Controllable Preparation And Nano-modification Of Nanosized LimnpO₄Cathode Materials

During the past decades, lithium ion batteries (LIBs), due to their high energydensity, safe and good cycleability, have been dominating the market of power sourcesfor electronic devices. The strong covalent P-O bonds in the tetrahedral (PO4)3-anionenhance the cycle life and restrain oxygen loss, which makes the LiMPO4stable. In thisstudy, we report the synthesis and electrochemical performance of LMP (LMFP)prepared by the solvothermal method followed by ball milling. The effect of synthesiscondition on structure and performance of lithium manganese ion phosphates wasextensively investigated by XRD, SEM, FT-IR, TEM et al. We studied the synthesisconditions, morphology, structure and electrochemical properties of the compsitematerial. In order to enhance the storage performance of the LiMnPO4, we designed theconductivity network and Fe2+cationic doping, improving the electrochemicalperformance of the composite significantly.Rhombus-like LiMnPO4was synthesized via a simple solvothermal process inwater-ethanol solvent mixtures. The effect of synthesis condition such as initialconcentration of reactant and the feed methods on structure and performance of lithiummanganese ion phosphates was extensively investigated. The LiMnPO4-PAS delivers adischarge capacity of138mAh/g,127mAh/g,119mAh/g,95mAh/g,73mAh/g and53mAh/g, at0.1C,0.5C,1C,5C,10C and20C, respectively. To comprehend the slightcapacity decrease during delithiation/lithiation and proposed improved electrochemicalproperties of the LMP-PAS composite, we speculate that the capacity decrease is relatedto Mn dissolution in the electrolyte and the defect of the cation mixing of MnLi·.The LiMn0.9Fe0.1PO4nanomaterials were ascorbic acid-assistedly synthesized by asolvothermal method in a mixed solvent of water and ethanol. TheLiMn0.9Fe0.1PO4-PAS composite with only5.6wt%PAS exhibits a high conductivity(0.15S/cm), resulting in an excellent rate performance and good cycle life. Thewell-distributed conducting PAS surrounding the LiMn0.9Fe0.1PO4nanoplates enhancesthe electronic contact of the nanosized crystalline particles and suppresses themanganese dissolution related to the structure evolution during cycling. TheLiMn0.9Fe0.1PO4-PAS delivers a discharge capacity of157mAh/g,141mAh/g, and107mAh/g, at0.1C,1C and10C, respectively.