N-Doped Three-Dimensional Graphene-Loaded Co as a Sulfur Carrier for High-Performance Lithium–Sulfur Batteries

Lithium–sulfur batteries (LSBs) hold significant promise as next-generation energy storage solutions for electric vehicles (EVs), owing to their unparalleled theoretical energy density and inherent environmental benignity. However, the shuttle effect of polysulfides and the low conductivity of sulfur have hindered their practical application. To surmount these barriers, we report the rational design of three-dimensional nitrogen-doped graphene (3D NG) frameworks decorated with cobalt nanoparticles (denoted as Co-NG) through a controlled two-step carbonization strategy. The three-dimensional graphene framework offers a high specific surface area and superior electrical conductivity, thereby establishing a highly efficient pathway for the rapid transfer of ions and electrons. Additionally, its abundant porous structure effectively mitigates the volume expansion of sulfur during charge–discharge cycles. Moreover, the cobalt nanoparticles and nitrogen doping impart strong adsorption capabilities and catalytic activity toward lithium polysulfides (LiPSs), effectively suppressing their shuttle effect. Benefiting from the aforementioned merits, Co-NG, as a sulfur-carrying carbon material, demonstrates remarkable cycling stability in LSBs. Specifically, at a current density of 1 C, the battery retains 56.7% of its initial capacity after 700 cycles, with an average capacity decay rate of merely 0.062% per cycle. This work presents a viable approach for the development of carbon-based sulfur carrier materials, paving the way for high-performance LSBs.