本文關(guān)鍵詞： 負極材料 靜電紡絲 錫銻合金 錫銻氧化物 電化學性能　出處：《深圳大學》2017年碩士論文　論文類型：學位論文

【摘要】：鋰離子電池負極材料作為影響電池性能的重要因素,近年來受到了廣泛的關(guān)注和研究。目前研究較多的負極材料主要包括硅基、錫基、鍺基、銻基等合金及其氧化物,它們均具有非常高的理論比容量。然而這些負極材料往往因為在充放電過程中產(chǎn)生巨大的體積變化,導致其循環(huán)穩(wěn)定性變差、容量衰減明顯。因此,在獲得高容量的同時,提高負極材料的循環(huán)穩(wěn)定性成為了研究的重點。本文利用錫基合金或氧化物與碳復合,來制備不同結(jié)構(gòu)的納米復合材料,用以改善負極材料的電化學性能。1.通過化學還原共沉淀法制備出了SnSb合金納米顆粒,并結(jié)合靜電紡絲技術(shù)與水熱法將合金顆粒分別與碳纖維(PAN)和石墨烯(RGO)進行復合,制得具有一維線狀結(jié)構(gòu)的PAN-SnSb復合材料和二維層狀結(jié)構(gòu)的RGO-SnSb復合材料。SEM及TEM觀察表明,在制成的復合材料中,合金顆粒在纖維及石墨烯中分散均勻。電化學測試表明,復合后的材料很好地改善了負極材料的循環(huán)穩(wěn)定性,PAN-SnSb復合材料和RGO-SnSb復合材料在循環(huán)200圈后其比容量仍有503 mAh/g和556 mAh/g。2.利用原位靜電紡絲的方法,成功制備出了包覆狀SnSbZn-C復合納米纖維負極材料。材料中SnSb和SbZn納米合金顆粒被很好地裝載進了納米纖維中,并且互相交織形成網(wǎng)狀的特殊結(jié)構(gòu)。因此,材料表現(xiàn)出了非常高的儲鋰性能及優(yōu)異的循環(huán)穩(wěn)定性:樣品SnSbZn0.4-C在0.2 A/g電流密度下循環(huán)200次后,放電比容量仍有663 mAh/g,其對應于第二次循環(huán)的容量保持率為84%。如此高的循環(huán)穩(wěn)定性可以歸因于合金顆粒被包覆在了納米纖維中,從而形成了碳纖維包覆合金顆粒的特殊結(jié)構(gòu),這種結(jié)構(gòu)可以有效緩解合金顆粒在循環(huán)過程中的體積變化并防止其團聚。3.在靜電紡絲制備納米纖維復合材料的基礎上,通過改變碳化過程,制備出了具有不同結(jié)構(gòu)的錫銻氧化物纖維。在碳化溫度為400℃、500℃和600℃時,分別形成多孔納米纖維、中空納米纖維與破碎的納米管狀結(jié)構(gòu)。通過多種測試,分析了不同結(jié)構(gòu)形成的機理。電化學測試表明,材料具有良好的充放電性能、循環(huán)穩(wěn)定性、及倍率性能。在0.2 A/g的電流密度下,循環(huán)200圈后仍有730 mAh/g的容量,相對于第二圈容量保持率為76%。這得益于納米纖維獨特的多孔結(jié)構(gòu),在充放電過程中有效地緩解了體積膨脹效應、縮短了電子傳輸距離、保持了材料的整體性。
[Abstract]:As an important factor affecting the performance of lithium-ion batteries, anode materials of lithium ion batteries have attracted extensive attention and research in recent years. At present, more and more anode materials mainly include silicon, tin, germanium, antimony and other alloys and their oxides. All of them have very high theoretical specific capacity. However, these negative electrode materials often have great volume changes in charge and discharge process, which leads to poor cycle stability and obvious capacity attenuation. Therefore, while obtaining high capacity, Improving the cyclic stability of anode materials has become the focus of research. In this paper, tin based alloys or oxides are used to prepare nanocomposites with different structures. The SnSb alloy nanoparticles were prepared by chemical reduction coprecipitation method. The alloy particles were prepared by electrospinning and hydrothermal method, respectively, and the alloy particles were compounded with carbon fiber (PAN) and graphene (RGO), respectively. PAN-SnSb composites with one-dimensional linear structure and RGO-SnSb composites with two-dimensional layered structure were prepared. SEM and TEM observations showed that the alloy particles were dispersed uniformly in fibers and graphene. The composite material can improve the cyclic stability of the negative electrode material. The specific capacity of PAN-SnSb composite and RGO-SnSb composite is still 503 mAh/g and 556 mg / g 路2 after the 200th cycle. The method of in situ electrospinning is used to study the properties of PAN-SnSb composite and RGO-SnSb composite. The coated SnSbZn-C composite nano-fiber negative electrode material was successfully prepared. The SnSb and SbZn nano-alloy particles were well loaded into the nanofibers and intertwined with each other to form a special network structure. The material showed very high lithium storage performance and excellent cycling stability: sample SnSbZn0.4-C was recirculated 200 times at 0.2A / g current density. The specific discharge capacity is still 663 mAh/ g, and the capacity retention rate corresponding to the second cycle is 84. The high cyclic stability can be attributed to the alloy particles being coated in nanofibers, thus forming the special structure of carbon fiber coated alloy particles. This structure can effectively alleviate the volume change of alloy particles during cycling and prevent them from agglomeration. 3. On the basis of electrospinning to prepare nanofiber composites, the carbonization process can be changed. Tin antimony oxide fibers with different structures were prepared. Porous nanofibers, hollow nanofibers and broken nanotubes were formed at 400 鈩，

本文編號：1500148