本文關(guān)鍵詞：鋰離子電池新型負(fù)極材料一氧化鈮及碳化硅的研究　出處：《中南大學(xué)》2014年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： NbO SiC 電化學(xué)性能 嵌鋰動力學(xué) 鋰離子電池

【摘要】：摘要：立方結(jié)構(gòu)的一氧化鈮(NbO)材料和碳化硅(SiC)材料因其具有安全、穩(wěn)定、環(huán)保、低價等優(yōu)勢,有望成為新型的鋰離子電池負(fù)極材料。本論文采用高溫固相還原法制備了NbO材料,采用直接購買的SiC粉末為原材料,用XRD、SEM,激光粒度測試、CV曲線、EIS曲線及充放電曲線等檢測分析手段,研究了一氧化鈮和碳化硅兩種不同材料的理化性能和電化學(xué)性能,并初步探究了兩種材料的嵌鋰動力學(xué)過程。得出主要結(jié)論如下： (1)以鈮粉和五氧化二鈮粉末為原料,采用高溫固相法,制備了純相的NbO粉末。通過球磨處理,減小了粉末顆粒粒徑,改變了顆粒的表明形貌,使得NbO粉末分布更加均勻,提高了材料的電化學(xué)性能；NbO電極材料在0.1C倍率下首次放電比容量高達(dá)355mAh·g-1,循環(huán)50次后,仍有2931nAh·g-1的可逆比容量保留；NbO負(fù)極材料的嵌鋰平臺大概在1.6V左右；NbO材料的對鋰的插嵌機理為鋰離子的直接脫嵌,是一個單相轉(zhuǎn)變的過程。 (2)以直接購買的碳化硅為原料,通過球磨處理后,SiC電極材料首次以0.02C倍率條件下放電,比容量高達(dá)468mAh·g-1,循環(huán)50次后,仍有335mAh·g-1的可逆比容量保留,不可逆容量損失為28.4%；不同倍率條件下,SiC電極的容量保持率都較高；SiC負(fù)極材料的嵌鋰平臺大概在0.8V左右；采用原位X射線衍射的方法對SiC電極材料的嵌鋰機理進(jìn)行了初步的探究,推斷SiC材料的對鋰的插嵌機理為單相鋰離子的直接脫嵌。 (3)采用恒電流滴定(PITT)、循環(huán)伏安(CV)和交流阻抗(EIS)三種不同方法對NbO和SiC電極材料在充放電反應(yīng)中進(jìn)行了鋰離子擴散系數(shù)的研究,結(jié)果表明：恒電位間歇滴定法研究測定的NbO電極在充放電過程中的鋰離子在固相中的擴散系數(shù)在2.09×10-10～5.33×10-11cm2·S-1的范圍；循環(huán)伏安法研究NbO電極的界面過程中NbO電極在氧化和還原過程中的鋰離子在固相中的擴散濃度系數(shù)Ds分別為1.56×10-12和1.25×10-12cm2·s-1,兩種方法測試結(jié)果相差不大,NbO電極具有較好的鋰離子脫嵌可逆性；交流阻抗法計算測得了SiC電極中的鋰離子擴散系數(shù)在6.2×10-13～7.9×10-13cm2·S-1的范圍,電荷轉(zhuǎn)移電阻Rct在0.8V處有一個最小值265.4Ω,表明了SiC在電位平臺附近最容易發(fā)生界面電荷的轉(zhuǎn)移。 研究結(jié)果表明NbO和SiC材料均可作為新型負(fù)極材料用于鋰離子電池領(lǐng)域,并具有一定的產(chǎn)業(yè)化前景。
[Abstract]:Abstract: cubic niobium oxide (NbO) and silicon carbide (sic) materials have the advantages of safety, stability, environmental protection and low cost. It is expected to be a new cathode material for lithium ion battery. In this paper, NbO materials were prepared by high temperature solid state reduction method. The SiC powder purchased directly was used as raw material and SiC was used as raw material. The physical and chemical properties and electrochemical properties of niobium oxide and silicon carbide were studied by means of laser particle size measurement CV curve EIS curve and charge-discharge curve. The kinetic processes of lithium intercalation between the two materials are preliminarily investigated. The main conclusions are as follows: Using niobium powder and niobium pentoxide powder as raw materials, pure phase NbO powder was prepared by high temperature solid state method. The particle size was reduced and the morphology of particle was changed by ball milling. The distribution of NbO powder is more uniform, and the electrochemical performance of the material is improved. The initial discharge specific capacity of NbO electrode was 355mAh 路g-1 at 0.1C ratio, and the reversible specific capacity of 2931nAh 路g-1 remained after 50 cycles. The lithium intercalation platform of NbO anode material is about 1.6 V; The intercalation mechanism of lithium in NbO is the direct deintercalation of lithium ion, which is a single phase transition process. (2) the sic electrode material, which was directly purchased from silicon carbide, was discharged at 0.02C rate for the first time, with a specific capacity of 468mAh 路g ~ (-1) after ball-milling treatment. After 50 cycles, the reversible specific capacity of 335mAh 路g-1 was retained, and the irreversible capacity loss was 28.4kb. The capacity retention rate of sic electrode is higher than that of sic electrode under different ratio. The lithium intercalation platform of SiC anode material is about 0.8V; The mechanism of lithium intercalation in SiC electrode materials was preliminarily investigated by in situ X-ray diffraction. It was inferred that the intercalation mechanism of lithium in SiC materials was the direct deintercalation of single phase lithium ion. (3) using constant current titration (PITT). The diffusion coefficients of lithium ions in charge and discharge reactions of NbO and SiC electrode materials were studied by cyclic voltammetry (CV) and AC impedance spectroscopy (EIS). The results show that:. The diffusion coefficient of lithium ion in solid phase of NbO electrode studied by potentiostatic intermittent titration is in the range of 2.09 脳 10 ~ (-10) 10 ~ (-1) 5.33 脳 10 ~ (-11) cm ~ (2) 路s ~ (-1). ; Cyclic voltammetry study of the diffusion concentration coefficients of lithium ions in solid phase of NbO electrode during redox and reduction at the interface of NbO electrode were 1.56 脳 10 ~ (-12) and 1.25 脳 10 ~ (-1) 脳 10 ~ (-1), respectively. -12 cm 2 路s -1. The results of the two methods are similar to those of the NbO electrode, and the results show that the lithium ion deintercalation reversibility is better than that of the NbO electrode. The diffusion coefficient of lithium ion in SiC electrode was measured by AC impedance method in the range of 6.2 脳 10 ~ (-13) ~ 7.9 脳 10 ~ (-13) cm ~ (-2) 路S ~ (-1). The charge transfer resistance (Rct) has a minimum value of 265.4 惟 at 0.8 V, which indicates that SiC is the most prone to interfacial charge transfer near the potential platform. The results show that both NbO and SiC can be used as new anode materials for lithium ion batteries and have a certain industrial prospect.
【學(xué)位授予單位】：中南大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TM912

【參考文獻(xiàn)】

相關(guān)期刊論文 前2條

1 陳敬波,胡國榮,彭忠東,陳艷玲,桂陽海;鋰離子電池氧化物負(fù)極材料研究進(jìn)展[J];電池;2003年03期

2 周鑫;趙新兵;余紅明;胡潔梓;;F摻雜LiFePO_4/C的固相合成及電化學(xué)性能[J];無機材料學(xué)報;2008年03期

，

本文編號：1432321