制备方法对磷酸亚铁锂-磷酸钒锂的影响

The influences of the preparation methods on the lithium iron(Ⅱ) phosphate-lithium vanadium phosphate mixing materials

分别采用"物理混合法"和"化学混合法"制备磷酸亚铁锂-磷酸钒锂混合材料。对两种材料进行了晶型结构、碳含量、粒径分布、表观形貌及表面碳元素、导电率等分析测试,发现采用"物理混合法"制备磷酸亚铁锂-磷酸钒锂混合材料时,对材料的结晶度产生一定的影响,物理混合破坏了材料表面的碳包裹层,并造成部分材料颗粒的团聚;"化学混合法"制备出形貌较为规则、粒径较小、粒度分布窄的混合材料,材料结晶良好存在痕量的杂相,表面光滑、碳包裹情况良好。"化学混合法"制得的材料导电率大于"物理混合法"制得的材料。充放电循环性能测试表明,采用"化学混合法"制备的材料具有优良的电化学性能,0.1C放电容量达到194.5mAh/g,20C放电容量仍有85mAh/g且循环稳定性均较好;1C进行1000次循环之后仍然保持120mAh/g的容量,具有较高的实用价值。因此"化学混合法"是制备磷酸亚铁锂-磷酸钒锂混合材料的优选方法。

Lithium iron（Ⅱ） phosphate lithium vanadium phosphate mixing materials（LFVP） were prepared by ＂physical blending method＂ and ＂chemical blending method＂,and the obtained materials were characterized by crystal structure,carbon analysis,grain size distribution,morphology and conductivity.We found in the process of ＂physical blending method＂,the strong mechanical force impacted the material＇s crystal structures and the carbon coating on the surface of the materials;a few materials grains may also agglomerate.The good crystal structural material synthesized by ＂chemical blending method＂ has more excellent electrochemical performance,its discharge capacity is 194.5 and 85mAh/g at 0.1 and 20C respectively;when the material was discharged at 1C for 1000 times,the capacity also remained 120mAh/g,so it has important practical value.All of the excellent electrochemical performances can be attributed to its fine and uniformly distributed materials grains,carbon-coating,and the trace impurities.Therefore ＂chemical blending method＂ is the preferred method to prepare LFVP.