發(fā)布時間：2018-03-14 15:34

  本文選題：溶液相轉(zhuǎn)化法　切入點：直孔電極　出處：《中國科學(xué)技術(shù)大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：鋰二次電池是重要的電化學(xué)儲能體系,如今的商業(yè)化應(yīng)用對其能量密度和功率密度有更高的要求。提高能量密度和功率密度的方法之一是從成型工藝和裝配技術(shù)的角度入手優(yōu)化電極的微結(jié)構(gòu)。當(dāng)電極上的活性物質(zhì)負載量較大且處于大倍率充放電時,電極中曲折的孔道將會阻礙鋰離子的液相擴散,導(dǎo)致鋰離子分布不均而存在濃差極化。針對這一問題,本文從成型工藝的角度出發(fā),利用溶液相轉(zhuǎn)化法成型具有直孔結(jié)構(gòu)的LiFeP04電極并研究了直孔對電極電化學(xué)性能的影響。另一種提高能量密度以及功率密度的方法是優(yōu)化正、負極材料,即從電極材料入手。鋰金屬因具有極高的理論能量密度和極低的氧化還原電位而被認為是理想的負極材料。然而,鋰金屬負極中枝晶的不可控生長給電池體系造成了潛在的短路風(fēng)險。針對這一問題,本文提出了利用溶液相轉(zhuǎn)化法成型多孔銅集流體,以抑制枝晶的產(chǎn)生和生長,優(yōu)化鋰金屬負極的電化學(xué)性能。本論文的第一部分內(nèi)容是利用溶液相轉(zhuǎn)化法制備多孔LiFePO4電極,主要探究了溶液相轉(zhuǎn)化法的成型工藝、實驗參數(shù)等對電極的微結(jié)構(gòu)和電化學(xué)性能的影響。實驗表明采用NMP為溶劑、PVDF為粘結(jié)劑、水為絮凝劑,并在10℃條件下完成溶液相轉(zhuǎn)化可以成型出具有直孔結(jié)構(gòu)的電極。電化學(xué)數(shù)據(jù)表明當(dāng)電極處于高負載量大倍率條件下,直孔結(jié)構(gòu)對改善濃差極化有明顯的作用,溶液相轉(zhuǎn)化制備的電極表現(xiàn)出比傳統(tǒng)電極更加突出的電化學(xué)性能。本論文的第二部分內(nèi)容研究了利用溶液相轉(zhuǎn)化法成型具有雙極孔結(jié)構(gòu)的多孔銅,并分別利用一步法和兩步法兩種熱處理工藝去除其中的聚合物相而得到具有一定強度的多孔銅集流體。將它應(yīng)用于鋰金屬負極時,多孔銅中的大比表面為鋰的沉積提供了大量的有效沉積位點,而其中的孔隙起到了抑制鋰枝晶生長的作用。以兩步法熱處理的多孔銅作為集流體的鋰金屬電池表現(xiàn)出良好的電化學(xué)性能,在鋰沉積量為1mAh/cm2、電流密度為1 mA/cm2的條件下,循環(huán)壽命高達470小時,在前225個循環(huán)中庫倫效率不低于96%。
[Abstract]:Lithium secondary battery is an important electrochemical energy storage system. Today's commercial applications require higher energy density and power density. One of the ways to improve energy density and power density is to optimize the microstructure of the electrode from the point of view of molding process and assembly technology. When the loading amount of active substances is large and the charge / discharge rate is large, The zigzag pore channel in the electrode will hinder the liquid phase diffusion of lithium ion and lead to the concentration polarization due to the uneven distribution of lithium ion. The LiFeP04 electrode with straight pore structure was fabricated by solution phase inversion method and the effect of straight hole on the electrochemical performance of the electrode was studied. Another way to improve the energy density and power density is to optimize the positive and negative electrode materials. Lithium metal is considered to be an ideal negative electrode material because of its high theoretical energy density and extremely low redox potential. The uncontrollable growth of dendrite in lithium metal negative electrode causes potential short circuit risk for the battery system. In order to suppress the generation and growth of dendrite, a solution phase inversion method is proposed to form porous copper in this paper. The first part of this thesis is to prepare porous LiFePO4 electrode by solution phase inversion method. The effects of experimental parameters on the microstructure and electrochemical properties of the electrode showed that NMP was used as binder and water as flocculant. The electrode with straight pore structure can be formed by the solution phase transformation at 10 鈩，

本文編號：1611828