Rational design of hierarchically structured dual-encapsulated CoMoO₄ nanosheets via in situ plasma tuning for efficient Li⁺ storage

Abstract: Engineering electrodes with desirable nanostructures are regarded as an urgent challenge to achieve enhanced electrical conductivity, stable structural integrity, and advanced performance for Li⁺ storage. Various approaches with processing complexity and multiple reactions have suffered serious limitation in industrialization. Here, we develop a facile carbon plasma (C-plasma) strategy combined with controlled reaction temperature to achieve in situ hierarchical metallic nanoparticles and graphene-encapsulated CoMoO₄ nanosheets (hCCO). The nano-frameworks of Co₃Mo and graphene shell are simultaneously modulated via simply controlling reaction temperature. The incorporation of nanoalloy component effectively enhances the conductivities of nanosheet, and uniformly coated graphene releases the structural stress caused by conversion reaction of metal oxides, maximizing the capacity utilization. The synergetic combination of these advantages enables the synthesized hCCO to deliver excellent electrochemical performances. Our C-plasma exhibits a great potential in tuning nano-architectures with high-performance Li⁺ storage behavior. Impact statement: Designing electrode with controllable nano-framework for high-performance lithium-ion batteries is a formidable challenge. A typical strategy to improve the structural integrity and performance of electrode during cycling is to use metallic and carboneous dual encapsulation to integrate the advantages of both encapsulations. Most approaches of dual encapsulation use environmentally hazardous species and long-term annealing with multi-reaction steps, restricting the scalable application. Our work provides a facile carbon plasma (C-plasma) strategy to achieve hierarchical dual encapsulation with tunable nanostructures. The metallic nanostructures and graphene shell can be precisely controlled by simply modulating plasma processing temperature. Moderate temperature (450°C) and rapid C-plasma treatment (30 s) allow for the structural integrity of the resultant hierarchically dual-encapsulated CoMoO₄ (hCCO) composites. Our C-plasma-based approach provides binder-free electrode that delivers Li-ion storage with high specific capacity of 641 mA h g⁻¹ with imposing cycling performance for 1000 cycles at 1.6 A g⁻¹. Our C-plasma technique, unveils a novel and simple pathway in tuning nano-architectures with dual encapsulation for high-performance energy-storage materials. Graphical Abstract: [Figure not available: see fulltext.]