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以海藻酸为碳源,采用流变相法制备出碳包覆改性的Li_3V_2(PO_4)_3/C(LVP/C)正极材料。X射线衍射(XRD)结果显示所合成样品均为标准的单斜结构Li_3V_2(PO_4)_3。扫描电子显微镜(SEM)和透射电子显微镜(TEM)图像显示所合成的LVP/C活性材料颗粒尺寸较均匀。海藻酸质量分数为10%的LVP/C样品展现出最优的循环稳定性。0.1C放电电流下,首次放电容量为117.5 m Ah?g~(-1),50周循环后容量保持在116.5m Ah?g~(-1)。LVP/C-10%材料在3.0–4.3 V和3.0–4.8 V电压范围内循环50周后的容量保持率分别为99.1%和76.8%,明显优于未包覆的LVP材料。海藻酸基碳包覆层可以有效增加材料的电子导电性、缓冲活性材料在脱嵌锂过程产生的机械损伤,进而提高材料的电化学性能。
Li3V_2 (PO_4) _3 / C (LVP / C) cathode material modified by carbon coating was prepared by rheological phase method using alginic acid as carbon source. X-ray diffraction (XRD) results show that the synthesized samples are all monoclinic Li 3 V 2 (PO 4) 3. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images showed that the synthesized LVP / C active material particles were more uniform in size. LVP / C samples with 10% alginate showed the best cyclic stability. The initial discharge capacity was 117.5 m Ah? G -1 at 0.1 C discharge current, and the capacity remained at 116.5 m Ah? G -1 after 50 cycles. The capacity retention of LVP / C-10% material after cycling for 50 weeks at 3.0-4.3 V and 3.0-4.8 V was 99.1% and 76.8%, respectively, which was significantly better than that of uncoated LVP material. The alginate-based carbon coating can effectively increase the electronic conductivity of the material and buffer the mechanical damage caused by the active material during deintercalation of lithium, thereby improving the electrochemical performance of the material.