in the potential range of ∼0.12 V. In a similar manner, a vanadyl cation (VO2+) can gain 3e− and produce capacitance of 670 F g−1 in the potential range of ∼0.7 V. It is important to mention that use of the electrolytes featuring multi-electron redox requires an ion separation membrane to prevent mixing of the electrochemically active species and self-discharge70. Also, such substantial changes in the iodine oxidation state are possible in aqueous electrolytes, whereas in organic electrolytes iodide ions can gain only 1e− per iodine atom71. Transition metal oxides that can change their oxidation state while staying in solution (for example, Ce3+ to Ce4+), may also be attractive72. Use of redox-active electrolytes can compensate for the energy density lost due to the development of open electrode architectures that promote ion accessibility.