<p>Energy storage technologies are fundamental to overcoming global energy challenges, particularly with the increasing demand for clean and efficient power solutions. Batteries and capacitors serve as the cornerstone of modern energy storage systems, enabling the operation of electric vehicles, renewable energy grids, portable electronics, and wearable devices. This review offers an in-depth analysis of these technologies, focusing on their fundamental properties, classifications, electrode materials, and electrolytes. Batteries are recognized for their high energy density, making them suitable for long-duration storage, while capacitors exhibit superior power density, making them ideal for fast charge–discharge applications. Key cathode materials such as lithium cobalt oxide, lithium nickel manganese cobalt oxide, and lithium iron phosphate are examined, along with anodes like graphite, silicon, and lithium metal. Capacitor electrodes including activated carbon, carbon nanotubes, and graphene are also discussed. The role of electrolytes—liquid, solid-state, and polymer-based—is analyzed in the context of ionic conductivity, stability, and electrode compatibility. The review further addresses degradation mechanisms, safety concerns, and scalability challenges while exploring hybrid systems that combine the strengths of batteries and capacitors. Emerging applications in electric vehicles, grid energy storage, and next-generation electronics are highlighted. Finally, we discuss future trends in sustainable materials, solid-state devices, and hybrid configurations, emphasizing the need for continued innovation to meet the demands of a sustainable and energy-efficient future.</p>