共聚物模板辅助合成高倍率性能多孔Li_2FeSiO_4@C/CNTs纳米复合正极材料(英文)

Copolymer Template-Assisted Synthesis of Porous Li_2FeSiO_4@C/CNTs Nanocomposite as Cathode Material with High Rate Capability

通过溶胶-凝胶法制备了Li_2FeSiO_4@C/CNTs(LFS@C/CNTs)纳米复合材料,其中三嵌段共聚物P123用作结构导向剂和碳源,碳纳米管作为导电线提高材料的导电性。LFS@C/CNTs不仅具有海绵状纳米孔,能够与电解液充分接触改善锂离子的传输路径,同时由非晶碳和碳纳米管构成的三维桥联导电网络利于电子的快速传递,提高了材料大电流充放电能力和循环稳定性。复合后的LFS@C/CNTs的高倍率性能相比LFS@C明显提高,当CNTs的掺量为4%,电压窗口为1.5~4.5 V,0.1C电流密度下放电比容量为182 m Ah·g^(-1)。在10C经70次循环后该材料的放电比容量能保持在117 m Ah·g^(-1),是LFS@C放电比容量(55 m Ah·g^(-1))的两倍。

Li_2FeSiO_4@C/CNTs（LFS@C/CNTs） nanocomposite was synthesized by a sol-gel method. A triblock copolymer P123 was used as the direction agent for nanopores and carbon source, and carbon nanotubes were used as conductive wires to further increase the conductivity of the material. The resulting LFS@C/CNTs nanocomposite possesses not only a nanoporous sponge-like structure for improving Li-ions transport by means of liquid electrolyte, but also a 3D self-bridged conduction hybrid network consisted of amorphous carbon coating and graphitized CNTs for electron fast transport that ultimately improves the high rate capability and cycling performance. As a result, the porous LFS@C/CNTs nanocomposite compared with nanoporous LFS@C exhibits a remarkable improvement in high-rate capability. The LFS@C/CNTs nanocomposite with 4wt% of CNTs delivers a specific discharge capacity of approximately 182 m Ah·g^（-1）at 0.1C in the voltage window of 1.5~4.5 V, and the specific discharge capacity at 10 C after 70 cycles maintains at 117 m A·h·g^（-1）, which is more than two times that of LFS@C（55 m Ah·g^（-1）） as a cathode material for high power lithium ion battery.