基于银镜反应的硅/银复合负极材料的制备及其表征

Preparation and Characterization of Silicon/Silver Anode Materials

基于银镜反应,在动态下用稀氨水将银氨配离子还原为纳米银颗粒,并沉积在硅颗粒表面。与常用含银复合材料之银盐直接还原法和硝酸盐高温分解法相比,配位还原法具有制备工艺简单快速、银颗粒分散度高和银盐转化率高等特点。得到的硅/银复合材料中粒径小于20 nm的银颗粒均匀分布在硅颗粒表面,无其他杂质相。与纯硅粉负极相比,硅/银复合材料(含银10wt%)能有效抑制硅负极在循环初始阶段的容量快速衰减,30次循环可逆容量大于500 mAh.g-1。交流阻抗测试显示,纳米银颗粒的存在能显著提高电子电导,进而改善硅负极的循环稳定性。

Silicon/Silver composite with nano-sized silver particles was synthesized based on principle of a disturbed silver-mirror reaction. Comparing with the direct method, highly dispersed nano-silver particles are easier to be obtained by the present method with simple preparation technology and high productivity of silver. Silver particles with particle size less than 20 nm were uniformly dispersed on the surface of silicon particles, no any other phase except silicon and silver could be observed in the composite. The composite with 10wt% of silver could deliver a reversible capacity more than 500 mAh·g^-1 after 30 cycles. AC impedance spectra indicate that existence of nano-silver is favorable to electrical conductivity; therefore, cycleability of composite is improved.