Lithium Manganese Spinel Cathodes for Lithium-Ion Batteries

Spinel LiMn₂O₄, whose electrochemical activity was first reported by Prof. John B. Goodenough's group at Oxford in 1983, is an important cathode material for lithium-ion batteries that has attracted continuous academic and industrial interest. It is cheap and environmentally friendly, and has excellent rate performance with 3D Li⁺ diffusion channels. However, it suffers from severe degradation, especially under extreme voltages and during high-temperature operation. Here, the current understanding and future trends of the spinel cathode and its derivatives with cubic lattice symmetry (LiNi_0.5Mn_1.5O₄ that shows high-voltage stability, and Li-rich spinels that show reversible hybrid anion- and cation-redox activities) are discussed. Special attention is given to the degradation mechanisms and further development of spinel cathodes, as well as concepts of utilizing the cubic spinel structure to stabilize high-capacity layered cathodes and as robust framework for high-rate electrodes. “Good spinel” surface phases like LiNi_0.5Mn_1.5O₄ are distinguished from “bad spinel” surface phases like Mn₃O₄.