本文關(guān)鍵詞：鋰離子電池硅基復(fù)合負(fù)極材料的制備及其電化學(xué)性能的研究　出處：《太原理工大學(xué)》2017年碩士論文　論文類(lèi)型：學(xué)位論文

  更多相關(guān)文章： 硅基復(fù)合材料 負(fù)極 鋰離子電池 電化學(xué)

【摘要】：在新型電化學(xué)儲(chǔ)能系統(tǒng)中,鋰離子電池因具有能量密度高、環(huán)境友好、無(wú)記憶效應(yīng)和循環(huán)性能好等優(yōu)點(diǎn)[1,2],在手機(jī)、筆記本電腦等高端便攜式電子設(shè)備的電源中占據(jù)絕對(duì)市場(chǎng)份額。然而,市場(chǎng)上現(xiàn)有鋰離子電池采用的石墨類(lèi)碳負(fù)極材料的實(shí)際容量已經(jīng)非常接近其理論容量[3],性能提升空間十分有限。因此,尋找具有更高質(zhì)量比容量的負(fù)極材料是鋰離子電池研究的一個(gè)重要方向。硅(Si)基材料是最有潛力的可替代負(fù)極材料之一,但其導(dǎo)電性較差,且在高度嵌脫鋰的條件下存在著嚴(yán)重的體積效應(yīng),反復(fù)的充放電過(guò)程會(huì)造成Si材料的粉化,從而與集流體分離,最終造成電池容量的迅速衰減。雖然各國(guó)研究者探索了許多方法解決Si基材料的問(wèn)題,但多數(shù)材料制備的過(guò)程非常復(fù)雜,限制了其大規(guī)模生產(chǎn)的可能性,針對(duì)這個(gè)問(wèn)題,本文嘗試探究過(guò)程簡(jiǎn)單且成本較低的制備方法合成Si基復(fù)合材料,并研究和優(yōu)化了其電化學(xué)性能,主要研究?jī)?nèi)容及結(jié)論如下:一、采用溶劑熱法在納米Si顆粒表面包覆間苯二酚-甲醛樹(shù)脂層,后通過(guò)炭化處理,制備了具有核-殼結(jié)構(gòu)的Si/C復(fù)合負(fù)極材料,并研究了粘結(jié)劑類(lèi)型和炭化溫度對(duì)其儲(chǔ)鋰性能的影響。透射電子顯微鏡分析結(jié)果表明,該復(fù)合材料由厚度為5~15 nm的無(wú)定型碳層所包覆的Si顆粒組成。電化學(xué)測(cè)試結(jié)果表明,750°C炭化處理所得復(fù)合材料在粘結(jié)劑為海藻酸鈉時(shí)的電化學(xué)性能最優(yōu),其初始放電容量為2025.5 mAh g-1(首次庫(kù)侖效率:76.6%),循環(huán)100次后仍可保持571.4 mAh g-1的可逆容量。二、采用溶劑熱法先以間苯二酚-甲醛樹(shù)脂包覆納米Si顆粒,然后引入可膨脹微球,對(duì)兩者研磨混合并一同炭化處理,制備了具有多級(jí)結(jié)構(gòu)的Si/C復(fù)合材料,并優(yōu)化了電化學(xué)性能最佳時(shí)可膨脹微球的含量。掃描電子顯微鏡分析結(jié)果表明,核-殼結(jié)構(gòu)Si@C顆粒附著于可膨脹微球炭化后的碳層骨架上,使該復(fù)合材料具有多層級(jí)的微觀形貌。電化學(xué)研究結(jié)果表明,多層級(jí)結(jié)構(gòu)Si/C復(fù)合材料比核-殼結(jié)構(gòu)Si/C復(fù)合材料的電化學(xué)性能更優(yōu),其首次放電質(zhì)量比容量為1739.3 mAh g-1,100圈充放電循環(huán)后,容量保持率約為60%。三、通過(guò)對(duì)納米Si粉、可膨脹微球和環(huán)氧導(dǎo)電銀膠的一步炭化處理制備了Cu-Si/Ag/C復(fù)合材料,并測(cè)試了其電化學(xué)性能。XRD測(cè)試表明,該復(fù)合材料中包含Si、Ag、Cu、Cu3Si以及無(wú)定型碳等主要物相。電化學(xué)測(cè)試表明,Cu-Si/Ag/C復(fù)合材料的初始放電容量為1016.8 mAh g-1,恒電流充放電50圈后,可逆容量保持率為69.1%。
[Abstract]:In the new electrochemical energy storage system, lithium ion battery has the advantages of high energy density, environmental friendliness, no memory effect and good cycling performance. [In the power supply of high-end portable electronic devices, such as mobile phones, laptops and so on, it occupies an absolute market share. The actual capacity of graphite carbon anode materials used in lithium ion batteries on the market is very close to its theoretical capacity. [3], the performance improvement space is very limited. It is an important research direction of lithium ion batteries to find anode materials with higher mass specific capacity. Si-based materials are one of the most potential alternative anode materials, but their electrical conductivity is poor. And there is a serious volume effect under the condition of high intercalation of lithium, and the repeated charging and discharging process will result in the powder of Si material, which will be separated from the collector. Although researchers all over the world have explored many ways to solve the problem of Si-based materials, the preparation process of most materials is very complex, which limits the possibility of large-scale production. In order to solve this problem, this paper attempts to explore a simple and low-cost preparation method to synthesize Si matrix composites, and study and optimize its electrochemical properties. The main research contents and conclusions are as follows: 1. Resorcinol-formaldehyde resin layer was coated on the surface of nano-Si particles by solvothermal method. After carbonization, Si/C composite anode materials with core-shell structure were prepared. The effects of binder type and carbonization temperature on the lithium-storage properties were studied. The composite is composed of Si particles coated with amorphous carbon layer of 5 ~ 15 nm thick. The electrochemical test results show that the composite is composed of Si particles. The electrochemical properties of the composite treated with 750 擄C carbonization are optimal when the binder is sodium alginate. The initial discharge capacity is 2025.5 mAh g-1 (the first Coulomb efficiency: 76.6C), and the reversible capacity of 571.4 mAh g-1 can be maintained after 100th cycle. Si/C composites with multistage structure were prepared by solvothermal coating of nano-Si particles with resorcinol-formaldehyde resin, then expandable microspheres were introduced. The results of scanning electron microscopy (SEM) show that the core-shell structure Si@C particles are attached to the carbonized carbon layer skeleton of the expandable microspheres. The electrochemical research results show that the electrochemical performance of the multilayered Si/C composite is better than that of the core-shell structure Si/C composite. After the first discharge mass specific capacity is 1739.3 mAh g-1 / 100 cycle, the capacity retention rate is about 60.3 through the nano-Si powder. Cu-Si/Ag/C composites were prepared by one-step carbonization of expandable microspheres and epoxy conductive silver adhesives. The electrochemical properties of the composites were measured. The electrochemical measurements show that the initial discharge capacity of Cu-Si / Ag / C composite is 1016.8 mAh / g ~ (-1). After 50 cycles of constant current charge and discharge, the reversible capacity retention rate is 69.1.
【學(xué)位授予單位】：太原理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：TM912

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