Boron-driven energy technologies: Borophene and its derivatives in supercapacitors

Abstract

Boron-based two-dimensional materials have emerged as promising candidates for high-performance supercapacitor electrodes owing to their intrinsic high conductivity, structural tunability, and excellent chemical stability. Within this family, borophene stands out for its metallic transport behavior, ultrahigh carrier mobility, pronounced anisotropic Dirac dispersion, and remarkable mechanical flexibility. Theoretical studies further reveal a significantly enhanced electronic density of states near the Fermi level, endowing borophene with an high quantum capacitance (>1900 F·g⁻¹), while experimentally fabricated CVD-grown borophene electrodes have demonstrated specific capacitances exceeding 350 F·g⁻¹. In parallel, transition-metal borides and their derivatives, characterized by strong M-B covalent bonding, metallic conductivity, and multivalent redox activity, offer substantial pseudocapacitive contributions, with typical specific capacitances of 600-800 F·g⁻¹ and competitive rate capability and cycling durability. Taken together, borophene and borides constitute a coherent “boron-driven” materials space that couples quantum electric-double-layer storage with faradaic charge transfer in a single compositional landscape, enabling simultaneous optimization of energy density, power density, and durability. This review systematically summarizes recent advances in the synthesis, structural engineering, electronic properties, and electrochemical performance of borophene and borides, establishing correlations between their intrinsic physicochemical characteristics and charge-storage mechanisms. Moreover, we critically examine the key challenges that remain, including the limited scalability of high-quality borophene synthesis, its susceptibility to oxidation, interfacial instability, compositional control in multimetal borides, and the still-incomplete understanding of underlying storage mechanisms. Finally, we outline future research directions, such as atomic-scale structural design, heterointerface engineering, multidimensional hybrid architectures, and sustainable manufacturing strategies, which are expected to advance the practical deployment of boron-based materials in next-generation high-performance energy-storage systems.