## 5 Applications
### Energy Storage
The ball milling method leads to a reduction in the contact resistance between layered oxide material and carbon results in increased conductivity of lithium ions and improves the performance of battery. Anode material prepared by Si powder and carbon coating reported by [PERSON] et al. [8] was used in lithium-ion batteries. The uniform layer (4.5 nm) of carbon coated on porous silicon prepared by milling process of 2 h showed 1016.1 and 834.1 mA h g\({}^{-1}\) of reversible capacities at 1000 and 2000 mA g\({}^{-1}\) of current densities, respectively, over 200 cycles. It showed 99.5% of coulombic efficiency with stable cycling performance. Theoretically, Si has the highest capacity compared to the graphite-based electrodes, but structural degradation and decaying the electrode capacity with cycling performances limit its uses in practical applications. High energy ball milling with etching process improves the structural and morphological properties of precursor with reducing the particle size and increasing the surface area. The milling time has a powerful impact on crystallinity, morphology, and electrochemical performance of anode materials. Electrode material prepared by Si particles coated with hierarchical carbon and carbon nanofibers investigated by [PERSON] et al. [118]. Particles prepared by different Si sources showed cycling performance up to 1000 mA h g\({}^{-1}\) at 2 A g\({}^{-1}\) of current density after 1000 cycles. After the cycling performances, Si was well bound with the carbon shell. The energy density of the fuel cell was enhanced by the pairing of a light weighted, free-standing electrode prepared by hierarchical carbon coated Si with LiNi\({}_{0.5}\)Mn\({}_{1.5}\)O\({}_{4}\) up to 547 W h Kg\({}^{-1}\) over 100 cycles. The fuel cell exhibited 46% of energy density with LiNi\({}_{0.5}\)Mn\({}_{1.5}\)O\({}_{4}\) cathode than LiCoO\({}_{2}\) cathode. Solvothermal ball milling technique used by [PERSON] et al. [120] to synthesize the Na\({}_{3}\)V\({}_{2}\)(PO\({}_{4}\))\({}_{2}\)F\({}_{3}\) cathode material. The effect of change in pH concentration resulted in a change in morphological structures from 0-D particle to 3-D cube in acidic environment. The short time ball milling was performed to obtain nanosized Na\({}_{3}\)V\({}_{2}\)(PO\({}_{4}\))\({}_{2}\)F\({}_{3}\) coated with Ketjenblack (KB) (conductive carbon). The Na\({}_{3}\)V\({}_{2}\)(PO\({}_{4}\))\({}_{2}\)F\({}_{3}\) and KB composite with pH value of 3 exhibited 138 mA h g\({}^{-1}\) and 122 mA h g\({}^{-1}\) of discharge specific capacity at 0.5C and 40C, respectively. Electrochemical performance of composite materials (Fe\({}_{2}\)O\({}_{3}\), MWCNT PVB) on Ni foam as current collector was reported by [PERSON] and [PERSON] [122]. In this work, the authors prepared three different composites by using maghemite (\(\gamma\)-Fe\({}_{2}\)O\({}_{3}\)), multi-walled carbon nanotubes (MWCNT), polyvinyl butyl (PVB), and gallocyanine. In composite-1, non-ball milled Fe\({}_{2}\)O\({}_{3}\) powder was used, while in composite-2, ball milled Fe\({}_{2}\)O\({}_{3}\) powder was used without the gallocyanine. In composite-3, ball milled Fe\({}_{2}\)O\({}_{3}\) powder was used with the gallocyanine. Among the other two composites, composite-3 showed capacitance up to 1.53 F cm\({}^{-2}\) in 0.5 M sodium sulfate electrolyte. Gallocyanine provided effective co-dispersion for the Fe\({}_{2}\)O\({}_{3}\) powder and MWCNT. The adequate capacitance led to effective charging and discharging phenomenon favorable for enhancing the capacitive properties in the energy storage devices. The obtained composite material showed mutual interaction between ferromagnetic and capacitive properties, which could be useful in the fabrication of multifunctional devices. The composite of Selenium: Phosphorous: Carbon (Se:P:C) synthesized by a Plasma assisted ball milling (P-milling) method by varying the molar ratios of raw materials and milling time was reported by [PERSON] et al. [127].