Improved battery performance of silicon modified Na0.67Fe0.5Mn0.5O2 and its structural and electrochemical properties: An investigation of infrared thermal imaging

•The Si modification on the Na0.67Fe0.5Mn0.5O2.•In-situ thermal imaging of coin cells.•Development of in-situ thermal imaging system of button battery. Here, we present a systematically Si-doping strategy to improve the structural stability and battery performances of P2-type Na0.67Mn0.5Fe0.5O2 samples. Through Si4+ doping intended to settlement of the interstitial region in the crystal structure and investigate the effect on the electrical conductivity of the Na0.67Mn0.5Fe0.5O2. The structural properties were examined by x-ray absorption near-edge structure (XANES), x-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) measurements. The XANES spectra showed that the valence of both Manganese and iron ions was unchanged by Si. According to charge/discharge cycling measurements for constant current at room temperature, the lowest capacity fade was obtained for Na0.67Mn0.5Fe0.48Si0.02O2. The cycling measurements were also investigated at 50°C, and it was observed that the electrochemical properties were changed with temperature. It was developed an experimental setup for the measurements of the internal temperature of the battery cells during the charging/discharging process of CR2032 coin cells using an infrared thermal camera. The ohmic heat was calculated from chronoamperometry measurements using a developed setup, and the heat generation was explained by a quadratic equation in the system.