Rational design of porous nitrogen-doped Ti3C2 MXene as a multifunctional electrocatalyst for Li–S chemistry

Abstract

The detrimental shuttle effect and retarded sulfur reaction kinetics in lithium–sulfur (Li–S) chemistry mainly lead to inferior electrochemical performances, posing a fatal threat to the practical application of Li–S batteries. Herein, porous N-doped Ti3C2 MXene (P-NTC) has been realized by a scalable sacrificial templating route, resulting in the rational design of active electrocatalyst for Li–S chemistry. Benefiting from the superb electron conductivity, large surface area and strong interaction with lithium polysulfides (LiPSs), P-NTC can trigger the surface-mediated redox reaction of LiPSs. Moreover, the homogenous nitrogen doping on Ti3C2 gives rise to enhanced interfacial interaction with Li atom and lowered dissociation barrier for Li2S. Therefore, the template-derived P-NTC not only acts as an effective LiPS immobilizer but also serves as a multifunctional electrocatalyst to propel the nucleation and decomposition of Li2S in discharge and charge processes, respectively. As expected, thus-fabricated S/P-NTC cathode maintains a low capacity decay of only 0.033% per cycle at 2.0 C over 1200 cycles. In further contexts, our ability to tune the sulfur mass loadings enables fabricated cathodes to harvest a high areal capacity of 9.0 mAh cm−2, holding great promise in future practical applications.