Bicontinuous Transition Metal Phosphides/rGO Binder-free Electrodes: Generalized Synthesis and Excellent Cycling Stability for Sodium Storage

Transition metal phosphides (TMPs) have received considerable attention owning to their great potential in energy conversion and storage technologies. Elaborate design and synthesis of various TMPs with abundant structures in order to meet the requirement of various applications is one of the major goals and challenge of sustainable chemistry. In this work, an electrostatic spray deposition (ESD) approach has been developed, which demonstrates to be a general strategy to fabricate TMPs for the first time. Various bicontinuous TMPs/carbon nanocomposites can be constituted by this approach. This novel architecture, when applied in the energy storage system, can provide an efficient electron/ion mixed-conducting network, therefore inducing fast electron/ion transfer kinetic and enhancing the structural stability upon long term cycling. As a proof of the concept application, 3D porous Cu3P/rGO nanocomposites as modeling anodes for Na-ion storage show excellent cycling performance and remarkable rate capacities. The sodium storage mechanism is proposed to be a reversible conversion reaction. The microstructural evolution of the electrodes upon cycling correlates well with the capacity variation. The facile and versatile ESD technique is quite universal and can be further extended to various TMPs. This opens exciting opportunities for the incorporation of TMPs in a variety of new applications.