Improvement in Electrochemical Performance of Lithium Rich Li2RuO3 Cathode With Co-doping Strategy

Abstract

Lithium-rich layered oxides based on Ru are interesting as cathode materials because they have high energy density and reversible capacity. However, due to the problems of weak structural stability and voltage decay, their commercial utility is limited. To address this, we use a DFT+U quantum mechanics to investigate the co-doping strategy on Li2RuO3 (LRO) for improved battery performance. In particular, the effect of two co-dopants Ti and Co has been studied. The co-doping strategy has been found to significantly improve the structural and thermal stability of LRO. By slowing the oxygen removal reaction, Ti and Co improve structural stability. Co-doping with Ti and Co increases the maximum open circuit voltage at least by 5.5% and decreases the voltage reduction by a minimum of 44%. Bandgap is also increased by a minimum of 6% with co-doping. In particular, Li2Ru0.5Ti0.375Co0.125O3  provides the highest maximum voltage of 4.4V with 61% decrease in the voltage reduction and 40% lower bandgap (0.45eV).