We present highly promising results for the use of graphite as both electrodes in a “dual-carbon” cell. An ionic liquid-based electrolyte mixture allows stable and highly reversible ion intercalation/de-intercalation into/from the electrodes.

While lithium-ion batteries dominate the field of high-energy-density applications, a variety of promising alternative battery technologies exist that might be suitable for various application purposes. Their requirements may vary considerably, e.g., for stationary batteries they are significantly different from those of traction batteries in electric vehicles, i.e., low installation and lifetime cost and a long cycle life are the key parameters for the former ones. Here, we review the recent developments of dual-ion battery (DIB) and particularly of dual-graphite battery technologies, which may be considered as sustainable option for grid storage. We present the progress and challenges of DIB materials and electrolytes, especially with respect to performance parameters, e.g., energy density and cycling stability as well as cost. We discuss the major challenges for practical application and critically evaluate the DIB technology along with an assessment of the potential to fulfill the targets for grid storage.

In order to increase the energy content of lithium ion batteries (LIBs), researchers worldwide focus on high specific energy (Wh/kg) and energy density (Wh/L) anode and cathode materials. However, most of the attention is primarily paid to the specific gravimetric and/or volumetric capacities of these materials, while other key parameters are often neglected. For practical applications, in particular for large size battery cells, the Coulombic efficiency (CE), voltage efficiency (VE), and energy efficiency (EE) have to be considered, which we point out in this work by comparing numerous LIB active materials. For all presented active materials, energy inefficiency is mainly caused by a voltage inefficiency, which in turn is affected by the voltage hysteresis between the charge and discharge curves. Hence, this study could show that materials with larger voltage hysteresis such as the ZnFe 2 O 4 (ZFO) anode or the Lirich cathode material exhibit also a lower VE and EE than for instance graphite and LiNi 0.5 Mn 1.5 O 4 . Furthermore, from the accumulated EE losses the resulting "extra energy costs" are calculated based on industry and domestic electricity costs in Germany, in Japan and in the U.S.A. In particular, in countries with higher electricity costs such as Germany, the accumulated extra energy, which is necessary to compensate the energy inefficiency while retaining a certain energy level in the electrode material, has a stronger impact on the extra energy costs and thus on the total cost of ownership of the battery cell system.