A team from Stanford University led by Prof. Yi Cui has demonstrated a new type of safe, fast, inexpensive, long-life aqueous electrolyte battery targeted an grid-scale storage. The new battery, described in a paper published in the journal Nature Communications, relies on the insertion of potassium ions into a copper hexacyanoferrate (CuHCF) cathode and a novel activated carbon/polypyrrole hybrid anode (PPy/AC).
New types of energy storage are needed in conjunction with the deployment of solar, wind and other volatile renewable energy sources and their integration with the electric grid. No existing energy storage technology can economically provide the power, cycle life and energy efficiency needed to respond to the costly short-term transients that arise from renewables and other aspects of grid operation.—Pasta et al.
The cathode reacts rapidly with very little hysteresis;the hybrid anode uses an electrochemically active additive to tune its potential. The high-rate, high-efficiency cell has a 95% round-trip energy efficiency when cycled at a 5C rate, and a 79% energy efficiency at 50C. It also has zero-capacity loss after 1,000 deep-discharge cycles.
M. Pasta, C.D. Wessells, R.A. Huggins & Yi Cui (2012) A high-rate and long cycle life aqueous electrolyte battery for grid-scale energy storage. Nature Communications doi: 10.1038/ncomms2139