Progress and challenges in carbon nanomaterial-based supercapacitors: Towards sustainable high-energy storage

Graphene and nanotubes are examples of carbon nanomaterials that are highly conductive, possess high surface area and adjustable porosity thus can make charge discharge, high power density and long life cycle a reality in supercapacitors. However, low energy density, structural degradation, and voltage-induced interfacial instability arising from electrolyte decomposition, carbon corrosion, and interfacial degradation remain key obstacles to practical implementation. Structural and surface properties of chemistry are linked to the electrochemical behavior and the approaches to enhance the charge storage, rate performance, and the reduction of failure mechanisms are categorized in this review. MOF-based ultrathin carbons and 3D lattice's structure hierarchy is beneficial because it decreases the transport distances between ions in thick electrodes, increasing areal measures. The doping of hetero atoms, in particular, nitrogen, regulates electronic structure and quantum capacitance, providing nitrogen with an excellent instrument in raising higher double-layer storage. A representative example is provided by MnO 2 /carbon nanostructures, in which conductive carbon skeletons are hybridized with pseudocapacitive components to optimize the trade-off between energy density, power output, and cycling stability. Devices of high volume and flexible are produced using printing and roll-to-roll processing in high-speed rate. The application of biomass-based carbons and low-tortuosity scaffoldings are also applauded as the future of multifunctional, long-term, supercapacitors and commercial applications. Distinct from prior reviews, this work emphasizes design-driven synthesis by systematically benchmarking carbon nanomaterial strategies across material classes, device architectures, voltage windows, mass loadings, and electrolytes to extract practical structure–performance guidelines. This review systematically discusses material design principles, synthesis strategies, structure–property relationships, and electrochemical performance metrics, followed by current challenges and future research directions. • Comprehensive review of carbon nanomaterials (0D–3D) for high-performance supercapacitors. • Correlates hierarchical pore design and heteroatom doping with improved energy and power density. • Discusses mechanism-aware stability and interfacial protection strategies for long cycle life.