In the most recent years, carbon-based nanocomposites have been developed to satisfy the energy demand throughout the globe. Carbon-based nanocomposites are microscopic materials with size 1–100 nm and are often created by combining different materials such as polymer and alloys. Due to its tunable physical and chemical characteristics such as nanosize, shape, and increased surface-to-volume ratio of carbon complex matrix, these nanocomposites possess enhanced mechanical strength, toughness, and their thermal and electrochemical conductivity. Due to its excellent characteristics, carbon-based nanomaterials have found with a variety of applications such as storage, sensors, catalyst, electrodes, and so on. Carbon nanomaterials have been successfully applied in the commercial sectors nowadays, especially in the automobile industries due to its lower manufacturing cost, eco-friendly, and long durability. In addition to giving a brief overview of the carbon-based nanocomposites that are frequently employed in energy-harvesting applications, this chapter concentrates on the employment of various kinds of carbon nanomaterials in the development of storage applications.