LiCl is highly soluble (832 g dm3 in water) and LiFePO4/FePO4 is a two-phase system with a well defined potential capable of rapid charging and discharging. With the exception of Ag, these
materials are inexpensive and environmentally benign. In tests with 0.03 and 1.5 M solutions, we produce an energy density of 38.2 mJ cm2 (power density 13.8 μWcm2) that was stable over 100 cycles (Figure 4). These results indicate that this system has significant potential as a method of harnessing solar energy, and has the possibility to be completely renewable, due to repeated
cycling of the materials with no loss of reagent.