On the challenge of large energy storage by electrochemical devices

This paper reviews work that promotes the effective use of renewable energy sources (solar and wind) by developing technologies for large energy storage, concentrating on electrochemical devices. Unfortunately, we are not far from a non-return situation related to global warming due to green-house gasses emission, 88% of which is contributed through release of CO2 by combusting fossil fuels. Major contributors to CO2 emission are power stations that produce electricity. Only a massive replacement of fossil fuels combustion by photovoltaic solar panels and wind turbines for electricity production can reduce drastically the detrimental CO2 emission. The success of using renewable energy depends on the availability of technologies for large energy storage. We believe that modern electrochemistry can provide them. We review herein relevant options. While hydrogen based technology using fuel cells and flow batteries are valid options, we believe that stationary rechargeable batteries are most important for large energy storage and load leveling applications. We review herein a plethora of systems: Li and Na ion batteries, systems based on multivalent metal anodes (Mg, Ca, Zn, Al), aqueous batteries and hybrid systems comprising capacitive and redox electrodes. For the latter systems we discuss in detail relevant options for capacitive electrodes. Highly important is the use of systems composed of abundant elements. Improved lead-acid batteries are interesting thanks to the possibility to recycle lead effectively. Li ion batteries comprising Li4Ti5O12 anodes and LiFePO4 or LiMn0.8Fe0.2PO4 cathodes are also very suitable for load leveling applications, depending on the availability of lithium, which is discussed herein as well.