Ultrafine zirconium boride nanoparticles constructed bidirectional catalyst for ultrafast and long-lived lithium-sulfur batteries

Abstract

Multi-functional host materials possess high conductivity and strong chemical adsorption ability that could directionally catalyze electrochemical conversion of lithium polysulfides, therefore, their rational design is considered to be an effective strategy to solve the notorious “shuttle effect” for Li-S batteries. Herein, ultrafine zirconium boride (ZrB2) nanoparticles of high conductivity is conveniently fabiricated via a solid-state synthesis at relatively low temperature and applied as sulfur host material. The obtained ZrB2/Nitrogen-doped graphene/S (defined as “ZrB2/NG/S”) cathode stably works for 135 cycles at ultrahigh rate of 20 C with capacity of ∼400 mAh g−1. It is worth to note that a long-term cycling performance has been achieved with low decay rate of 0.02% per cycle within 4000 cycles at 5 C. Moreover, the designed cathode delivers an areal capacity of 6.43 mAh cm−2 upon a high sulfur loading (7.77 mg cm−2) with a lean electrolyte at 1C. Investigations including kinetics analysis, deposition/dissolution of Li2S, in-situ XRD, and density functional theory have been further conducted, and the successfully assembled pouch cell shows a high capacity. The high conductivity, strong chemical adsorption, and bi-functional catalytic ability of ZrB2 based composite endow its high potential for practical application.