Thermal spray coatings in batteries, electrolyzers and solid oxide electrochemical systems

Energy systems based on electrochemically active materials frequently suffer from poor performance and limited lifetimes due to interfacial problems that can be mitigated by micro- to nanoscale structuring with thermal spray coatings (TSC). This review synthesizes existing knowledge and develops a process-structure-property framework that uniquely links TSC process parameters to the coating microstructure and interfacial chemistry across different electrochemical systems, with a focus on innovative cross-system design principles. This review covers various TSC technologies (atmospheric plasma spray, suspension plasma spray, high-velocity oxy-fuel, and cold spray) with reference to their ability to control porosity and phase distribution. These process parameters affect ion or electron conduction, interfacial resistance, and mechanical stability. The issues of transport limitations caused by porosity, inter-splat bonding, and non-equilibrium phase transformations were studied. Functionally graded interfaces, adaptive coating systems, and machine learning-based process development are innovative approaches investi­gated to achieve defect-tolerant functional interfaces. This study offers guidelines for designing next-generation TSC that are more durable, scalable, and exhibit better electro­chemical properties, thereby improving the performance and lifespan of electrochemical energy systems. The battery, proton exchange membrane, alkaline fuel cells and solid oxide fuel cell/solid oxide electrolysis cell systems were analysed with respect to one another to establish general process-structure-property relationships for electrochemical interfaces.