Computational screening of spinel structure cathodes for Li-ion battery with low expansion and rapid ion kinetics

Abstract

Lithium ion batteries (LIBs) dominate the market of energy storage systems due to their high energy density and light weight. Spinels, a group of environmentally friendly, low cost and thermal stable materials, have been reported as high-performance cathode candidates of LIBs. In spinel LIBs, Mn-based spinels (LiMnO4) have been widely studied, and further reports have been carried out on the doping of LiMnO4 structures to suppress the disproportionation reaction of the Mn3+. However, the application of spinel cathodes in LIBs is still affected by the volume expansions and slow ion diffusion kinetics. In this work, we generated 62 spinel materials from the periodic table based on the widely studied LiB2X4 and LiMn1.5B0.5X4 structures (i.e., Mn-based spinel with doping of elements B), where the element B can be chosen from the Co, Cr Fe Ir, Mn, Mo, Ni, Pd, Pr, Rh, Ti, V, Ce, Tb, Ru or Ta while the element X can be an anion of O or S. Based on the density functional theory (DFT), the electronic conductivities, expansion coefficients and ion kinetics of the selected 62 spinel structures were predicted. Finally, we screened out 18 structures having excellent electronic conductivity (i.e., the band gap, Eg = 0), low expansion coefficient (<10%) and low diffusion energy barrier (<0.4 eV). In addition, 8 spinel structures were found to be superionic conductor with extremely high ionic conductivity (>10−4 S·cm−1). The proposed work not only filtered out the spinel electrode materials with the best performance for LIBs and found the superionic conductor based on lithium spinel, but also provided an efficient solution for the search of other excellent electrode materials with optimal structures.