A Review of MnO₂ Composites Incorporated with Conductive Materials for Energy Storage

Manganese dioxide (MnO₂) has been widely used in the field of energy storage due to its high specific capacitance, low cost, natural abundance, and being environmentally friendly. However, suffering from poor electrical conductivity and high dissolvability, the performance of MnO₂ can no longer meet the needs of rapidly growing technological development, especially for the application as electrode material in metal-ion batteries and supercapacitors. In this review, recent studies on the development of binary or multiple MnO₂-based composites with conductive components for energy storage are summarized. Firstly, general preparing methods for MnO₂-based composites are introduced. Subsequently, the binary and multiple MnO₂-based composites with carbon, conducting polymer, and other conductive materials are discussed respectively. The improvement in their performance is summarized as well. Finally, perspectives on the practical applications of MnO₂-based composites are presented.