在多元醇体系中一锅法合成具有良好储锂性能的介孔碳-锡复合材料

One-pot Synthesis of Sn/Mesoporous Carbon Composite in a Polyol System with Well-improved Lithium Storage Capability

以介孔碳(MC)为导电和支撑介质,在多元醇体系中通过简便的化学还原方法制备纳米结构的介孔碳-锡(MC-Sn)复合材料.采用扫描电子显微镜(SEM)、高分辨透射电子显微镜(HRTEM)和恒电流充放电实验对所得产物的形貌、结构及电化学性能进行表征.结果表明,大量的Sn纳米颗粒均匀且致密地附着在介孔碳上.作为锂离子电池负极材料,MC-Sn复合物表现出了较好的循环性能和倍率性能.例如,在100 m A·g-1的充放电速率下循环40圈,其放电比容量保持在721.5 m Ah·g-1;当充放电速率增大到1 A·g-1时,其放电比容量仍高达265.8 m Ah·g-1.简单的制备方法和优越的储锂性能,使得MC-Sn复合材料成为一种理想的高性能锂离子电池负极材料.

By introducing three-dimensional mesoporous carbon(MC) as a conducting and buffering matrix, MC-Sn composite has been synthesized through a facile chemical reduction approach in a polyol system at the temperature of 170 ℃ which is protected by nitrogen atmosphere. Pure Sn nanoparticles were synthesized through the same methodology, but without the addition of MC. The morphology, structure and electrochemical performance of the products have been characterized by scanning electron microscopy(SEM), high-resolution transmission electron microscopy(HRTEM), and constant current discharge/charge tests. It is indicated that numerous Sn nanoparticles have been uniformly and densely decorated on the MC matrix. When evaluated as an anode material for lithium-ion batteries(LIBs), the as-prepared MC-Sn composite exhibits markedly improved cycling stability and rate capability compared to pure Sn nanoparticles. For example, a high discharge capacity of 721.5 m Ah·g-1 can be retained after 40 discharge/charge cycles at a current density of 100 m A·g-1 in the potential range of 0.01~2 V. When tested under the same condition, pure Sn nanoparticles remain only 361.7 m Ah·g-1. The rate capability of MC-Sn composite was examined in comparison with pure Sn nanoparticles at various current densities from 100 to 200, 500 and 1000 m A·g-1. The MC-Sn composite delivers a discharge capacity of 760.5 m Ah·g-1 at a current density of 100 m A·g-1 after 10 cycles. This value decreases to 555.6 m Ah·g-1(200 m A·g-1), 366.2 m Ah·g-1(500 m A· g-1), 265.8 m Ah·g-1(1000 m A·g-1), and finally returns to 684.3 m Ah·g-1 at 100 m A·g-1. In sharp contrast, the discharge capacities of pure Sn nanoparticles decrease rapidly with the increase of current densities. These results demonstrate that the MC-Sn composite possesses markedly improved rate capability, making it a promising anode for LIBs with high power densities.