Binder-free, multidentate bonding-induced carbon nano-oligomer assembly for boosting charge transfer and capacitance of energy nanoparticle-based textile pseudocapacitors

Energy storage performance of pseudocapacitors (PCs) critically depends on the integration and distribution of electrochemically active materials and conductive fillers as well as the intrinsic energy storage capacity of active materials. This is particularly challenging for nano-sized pseudocapacitive materials that offer high energy density but suffer from low electrical conductivity. Additionally, conventional electrode fabrication methods often neglect crucial interfacial interactions and electrolyte wettability essential for nanoparticle-based PC electrodes in a 3D structure, which can lead to performance degradation. Here, we present a novel approach to fabricate 3D-structured pseudocapacitor electrodes by directly and sequentially assembling hydrophobic energy nanoparticles (NPs) and hydrophilic carbon nano-oligomers (CNOs) with branched space arms onto 3D textile current collectors, eliminating the need of insulating and hydrophobic organic components. This assembly based on direct interfacial multidentate interactions between MnO_x NPs and CNOs ensure a uniform nano-level distribution over the entire metallic textile surface. The resulting positive electrodes (i.e., MnO_x NP/CNO-based textiles) exhibit the outstanding areal capacitance of ∼1,725 mF cm⁻² at 5.0 mA cm⁻². This capacitance can be further increased to ∼3,244 mF cm⁻² at 10 mA cm⁻² via a multi-stacking method. When paired with negative electrodes (i.e., Fe₃O₄ NP/CNO-based textiles) fabricated using the same approach, asymmetric full-cell demonstrate remarkable areal energy/power densities that surpass those of conventional pseudocapacitors.