## 5 Applications
### Energy Storage
Defect sites can act as sites with increased electron charge density or lower charge density and in the process influence the charge transfer process. Some reports where ball milling has been employed for energy storage/conversion are now discussed briefly. A significant increase in the catalytic activity towards oxygen reduction has been observed in the mechanical alloyed GO/\(\alpha\)-MnO\({}_{2}\) nanocomposites due to the chemically stable and mechanically flexible nature of GO nanosheet and porous morphology of \(\alpha\)-MnO\({}_{2}\) nanowire [113]. A cathodic catalyst has significant influence on the power density, cyclic ability, and energy efficiency of batteries. An air breathable composite of nanosheet as matrix and nanowire as transport structure is seen as a promising material for ultrafast Li\({}^{+}\) and electronic charge transportation. The morphology of the cathodic catalyst plays a major role in the enhancement of capacity and reversibility of the Li-O\({}_{2}\) battery. An excellent electrochemical performance was observed in anodic ball milled SnSe/carbon nanocomposite in sodium-ion and lithium-ion batteries [114]. SnS\({}_{2}\)-carbon nanocomposite anode material facilitating a large number of Li\({}^{+}\) ion storage sites, high current density, and faster ion diffusion capability was developed by the facial ball milling process [115]. Table 2 summarizes some recent studies that have employed ball milling technique for processing materials and their subsequent application in the area of energy storage. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Type of Ball Milling** & **Specification** & **Battery/Supercapacitor** & & **Highlights** & **Ref.** \\ \hline \multirow{3}{*}{Planetary ball mill} & Nano sized My-nanostructured MyH\({}_{2}\) & & \(\times\) & MgH\({}_{2}\) and benzene ball milled together increases the capacity of hydrogen storage and reversibility \\  & was obtained by 0-3 h of ball milling & Hydrogen storage & \(\times\) & MGP\({}_{2}\) and benzene ball milled together increases the capacity of hydrogen \\  & the magnesium and benzene in zirconia & Hydrogen storage & \(\times\) & MGP\({}_{2}\) with MgH\({}_{2}\) sample exhibits \(-60\%\) of \\  & control mill & & hydrogen storage capacity & \\ \hline \multirow{3}{*}{Discharge-plasma assisted milling (Vibration type ball mill)} & By taking nano sized Si powder and & & \(\times\) & \\  & graphite in mass ratio of 30\(\aas@@fstack{\circ}\)0 and ball & & & \\  & to powder ratio of 50 h1 in Pulling for a & & & \\  & time duration of 5.0 and 20 h in & & & \\  & presence of pure argon atmosphere to & & & \\  & made composite of nano Si & & & \\  & and graphene & & & \\ \hline \multirow{3}{*}{Planetary ball mill} & 180 balls of same size and same materials used in filling of binary & & & \\  & fluoride (MgH\({}_{2}\) and SnH\({}_{2}\)): 17 ratio of & Electrochemical & & \\  & ball powder taken with 10 h of & & & \\  & milling time & & & \\ \hline \multirow{3}{*}{Ball milling} & Graphite powder and nickel powder & & & \\  & were milled using Zirconia balls for 1 h & Supercapacitor & & \\  & with 1200 rpm. & & & \\ \hline \multirow{3}{*}{High energy ball milling} & Si powder of micro sized dimensions & & & \\  & and stainless steel balls are used in the & & & \\  & ball milling with ball powder ratio of & Lithium-ion batteries & & \\ \cline{1-1}  & & & & \\ \cline{1-1}  & time durations having 120 rpm & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Materials that were processed via ball milling demonstrated better performance as energy storage materials. \begin{table}
\begin{tabular}{l l l l l l} \hline \multicolumn{1}{c}{**Type of Ball Milling**} & \multicolumn{1}{c}{**Specification**} & \multicolumn{1}{c}{**Battery/Supercapacitor**} & \multicolumn{1}{c}{**Highlights**} & \multicolumn{1}{c}{**Ref.