本文選題：鋰離子電池　切入點：正極材料　出處：《桂林理工大學(xué)》2014年碩士論文　論文類型：學(xué)位論文

【摘要】：與傳統(tǒng)的鋰離子電池正極材料（LiCoO2等）相比，層狀結(jié)構(gòu)V6O13和VO2(B)具有比容量大、能量密度高、合成方法簡單、價格便宜等優(yōu)點，，被越來越多的研究者認(rèn)為是具有開發(fā)和應(yīng)用潛力的新一代鋰離子正極材料。釩氧化物的常用合成方法為固相法和水熱法，但是較難制備出純相的釩氧化物。而溶劑熱具有容易生成特殊價態(tài)的化合物、能夠控制產(chǎn)物的形貌、能夠均勻摻雜等優(yōu)點。 本文采用水熱法、固相法制備出了V6O13，用溶劑熱法制備了V6O13、VO2(B)、MnV2O6。對不同方法合成釩氧化物進(jìn)行了電化學(xué)性能對比后發(fā)現(xiàn)溶劑熱法制備的釩氧化物電化學(xué)性能較好。本文主要研究了溶劑熱合成過程，并分別對V6O13和VO2(B)的溶劑熱合成工藝進(jìn)行了探討，主要研究了乙醇和水的配比、溶劑熱保溫溫度、溶劑熱保溫時間、煅燒溫度等條件對產(chǎn)物物相和電化學(xué)性能的影響，得到了溶劑熱制備V6O13和VO2(B)的最佳工藝。 為了提高V6O13和VO2(B)在脫嵌鋰過程中的結(jié)構(gòu)穩(wěn)定性，對V6O13分別進(jìn)行Mn2+、Ni2+摻雜，對VO2(B)分別進(jìn)行Cu2+、Ti4+摻雜。同時用溶劑熱合成了塊狀和管狀MnV2O6，并對其充放電性能進(jìn)行了初步探討。對V6O13分別進(jìn)行Mn2+、Ni2+摻雜后發(fā)現(xiàn)，Mn2+或Ni2+都能夠進(jìn)入到V6O13正極材料的晶格中。摻雜后的V6O13脫嵌鋰離子時的結(jié)構(gòu)穩(wěn)定性能得到提高。CV和EIS測試表明部分Mn2+或Ni2+取代了的釩位置，在鋰離子的脫出和嵌入過程中材料被破壞的程度降低，抑制了容量衰減，循環(huán)性能得到改善。對VO2(B)進(jìn)行Cu2+摻雜后發(fā)現(xiàn)，Cu2+的加入使VO2(B)正極材料的脫嵌鋰離子的能力和充放電穩(wěn)定性都得到提高。當(dāng)摻Cu2+量為1.03at.%時，VO2(B)在低倍率和高倍率的性能都得到提高，在0.132C放電首次放電比容量317.1mAh/g，51次循環(huán)后的放電比容量仍然保存在234.3mAh/g。對VO2(B)進(jìn)行Ti4+摻雜后增強了脫嵌鋰能力和結(jié)構(gòu)穩(wěn)定性，尤其會提高正極材料在高倍率下的充放電性能。當(dāng)摻Ti4+量為0.68at.%時，VO2(B)在6.563C下具有171mAh/g的放電比容量，50次循環(huán)后容量保持率達(dá)到83.6%。 塊狀MnV2O6在40mA/g的電流密度下具有409mAh/g的放電比容量，但是容量衰減較快。管狀MnV2O6它能夠減少鋰離子擴散在界面的距離，從而影響MnV2O6在充放電過程形成非晶態(tài)，在40mA/g的電流密度下具有216mAh/g的放電比容量，循環(huán)過程中其結(jié)構(gòu)有所破壞，性能也有所降低。
[Abstract]:Compared with traditional cathode materials such as LiCoO _ 2, layered V6O13 and VO2B) have many advantages, such as high specific capacity, high energy density, simple synthesis method and low price. More and more researchers consider it a new generation of lithium ion cathode materials with potential for development and application. The common synthesis methods of vanadium oxide are solid phase method and hydrothermal method. However, it is difficult to prepare pure vanadium oxides, and solvothermal has the advantages of easily forming special valence compounds, controlling the morphology of the products and doping them uniformly. The hydrothermal method is used in this paper. V6O13 was prepared by solid state method, and V6O13 VO2O2V2O6 was prepared by solvothermal method. After comparing the electrochemical properties of vanadium oxide synthesized by different methods, it was found that the electrochemical performance of vanadium oxide prepared by solvothermal method was better. In this paper, the process of solvothermal synthesis was studied. The effects of the ratio of ethanol and water, the temperature of solvothermal insulation, the time of solvothermal insulation and the calcination temperature on the phase and electrochemical properties of the product were studied. The optimum solvothermal preparation process of V6O13 and VO2 / B was obtained. In order to improve the structural stability of V6O13 and VO2B in the process of lithium deintercalation, V6O13 was doped with Mn2 and Ni2, respectively. VO _ 2 O _ 2 B) was doped with Cu2 / Ti _ 4. Bulk and tubular MNO _ 2 O _ 6 were prepared by solvothermal method, and their charge-discharge properties were preliminarily discussed. It was found that both MNO _ 2 and Ni2 could enter the V6O13 cathode material after V6O13 was doped with Mn2 ~ (2 +) Ni _ (2) respectively. In the lattice, the structure stability of the doped V6O13 is improved. CV and EIS measurements show that some Mn2 or Ni2 have replaced the vanadium position. During the removal and intercalation of lithium ions, the material is destroyed to a lesser extent, which inhibits the capacity decay. The cycling performance was improved. It was found that the ability and charge-discharge stability of the cathode material were improved with the addition of Cu2 + after Cu2 doping. When the Cu2 content was 1.03at.wt%, the properties of VO _ 2B) at low rate and high rate were improved. After the first discharge capacity of 0.132C discharge was 317.1mAh/ g ~ (-1) cycle, the discharge specific capacity was still preserved at 234.3 mAh/ g. The Ti4 doping of VO _ 2H _ (2) B enhanced the deintercalation capacity and structure stability of VO _ (2) O _ (2) O _ (2) O _ (2) O _ (2) B, In particular, the charge-discharge performance of cathode materials at high rate can be improved. When the content of Ti4 is 0.68 at.%, the specific discharge capacity of 171mAh/g at 6.563C can be increased to 83.6% after 50 cycles. Bulk MnV2O6 has the specific discharge capacity of 409mAh/g at the current density of 40mA/g, but the capacity decays rapidly. Tubular MnV2O6 can reduce the distance of lithium ion diffusion at the interface, thus affecting the formation of amorphous MnV2O6 during charge and discharge. Under the current density of 40mA/g, the specific discharge capacity of 216mAh/g is obtained. During the cycle, the structure is destroyed and the performance is decreased.
【學(xué)位授予單位】：桂林理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TM912

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