Polyvinylpyrrolidone assisted sol–gel route LiCo1/3Mn1/3Ni1/3PO4 composite cathode for aqueous rechargeable battery

Olivine-phosphate LiCo1/3Mn1/3Ni1/3PO4, synthesized via conventional solid state (SS) and polymer assisted sol–gel (SG) methods, is reported as a cathode material for aqueous rechargeable batteries. X-ray diffraction (XRD) analysis confirms phase pure compounds in an orthorhombic structure for both these methods. However, microstructural images show polyvinylpyrrolidone (PVP) assisted SG method aids colloidal growth giving evenly distributed microparticles while SS method tend to an agglomeration during high-temperature processing. The electrochemical properties for SG are seen to be dramatically superior to those of SS. The galvanostatic analysis of the SG shows improved specific capacity over the initial cycles (45 mAh/g and 60 mAh/g for the 1st and 20th cycles) and stabilized upon cycling. This unique capability is due to the trapped organic products from the thermal decomposition of PVP that facilitates Li+ transfer. The trapped organic coating on the cathode surface without affecting the bulk olivine is evidenced by XRD, FTIR and XPS spectroscopic techniques.