Integrating a three-dimensional Cu2MoS4 electrode and solid-state polymer electrolyte for sodium-ion batteries

The improvement of solid-state batteries (SSBs) in terms of safety performance and energy density has an unusual significance for it to apply to power batteries, and the interface matching of solid-state electrolytes and adapted electrode materials has become the key. Due to poor electrode-electrolyte interface contact in SSBs which could result in low ionic conductivity, we designed a 3D integrated electrode constructed from a Cu2MoS4 electrode grown in situ on the surface of copper foam with a polymer-in-salt solid electrolyte based on PVDF-HFP. The ion clusters formed by NaPF6 near the PVDF-HFP network structure can effectively shorten the Na+ transport path, and then adding 1-(4-cyanophenyl)-guanidine can also provide more ion transport routes by forming coordination bonds. The polymer electrolyte exhibited excellent ionic conductivity (1.67×10−5 S cm−1 at room temperature) and electrochemical stability (5.6 V vs Na|Na+). At the same time, it showed excellent stability during the cycle performance test of the symmetrical batteries, compared with the liquid electrolytes, the polymer-in-salt solid electrolytes were not short circuit under the same test conditions, indicating that the polymer-in-salt solid electrolytes can effectively inhibit the growth of Na dendrites. This 3D integrated electrode exhibited excellent interface-contact compatibility, mechanical stability, and electrochemical performance closed to that of liquid electrolytes and even outperformed liquid electrolytes at a high rate cycle.