Preparation of LiMn₂O₄ cathode with excellent cycling performance

In order to enhance the rate capability as well as the cycleability at room temperature and elevated temperature, an especial method to modify pure spinel LiMn₂O₄ was investigated. Both of pristine LiMn ₂O₄ and modified-LiMn₂O₄ were characterized by XRD, SEM, EDAX and electrochemical techniques. XRD results showed that modified-LiMn₂O₄ did not change the basic LiMn₂O₄ structure. SEM and EDAX indicated that the thin LiNi_xMn_2.xO₄ solid solution layer was covered uniformly on the surface of modified-LiMn₂O₄. CV and charge-discharge tests at room temperature revealed that modified-LiMn ₂O₄ had excellent cycle stability compared to pristine LiMn₂O₄, maintained 97.6% of the maximal discharge capacity after the 190 cycles, however, only 68.3% after 170 cycles for pristine LiMn₂O₄. In addition, modified-LiMn₂O ₄ showed superior cycling performance at the elevated temperature and better rate capability than pristine LiMn₂O₄. The improving remarkably is attributed to that the solid solution layer reduces the dissolution of Mn cations and suppresses the Jahn-Teller distortion. copyright The Electrochemical Society.