2D Nano‐Channeled Molybdenum Compounds for Accelerating Interfacial Polysulfides Catalysis in Li–S Battery

Abstract

The shuttle effect, which causes the loss of active sulfur, passivation of lithium anode, and leads to severe capacity attenuation, is currently the main bottleneck for lithium‐sulfur batteries. Recent studies have disclosed that molybdenum compounds possess exceptional advantages as a polar substrate to immobilize and catalyze lithium polysulfide such as high conductivity and strong sulfiphilicity. However, these materials show incomplete contact with sulfur/polysulfides, which causes uneven redox conversion of sulfur and results in poor rate performance. Herein, a new type of 2D nano‐channeled molybdenum compounds (2D‐MoNx) via the 2D organic‐polyoxometalate superstructure for accelerating interfacial polysulfide catalysis toward high‐performance lithium‐sulfur batteries is reported. The 2D‐MoNx shows well‐interlinked nano‐channels, which increase the reactive interface and contact surface with polysulfides. Therefore, the battery equipped with 2D‐MoNx displays a high discharge capacity of 912.7 mAh g−1 at 1 C and the highest capacity retention of 523.7 mAh g−1 after 300 cycles. Even at the rate of 2 C, the capacity retention can be maintained at 526.6 mAh g−1 after 300 cycles. This innovative nano‐channel and interfacial design of 2D‐MoNx provides new nanostructures to optimize the sulfur redox chemistry and eliminate the shuttle effect of polysulfides.

Sieve Tube‐Inspired Polysulfide Cathode with Long‐Range Ordered Channels and Localized Capture‐Catalysis Microenvironments for Efficient Li–S Batteries

“…[8,9] To overcome these problems, numerous electrocatalysts have been developed and introduced into the sulfur cathode to accelerate the polysulfide conversion, which is considered to be an effective strategy to alleviate the shuttle effect. Among these, the metal sulfides, [10][11][12] oxides, [13][14][15][16] nitrides, [17][18][19][20][21] and their heterojunction, [22][23][24] have been investigated as efficient catalysts by polar-polar interactions with LiPSs to accelerate the LiPSs conversion and realized excellent Li-S battery performance. [14] Nonetheless, to ensure the overall energy density of entire batteries, it's necessary to reduce the weight percentage of inactive additives as much as possible, thus presenting an even tougher challenge to the efficiency of LiPSs catalysts.…”