Mo2C catalyzed low-voltage prelithiation using nano-Li2C2O4 for high-energy lithium-ion batteries

Abstract

Irreversible lithium loss in the initial cycles appreciably reduces the energy density of lithium-ion batteries. Prelithiation is an effective way to compensate for such lithium loss, but current methods suffer from either the instability or low capacity of prelithiation reagents. Lithium oxalate (Li2C2O4) has shown great potential as a lithium-compensation material because of its high theoretical capacity (equivalent to lithium metal), low cost, and air stability. However, the practical applications of Li2C2O4 are limited by its low electrochemical activity and high critical decomposition voltage. In this study, we performed the prelithiation of a low-voltage cathode by using Mo2C catalysis and nano-Li2C2O4. Results show that the Mo2C catalyst changes the electron cloud distribution around Li2C2O4 and greatly reduces the activation energy, thereby significantly accelerating the lithium release from Li2C2O4. The nano-Li2C2O4 prepared by freeze-drying shows accelerated ionic and electronic conduction as well as close contact with Mo2C. Benefiting from the synergistic effect, the decomposition potential of Li2C2O4 is decreased by 0.5 V with an efficiency close to 100%. The LiCoO2∥SiO full cell empowered with the nano-Li2C2O4/Mo2C prelithiation composite demonstrates 46.9% higher capacity than the control and thus has great potential for practical applications.