Fig. 4.

Demonstration of energy recovery. a Voltage magnitude |V| across C1 (thin red line) and C2 (thick blue line) after charging C1 at time t = 0 (red arrow) and then transferring charge between C1 and C2 every 30 s (transfer i took place at t = 30i s). Inset: ${\eta }_i^{\Delta }\mathrm{∕}{\eta }_i=W_i\mathrm{∕}\left(W_i-W_{i\mathrm{+1}}\right)$ and WR = 1 − ${\eta }_i\mathrm{∕}{\eta }_i^{\Delta }=W_{i\mathrm{+1}}\mathrm{∕}{W}_i$, where work $W_i$ denotes the work done in transfer i by the MLC that discharges. b The corresponding changes of EC temperature ΔT_MLC for C1 (thin red line) and C2 (thick blue line). Inset: for C1 and C2, we plot the sharp jumps of |ΔT_MLC| in b vs. the corresponding jumps of |ΔV| in a