Studies on capacity fade of spinel based Li-ion batteries

Abstract

This paper focuses on studying the performance of Li-ion cells using LiMn 2O 4 as the positive electrode material. The capacity of the cell has been optimized based on varying the charging current and the end potential. The capacity fade of these batteries has been studied at different charge currents, namely 0.1 A, 0.25 A, 0.5 A, 0.75 A and 1 A. The discharge rate for all cells was kept constant at 1 A. The lowest capacity fade is seen for the cell charged at 0.5 A indicating that this was optimum charging current for these batteries. For all charge currents, the resistance of the LiMn 2O 4 cathode remains lower than that of the carbon anode with cycling. This result is in contrast with cells made with LiCoO 2 cathode where the increase in cathode resistance with cycling causes the fade in capacity. XRD studies of carbon and LiMn 2O 4 at different cycles, reveals no structural changes. However, the lattice constants vary with cycling indicating changes in the lithium intercalated at both electrodes. Further studies are being done to understand the cause for the capacity fade.