## 3 Status and Future Development of Electrochemical Capacitors
### Projections of the Future Development of Advanced Supercapacitors  
A method of analysis was developed in [1] to project the performance of ECCs using advanced materials in terms of their energy and power characteristics. The method was implemented using Excel and applied to symmetric and asymmetric devices (EDLCs and hybrid HSC) using advanced carbons, metal oxides and polymer composites in the electrodes. The inputs for the calculations are based on available test data from the literature, which are summarized in [9; 10]. The ECCs analyzed are unpackaged devices, but all other weights and volumes are considered. The resistances do not include interface and micro-pore resistances, but all others are included. The electrode material and electrolyte characteristics for each of the advanced ECs analyzed and the results of the performance \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multicolumn{6}{c}{**Constant Current Tests**} \\ \hline \
\begin{tabular}{c} **Test** \\ **Conditions** \\ \end{tabular} & **Discharge Time s** & **Capac. F** &
\begin{tabular}{c} **Resistance** \\ **mOhms** \\ \end{tabular} & **Wh** & **Wh/kg** \\ \hline \multicolumn{6}{c}{**3.8–2.8 V charge 100 A ***} \\ \hline  
issing & 2000 & — & — & — \\
**500 W** & 76/63 & 2500 & 10.56/8.75 & 53.6/44.4 & 7480 \\ \hline \hline \end{tabular}  
* Cell weight 197 g, RC = 20 s, (W/kg)\({}_{95\%}\) = 1142; Resistance of cell measured using an impedance meter 1.15–1.25 mOhms;
* 50 A charge was applied with a 120 s hold at charge cutoff voltage; **100 A charge was applied with a 60 s hold at charge cutoff voltage; Discharge cutoff voltage 2.5/2.8.  
\end{table} 
Table 4: Test data for the Aowei 9000 F supercapacitor. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multicolumn{6}{c}{**Constant Power Tests**} \\ \hline
\begin{tabular}{c} **Power W** \\ \end{tabular} & **W/kg** & **Time s** & **Wh** & **Wh/kg** \\ \hline
80 & 140 & 215 & 4.77 & 8.4 \\
150 & 264 & 113 & 4.71 & 8.29 \\
300 & 528 & 55 & 4.58 & 8.06 \\
400 & 704 & 40 & 4,44 & 7.82 \\ \hline RC = 1.26 s, (W/kg)\({}_{95\%}\) = 1783; Charge/discharge 3 V–1.5 V, Charge 150 A, hold 60 s, Weight 0.568 kg, Volume 0.39 L. & \\ \end{tabular}  
* RC = 1.26 s, (W/kg)\({}_{95\%}\) = 1783; Charge/discharge 3 V–1.5 V, Charge 150 A, hold 60 s, Weight 0.568 kg, Volume 0.39 L.  
\end{table} 
Table 3: _Cont._calculations are shown in Table 5. The results for the performance of the devices are given in terms of both the weight of the active material in the cell and the total weight of the cell. The characteristics of small laboratory cells described in the literature are in most cases given in terms of the weight of the active material in the electrodes, which significantly overestimates the energy density and power capability potential of cells fabricated using the materials being studied. However, the present projections of the performance (Wh/kg, Wh/L, and (W/kg)\({}_{95\%}\)) of the cells shown in Table 5 indicate that the future development of ECCs should yield devices with large improvements in performance. Key to the improvements in both EDLCs and hybrid supercapacitors will be the development of nano-carbons and graphene materials with high specific capacitance (>200 F/g) in organic and ionic liquid electrolytes with ionic conductivity greater than 10 mS/cm.