CAJ | 학술논문

采用溶胶-凝胶法制备锂离子电池正极材料Li3V2(PO4)3/C.通过恒电流充放电测试、循环伏安(CV)、电化学阻抗谱(EIS)等方法,研究了Li3V2(PO4)3/C在不同电压区间的电化学行为(3.0-4.5 V和3.0-4.8 V).结果表明,3.0-4.8 V电压区间的循环性能和倍率性能均不及3.0-4.5 V电压区间的.3.0-4.5 V区间0.1C (1C=150 mA?g-1)倍率首次放电比容量为127.0 mAh?g-1,循环50次后容量保持率为99.5%,而3.0-4.8 V区间的分别为168.2 mAh?g-1和78.5%.经过高倍率测试后再回到0.1C倍率充放电,3.0-4.5 V和3.0-4.8 V的放电比容量分别为初始0.1C倍率的99.0%和80.7%.经过3.0-4.8 V电压区间测试后,少部分第三个锂离子能够在低于4.5 V的电压脱出,使3.0-4.5 V电压区间的放电比容量提升了7.4%. CV结果表明3.0-4.8 V区间的容量损失主要表现为第一个锂离子的不可逆损失.极片的X射线衍射(XRD)和X射线光电子能谱(XPS)分析测试结果表明经过3.0-4.8 V测试后, Li3V2(PO4)3的结构发生了轻微的改变.电感耦合等离子体(ICP)测试结果表明循环后的电解液中含有少量的V.结构变形和V溶解可能是Li3V2(PO4)3在3.0-4.8 V区间容量衰减的主要原因.
채용용효-응효법제비리리자전지정겁재료Li3V2(PO4)3/C.통과항전류충방전측시、순배복안(CV)、전화학조항보(EIS)등방법,연구료Li3V2(PO4)3/C재불동전압구간적전화학행위(3.0-4.5 V화3.0-4.8 V).결과표명,3.0-4.8 V전압구간적순배성능화배솔성능균불급3.0-4.5 V전압구간적.3.0-4.5 V구간0.1C (1C=150 mA?g-1)배솔수차방전비용량위127.0 mAh?g-1,순배50차후용량보지솔위99.5%,이3.0-4.8 V구간적분별위168.2 mAh?g-1화78.5%.경과고배솔측시후재회도0.1C배솔충방전,3.0-4.5 V화3.0-4.8 V적방전비용량분별위초시0.1C배솔적99.0%화80.7%.경과3.0-4.8 V전압구간측시후,소부분제삼개리리자능구재저우4.5 V적전압탈출,사3.0-4.5 V전압구간적방전비용량제승료7.4%. CV결과표명3.0-4.8 V구간적용량손실주요표현위제일개리리자적불가역손실.겁편적X사선연사(XRD)화X사선광전자능보(XPS)분석측시결과표명경과3.0-4.8 V측시후, Li3V2(PO4)3적결구발생료경미적개변.전감우합등리자체(ICP)측시결과표명순배후적전해액중함유소량적V.결구변형화V용해가능시Li3V2(PO4)3재3.0-4.8 V구간용량쇠감적주요원인.
Li3V2(PO4)3/C cathode material was synthesized by the sol-gel method. The electrochemical properties of the sample in different voltage ranges (3.0-4.5 V and 3.0-4.8 V) were investigated by galvanostatic charge/discharge tests, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). Results show that the cycling performance and rate capability of Li3V2(PO4)3/C in voltage range of 3.0-4.8 V are worse than those in voltage range of 3.0-4.5 V. The initial specific discharge capacity in voltage range of 3.0-4.5 V at 0.1C rate (1C=150 mA?g-1) is 127.0 mAh?g-1, and 99.5%of the initial capacity was maintained after 50 cycles in contrast to 168.2 mAh?g-1 and 78.5%in voltage range of 3.0-4.8 V. The discharge capacities in voltage ranges of 3.0-4.5 V and 3.0-4.8 V are 99.0%and 80.7%of the initial 0.1C rate respectively when the charge/discharge rate recovered to 0.1C rate after the high rate test. Part of the third lithium ion may be extracted at less than 4.5 V after several cycles in voltage range of 3.0-4.8 V with a capacity increase of 7.4%. CV results indicate that the irreversible capacity fading between 3.0 and 4.8 V may be attributed to irreversible behavior of the first lithium ion. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) results show that the structure of Li3V2(PO4)3 changes slightly after operating between 3.0 and 4.8 V. Inductively coupled plasma (ICP) results indicate the presence of dissolved V in the cycled electrolytes. The structural distortion and the V dissolved in the electrolyte may be the main reasons for the decrease in capacity.