本文選題：鋰離子電池 + 負(fù)極�。� 參考：《大連理工大學(xué)》2014年博士論文

【摘要】：為了滿足節(jié)能環(huán)保的新能源汽車對(duì)鋰離子動(dòng)力電池的需求,發(fā)展具有長(zhǎng)循環(huán)穩(wěn)定性、高可逆容量、良好的安全性能和快速充放電能力的電極材料成為當(dāng)務(wù)之急。根據(jù)電極中活性物質(zhì)的電化學(xué)特性定向設(shè)計(jì)合適的結(jié)構(gòu)以提高鋰離子電池的電化學(xué)性能,尤其是循環(huán)穩(wěn)定性,是一個(gè)具有挑戰(zhàn)性的研究課題。鑒于炭材料在能量?jī)?chǔ)存方面的優(yōu)勢(shì),本論文以納米電極材料的結(jié)構(gòu)設(shè)計(jì)為導(dǎo)向,制備一系列多孔炭修飾的金屬氧化物／硫化物復(fù)合負(fù)極材料,旨在提高鋰離子電池負(fù)極材料的循環(huán)穩(wěn)定性,在此基礎(chǔ)上,研究材料的結(jié)構(gòu)特點(diǎn)對(duì)其電化學(xué)性能和反應(yīng)機(jī)理的影響。具體包括如下幾個(gè)方面： (1)針對(duì)Sn02負(fù)極材料在充放電過程中體積膨脹大(250%)和導(dǎo)電性低的問題,以薄壁(-2nm)高孔容(2.16cm3g-1)的管狀介孔炭為載體,構(gòu)筑Sn02顆粒尺寸5nm的Sn02@C復(fù)合材料。對(duì)Sn02在炭孔道中的填充度進(jìn)行調(diào)變,調(diào)變范圍為7-27%。當(dāng)Sn02的負(fù)載量高達(dá)80wt%時(shí),Sn02納米顆粒還能高度分散于炭載體的介孔孔道中,且無(wú)團(tuán)聚現(xiàn)象發(fā)生。這種管狀復(fù)合材料表現(xiàn)出高的可逆容量和穩(wěn)定的循環(huán)性能,經(jīng)過100次循環(huán)后,可逆容量為1039mAh g-1,容量保持率為106%。其穩(wěn)定后的容量高于Sn02的傳統(tǒng)理論容量(782mAhg-1),這可能歸因于在充放電過程中Sn02與Sn之間發(fā)生了可逆的轉(zhuǎn)化反應(yīng)。 (2)為了從本質(zhì)上降低Sn02的體積膨脹,將體積變化相對(duì)較小的ZnO(體積膨脹：103%)引入到Sn02體相中,制備出ZnSn03(體積膨脹：-191%)負(fù)極材料。同時(shí),結(jié)合炭材料的優(yōu)勢(shì),設(shè)計(jì)合成了核殼結(jié)構(gòu)的炭包覆ZnSnO3(ZnSnO3@C)納米方塊。其中,ZnSnO3方塊的尺寸為37nm,具有無(wú)定形結(jié)構(gòu)和豐富的介孔孔道；外部的炭層相互交聯(lián),構(gòu)成連續(xù)的電子導(dǎo)通骨架和相互貫通的大孔通道(74nm)。電化學(xué)測(cè)試結(jié)果表明,ZnSnO3@C復(fù)合物的儲(chǔ)鋰反應(yīng)綜合了合金反應(yīng)和轉(zhuǎn)化反應(yīng)的特點(diǎn)(Li4.4Sn與LiZn合金可逆地轉(zhuǎn)變?yōu)槌跏嫉?ZnSnO3),因而可以提供高的可逆容量。經(jīng)過100次循環(huán)后,可逆容量達(dá)到1060mAh g-,并且其容量保持率為93%。 (3)考慮到電極／電解液表界面的穩(wěn)定性問題,以過渡金屬氧化物Fe2O3為研究對(duì)象,探索了提高界面穩(wěn)定性的方法。為了獲取穩(wěn)定的固體電解質(zhì)界面(SEI)膜,根據(jù)各組分的不同功能,采用納米工程技術(shù)將Fe203納米顆粒、管狀介孔炭載體和導(dǎo)電聚吡咯分層次地組裝在一起,構(gòu)筑了一種多功能復(fù)合負(fù)極材料。在復(fù)合物中,Fe203高度分散于炭載體中,同時(shí)導(dǎo)電聚吡咯均勻地包覆在Fe203@C的孔道口和外表面,將Fe2O3@C顆粒橋接起來(lái)構(gòu)成一個(gè)大的單元。作為鋰離子電池負(fù)極材料,聚吡咯包覆的Fe2O3@C表現(xiàn)出穩(wěn)定的循環(huán)性能,100次循環(huán)后,容量保持率高達(dá)97%。另外,復(fù)合材料還具有快速的充放電速度、高的Fe203利用率和大的體積比容量。 (4)以負(fù)載于管狀介孔炭中的硫?yàn)槠鹗嘉镔|(zhì),銅箔代替?zhèn)鹘y(tǒng)的鋁箔作為集流體,依靠恒流充放電過程中的電化學(xué)反應(yīng)在管狀介孔炭中原位生成Cu2S納米顆粒。對(duì)反應(yīng)機(jī)理進(jìn)行研究發(fā)現(xiàn)：S顆粒與Li+反應(yīng)生成的Li2Sn溶解于電解液中變?yōu)镾n2-,來(lái)自于銅箔的Cu+會(huì)與Sn2-反應(yīng)生成難溶性的CuxS中間產(chǎn)物,隨著循環(huán)次數(shù)的增加,CuxS逐漸轉(zhuǎn)變?yōu)樽罱K的Cu2S產(chǎn)物,得到高度分散于管狀介孔炭中的Cu2S。這種原位制備的Cu2S/C復(fù)合材料表現(xiàn)出穩(wěn)定的循環(huán)性能和優(yōu)異的倍率性能。在0.2C下循環(huán)300次,可逆容量為270mAh g-1,容量保持率為104%。在10C的大電流密度下,可逆容量保持在225mAhg-1左右,是0.2C下可逆容量的86%。
[Abstract]:In order to meet the needs of energy saving and environment-friendly energy vehicles for lithium ion batteries, it is urgent to develop the electrode materials with long cycle stability, high reversible capacity, good safety performance and fast charging and discharging capacity. The design of suitable structure to improve the lithium ion battery according to the electrochemical characteristics of active substances in the electrode The electrochemical performance, especially the cyclic stability, is a challenging research topic. In view of the advantages of carbon materials in energy storage, this paper is guided by the structure design of nanomaterials. A series of porous carbon modified metal oxide / sulfide composite negative materials are prepared to improve the anode of lithium ion batteries. Based on the cyclic stability of materials, the effects of structural characteristics of materials on their electrochemical properties and reaction mechanism are studied.
(1) aiming at the problem of large volume expansion (250%) and low conductivity of Sn02 negative electrode in charge and discharge process, a Sn02@C composite with Sn02 particle size 5nm is constructed with thin-walled (-2nm) high pore volume (2.16cm3g-1) tubular mesoporous carbon as carrier. The filling degree of Sn02 in the carbon channel is adjusted and the adjustment range is 7-27%. when the load of Sn02 is as high as 80W. At t%, Sn02 nanoparticles can also be highly dispersed in mesoporous pore channels of carbon carriers, and no aggregation occurs. This tubular composite exhibits high reversible capacity and stable cycling performance. After 100 cycles, the reversible capacity is 1039mAh g-1, and the capacity retention rate is 106%. with the traditional theoretical capacity of higher than Sn02 (78). 2mAhg-1), which may be attributed to the reversible conversion reaction between Sn02 and Sn in charge discharge process.
(2) in order to reduce the volume expansion of Sn02 in essence, the ZnO (volume expansion: 103%), which has a relatively small volume change, is introduced into the Sn02 body phase and the ZnSn03 (volume expansion: -191%) negative electrode is prepared. At the same time, the carbon coated ZnSnO3 (ZnSnO3@C) nano block of the nuclear shell structure is designed and synthesized by combining the advantages of the carbon material. Among them, the ruler of the ZnSnO3 square block is designed. The 37nm has an amorphous structure and a rich mesoporous channel, and the external carbon layers cross linked together to form a continuous electronic conduction skeleton and a large pore channel (74nm). The electrochemical test results show that the lithium storage reaction of the ZnSnO3@C complex synthesizes the characteristics of the alloy reaction and the conversion reaction (Li4.4Sn and LiZn alloy reversible transformation. For the initial 2ZnSnO3, it can provide high reversible capacity. After 100 cycles, the reversible capacity reaches 1060mAh g-, and its capacity retention rate is 93%.
(3) taking into account the stability of the electrode / electrolyte surface interface, a method for improving the stability of the interface is explored with the transition metal oxide Fe2O3 as the research object. In order to obtain a stable solid electrolyte interface (SEI) film, Fe203 nanoparticles, tubular mesoporous carbon carriers and conductance are used in accordance with the different functions of each component. Polypyrrole is assembled together to construct a multi-functional composite negative material. In the complex, the Fe203 is highly dispersed in the carbon carrier. At the same time, the conductive polypyrrole is evenly coated on the orifice and the outer surface of the Fe203@C, and the Fe2O3@C particles are bridged to form a large unit. As a anode material for lithium ion batteries, polypyrrole (PPy) The coated Fe2O3@C shows a stable cycle performance. After 100 cycles, the capacity retention rate is up to 97%., and the composite also has rapid charge discharge speed, high Fe203 utilization and large volume specific capacity.
(4) the sulfur in the tubular mesoporous carbon is used as the starting material, and the copper foil is replaced by the traditional aluminum foil as the collector. The Cu2S nanoparticles are produced in situ by the electrochemical reaction in the constant current charge discharge process. The reaction mechanism was studied. The reaction of the S particles and the Li+ reaction was found to be dissolved in the electrolyte to Sn2-, The Cu+ from copper foil reacts with Sn2- to produce insoluble CuxS intermediates. With the increase of the number of cycles, CuxS gradually transforms into the final Cu2S product, and the Cu2S., which is highly dispersed in the tubular mesoporous carbon, has a stable cycling performance and excellent multiplier performance. 300 cycles under 0.2C are circulate under 0.2C. The reversible capacity is 270mAh g-1, and the capacity holding rate is 104%.. Under the high current density of 10C, the reversible capacity remains at 225mAhg-1, which is 86%. under the reversible capacity of 0.2C.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2014
【分類號(hào)】：TM912

【參考文獻(xiàn)】

相關(guān)期刊論文 前3條

1 吳超;崔永麗;莊全超;徐守冬;沈明芳;史月麗;孫智;;基于轉(zhuǎn)化反應(yīng)機(jī)制的鋰離子電池電極材料研究進(jìn)展[J];化學(xué)通報(bào);2011年11期

2 韓飛;陸安慧;李文翠;;結(jié)構(gòu)可控的炭基材料在鋰離子電池中的應(yīng)用[J];化學(xué)進(jìn)展;2012年12期

3 曾耀明;史忠良;;中外新能源汽車產(chǎn)業(yè)政策對(duì)比分析[J];企業(yè)經(jīng)濟(jì);2011年02期

，

本文編號(hào)：2023011