Facile Synthesis of Salt-Assisted Multiroom Carbon/Vanadium Sulfide Microspheres for Fast and Durable Potassium-Ion Storage

Potassium-ion batteries hold great promise for large-scale energy storage, but their commercialization is hindered by the large ionic radius of potassium, which causes sluggish kinetics and severe volume expansion in anode materials. To address this, we present a scalable spray-drying strategy coupled with NaCl salt-templating to synthesize hierarchical porous carbon/vanadium sulfide microspheres (p-V3S4/C MS). In this structure, V3S4 nanoparticles are uniformly encapsulated within a dextrin-derived amorphous carbon matrix, and pores are formed via selective NaCl etching. This unique architecture accommodates volume fluctuations while providing rapid ion diffusion pathways. As a result, the p-V3S4/C MS anode exhibits outstanding electrochemical performance, maintaining a reversible capacity of 107 mA h g−1 after 2000 cycles at 2.0 A g−1, and achieves a high pseudocapacitive contribution of 93% at 2.0 mV s−1. Furthermore, a full cell paired with a Prussian blue (PB) cathode demonstrates practical viability and robust reversibility. Our findings demonstrate that this structural engineering effectively mitigates internal resistance and structural degradation, offering a cost-effective route for mass-producing high-performance anodes for next-generation energy storage.