A review on the recent advancement of metal-boride derived nanostructures for supercapacitors

The main limitation standing for the fabricating of the supercapacitors compared to the batteries is their low energy densities. Recently, great efforts have been made to improve the energy densities to levels achieved in batteries without losing their power densities. Facing this challenge, the improvement of high-performance electrode materials is of great importance. As an electrode material, transition metal borides have been a possible choice for supercapacitors because of their superior conductivity and great electrochemical properties. In the periodic table of elements, the metallic characteristics of boron (B) are higher than those of oxygen, sulfur, selenium, and phosphorus, proposing that transition metal borides have better electronic properties. Also, the electron-deficient nature of the boron atom promotes the adsorption of ions during the electrochemical reaction and therefore it performs a critical role in the ability to store the charge. This comprehensive review aims to provide an overview of the recent advancements in transition metal borides for supercapacitors. The review examines various fabrication methods employed for Ni, Co, bimetallic, or ternary borides and their impact on the structure and surface chemistry of these materials. Subsequently, the review then delves into the capacitive energy-storage mechanisms associated with transition metal borides, shedding light on the factors that influence their electrochemical behavior and overall performance in supercapacitors. Furthermore, the various types of transition metal boride-based supercapacitors are thoroughly summarized to emphasize the significant role played by transition metal borides in the construction of efficient energy storage devices. To conclude, the review discusses the existing challenges and prospects within this rapidly growing field, aiming to facilitate further advancements in transition metal borides utilization for supercapacitors.