Encapsulation of LiFePO₄ Nanoparticles into 3D Interpenetrating Ordered Mesoporous Carbon as a High-Performance Cathode for Lithium-Ion Batteries Exceeding Theoretical Capacity

A nanocomposite cathode based on LiFePO₄ (LF) nanoparticles embedded 3D cubic ordered mesoporous carbon CMK-8 for lithium-ion batteries is synthesized by a facile impregnation method followed by further modification with carbon coating. The effects of variation of carbon contents on electrochemical performances of cathodes are investigated. The highly crystalline nanophase of LiFePO₄ particles is confirmed by X-ray diffraction and TEM analysis. Nitrogen adsorption-desorption isotherms reveal persistence mesoporosity after encapsulation of LiFePO₄ nanoparticles. The graphitic phase in LF/C@CMK-8-X (X = amount of CMK-8) nanocomposites is detected by analyzing the Raman spectra of the matrix carbon due to CMK-8 and the coated carbon (C). The electrochemical properties of the LF/C@CMK-8-X nanocomposites are evaluated with cyclic voltammetry, impedance spectroscopy, and charge-discharge cycling. The excellent rate capability with a discharge capacity value of 184.8 mA h g^-1 is obtained for LF/[email protected] nanocomposite electrode at a current rate of 0.05C, which is higher than the theoretical capacity of LiFePO₄ (170 mA h g^-1). The discharge capacity (178.3 mA h g^-1) is higher than the theoretical capacity up to the current rate of 0.2C. The long cycle stability test at a higher current rate of 10C exhibits remarkable discharge capacity of 120 mA h g^-1 with 96.7% capacity retention after 1000 cycles and demonstrates the great potential of LF/[email protected] nanocomposite cathode for use in lithium-ion batteries.