Transition Metal Selenide (TMSe) electrodes for electrochemical capacitor devices: A critical review

Abstract

The increasing demand for clean energy is a primary force driving the energy storage industry's innovations and the search for cost-affordable materials with high specific energy. Developing novel materials and scalable production processes is essential for the advancement of supercapacitor technologies in both scientific exploration and practical applications. To this end, transition metal selenides (TMSes) are a class of materials that can provide the required specs to realize such technology. Herein, a wide range of TMSe materials have been reviewed and discussed, including monometallic and binary metallic selenides. In particular, we shed the light on the diverse strategies adopted to boost the capacitive performance of TMSe-based devices, while highlighting the pros and cons of the currently used materials and ways to further enhance the performance of such materials. Moreover, we demonstrated the significance of controlling the fabrication parameters including molar ratios of different metals, utilizing shape directing agents, the reaction duration, and the heating rate during the synthesis process in constructing diverse hierarchal structures and versatile morphologies with higher specific surface area, more accessible active sites, and facile diffusion pathways. Also, the effect of hybridizing TMSe with different carbon or faradic-based materials on enhancing the specific surface area, the electrical conductivity, and the cyclic performance of the designed electrodes is illustrated. We hope this review will provide a roadmap to the researchers to better design high-performance supercapacitor devices based on TMSes.