The global drinking water crisis has driven the development of efficient desalination technologies, with capacitive deionization (CDI) gaining attention due to its low energy consumption and environmental friendliness. However, traditional carbon-based electrodes face challenges such as low desalination capacity and side reactions. This study explores the design and application of transition metal compound-based electrode materials to enhance CDI performance. Carbon-coated sodium vanadium phosphate (NVP@C), with a high theoretical capacity and excellent ion mobility, demonstrated strong performance under varying salt concentrations. To enhance long-term stability, a 3D hydrogel composite of copper ferrocyanide and polypyrrole (CuHCF@PVA/PPy) was developed, providing improved conductivity, mechanical resilience, and cycle life. Together, these materials show great promise in advancing high-performance CDI desalination systems.