Atomic bridging for constructing flexible boron-doped diamond supercapacitors with extended cycling longevity

Abstract

Boron-doped diamond (BDD) has emerged as a promising electrode material for supercapacitors (SCs); however, the issue of inadequate adhesion between the BDD electrode and the substrate has restricted its application in flexible electronic energy storage devices. This study introduces a titanium dioxide (TiO₂) layer to establish a sandwich structure between BDD and copper (Cu) foam. This configuration enhances adhesion and facilitates the fabrication of flexible BDDSC electrodes. The Cu₁₃₀/Ti/BDD configuration features a dense BDD film covering the Cu foam. In comparison to Cu₁₁₀/Ti/BDD (24.0 mF cm⁻²) and Cu₁₅₀/Ti/BDD (22.7 mF cm⁻²), the Cu₁₃₀/Ti/BDD electrode achieves a higher specific capacitance of 45.0 mF cm⁻². Additionally, the symmetrical Cu₁₃₀/Ti/BDDSC device demonstrates prolonged cycling durability that retains 91.5% of capacity after 100 000 cycles and exhibits impressive energy and power densities of 1.51 mJ cm⁻² and 0.42 mJ cm⁻², respectively. More importantly, the Cu₁₃₀/Ti/BDD electrodes can endure various bending levels while retaining a capacitance loss of less than 30%. This study establishes the viability of BDD as a flexible electrode for SCs and underscores its promising applications in wearable electronics.