本文選題：鈉離子電池　切入點(diǎn)：鈦酸鈉　出處：《齊魯工業(yè)大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：本文首先對(duì)鋰離子電池和鈉離子電池進(jìn)行了簡(jiǎn)要概述,同時(shí)對(duì)現(xiàn)有文獻(xiàn)報(bào)道的鈉離子電池材料進(jìn)行歸類整理并做了詳細(xì)的介紹,并對(duì)現(xiàn)有材料的優(yōu)點(diǎn)和不足進(jìn)行了分析,然后提出了本論文的研究重點(diǎn)：利用具有優(yōu)良導(dǎo)電性的材料對(duì)現(xiàn)有電極材料進(jìn)行表面修飾改性,提高電極的電導(dǎo)率,使制備的材料具有更優(yōu)異的電化學(xué)性能。主要內(nèi)容包括：層狀Na2Ti3O7作為鈉離子電池負(fù)極材料時(shí),存在導(dǎo)電性差、高溫下容易形成棒狀或塊狀結(jié)構(gòu),Na+離子擴(kuò)散率低及倍率性能較差等問(wèn)題。本文以介孔二氧化鈦?zhàn)鳛榍膀?qū)體,熱固性酚醛樹(shù)脂作為碳源和保護(hù)層,制備了內(nèi)部由導(dǎo)電碳網(wǎng)絡(luò)分割、表面均勻包覆一層導(dǎo)電碳的Na2Ti3O7@C復(fù)合材料。通過(guò)X射線衍射技術(shù)、掃描電子顯微鏡及透射電子顯微鏡等測(cè)試手段對(duì)所得復(fù)合材料的結(jié)構(gòu)和形貌進(jìn)行了一系列表征,并以之為鈉離子電池電極材料與金屬鈉組裝成半電池進(jìn)行電化學(xué)測(cè)試。測(cè)試結(jié)果表明,所得電極材料為碳層包覆的純相Na2Ti3O7。TEM和SEM表征證明電極材料呈直徑500 nm左右的球狀核殼結(jié)構(gòu)。這種納米結(jié)構(gòu)的存在縮短了Na+離子的傳輸距離,因而提高了電極材料中Na+離子的擴(kuò)散速率。電極材料表面所包覆的很薄的碳?xì)拥拇嬖?提高了材料的導(dǎo)電性能。因此,制備的Na2Ti3O7@C復(fù)合材料較純Na2Ti3O7材料的電化學(xué)儲(chǔ)鈉性能有非常大的提高,在O.1C倍率下第2周循環(huán)的放電容量由109.2mAh/g提高到155 mAh/g,50周循環(huán)后放電容量仍保持在100 mAh/g,而Na2Ti307材料50周循環(huán)后放電容量?jī)H保持有60.1 mAh/g。在NASICON型的Na3V2(PO4)3晶體結(jié)構(gòu)中,VO6八面體和PO4四面體以頂角相連的形式組成三維框架構(gòu)造,表現(xiàn)出可供Na+離子快速通過(guò)的通道結(jié)構(gòu),因此在理論上Na+離子具有非常高的傳導(dǎo)率。然而電極材料的電導(dǎo)率相對(duì)較低,儲(chǔ)鈉的電化學(xué)活性也較差。聚苯胺是一種具有共軛π-π鍵結(jié)構(gòu)的聚合物,在經(jīng)過(guò)“摻雜”后,π電子可以沿著聚合物鏈方向移動(dòng),因而表現(xiàn)出良好的導(dǎo)電性。本文利用化學(xué)氧化的方法成功地制備了質(zhì)子酸摻雜的聚苯胺,并將其均勻地包覆在Na3V2(PO4)3材料表面對(duì)材料進(jìn)行表面修飾。相應(yīng)結(jié)構(gòu)表征證明了聚苯胺在電極材料表面的成功包覆；相應(yīng)電化學(xué)性能測(cè)試證明,經(jīng)聚苯胺包覆改性后的Na3V2(PO4)3電極材料的充放電比容量以及循環(huán)穩(wěn)定性較Na3V2(PO4)3本征電極材料有顯著提高。其中,在700℃C焙燒條件下獲得的電極材料經(jīng)導(dǎo)電聚合物包覆后,其電性能尤為優(yōu)異。當(dāng)聚苯胺的含量為Na3V2(PO4)3的萬(wàn)分之一時(shí),復(fù)合材料具有最好的儲(chǔ)鈉性能,0.2C倍率下放電容量為96.5 mAh/g,20周循環(huán)后穩(wěn)定在62 mAh/g。本工作擴(kuò)展了導(dǎo)電聚合物在二次電池電極材料中的應(yīng)用范圍,也為鈉離子二次電池電極材料的改性提供了一定的參考價(jià)值。
[Abstract]:In this paper, the lithium ion battery and sodium ion battery are briefly summarized, and the materials of sodium ion battery reported in the literature are classified and summarized in detail, and the advantages and disadvantages of the existing materials are analyzed. Then the research focus of this paper is put forward: the surface modification of the existing electrode materials is carried out by using the materials with excellent conductivity to improve the conductivity of the electrode. The main contents include: when layered Na2Ti3O7 is used as anode material of sodium ion battery, its conductivity is poor. It is easy to form rod or block structure Na ion at high temperature. In this paper, mesoporous titanium dioxide is used as precursor, thermosetting phenolic resin is used as carbon source and protective layer, and the interior is separated by conductive carbon network. The structure and morphology of Na2Ti3O7@C composites were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscope. It was used as electrode material of sodium ion battery and assembled into a half cell with sodium metal for electrochemical test. The carbon coated pure phase Na2Ti3O7.TEM and SEM showed that the electrode material was spherical core-shell structure about 500nm in diameter. The existence of the nanostructure shortened the transport distance of Na ~ (2 +). As a result, the diffusion rate of Na ions in the electrode material is increased. The existence of a thin carbon shell coated on the surface of the electrode material improves the conductivity of the electrode material. Compared with pure Na2Ti3O7 composites, the electrochemical sodium storage properties of the prepared Na2Ti3O7@C composites are greatly improved. The discharge capacity of the second cycle was increased from 109.2 mAh/ g to 155mAh/ g at the 0.1 C ratio, and the discharge capacity of the Na2Ti307 material remained at 100mAh/ g after 50 cycles, while the discharge capacity of the Na2Ti307 material remained only 60.1 mAh/ g after the 50-week cycle. In the Na3V2(PO4)3 crystal structure of NASICON type, VO6 octahedron and VO _ 6 octahedron and octahedron were obtained. The PO4 tetrahedron forms a three-dimensional frame structure in the form of a contiguous vertex. It shows that Na ion can pass through the channel structure quickly, so Na ion has very high conductivity in theory. However, the conductivity of electrode material is relatively low. The electrochemical activity of sodium storage is also poor. Polyaniline is a polymer with conjugated 蟺-蟺 bond structure. After doping, 蟺 electrons can move along the polymer chain. In this paper, the proton acid doped Polyaniline was successfully prepared by chemical oxidation. The corresponding structure characterization proved that Polyaniline was successfully coated on the surface of the electrode material, and the corresponding electrochemical performance test proved that, The charge / discharge capacity and cyclic stability of the modified Na3V2(PO4)3 electrode materials coated with Polyaniline were significantly higher than those of the Na3V2(PO4)3 intrinsic electrode materials, among which the electrode materials calcined at 700 鈩，

本文編號(hào)：1626315