Is superparelectric 2-dimensional Sn2P2S6 having a “higher dielectric constant” desirable for more real Na+ pseudocapacitance?

Pseudocapacitive Na+ storage based on the fast absorption/desorption kinetics is a new alternative to realize the high rate capability, which rely on increasing the surface area and creating surface vacancies. This means low Na+ capacity because of low dielectric constant for the reported pseudocapacitive Na+ storage materials. According to the capacitance formula, we find increasing the dielectric constant is a new path to improve the Na+ capacity. This dielectricity (other than surface engineering) based pseudocapacitance can be called more real pseudocapacitance. The superparaelectric 2-dimensional (2D) Sn2P2S6 has much higher dielectric constant than the bulk counterpart. The identical polaron direction triggered superparaelectricity and high dielectric constant of 2D Sn2P2S6 are well verified. And 2D assembly between the 2D Sn2P2S6 and graphene construct the compact network for conductivity of electron and Na+. As results, the 2D Sn2P2S6 battery based on more real pseudocapacitance delivers alloy-like capacity and long cycle stability.