本文選題：鋰離子電池 + Ge負(fù)極��； 參考：《鄭州大學(xué)》2017年碩士論文

【摘要】：作為儲(chǔ)能設(shè)備的鋰離子電池(LIBs)具有能量密度高、功率大、壽命長(zhǎng)和環(huán)境友好等特點(diǎn)。但市售LIBs石墨負(fù)極的理論容量?jī)H有372 mAh g~(-1),這難以滿足能量?jī)?chǔ)存系統(tǒng)的建立、大型電動(dòng)汽車等發(fā)展的要求。負(fù)極材料是LIBs的重要組成部分,因而,高容量負(fù)極材料的開(kāi)發(fā)成為提高LIBs性能的決定因素。作為鋰離子電池負(fù)極材料,Ge具有比容量高,操作電壓低、電子傳輸速率快等優(yōu)勢(shì),有望替代石墨負(fù)極。但在循環(huán)過(guò)程中,Ge體積膨脹嚴(yán)重,造成它的循環(huán)性能差,阻礙了實(shí)際應(yīng)用。為了提高Ge負(fù)極材料的循環(huán)穩(wěn)定性,研究者提出了納米結(jié)構(gòu)化和碳材料復(fù)合兩種方法。具有不同相貌的納米結(jié)構(gòu)具有表面積大,離子/電子傳輸快的特點(diǎn)。而碳質(zhì)材料具有高的導(dǎo)電性、好的機(jī)械柔韌性以及熱和化學(xué)穩(wěn)定性。在前人工作的基礎(chǔ)上,本文開(kāi)展了以下兩方面的內(nèi)容:(一)以市售的GeO_2、GO和純水為原料,基于溶解-重結(jié)晶的機(jī)理制得了GeO_2/graphene復(fù)合物。復(fù)合物制備過(guò)程中所用的化學(xué)試劑和儀器無(wú)毒且便宜。用作LIBs負(fù)極材料進(jìn)行性能測(cè)試時(shí),結(jié)果表明:該電極具有好的循環(huán)性能和高的可逆容量:首次充電容量高達(dá)1637 mAh g~(-1),循環(huán)80圈后可逆容量保持在640mAh g~(-1)。(二)針對(duì)傳統(tǒng)1 D納米結(jié)構(gòu)合成過(guò)程復(fù)雜、使用貴金屬催化劑的缺點(diǎn),本文通過(guò)靜電紡絲的方法合成了Ge/CNFs。該材料表現(xiàn)出良好的儲(chǔ)鋰性能:在100mA g~(-1)的電流密度下,循環(huán)30圈后仍具有643.2 mAh g~(-1)的可逆容量,約為石墨負(fù)極的2倍。這主要?dú)w因于:(1)多孔結(jié)構(gòu)能夠增加電極與電解質(zhì)的接觸面積;(2)Li~+較短的擴(kuò)散距離;(3)電子沿1 D方向快速傳輸,提高了電極的導(dǎo)電性。
[Abstract]:Li-ion battery as energy storage equipment has the characteristics of high energy density, high power, long life and friendly environment. However, the theoretical capacity of the LIBs graphite anode is only 372 mAh / g ~ (-1), which is difficult to meet the requirements of the establishment of energy storage system and the development of large electric vehicles. Negative electrode material is an important part of LIBs. Therefore, the development of high capacity anode material becomes the decisive factor to improve the performance of LIBs. As a cathode material for lithium-ion batteries, GE has the advantages of high specific capacity, low operating voltage and fast electron transfer rate, which is expected to replace graphite negative electrode. However, the volume expansion of GE in the process of circulation is serious, which results in its poor cycling performance and hinders its practical application. In order to improve the cyclic stability of GE anode materials, two methods of nanostructured and carbon composite were proposed. The nanostructures with different appearance are characterized by large surface area and fast ion / electron transport. Carbon materials have high electrical conductivity, good mechanical flexibility and thermal and chemical stability. On the basis of previous work, the following two aspects were carried out in this paper: (1) GeO_2/graphene complexes were prepared by using geo _ 2go and pure water as raw materials, based on the mechanism of solution-recrystallization. The chemical reagents and instruments used in the preparation of the complex are nontoxic and inexpensive. When used as LIBs anode material, the results show that the electrode has good cycling performance and high reversible capacity: the initial charge capacity is up to 1637 mAh / g ~ (-1) and the reversible capacity is kept at 640mAh ~ (-1) after 80 cycles. (2) in view of the complex synthesis process of traditional 1D nanostructure and the disadvantage of using noble metal catalyst, Ge- / CNFs were synthesized by electrospinning method in this paper. The material shows good lithium storage performance: at the current density of 100mA / GG ~ (-1), it still has a reversible capacity of 643.2 mAh / g ~ (-1) after 30 cycles, which is about 2 times as high as that of graphite negative electrode. This is mainly attributed to the fact that the porous structure can increase the contact area between the electrode and the electrolyte and increase the diffusion distance between the electrode and the electrolyte. The electron is transported rapidly along the direction of 1D and the conductivity of the electrode is improved.
【學(xué)位授予單位】：鄭州大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TB33;TM912

【參考文獻(xiàn)】

相關(guān)期刊論文 前2條

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本文編號(hào)：1876692