Spherical shaped LiCo0.5Mn0.5PO4-carbon composite as high voltage cathode material for conventional and flexible Li-ion batteries

Abstract

A unique approach of Co-doping at the Mn site was used to prepare spherical shaped LiMn0.5Co0.5PO4@C (LMCP@C) nanoparticles by supercritical fluid hydrothermal method. The high-resolution transmission electron microscopy (HR-TEM) study of LMCP@C nano-particles explores that the average diameter of nanospheres is in the range of 7–50 nm. XPS analysis reveals that the Mn/Co-ion exists in the divalent oxidation state. First-principle calculations explore that Co doping increases the operating voltage, specific capacity, gravimetrical energy, and power density. The corresponding theoretical values are 5.23 V, 169.1 mA h g−1, 85.164 kW h kg−1, and 85.164 kW kg−1. At the same time, the theoretical volumetric energy and power densities are 8.008 kWh cm−3 and 8.008 kW cm−3. It also reveals that Co-doping enhances the bulk modulus (∼87 GPa), shear modulus (∼92.5 GPa), and Poisson ratio (0.107). The electrochemical analysis of secondary Li-ion batteries (LIBs) explores that the initial discharge capacities at 0.1 and 100 C are 156.5, and 80 mA h g−1, gravimetrical energy, and power densities are within the range of 591.3–312 W h kg−1 and 312.2 kW kg−1, respectively. All-solid-state thin and flexible LIBs have the initial discharge capacities under different bending states at 0.1 C within the range of 141 - 140 mA h g−1. Volumetric power and energy densities are within the limit of 6.575–6.30 W cm−3 and 0.6575–0.631 W h cm−3, respectively.