(Georgia Institute of Technology, 2023-05-02)
Jakhar, Rishika
Sodium-ion batteries (SIBs) are an attractive alternative to lithium-ion batteries (LIBs) given sodium’s (Na) abundant availability, lower cost, and comparable energy storage characteristics. There is an increasing impetus to increase the energy densities and specific energies of SIBs. One of the ways to achieve this is to produce thicker electrodes with higher areal mass and capacity loadings in order to reduce the relative weight and volume fractions of inactive SIB components, such as current collectors and separators. Unfortunately, fabricating thicker electrodes by conventional slurry-casting methods presents two challenges – (i) avoiding the loss of mechanical strength and (ii) retaining fast ion transport within thick electrodes. In our proof-of-concept studies, SIB cathodes were fabricated using a phase inversion technique to be free-standing, exhibit over 100 µm thickness and possess vertically aligned pores. The electrochemical performance of such electrodes was investigated by studying their charge-discharge (C-D) profiles at different current densities and conducting cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements in half cell configurations. The effects of electrolyte composition and solid electrolyte interphase (SEI) additives were additionally investigated in symmetric cell configurations. The performance characteristics attained suggest a promise of this approach for a broad range of SIB and other battery chemistries. Further work on optimizing the pore shape, pore size distribution and pore volume is expected to further boost cell performance.