What are the right systems to succeed the Lithium Ion Battery...? All of this is clearly fundamental research, but as synthetic chemist, one can always think on possible reaction that could work as reversible battery reactions. Currently our group works on using Mg and Al as an Anode as well as sulfur as the cathode. In addition, we have worked out an all maganese redox flow battery.
A new all‑Manganese flow battery (all‑MFB) as non‑aqueous hybrid redox‑flow battery is reported. The discharged active material [Cat]2[MnIICl4] (Cat = organic cation) utilized in both half‑cells supports a long cycle life. The reversible oxidation of [MnIICl4]2– to [MnIIICl5]2– at the positive electrode and manganese metal deposition from [MnIICl4]2– at the negative electrode give a cell voltage of 2.59 V. Suitable electrolytes were prepared and optimized, followed by a characterization in static battery cells and in a pumped flow‑cell. Several electrode materials, solvents and membranes were tested for their feasibility in the all‑MFB. An electrolyte consisting of [EMP]2[MnCl4] and some solvent g-butyrolactone was cycled 500 times, both in a static as well as a flow‑cell, over a period of two months, with coulombic efficiencies up to 83 %. With the electrolytes prepared in this work, energy densities up to 74 Wh L–1 are possible, exceeding the VRFB benchmark system, using solely the cheap and abundant element manganese as the active material. Although further optimizations are necessary, this system describes a new and promising setup towards sustainable stationary energy storage.
First investigations towards the feasibility of an Al/Br2-battery (see picture) based on bromoaluminate and polybromide ionic liquids are presented. The battery exhibited an open circuit voltage of 1.1 V and a theoretical energy density of 33 Wh L–1 based on the migration of cations, which was determined by NMR studies. The battery could be discharged with high resistance values, while preliminary charging attempts revealed high over potentials.