Morphology-control preparation and electrochemical performance of Mn-spinel cathode materials

Abstract

The disadvantage of the LiMn2O4 batteries is a capacity fade during charge-discharge cycling or high temperature storage. It is well known that this deterioration is mainly caused by Mn dissolution from spinel, especially at elevated temperature (60℃). Extensively studies have been made to explain its degraded cycling performance, but these studies mainly focused on investigating the structural change during lithium intercalation/de-intercalation process. In fact, the recent researches have shown that the surface structure and interface reaction of Mn-spinel greatly affect the Mn dissolution of spinel. In this study, we have successfully synthesized oxygen stoichiometric Mn-spinel cathode with spherical-like morphology. It has a much smaller (111) plane area compared with the single crystal octahedral or polyhedral Mn-spinel products. The decrease of the plane area could reduce the Mn dissolution during cycling process, which made it have better cycling performance than the commercial products. The electrochemical test results showed that 18650 cylinder batteries using this spherical-like Mn-spinel cathode material has an excellent cycle performance with the capacity retention of 80% after 2500 cycles at room temperature. Even at elevated temperature of 60℃, the capacity retention still reached 80% after 400 cycles.