镁可充电池正极材料V6O13/VO2的制备与电化学性能研究

摘要

In this work,the VO 2/V6 O 1 3 composites have been prepared by sol-gel method combined with etha-nol ultrasonic method.The composites were characterized to study the micro-morphology,phase composition and electrochemical Mg-intercalation performances by SEM,XRD,CV,CP,respectively.The results indicated that the composites including 45%VO 2 and 55% V6 O 1 3 were synthesized with reducing V2 O 5 by sonicating in ethanol and calcinning in Ar.The micromorphology of the composites were urchin-like with the dimension of 50-200 nm.The CVs showed that there were two-step procedure of Mg-ion insertion and extraction in the com-posites and only a portion of Mg ion could insert and extract reversiblely.At current density of 0.3 mA/cm2 ,the initial discharge specific capacity of the VO 2/V6 O 1 3 reached 365 mAh/g and the initial discharge plateau poten-tial was approximately - 0.5 V(vs.SCE).After 1 1 discharge-charge cycle,the specific capacity still reached 1 60 mAh/g,exhibiting better charge-discharge performance.However,the insertion and extraction process of the VO 2/V6 O 1 3 composite was controlled by the diffusion of Mg ion.In summary,the VO 2/V6 O 1 3 composite was a promising cathode material for Mg rechargeable batteries.%采用溶胶-凝胶法结合乙醇超声法制备了复合材料 VO 2/V6 O 13。通过 SEM、XRD、CV、CP 方法对复合材料 VO 2/V6 O 13的微观形貌、相组成、电化学储镁性能进行了研究。结果表明,通过乙醇超声和 Ar气氛煅烧还原 V2 O 5可得到两相复合物45％ VO 2和55％V6 O 13；复合材料微观形貌为50~200 nm 的海胆状产物；复合材料 VO 2/V6 O 13的脱嵌镁过程均为两步,仅有部分镁离子能可逆脱嵌；在0．3 mA/cm2充放电密度下,复合材料 VO 2/V6 O 13的首次放电比容量高达365 mAh/g,放电平台约为－0．50 V(vs．SCE),经过11次充放电循环,它的放电比容量仍然有160 mAh/g,保持了较好的充放电循环性能,但是复合材料 VO 2/V6 O 13的脱嵌镁过程仍然受到镁离子扩散控制。总的来看,复合材料 VO 2/V6 O 13是一类有希望用于镁可充电池的钒系正极材料。