【摘要】：鋰離子電池作為能源儲(chǔ)存與轉(zhuǎn)化設(shè)備廣泛的應(yīng)用在移動(dòng)設(shè)備上。電極材料在調(diào)節(jié)鋰電池儲(chǔ)鋰性能中的起著重要作用,石墨作為傳統(tǒng)的鋰電池負(fù)極材料比容量較低(～372mAhg-1),不能滿足大容量電池的需要,因此需要開發(fā)具有高比容量的負(fù)極材料。金屬氧化物作為鋰電池負(fù)極材料的一種比容量較高,而且其合成方法簡單,自然資源豐富,廉價(jià)。但是依舊存在不少問題,在充放電過程中不可逆容量較大,鋰離子的反復(fù)嵌入脫出易導(dǎo)致電極材料結(jié)構(gòu)發(fā)生破壞以及粉化,使得電池的容量嚴(yán)重衰減。為了解決上述出現(xiàn)的問題,我們將金屬氧化物與導(dǎo)電性物質(zhì)相結(jié)合,同時(shí)調(diào)控電極材料的微結(jié)構(gòu)和多孔特性可在一定程度上改善電極材料的儲(chǔ)鋰性能和結(jié)構(gòu)穩(wěn)定性。在本論文中我們采用溫和的方法制備了金屬氧化物納米顆粒/碳復(fù)合材料,并對所合成材料的鋰電性能進(jìn)行了研究。本文中提出了一些新的合成思路,具體內(nèi)容如下:一、以二氧化硅凝膠為模板合成了 SnO2/多孔碳復(fù)合材料(SnO2@PC)。二氧化硅凝膠將葡萄糖和SnO2納米顆粒固定起來,在一定程度上保證了 SnO2納米顆粒的分散性,經(jīng)煅燒后轉(zhuǎn)化為SiO2可充當(dāng)SnO2@PC的模板。所合成的SnO2@PC復(fù)合材料為大塊的多孔結(jié)構(gòu),其比表面積和孔體積分別高達(dá)236.22 m2 g-1和0.505 cm3 g-1。SnO2@PC用作鋰電池負(fù)極材料其首次放電比容量高達(dá)1803 mAh g-1,在0.5 A g-1電流密度下,經(jīng)過300次充放電循環(huán)后其比容量高達(dá)770 mAh g-1。二、以殼聚糖和四氯化錫為原料,通過殼聚糖的交聯(lián)和四氯化錫的水解合成了Sn(OH)4@殼聚糖水凝膠,經(jīng)進(jìn)一步干燥,煅燒即可得到SnO2@C復(fù)合材料。對所合成材料的結(jié)構(gòu)和鋰電性能進(jìn)行了表征和分析,SnO2@C負(fù)極材料展示出極好的循環(huán)穩(wěn)定性。SnO2@C復(fù)合材料在0.1A g-1電流密度下經(jīng)100次充放電循環(huán)后其容量可達(dá)到579.5 mAh g-1,容量保持率大于90%。三、以二氧化硅凝膠為模板,采用SnO2@PC類似的合成思路合成了 TiO2/多孔碳復(fù)合材料(TiO2@PC),并對所合成材料進(jìn)行了結(jié)構(gòu),形貌表征和儲(chǔ)鋰性能測試。TiO2@PC同樣具有較大的比表面積和合適的孔徑分布。TiO2@PC作為鋰離子電池的負(fù)極材料,當(dāng)TiO2/葡萄糖的質(zhì)量比為5/1時(shí)所合成電極材料具有最佳的電化學(xué)性能,即在0.5 A g-1電流密度測試條件下,經(jīng)過450次充放電后,其容量還能保持在180 mAh g-1。
[Abstract]:Lithium ion batteries are widely used in mobile devices as energy storage and conversion devices. Electrode materials play an important role in regulating the lithium storage performance of lithium batteries. Graphite, as a traditional cathode material for lithium batteries, has a low specific capacity (372mAhg-1), which can not meet the needs of large capacity batteries. Therefore, it is necessary to develop anode materials with high specific capacity. Metal oxide is a kind of lithium battery anode material with high specific capacity, simple synthesis method, abundant natural resources and low cost. However, there are still many problems. During charge and discharge, the irreversible capacity is large, and the repeated intercalation of lithium ion easily leads to the destruction and pulverization of the electrode material, which makes the capacity of the battery seriously attenuate. In order to solve the above problems, we combine metal oxides with conductive materials, and regulate the microstructure and porous properties of electrode materials to improve the lithium storage performance and structural stability of electrode materials to some extent. In this thesis, the metal oxide nanoparticles / carbon composites were prepared by mild method, and the lithium electrical properties of the composites were studied. In this paper, some new synthetic ideas are proposed. The main contents are as follows: firstly, SnO2/ porous carbon composites (SnO2@PC) were synthesized using silica gel as template. Silica gel immobilized glucose and SnO2 nanoparticles to a certain extent, which ensured the dispersion of SnO2 nanoparticles. After calcination, SiO2 could be used as a template for SnO2@PC. The synthesized SnO2@PC composite is a bulk porous structure with a specific surface area of 236.22 m2 g ~ (-1) and a pore volume of 0.505 cm3 g-1.SnO2@PC as a cathode material for lithium batteries. The initial discharge specific capacity of the composite is up to 1803 mAh g ~ (-1), and the specific discharge capacity is up to 1803 mAh / g ~ (-1) at the current density of 0.5 A g ~ (-1). After 300 cycles, the specific capacity is as high as 770 mAh g -1. Secondly, Sn (OH) _ 4 @ chitosan hydrogel was synthesized from chitosan and tin tetrachloride by crosslinking of chitosan and hydrolysis of tin tetrachloride. The SnO2@C composite was obtained by further drying and calcining. The structure and lithium electrical properties of the synthesized materials were characterized and analyzed. The SnO2C anode material showed excellent cyclic stability. The Sno 2C composite material has a capacity of 579.5 mAh g-1 and a capacity retention greater than 90% after 100 charge-discharge cycles at current density of 0.1A g ~ (-1). Thirdly, TiO2/ porous carbon composites (TiO2@PC) were synthesized by using silica gel as template and SnO2@PC as a synthesis method. Morphology characterization and lithium-storage performance test. TiO2@ PC also has large specific surface area and appropriate pore size distribution. TiO2@ PC is used as anode material for lithium ion battery. When the mass ratio of TiO2/ and glucose is 5 / 1, the synthesized electrode material has the best electrochemical performance. That is to say, under the condition of 0.5 A g ~ (-1) current density measurement, the capacity can be kept at 180 mAh g ~ (-1) after 450 times of charge and discharge.
【學(xué)位授予單位】：西北大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TB33;TM912

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