本文關(guān)鍵詞： 錳酸鋅 模板法 鋰離子電池 負(fù)極 儲(chǔ)鋰性能　出處：《安徽工業(yè)大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：鋰離子電池(LIBs)能量密度高,循環(huán)壽命好,工作電壓高、能量密度高,是目前作為二次電池中應(yīng)用最為廣泛的產(chǎn)品。為了適應(yīng)動(dòng)力電池發(fā)展的需要,鋰離子電池負(fù)極材料是LIBs重要的一個(gè)組成,目前受到了廣泛的關(guān)注。鋰離子電池負(fù)極材料過渡金屬氧化物來源廣泛,且具有很高的理論比容量,被眾多研究人員所青睞。錳酸鋅(ZnMn_2O_4)作為過渡金屬氧化物中的一員,具有過渡金屬氧化物所有優(yōu)點(diǎn),但是鑒于過渡金屬氧化物的一些缺點(diǎn),如導(dǎo)電性較差;在鋰離子的嵌/脫出的過程中,易造成材料的體積發(fā)生一定改變,引起結(jié)構(gòu)性坍塌;制約了其在鋰離子電池的電化學(xué)性能的展現(xiàn),本文通過對(duì)ZnMn_2O_4負(fù)極材料結(jié)構(gòu)的優(yōu)化設(shè)計(jì),為離子,電子傳輸提供更為豐富的活性位點(diǎn),提高了其導(dǎo)電性,優(yōu)化了其結(jié)構(gòu)穩(wěn)定性,以此來獲得高性能的LIBs負(fù)極材料。具體研究?jī)?nèi)容如下:(1)以氧化石墨烯(GO)為模板合成超薄MnO_2納米片,在室溫中利用一步快速還原生成超薄的ZnMn_2O_4納米片,方法非常的簡(jiǎn)便,具有普適性。并探究了超薄ZnMn_2O_4的形成機(jī)理和電化學(xué)性能。超薄ZnMn_2O_4納米片縮短了電子/離子的傳輸路徑,提升了電極的離子導(dǎo)電性,對(duì)于應(yīng)力具有很好的緩沖效果,有助于提高其材料的結(jié)構(gòu)穩(wěn)定性,使得超薄ZnMn_2O_4納米片表現(xiàn)出了優(yōu)秀的電化學(xué)儲(chǔ)鋰性能。通過電化學(xué)測(cè)試結(jié)果可以看出,在高倍率1 C(784 mA/g)條件下,該超薄ZnMn_2O_4納米首次放電比容量高達(dá)1353mAh/g,經(jīng)過100周循環(huán)后后,超薄的ZnMn_2O_4納米片依然保有510 mAh/g的容量,表現(xiàn)出超薄ZnMn_2O_4納米片非凡的循環(huán)穩(wěn)定性、倍率性能和庫(kù)倫效率。(2)利用生物質(zhì)材料棉花為模板,通過浸漬,煅燒,成功合成了多層次ZnMn_2O_4微米帶。由于棉花本身的特殊性能具有很強(qiáng)的吸附能力,在浸漬過程中大量鋅錳離子均勻的被棉花纖維吸附。在隨后煅燒的過程中隨著有機(jī)物質(zhì)和碳材料被慢慢氧化,棉花纖維狀形貌很好的被保持,最終形成由大量帶狀結(jié)構(gòu)交織于一起的獨(dú)特三維網(wǎng)絡(luò)結(jié)構(gòu)。此種結(jié)構(gòu)對(duì)應(yīng)力具有很好的緩沖作用,能夠有效的抵御結(jié)構(gòu)的坍塌,增加電極電解液接觸面積,有助于離/電子的傳輸,提高材料的導(dǎo)電性。通過對(duì)其物性表征以及電化學(xué)性能的表征可以看到其表現(xiàn)了優(yōu)異的電化學(xué)性能,在200 mA/g電流密度下首次放電容量為1090 mAh/g,1000 mA/g大電流密度下,循環(huán)350圈之后容量依然可以保持在409 mAh/g遠(yuǎn)高于石墨負(fù)極材料的理論容量。表現(xiàn)出了十分優(yōu)異的電化學(xué)性能。(3)以碳布為模板形成MnO_2@Carbon cloth(后文簡(jiǎn)稱MnO_2@CC),再以此為基礎(chǔ)進(jìn)行犧牲模板法最終形成了一維管狀中空ZnMn_2O_4,我們對(duì)此材料進(jìn)行了各種物性及電化學(xué)性能表征。通過測(cè)試發(fā)現(xiàn),一維管狀中空ZnMn_2O_4微管是由很多納米顆粒和納米片相互交織,最終形成疏松多孔的管狀結(jié)構(gòu)。首先一維結(jié)構(gòu)因其獨(dú)特的形態(tài)有利于離/電子的傳導(dǎo),有助于提高材料的離電子導(dǎo)電性。其次中空結(jié)構(gòu)具有一定的應(yīng)力緩沖作用,可以一定程度的緩沖體積變化對(duì)結(jié)構(gòu)帶來的不利影響。而且結(jié)構(gòu)中的納米顆粒、片狀結(jié)構(gòu)縮短了電子傳導(dǎo)路程,提高了材料的導(dǎo)電性。通過電化學(xué)測(cè)試結(jié)果可以看出,在電流密度100 mA/g條件下,其放電比容量為585 mAh/g。當(dāng)電流密度達(dá)到2000 mA/g時(shí),其放電容量仍可達(dá)到272 mAh/g,實(shí)驗(yàn)表明一維管狀中空ZnMn_2O_4具有很好的電化學(xué)性能表現(xiàn)。除了對(duì)于其電化學(xué)性能的表征以外,我們還發(fā)現(xiàn)了一些有趣的現(xiàn)象。原本碳布纖維在很高溫度下依然可以很好的保持它的形貌,在錳離子的加入后在較低的溫度下碳布纖維就被煅燒去除了。說明錳離子對(duì)于石墨化程度很高的碳熱解具有一定的催化效果。
[Abstract]:Lithium ion batteries (LIBs) high energy density, long cycle life, high working voltage, high energy density, is two times as the most widely used battery products. In order to meet the needs of the development of power battery, lithium ion battery anode material is an important component of LIBs, there has been widespread concern. Anode materials for lithium ion batteries of transition metal oxides originates widely, and has very high theoretical capacity, is favored by many researchers. Manganese zinc (ZnMn_2O_4) as a member of transition metal oxides, transition metal oxides has all the advantages, but because of some disadvantages of transition metal oxides, such as poor conductivity; lithium ion intercalation / extraction process, easy to cause the volume of the material changed, causing structural collapse; which show the electrochemical performance of lithium ion battery, based on ZnMn_2O_4 Optimization design of anode material structure for ion, electron transport provide more active sites for the rich, improve its conductivity, optimizing its structure stability, in order to obtain LIBs anode materials with high performance. The specific contents are as follows: (1) to graphene oxide (GO) template for synthesis of ultrathin MnO_2 nanosheets the use of ZnMn_2O_4, nano step fast reduction of generation ultra-thin at room temperature, the method is simple, it is universal. And to explore the formation mechanism and electrochemical properties of ultrathin ZnMn_2O_4. Ultrathin ZnMn_2O_4 nanosheets can shorten the transmission path from the electronic / sub, enhance the ionic conductivity of the electrode, the stress is a good cushioning effect, help to improve the structural stability of the material, the ultrathin ZnMn_2O_4 nanosheets exhibit excellent electrochemical lithium storage performance. The electrochemical test results showed that, in the high rate of 1 C (78 4 mA/g) under the condition of the ultra-thin nano ZnMn_2O_4 the first discharge capacity is up to 1353mAh/g, after 100 cycles, nano ZnMn_2O_4 thin still retains a capacity of 510 mAh/g, showing ultrathin ZnMn_2O_4 nanosheets extraordinary rate performance and cycle stability, Kulun efficiency. (2) the use of biomass materials of cotton as template and through the impregnation, calcination, successfully synthesized hierarchical ZnMn_2O_4 microbelts. Due to the special properties of cotton itself has a strong adsorption capacity, in the impregnation process of large quantities of zinc manganese ion by uniform cotton fiber adsorption. In the subsequent calcination process with organic matter and carbon materials are slowly oxidized cotton fiber like morphology good is maintained, eventually formed a unique three-dimensional network structure composed of a large number of banded structure interwoven together to. The structure stress has good buffer function, can effectively resist structure collapse Collapse, increasing the electrode electrolyte contact area, help from / electronic transmission, improve the conductivity of the material. By the characterization and electrochemical characterization see demonstrates its excellent electrochemical performance, under the current density of 200 mA/g the first discharge capacity of 1090 mAh/g, 1000 mA/g high current density, after 350 cycles the capacity can still maintain a theoretical capacity of 409 mAh/g is much higher than that of graphite electrode. Exhibit excellent electrochemical performance. (3) with carbon cloth as template form MnO_2@Carbon cloth (hereinafter referred to as the MnO_2@CC), and then as a basis for the sacrifice template eventually formed a one-dimensional tubular hollow ZnMn_2O_4, we this material has a variety of characterization and electrochemical performance. Through the test found that the one-dimensional tubular hollow ZnMn_2O_4 microtubules are composed of many nano particles and nano films are intertwined, eventually forming The tubular porous structure. Firstly, one-dimensional structure because of its unique form to leave / electron transfer, help to improve the material from the electronic conductivity. Secondly the hollow structure has certain stress buffering effect, can buffer the volume change of a certain degree of structure caused by the adverse effects of nanoparticles and structure. The lamellar structure reduces the electron conduction distance, improve the conductivity of the material. The electrochemical test results show that the current density of 100 mA/g, the discharge capacity is 585 mAh/g. when the current density reaches 2000 mA/g, the discharge capacity can reach 272 mAh/g, experiments show that the one-dimensional tubular hollow ZnMn_2O_4 with electrochemical properties a very good performance. In addition to the characterization of its electrochemical performance, we also found some interesting phenomena. The original carbon fiber cloth under very high temperature can still very OK, keep its shape. When the manganese ion is added, the carbon fiber will be calcined and removed at lower temperature. This indicates that manganese ion has certain catalytic effect for carbon pyrolysis with high graphitization degree.

【學(xué)位授予單位】：安徽工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TM912;TB383.1

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本文編號(hào)：1465850