**4.3 Energy storage devices**

The popularity for relatively speaking high power and energy density values, as well as good cycle life, has grown massively in the field of energy storage to assist the fast expanding businesses of mobile and adaptable digital equipment, e-mobility, and machine tools, and also the growing economies of power grid applications. Due to their flexible applicability, conductivity, surface area, aspect rations, stability, electrochemical potential windows are relatively high in Nanodiamonds which will make this material a desirable choice in energy storage systems. The advancement of ND-based electrode materials has been hastened by the discovery of effective methods for growth of Nanodiamond on conducting layers under sub-atmospheric environments. The Nanodiamond's nature can be changed by using an acceptor type doping substance (boron). Boron-doped diamond electrodes are extremely stable over a long range of operating potentials, even in water. HPHT, PECVD, and ion-implantation procedures are commonly used to dope NDs, with PECVD being the favored method for device construction as it allows both n and p-type Nanodiamonds to manage impurity concentrations [27]. In comparison with carbon containing electrodes or metals, Nanodiamond electrodes (conducting) doped substantially with boron have several interesting properties. Moreover, oxidized Nanodiamond electrodes has a higher capacitive current than hydrogen terminated Nanodiamond electrodes [28]. Surface functionalization of NDs can also be used to boost the ion-storage capacity of Nanodiamond-based electrodes by introducing extra pseudo-capacitive processes [29]. Different techniques, like as plasma and electrochemical treatments, can be used to terminate the surface of NDs with H2, O2, or OH groups, allowing for adjustable aqueous and due to the hydrophobic water sorption in anti-adherent scalpels and self-cleaning protective coatings [30]. In other words, the electrical characteristics of ND/electrolyte interfaces can be changed by aligning the energies of interaction levels properly. As a result, NDs have been used in energy-related applications as electrodes.
