacrylamide‐Assisted Co‐Precipitation Method

Abstract

A convenient strategy to construct microspherical LiNi0.5Mn1.5O4 (LNMO‐P) or Mg‐doped LiNi0.5Mn1.5O4 (LNMO‐P‐M) cathodes by polyacrylamide (PAAM)‐assisted coprecipitation is developed. Due to the coacervation effect of PAAM, the microspherical LNMO‐P and LNMO‐P‐M samples with small primary particle sizes and the uniform primary particles distribution are identified, resulting in a remarkable electrochemical performance with conventional electrolytes. The first coulomb efficiency of the LNMO‐P sample is enhanced to 84.7% and a high discharge capacity of 133.2 mAh g−1 is observed. Of significance, the LNMO‐P‐M sample prepared with PAAM shows excellent high‐rate electrochemical performance. Its capacity retention is 94.9% at the charge rate of 5C after 300 cycles and 95.3% at the discharge rate of 15C after 500 cycles. The improvement electrochemical performance of LNMO‐P‐M sample can be attributed to its strengthened crystal structure, moderate Mn3+ content by the action of Mg, and its improved uniform composition distribution caused by PAAM.