Self-discharge limits long-term energy storage in capacitive electrodes and leads to irreversible energy losses90. However, there is relatively little fundamental understanding of the self-discharge mechanisms and how it can be minimized in pseudocapacitive and hybrid systems, in devices containing redox electrolytes and in open 3D and 2D architectures. In particular, the use of redox electrolytes and open architectures may lead to faster self-discharge and novel approaches to mitigating this effect are necessary. Effects of electrode thickness, dimensionality and chemistry among other factors are likely to be significant and need further study.