本文選題：硅酸錳 + 碳包覆�。� 參考：《山東大學(xué)》2017年碩士論文

【摘要】：作為一種新型綠色能源,鋰離子二次電池受到了廣泛的關(guān)注和研究,并逐漸應(yīng)用于混合動(dòng)力汽車等大型設(shè)備中。負(fù)極材料的選擇會(huì)造成鋰離子電池電化學(xué)性能的優(yōu)劣差別。目前工業(yè)上碳材料應(yīng)用比較廣泛,但其容量較低,與現(xiàn)階段人們對(duì)高能量密度能源的要求還有一定的差距,因此當(dāng)下研究的方向?yàn)樘角蟾呷萘�、更低成本的新型材料。本文運(yùn)用簡(jiǎn)單的合成方法制備了硅酸錳負(fù)極材料,研究了其電化學(xué)性能。主要研究?jī)?nèi)容為:(1)利用Na_2SiO_3·9H_2O和MnCl_2·4H_2O的簡(jiǎn)單反應(yīng)合成了硅酸錳。經(jīng)過碳包覆的硅酸錳材料用作鋰離子電池負(fù)極材料展現(xiàn)出優(yōu)良的倍率性能及高倍率循環(huán)穩(wěn)定性。在100、200、400、800和1600 mA/g電流密度下其比容量分別為323、293、261、227和176mAh/g,遠(yuǎn)高于商用石墨化材料。而其在500mA/g的電流密度下循環(huán)400次后,比容量仍能達(dá)到343 mAh/g,也比常用鈦酸鋰負(fù)極材料性能優(yōu)良。結(jié)合電化學(xué)測(cè)試結(jié)果進(jìn)行分析發(fā)現(xiàn),在硅酸錳納米顆粒周圍均勻包裹的碳層提高了材料的導(dǎo)電性,且固態(tài)電解質(zhì)硅酸鋰的形成也有利于電化學(xué)性能的提升。碳包覆硅酸錳能夠滿足快速充放電鋰離子電池的要求。(2)通過水煮處理Na_2SiO_3·9H_2O和MnCl_2·4H_2O的水溶液成功合成了非晶硅酸錳。以葡萄糖為碳源進(jìn)行碳包覆后,即使在700 ℃下硅酸錳依舊能保持非晶態(tài)。將經(jīng)過碳包覆的非晶硅酸錳材料用于鋰離子電池負(fù)極材料并進(jìn)行電化學(xué)性能測(cè)試,結(jié)果表明水煮4小時(shí)并在600 ℃碳包覆后獲得的非晶硅酸錳材料具備最佳的循環(huán)性能,在500 mA/g電流密度下循環(huán)400次后,比容量仍能維持在421 mAh/g。這種非晶硅酸錳具有多孔結(jié)構(gòu)及較大的比表面積,有利于鋰離子的傳輸,并且在硅酸錳顆粒表面包覆的均勻碳層作為導(dǎo)電性材料也有助于其電子電導(dǎo)率的提升。
[Abstract]:As a new kind of green energy, lithium ion secondary battery has been widely paid attention to and studied, and has been gradually used in hybrid electric vehicles and other large equipment. The selection of anode materials will lead to the difference of electrochemical performance of lithium ion battery. At present, carbon materials are widely used in industry, but their capacity is relatively low, which is still far from the requirement of high energy density energy. Therefore, the current research direction is to explore new materials with higher capacity and lower cost. In this paper, manganese silicate anode materials were prepared by a simple synthesis method and their electrochemical properties were studied. The main research contents are as follows: (1) Manganese silicate was synthesized by the simple reaction of NaSZ _ 2SiO _ 3H _ 2O and MnCl _ 2H _ 2O. The carbon-coated manganese silicate used as anode material for lithium ion batteries shows excellent performance and high rate cycling stability. The specific capacity of 100200400800 and 1600 mA/g current density is 323293261227 and 176mAh/ g, respectively, which is much higher than that of commercial graphitization materials. After 400 cycles at the current density of 500mA/g, the specific capacity is 343mAh / g, which is better than that of lithium titanate anode material. The results of electrochemical measurement show that the carbon layer encapsulated uniformly around the manganese silicate nanoparticles improves the electrical conductivity of the material and the formation of lithium silicate as solid electrolyte is beneficial to the improvement of electrochemical performance. The carbon-coated manganese silicate can meet the requirements of rapid charge and discharge lithium-ion batteries. (2) Manganese silicate has been successfully synthesized by boiling Na2SiO3 9H 2O and MnCl 24 H 2O aqueous solutions. After carbon coating with glucose as carbon source, manganese silicate can remain amorphous even at 700 鈩，

本文編號(hào)：2107855