复合方式对V_2O_5/PPy的结构及电化学性能的影响

Effect of Composite Modes on Structure and Electrochemical Performance of V_2O_5/PPy

以五氧化二钒和过氧化氢为原料,采用溶胶-凝胶法合成片状V2O5,再采用化学氧化法,通过改变氧化剂的加入顺序,制备出了不同结构的五氧化二钒/聚吡咯(V2O5/PPy)复合材料。运用X射线粉末衍射(XRD)、扫描电子显微镜(SEM)和比表面积(BET)表征了材料的结构和形貌,用四探针测试了材料的电导率。结果表明,氧化剂的加入方式不同,所得复合材料结构和形貌明显不同。先加氧化剂时,吡咯在V2O5的层间聚合,XRD测试表明所得复合材料的主要衍射峰对应的层间距由0.40806nm(V2O5)增大到0.41019nm;而先加入吡咯单体时,吡咯在V2O5的表面吸附聚合,复合材料的层间距没有明显变化。先加入氧化剂所得复合材料具有最高的放电比容量(271.8mAh/g),并且循环50次后,仍有225.4mAh/g的放电比容量。

The plate-like vanadium pentoxide （V2O5） was prepared by sol-gel method using V2O5 and H2O2 as raw materials. The composites of V2O5/polypyrrole （PPy） were synthesized by chemical oxidative polymerization. By using different methods of adding oxidant, different structure composites were obtained. The composites were investigated and characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and Brunner-Emmett-Teller method （BET）. The conductivities of the composites were measured by a four-probe instrument. The results show that the composites obtained by using different methods of adding the oxidant have different structures and morphologies. When the oxidant is added first, polypyrrole intercalates into the sandwich of V2O5, leading to an increase in the d-spacing from 0.40806 nm for V2O5 to 0.41019 nm for the composites; when the pyrrole is added first, PPy deposits preferentially on the V2O5 particle surface, the d-spacing of the composite is not changed. The specific discharge capacity of the composites reaches 271.8 mAh/g at 0.1C rate and voltage limits of 1.8 V～4.0 V, and still owned 225.4 mAh/g after 50 cycles.