Carbonaceous Catalyst Boosting Conversion Kinetics of Na2S in Na-ion Batteries

Conversion-type metal sulfide anode with high theoretical capacity has received increasing attention in Na-ion batteries (SIBs), but the irreversible conversion of Na2S intermediate in charging process usually engenders low rate capability and poor cycling stability. Herein, guided by DFT calculation, a new-type carbonaceous graphitic carbon nitride (g-CN) catalyst is first reported to boost conversion kinetics of Na2S intermediate to pristine MoS2 in SIBs. Notably, the large chemisorbed energy, high selectivity and low catalytic energy barrier of g-CN catalyst can ensure its affluent charge transfers to Na2S intermediate, which chemically anchor and decompose Na2S intermediate for catalyzing its reversible conversion. Moreover, the microfluidic strategy is developed to enhance the mass diffusion of g-CN catalyst precursors into MoS2 skeleton for facilitating their subsequently covalent bonding process. The covalent bonding of g-CN catalyst on 1T-MoS2 (1T-MoS2/g-CN) superlattice with strong interfacial interaction via C-Mo bond can greatly promote Na+-storage kinetics of MoS2 in discharging process and reversible conversion reaction of Na2S intermediate to pristine MoS2 in following charging process, which is further evidenced by DFT calculation and in-situ characterizations. Consequently, the 1T-MoS2/g-CN superlattice reveals superb rate capacity and excellent cycling stability.