Stable Na-ion supercapacitor under non-ambient conditions using maricite-NaMnPO4 nanoparticles

Abstract Sodium ion supercapacitors are being considered as an alternative to lithium-based systems because of their natural abundance, cost effectiveness and low environmental impact. Using simple facile synthesis strategy, it is shown that NaMnPO4 can become a promising cathode material. The importance of the reported Na-ion supercapacitors becomes evident, when they are operated under non-ambient environments. Compared to other reported metal oxides, the electrochemical performance of NaMnPO4 shows much stable tolerance towards varying magnetic field. The conventional models do not have any parameter, which take into account the effects of varying magnetic field. Here, it is also shown that a modified theoretical model is required to explain the magnetic field dependent electrochemical behavior. The need for an additional parameter that allows the Lorentz force driven diffusion of ions is presented. For the case B = 0, the model reduces to conventional Stern model.