Direct Laser-Printing of Molecularly-Dispersed Strongly-Anchored Sulfur-Graphene Layers as High-Performance Cathodes for Polysulfide Shuttle Effect-Inhibited Lithium-Sulfur Batteries

Sulfur has recently emerged as a promising cathode material for lithium-ion batteries, offering high theoretical capacity and low cost. Its abundant availability and environmentally friendly nature make it an attractive alternative to conventional cathode materials. However, challenges such as sulfur's intrinsically low electrical conductivity and rapid degradation during cycling still need to be overcome for its widespread adoption in commercial batteries. This study presents an innovative, scalable and straightforward strategy to overcome these challenges of sulfur cathodes in lithium battery applications. Here, we present a novel method, using low-power laser irradiation to fabricate three-dimensional highly micro-porous molecularly dispersed and strongly anchored sulfur-graphene composite electrodes. By subjecting sulfur-embedded carbon precursors to laser irradiation, a well-structured graphene composite is formed, while molecularly-entrapping the sulfur moieties within its framework. This 3D porous architecture provides high surface area for improved electrolyte wetting, efficient ion transport, and effectively accommodates volume changes during cycling while strongly entrapping the active sulfur moieties and remarkably inhibiting the occurrence of the detrimental polysulfide shuttle effect. The resulting sulfur-graphene cathodes exhibit exceptional electrochemical properties. They demonstrate remarkable cyclic stability, sustaining over 1500 cycles with impressive capacity retention of >70% at fast cycling rates, and registering over 1000 mAh g-1 at lower rates with >70% retention over 400 cycles. Furthermore, high sulfur loading ratios, compatible to real world battery applications, are readily attainable. The simplicity and versatility of this laser-based writing single-step approach open various new avenues for the scalable and cost-effective production of high-performance lithium-ion batteries. This development brings us closer to realizing efficient energy storage solutions for various applications, from portable electronics to electric vehicles and grid storage systems.