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采用溶胶-凝胶法制备了纳米级磷酸钛钠(NaTi_2(PO_4)_3),以聚乙烯醇为碳源对其进行碳包覆,研究了碳包覆量对NaTi_2(PO_4)_3/C负极在硫酸钠水溶液中电化学性能的影响。结果表明,合成的NaTi_2(PO_4)_3材料为纳米级晶粒聚集而成。碳包覆量3.6%的NaTi_2(PO_4)_3/C电极表面包覆得较为均匀,表现出最佳的电化学性能。在高达4 C的倍率下,基于钠离子嵌入/脱出的首次放电比容量达到119 m Ah/g,循环20次后容量未见明显衰减,受析氢副反应等影响库仑效率缓慢降低,这与碳包覆表面的破坏,NaTi_2(PO_4)_3在水溶液中的结构变化有关。
Nanosized sodium titanate (NaTi_2 (PO_4) _3) was prepared by sol-gel method and its carbon coating was carried out by using polyvinyl alcohol as carbon source. The effect of carbon coating amount on NaTi_2 (PO_4) _3 / Effect on Electrochemical Performance in Sodium Sulfate Solution. The results show that the synthesized NaTi_2 (PO_4) _3 material is aggregated from nano-scale grains. The surface of NaTi_2 (PO_4) _3 / C electrode covered with 3.6% carbon coating was more uniform and showed the best electrochemical performance. The first discharge capacity based on sodium ion insertion / extraction reached 119 mAh / g at up to 4 C, no significant attenuation of capacity after 20 cycles, and slowly decreased Coulombic efficiency due to hydrogen side reaction, The destruction of coating surface, and the structural change of NaTi_2 (PO_4) _3 in aqueous solution.