Mingfeng Tan,Helei Wei,Qi Li,Zhipeng Yu,Qiang Zhang,Mingzhi Lin,Bo Lin
A novel composite consisting of fluorine-doped carbon and graphene double-coated LiMn0.6Fe0.4PO4(LMFP) nanorods was synthesized via a facile low-temperature solvothermal method that employs a hybrid glucose and polyvinylidene fluoride as carbon and fluorine sources. As revealed by physicochemical characterization, F-doped carbon coating and graphene form a ‘point-to-surface’ conductive network, facilitating rapid electron transport and mitigating electrochemical polarization. Furthermore, the uniform thickness of the F-doped carbon coating alters the growth of nanoparticles and prevents direct contact between the material and the electrolyte, thereby enhancing structural stability. The strongly electronegative F−can inhibit the structural changes in LMFP during charge/discharge, thus reducing the Jahn–Teller effect of Mn3+. The distinctive architecture of the LMFP/C-F/G cathode material exhibits excellent electrochemical properties, exhibiting an initial discharge capacity of 163.1 mAh g−1at 0.1 C and a constant Coulombic efficiency of 99.7% over 100 cycles. Notably, the LMFP/C-F/G cathode material achieves an impressive energy density of 607.6 Wh kg−1, surpassing that of commercial counterparts. Moreover, it delivers a reversible capacity of 90.3 mAh g−1at a high current rate of 5 C. The high-capacity capability and energy density of the prepared materials give them great potential for use in next-generation lithium-ion batteries.
Rongfeng Hu,Zhao Zeng,Shihao Jin,Kaixu Yang,Fei Liu,Yun Yi,Jianxin Cao
LiFe1–xMnxPO4 (0 < x < 1) has a high operating voltage range and theoretical energy density, but its actual capacity decreased due to its low electronic conductivity. To overcome this problem, we successfully prepared LiFe0.4Mn0.6PO4/C (LFMP/C) with a uniform carbon coating by a one-step solvothermal method using bamboo shavings as the carbon source. The results showed that heating at a reaction temperature of 180 °C for 18 h was the optimal synthesis condition to obtain LFMP/C. The addition of bamboo shaving-based carbon was effective in inhibiting excessive grain growth and reducing particle size. The disordered carbon layer enhanced the surface conductivity by connecting the surfaces of the particles. The synergistic effect of the nanoparticle size and the pores distributed around the particles increased the specific surface area and thus improved the contact area between the active substance and the electrolyte. Furthermore, there were improvements in electronic conductivity and ionic mobility. LFMP/C-16 showed initial discharge capacities of 150.1 and 143.5 mAh·g–1 at rates of 0.1 and 0.2C, respectively, with a capacity retention rate of 97.73% after 100 cycles, indicating excellent cyclic performance.
Graphical Cathode materials : Porous LiFe 0.4 Mn 0.6 PO 4 /CNF free-standing electrodes have been successfully prepared through a facile ionic liquid assisted electrospinning method. Owing to the hierarchical porosity and N-doped carbon layer derived from ionic liquid, the resulting electrodes exhibit superior electrochemical performances with the improvement of conductivity and pseudocapacitive contribution (see figure). In pursuit of high-performance cathode materials for lithium-ion batteries with high energy and power densities, porous LiFe 0.4 Mn 0.6 PO 4 /CNF free-standing electrodes have been successfully prepared through a facile ionic liquid (IL) assisted electrospinning method. Owing to the hierarchical porosity and N-doped carbon layer derived from the ionic liquid, the resulting electrodes exhibited superior electrochemical performances with an improvement of conductivity and pseudocapacitive contribution, delivering a discharge capability of 162.7, 133.5, 114.5, and 102.6 mAh g −1 at the current rates of 0.1, 1, 5, and 10 C, respectively. It is highly expected that this facile IL-assisted electrospinning method will lead to further developments for other phosphate-based free-standing electrodes, which offers a new route in designing polyanionic cathodes for high-performance Li-ion batteries.
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