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) Sn 2 P 2 S 6 has much higher dielectric constant than the bulk counterpart. The identical polaron direction triggered superparaelectricity and high dielectric constant of 2D Sn 2 P 2 S 6 are well verified. And 2D assembly between the 2D Sn 2 P 2 S 6 and graphene construct the compact network for conductivity of electron and Na⁺. As results, the 2D Sn 2 P 2 S 6 battery based on more real pseudocapacitance delivers alloy-like capacity and long cycle stability. Image 1 • Increasing the dielectric constant is a new path to improve the battery capacity. • Superparaelectric 2D Sn 2 P 2 S 6 have higher dielectric constant than ferroelectric bulk Sn 2 P 2 S 6. • High pseudocapacitance percentage in the superparaelectric Sn 2 P 2 S 6 contribute to long cycle stability. [ABSTRACT FROM AUTHOR]