鋰離子電池硅基負(fù)極用關(guān)鍵材料的研究
發(fā)布時(shí)間：2018-09-13 16:32
【摘要】：鋰離子電池結(jié)構(gòu)主要由電極、隔膜、電解液三部分組成,其中電極作為鋰離子電池的核心部分,對(duì)鋰離子電池的性能起決定性作用。電極主要由活性材料、導(dǎo)電劑、粘結(jié)劑組成。之前的研究中,活性物質(zhì)作為鋰離子電池的核心材料備受研究人員關(guān)注,而導(dǎo)電劑與粘結(jié)劑作為鋰離子電池中使用量最少的材料,所受關(guān)注相對(duì)較少。導(dǎo)電劑與粘結(jié)劑在電極中用量雖少,但起到的作用卻不容忽視,這一點(diǎn)在高容量負(fù)極中尤其明顯。對(duì)于高容量負(fù)極,活性材料在鋰離子電池充放電過程中的較大的體積變化會(huì)造成電極中導(dǎo)電通道斷開、活性層與集流體分離等問題,造成鋰離子電池容量大幅衰減。采用新型導(dǎo)電劑與粘結(jié)劑可以在對(duì)電池成本影響較小的前提下緩解或解決這些問題。因此,本論文希望通過對(duì)導(dǎo)電劑和粘結(jié)劑的開發(fā)和改善,來提升高容量負(fù)極的電性能。論文首先確定了一個(gè)適合高容量負(fù)極的基本電池裝配工藝。結(jié)合之前的研究,高容量負(fù)極在充放電循環(huán)中變化與傳統(tǒng)的碳基材料不同,傳統(tǒng)的電池工藝無法發(fā)揮出高容量負(fù)極的性能。因此我們通過多次嘗試找到了比較適合高容量負(fù)極的電池工藝,并選用了納米硅作為負(fù)極的活性材料,以此為基礎(chǔ)來研究導(dǎo)電劑與粘結(jié)劑。導(dǎo)電劑方面我們開發(fā)出了二維納米材料與三維納米材料復(fù)合的導(dǎo)電劑,以適應(yīng)高容量負(fù)極材料。二維納米材料我們選用了酸化(羧基功能化)多壁碳納米管。制備了酸化多壁碳納米管,在表面引入缺陷與接枝羧基、羥基等基團(tuán)的同時(shí),因多壁碳納米管的多通道傳輸特性,保證了碳納米管的導(dǎo)電性。羧基引入的作用有兩點(diǎn),一是極大的改善了碳納米管的分散性,保證了極片長(zhǎng)程導(dǎo)電網(wǎng)絡(luò)的暢通;二是增強(qiáng)了碳納米管與粘結(jié)劑之間的結(jié)合力。三維納米材料我們選用了SP,SP的比表面積較大,增大了導(dǎo)電劑與活性材料的接觸面積。與傳統(tǒng)的SP導(dǎo)電劑相比,0.1 C放電倍率下,混合導(dǎo)電劑將鋰離子電池的首次放電比容量從1938 m Ah g-1提升為2927 m Ah g-1,首次庫倫效率從79.2%提升到81.9%,100次循環(huán)后的容量保持率由59%提升到74.3%。粘結(jié)劑方面我們首次使用陰離子聚丙烯酰胺(APAM)作為鋰離子電池粘結(jié)劑。APAM作為粘結(jié)劑有以下優(yōu)點(diǎn)。一是水溶性好,環(huán)境友好。二是含有羧酸及羧酸鹽基團(tuán),能夠與金屬活性材料和金屬集流體具有更強(qiáng)的結(jié)合力。三是分子量較大,可以較好的緩沖活性材料的體積膨脹。四是分子中含有大量的酰胺基,可形成大量的分子間和分子內(nèi)氫鍵,增強(qiáng)了APAM的自修復(fù)能力。本論文對(duì)比了不同分子量的APAM與不同刷片配比對(duì)納米硅負(fù)極電池性能的影響。結(jié)果顯示當(dāng)使用1600萬分子量的APAM(APAM16)作為粘結(jié)劑時(shí),相比傳統(tǒng)的海藻酸鈉,鋰離子電池的首次放電比容量從2005.8 m Ah g-1提升為3485 m Ah g-1,首次庫倫效率從78.6%提升到85.9%。
[Abstract]:The structure of lithium-ion battery is mainly composed of three parts: electrode, diaphragm and electrolyte. As the core part of lithium-ion battery, electrode plays a decisive role in the performance of lithium-ion battery. The electrode is mainly composed of active material, conductive agent and binder. In previous studies, active substances as the core materials for lithium-ion batteries have attracted much attention, while conductive agents and binders have received relatively little attention as the least used materials in lithium-ion batteries. Although the amount of conductive agent and binder in the electrode is small, the effect can not be ignored, especially in the high capacity negative electrode. For the high capacity negative electrode, the large volume change of the active material in the charge and discharge process of the lithium ion battery will lead to the disconnection of the conductive channel in the electrode and the separation of the active layer from the collector, which will lead to the large attenuation of the lithium-ion battery capacity. These problems can be alleviated or solved by using new conductive agent and binder with little effect on battery cost. Therefore, this paper hopes to improve the electrical properties of high capacity anode by developing and improving the conductive agent and binder. Firstly, a basic battery assembly process suitable for high capacity negative electrode is determined. In combination with previous studies, the change of high capacity anode in charge-discharge cycle is different from that of traditional carbon based materials, and the traditional battery technology can not play the role of high capacity negative electrode. Therefore, we have found a battery process suitable for high capacity negative electrode through many attempts, and selected nano-silicon as the active material of negative electrode, based on which we studied the conductive agent and binder. In order to adapt to high capacity anode materials, we have developed two-dimensional nano-materials and three-dimensional nano-materials composite conductive agents. Two-dimensional nanomaterials we selected acidified (carboxyl functionalized) multi-wall carbon nanotubes. Acidified multiwalled carbon nanotubes were prepared. Defects and groups such as carboxyl groups and hydroxyl groups were introduced into the surface, and the conductivity of multi-walled carbon nanotubes was ensured because of the multi-channel transport characteristics of multi-walled carbon nanotubes. The introduction of carboxyl groups can greatly improve the dispersion of carbon nanotubes and ensure the smooth flow of the polar long range conductive network. The other is to enhance the binding force between carbon nanotubes and binders. The specific surface area of SP,SP is larger and the contact area between conductive agent and active material is increased. Compared with the conventional SP conductive agent, the initial discharge specific capacity of lithium-ion battery was increased from 1938 m Ah g ~ (-1) to 2927 m Ah g ~ (-1), and the first Coulomb efficiency was increased from 79.2% to 81.9%. The capacity retention rate was increased from 59% to 74.3%. Anionic polyacrylamide (APAM) as binder for lithium ion battery has the following advantages for the first time. First, water-soluble, environmental friendly. Second, it contains carboxylic acid and carboxylate groups, which can bind to metal active material and metal collector more strongly. The third is the bigger molecular weight, which can better buffer the volume expansion of active materials. Fourth, there are a large number of amide groups in the molecule, which can form a large number of intermolecular and intramolecular hydrogen bonds, enhancing the self-repair ability of APAM. In this paper, the effects of different molecular weight of APAM and different ratio of brushes on the performance of nanocrystalline silicon anode batteries were compared. The results show that when APAM (APAM16) with 16 million molecular weight is used as binder, the initial discharge specific capacity of lithium-ion battery is increased from 2005.8 m Ah g ~ (-1) to 3485 m Ah g ~ (-1), and the first Coulomb efficiency is increased from 78.6% to 85.9% compared with conventional sodium alginate.
【學(xué)位授予單位】：河南師范大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TM912
本文編號(hào)：2241720
[Abstract]:The structure of lithium-ion battery is mainly composed of three parts: electrode, diaphragm and electrolyte. As the core part of lithium-ion battery, electrode plays a decisive role in the performance of lithium-ion battery. The electrode is mainly composed of active material, conductive agent and binder. In previous studies, active substances as the core materials for lithium-ion batteries have attracted much attention, while conductive agents and binders have received relatively little attention as the least used materials in lithium-ion batteries. Although the amount of conductive agent and binder in the electrode is small, the effect can not be ignored, especially in the high capacity negative electrode. For the high capacity negative electrode, the large volume change of the active material in the charge and discharge process of the lithium ion battery will lead to the disconnection of the conductive channel in the electrode and the separation of the active layer from the collector, which will lead to the large attenuation of the lithium-ion battery capacity. These problems can be alleviated or solved by using new conductive agent and binder with little effect on battery cost. Therefore, this paper hopes to improve the electrical properties of high capacity anode by developing and improving the conductive agent and binder. Firstly, a basic battery assembly process suitable for high capacity negative electrode is determined. In combination with previous studies, the change of high capacity anode in charge-discharge cycle is different from that of traditional carbon based materials, and the traditional battery technology can not play the role of high capacity negative electrode. Therefore, we have found a battery process suitable for high capacity negative electrode through many attempts, and selected nano-silicon as the active material of negative electrode, based on which we studied the conductive agent and binder. In order to adapt to high capacity anode materials, we have developed two-dimensional nano-materials and three-dimensional nano-materials composite conductive agents. Two-dimensional nanomaterials we selected acidified (carboxyl functionalized) multi-wall carbon nanotubes. Acidified multiwalled carbon nanotubes were prepared. Defects and groups such as carboxyl groups and hydroxyl groups were introduced into the surface, and the conductivity of multi-walled carbon nanotubes was ensured because of the multi-channel transport characteristics of multi-walled carbon nanotubes. The introduction of carboxyl groups can greatly improve the dispersion of carbon nanotubes and ensure the smooth flow of the polar long range conductive network. The other is to enhance the binding force between carbon nanotubes and binders. The specific surface area of SP,SP is larger and the contact area between conductive agent and active material is increased. Compared with the conventional SP conductive agent, the initial discharge specific capacity of lithium-ion battery was increased from 1938 m Ah g ~ (-1) to 2927 m Ah g ~ (-1), and the first Coulomb efficiency was increased from 79.2% to 81.9%. The capacity retention rate was increased from 59% to 74.3%. Anionic polyacrylamide (APAM) as binder for lithium ion battery has the following advantages for the first time. First, water-soluble, environmental friendly. Second, it contains carboxylic acid and carboxylate groups, which can bind to metal active material and metal collector more strongly. The third is the bigger molecular weight, which can better buffer the volume expansion of active materials. Fourth, there are a large number of amide groups in the molecule, which can form a large number of intermolecular and intramolecular hydrogen bonds, enhancing the self-repair ability of APAM. In this paper, the effects of different molecular weight of APAM and different ratio of brushes on the performance of nanocrystalline silicon anode batteries were compared. The results show that when APAM (APAM16) with 16 million molecular weight is used as binder, the initial discharge specific capacity of lithium-ion battery is increased from 2005.8 m Ah g ~ (-1) to 3485 m Ah g ~ (-1), and the first Coulomb efficiency is increased from 78.6% to 85.9% compared with conventional sodium alginate.
【學(xué)位授予單位】：河南師范大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TM912
【參考文獻(xiàn)】
相關(guān)期刊論文 前1條
1 顧長(zhǎng)志;呂文剛;李海鈞;李俊杰;白雪冬;;多壁碳納米管中的多通道彈道輸運(yùn)特性[J];物理;2005年12期
，本文編號(hào)：2241720
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