Dual Pseudocapacitive Oxides Accelerate Kinetics of Sulfur Intermediates in Lithium-Sulfur Batteries

Abstract

The sluggish electrochemical kinetics of sulfur species has impeded the wide adoption of lithium-sulfur battery, which is one of the most promising candidates for next-generation energy storage system. Here, we present the electronic and geometric structures of all possible sulfur species and construct an electronic energy diagram to unveil their reaction pathways in batteries, as well as the molecular origin of their sluggish kinetics. By decoupling the contradictory requirements of accelerating charging and discharging processes, we select two pseudocapacitive oxides to enable the efficient transport of electron/Li+ to and from sulfur intermediates respectively. After incorporating Li x Nb2O5/Nb2O5 as electron-ion source and MnO2/Li y MnO2 as electron-ion drain, the electrochemical kinetics of sulfur cathode is significantly accelerated by a factor of 5 times and 1.8 times, respectively. This strategy, which couples a fast-electrochemical reaction with a spontaneous chemical reaction to bypass a slow-electrochemical reaction pathway, offers a solution to accelerate an electrochemical reaction, providing new perspectives for the development of high-energy battery systems.