Synthesis and characterization of carbon-modified Li2MnP2O7/C composites prepared by spray pyrolysis

Abstract

Pure crystalline Li2MnP2O7/C composite was prepared by spray pyrolysis (SP) followed by annealing (AN) process. Citric acid (CA) was added into the precursor solution as a carbon source to enhance the electrochemical property. The physical and electrochemical properties in conjunction with various synthesis conditions were evaluated. Variation of carbon content, specific surface area, lattice cell volume, and anti-site concentration was revealed along with different preparation conditions of the SP followed by AN process. Electrochemical properties were relevant to various physical properties of samples, and it provided a critical factor to find the most efficient synthesis condition in the SP method. Since incorporated carbon has a significant role in enhancing the electrical conductivity as well as inducing a delicate variation of physical properties, the limitation of incorporated carbon by CA was addressed with associated reaction mechanism. For the sake of exceeding these limitations, further carbon modification with acetylene black was carried out by ball milling (BM) process. The optimal condition of BM process was designated by the resulting of electrochemical property and observing the carbon distribution on the cross section of particles. Li2MnP2O7/C composite prepared under the whole optimal condition delivered the initial discharge capacity of 64 mAh g−1 at a current rate of C/10. The potential of Mn3+/Mn2+ redox couple revealed at 4.3 V versus Li/Li+ upon the discharge process.