Review on Metal Nanowire-Based Electrodes for Asymmetric Supercapacitors: Advances and Outlook

Abstract As the demand for high-performance electrochemical energy storage systems continues to grow, metallic nanowire (MNW)-based electrodes have emerged as promising platforms to bridge the energy–power gap in asymmetric supercapacitors (ASCs). Their one-dimensional architecture can provide continuous electron-transport pathways and favorable ion-diffusion distances, while enabling highly conductive and potentially binder-free electrode architectures. However, the translation of MNW electrodes from laboratory demonstrations to practical ASC devices remains limited by the incomplete mechanistic understanding of structure–property–performance relationships, insufficient distinction between electrode-level and device-level metrics, and inconsistent performance reporting. This Review also thoroughly evaluates recent progress in MNW-based ASC electrodes by integrating key factors such as nanowire diameter, aspect ratio, network percolation, porosity, mass loading, and core–shell interface design with properties such as charge-transfer resistance, ion transport kinetics, cycling stability, and charge-storage mechanisms, including electric double-layer capacitance, pseudocapacitance, and battery-like behavior. Particular attention is given to synthesis strategies, structural engineering approaches, electrode material categories, and the role of positive and negative electrode pairing in asymmetric device configurations. The Review also emphasizes the need for standardized electrochemical evaluation by clearly distinguishing three-electrode-level measurements from full-device performance parameters such as energy density, power density, rate capability, and long-term stability. In addition, recent advances in characterization, including in situ and operando methods, are discussed as essential tools for revealing local electrochemical processes, structural evolution, and degradation pathways during cycling. By identifying underexplored high-performance nanowire systems and outlining key challenges in scalable fabrication, electrolyte optimization, interface stability, and computationally guided material design, this Review provides a forward-looking roadmap for accelerating the transition of MNW-based ASCs toward practical energy-storage applications.