摘要
采用蒸发溶剂相转化方法对La-Mg-Ni系储氢合金表面实施包覆NAFION,研究了不同浓度的NAFION溶液对合金表面包覆效果和电化学性能的影响。结果表明,通过蒸发溶剂可使NAFION在储氢合金表面形成不同形态的NAFION功能性包覆层,随NAFION稀释比例不断增大,合金颗粒表面NAFION的包覆形态由分散和凸起的白色片状物逐渐向形成薄且铺展性较好的薄膜状产物变化,但未形成连续完整的包覆层。电化学分析表明,包覆后合金电极的循环稳定性有所提高,其中NAFION稀释比例为1∶5时的合金电极放电容量最大（387.3mA·h/g）和循环稳定性最好,经100次充放电循环后该合金电极容量的保持率S100达到89.0%,其性能优于未包覆的裸合金。表面包覆NAFION后,合金电极大电流放电性能明显下降,其HRD900由裸合金时的81.6%降至包覆后的68.1%。合金电极反应时表面电子交换阻力的增加（或交换电流密度I0减小）是影响包覆合金高倍率放电性能的主要因素之一。
La-Mg-Ni-based hydrogen storage alloy surface was coated NAFION using simple evaporation solvent phase conversion method. The effects of different concentrations of NAFION solution on the surface and electrochemical properties of La-Mg-Ni based hydrogen storage alloys were investigated. The results show that by evaporating the solvent, NAFION can form different forms of NAFION functional coating on the surface of hydrogen storage alloy. With the decrease of the concentration, The NAFION formed on the surface of the alloy particles is changed from a dispersed and raised white flakes to a thin, well-spread film, but the film can not completely coated alloy particles. Electrochemical performance test results show that the cycle stability of the alloy after coated NAFION is improved. When the NAFION dilution ratio is 1 ： 5, alloy electrode discharge capacity is the largest （387.3 mA· h/g） and the cycle stability is the best, after 100 times charge and discharge cycle, the alloy capacity retention rate S100 reached 89%, which is best bare alloy. After the surface coating of NAFION, the high current dischargeperformance of the alloy electrode was significantly decreased, and the HRDs00 was reduced from 81.6 G of the bare alloy to 68.1% after the coating. The increase of the surface electron exchange resistance （or the exchange current density I0 decreases） at the time of the alloy electrode reaction is one of the main factors affecting the high magnification discharge performance of the coated alloy.
出处
《金属功能材料》
CAS
2018年第1期23-29,共7页
Metallic Functional Materials
