Recyclable cobalt-molybdenum bimetallic carbide modified separator boosts the polysulfide adsorption-catalysis of lithium sulfur battery

Abstract

The polysulfide shuttling and sluggish redox kinetics, due to the notorious adsorption-catalysis underperformance, are the ultimate obstacles of the practical application of lithium-sulfur (Li-S) batteries. Conventional carbon-based and transition metal compound-based material solutions generally suffer from poor catalysis and adsorption, respectively, despite the performance gain in terms of the other. Herein, we have enhanced polysulfide adsorptioncatalytic capability and protected the Li anode using a complementary bimetallic carbide electrocatalyst, Co 3 Mo 3 C, modified commercial separator. With this demonstration, the potentials of bimetal compounds, which have been well recognized in other environmental catalysis, are also extended to Li-S batteries. Coupled with this modified separator, a simple cathode (S/Super P composite) can deliver high sulfur utilization, high rate performance, and excellent cycle stability with a low capacity decay rate of~0.034% per cycle at 1 C up to 1000 cycles. Even at a high S-loading of 8.0 mg cm −2 with electrolyte/sulfur ratio=6 mL g −1 , the cathode still exhibits high areal capacity of~6.8 mA h cm −2. The experimental analysis and the first-principles calculations proved that the bimetallic carbide Co 3 Mo 3 C provides more binding sites for adsorbing polysulfides and catalyzing the multiphase conversion of sulfur/polysulfide/sulfide than monometallic carbide Mo 2 C. Moreover, the modified separator can be reutilized with comparable electrochemical performance. We also showed other bimetallic carbides with similar catalytic effects on Li-S batteries and this material family has great promise in different energy electrocatalytic systems.

Recent advance on Co‐based materials for polysulfide catalysis toward promoted lithium‐sulfur batteries

“…[ 132 ] Higher sulfur loading increases the areal capacity of the cathode, and maximizes the specific energy of the whole cell, because the increased fraction of active material offsets the “dead weight” present from the various inactive components like the current collectors and separator. [ 133 ] It can be seen that the realization of high sulfur loading is crucial for Li‐S batteries to enter the market out of the laboratory. Future investigations into the sulfur cathode should strive for sulfur loadings of above 5 mg cm –2 to reach practically relevant results.…”

“…In addition to the Co‐based materials discussed above, there are some other materials such as cobalt boride, [ 132 ] cobalt carbide, [ 133 ] cobalt‐MOF, [ 130 ] and cobaltocene [ 131 ] which play an obvious advantage in catalytic sulfur electrochemistry due to their unique characteristics. For example, Cobalt boride (Co 2 B) whose B element has a unique electronic structure with an empty orbital can anchor LiPSs through B‐S bonds.…”

“…reported a Co 3 Mo 3 C modified commercial separator to enhance LiPSs adsorption, catalytic capability and protected the Li anode. [ 133 ] Interestingly, they found that the Co 3 Mo 3 C provides more binding sites for adsorbing LiPSs and catalyzing the multiphase conversion of sulfur/LiPSs/sulfide than monometallic carbide Mo 2 C. Moreover, the modified separator can be reutilized with comparable electrochemical performance. Moreover, the modified separator can be reutilized with comparable electrochemical performance.…”

The Synergy of La2O3 Nanoparticles and Graphene for Advanced Li‐S Batteries

“…Lithium‐sulfur (Li−S) batteries enabling a theoretical energy density of 2600 Wh kg −1 , low cost and non‐toxic make them one of the most promising next‐generation batteries [1,2] . Nevertheless, the notorious polysulfide “shuttle effect” caused by the migration of soluble lithium polysulfides (LiPSs) between the cathode and anode severely limit the cycle stability and energy density of Li−S batteries, thereby hindering the practical use of Li−S batteries [3,4]…”

Lightweight freestanding hollow carbon fiber interlayer for high‐performance lithium‐sulfur batteries

“…To solve these issues, various strategies such as design of the cathode, 6‐10 modification of the separator, 11,12 and optimization of the electrolyte 13‐15 have been used. Interlayer inserted between the separator and the cathode is one of the most effective methods to enhance the conductivity and confine polysulfides 16,17 .…”