High Performance, Stoichiometric ZnSnP2 Anode for Rechargeable Lithium‐Ion Battery with Concomitant Conversion from Chalcopyrite to Sphalerite Phase. Issue 8 (24th May 2022) - Patel, Shubham
Abstract: Herein, we report chalcopyrite phase of zinc tin phosphide (ZnSnP2 ) as an anode for high rate, rechargeable, lithium‐ion battery. In‐situ Raman spectroscopy reveals the conversion of chalcopyrite phase of ZnSnP2 to a symmetric sphalerite phase upon cycling, which helps in achieving stable and reversible capacity at high discharge rates. This is due to the low bandgap and high conductivity of the sphalerite phase. The in‐situ phase conversion is extremely important as it is difficult to synthesize bulk ZnSnP2 sphalerite phase by the known methods till date. After full phase conversion, a reversible capacity of 750 mAh g −1 is obtained towards the end of 1700 cycles at a rate of 5 A g −1 . Full cell assembled using LiCoO2 as the cathode material yields a stable performance with a discharge capacity of around 500 mAh g −1 at 0.5 A g −1 and the rate capability studies demonstrate reversible capacities up to 15 A g −1 current. Abstract : Phase conversion during cycling : ZnSnP2 is employed as an anode for high‐rate rechargeable Li‐ion battery. Upon cycling, tetragonal chalcopyrite phase is converted to a symmetric and highly conducting cubic sphalerite phase, which helps in achieving excellent cycling stability in half‐cell and full‐cell configurations. The performance of the anode material is quite appreciable at all current densities (0.5 A g −1 to 5 A g −1 ) rates, where discharge capacities of around 1400 and 750 mAh g −1 are obtained at the end of 500 and 1700 cycles.