Surfactant-Mediated and Morphology-Controlled Nanostructured LiFePO4/Carbon Composite as a Promising Cathode Material for Li-Ion Batteries.

The synthesis of morphology-controlled carbon-coated nanostructured LiFePO4 (LFP/Carbon) cathode materials by surfactant-assisted hydrothermal method using block copolymers is reported. The resulting nanocrystalline high surface area materials were coated with carbon and designated as LFP/C123 and LFP/C311. All the materials were systematically characterized by various analytical, spectroscopic and imaging techniques. The reverse structure of the surfactant Pluronic® 31R1 (PPO-PEO-PPO) in comparison to Pluronic® P123 (PEO-PPO-PEO) played a vital role in controlling the particle size and morphology which in turn ameliorate the electrochemical performance in terms of reversible specific capacity (163 mAh g-1 and 140 mAh g-1 at 0.1 C for LFP/C311 and LFP/C123, respectively). In addition, LFP/C311 demonstrated excellent electrochemical performance including lower charge transfer resistance (146.3 Ω) and excellent cycling stability (95 % capacity retention at 1 C after 100 cycles) and high rate capability (163.2 mAh g-1 at 0.1 C; 147.1 mAh g-1 at 1 C). The better performance of the former is attributed to LFP nanoparticles (<50 nm) with a specific spindle-shaped morphology. Further, we have also evaluated the electrode performance with the use of both PVDF and CMC binders employed for the electrode fabrication.

Electrochemical performance of nano-sized LiFePO4-embedded 3D-cubic ordered mesoporous carbon and nitrogenous carbon composites.

Herein, we report a single-step synthesis, characterization, and electrochemical performance of nano-sized LiFePO4 (LFP)-embedded 3D-cubic mesoporous carbon (CSI-809) and nitrogenous carbon (MNC-859) composites. Furthermore, in order to investigate the effects of both CSI-809 and MNC-859 on the electrochemical characteristics of LFP, a systematic study was performed on the morphology and microstructure of the composites, viz., LFP/CSI-809 and LFP/MNC-859, using XRD, FE-SEM, FT-Raman, and BET surface area analyses. Among these composites, LFP/MNC-859 exhibited better electrochemical performance with higher specific capacity and rate capability as compared to those of LFP/CSI-809. In addition, even after 100 cycles, LFP/MNC-859 retained 97% of its initial discharge capacity at 1C rate. The enhanced electrochemical performance of the nano-sized LFP-embedded MNC-859 can be attributed to the conductive nitrogenous carbon and mesoporosity, which facilitate electrolyte diffusion, and improved conductivity of the advanced LFP-nitrogenous porous carbon matrix.