【摘要】：在無機固體電解質中,硫化物固體電解質有著明顯的優(yōu)勢:鋰離子電導率高;對金屬鋰具有良好的穩(wěn)定性,電化學窗口比較寬(6V vs.Li/Li~+)。因此,硫化物固體電解質在新一代鋰離子電池的應用上具有極好的前景。雖然硫化物固體電解質具有以上各種優(yōu)勢,但是這類材料離實際應用還有一些問題需要解決。如部分二元硫化物固體電解質鋰離子電導率還不夠高,三元硫化物固體電解質的離子電導率高,但對金屬鋰不穩(wěn)定。針對上述問題,本論文從硫化物電解質材料的摻雜改性及復合處理的研究入手,尋找提高硫化物電解質離子電導率,改善硫化物電解質對鋰穩(wěn)定性的方法,主要研究內容如下:(1)75Li_2S·25P_2S_5玻璃材料由高能球磨法制備,75Li_2S·25P_2S_5玻璃陶瓷材料由適當熱處理制得。在球料比45/1,球磨轉速500 rpm的條件下,得出最佳球磨時間為12 h;最佳熱處理溫度為270 ℃,最佳熱處理時間為4 h。所制備的75Li_2S·25P_2S_5玻璃陶瓷是由粒徑一到數(shù)個微米的球狀顆粒組成。75Li_2S·25P_2S_5玻璃陶瓷的最高室溫離子電導率為3.67×10~(-4)Scm~(-1)。(2)75Li_2S·(25-x)P_2S_5·x P_2O_5(mol%)玻璃陶瓷固態(tài)電解質由合適的高能球磨法及后續(xù)熱處理工藝制備。摻雜了1%P_2O_5所得的電解質材料在室溫下的離子電導率為8×10-4 S cm~(-1)。電導率提升的原因在于氧原子的引入,在玻璃體網(wǎng)絡中是以共價鍵鏈接的,P-O鍵相比于P-S鍵具有更強的結合,從而導致P-O鍵的結構單元對鋰離子具有相對較弱的作用力,有利于鋰離子的快速遷移。新制備的75Li_2S·24P_2S_5·1P_2O_5對鋰金屬表現(xiàn)出極好的電化學穩(wěn)定性與兼容性。全固態(tài)鋰電池LiCoO_2/75Li_2S·24P_2S_5·1P_2O_5/Li在0.1C下的放電容量為10~9mAhg~(-1),以及25 ℃下循環(huán)30圈后85.2%的容量保持率。(3)將二元硫化物固體電解質75Li_2S·24P_2S_5·1P_2O_5(LPOS)的非晶前驅體與三元硫化物電解質Li_(10)Ge P_2S_(12)(LGPS)前驅體按不同質量比均勻混合后,在270 ℃下進行燒結制備得到系列新型固體電解質材料(1-ω%)LPOS-ω%(t-LGPS)(ω=3,5,7,10)。當ω=5時,制得的新型固體電解質95%LPOS-5%(t-LGPS)在室溫下具有最佳的離子電導率1.0×10~(-3) S cm~(-1)。采用XRD,EIS,SEM等手段對該新型電解質材料的結構、形貌及電化學性能等進行了系統(tǒng)表征,并對電導率提高的機理進行了探討。構建的全固態(tài)鋰電池LiCoO_2/95%LPOS-5%(t-LGPS)/Li表現(xiàn)出良好的電池性能,在25 ℃,0.1C下,電池首周放電容量為115.7 mAhg-1,循環(huán)20圈后仍有80.38%的容量保持率。
[Abstract]:Among inorganic solid electrolytes, sulfide solid electrolytes have obvious advantages: high conductivity of lithium ion, good stability to lithium metal, wide electrochemical window (6V vs.Li/Li~). Therefore, sulfides solid electrolytes have an excellent prospect in the application of new generation lithium ion batteries. Although sulfides solid electrolytes have the above advantages, there are still some problems to be solved from the practical application of these materials. For example, the lithium ion conductivity of some binary sulfide solid electrolytes is not high enough, and the ion conductivity of ternary sulfide solid electrolytes is high, but it is unstable to lithium metal. In order to solve the above problems, this paper starts with the study of doping modification and composite treatment of sulfide electrolyte materials, and finds out the methods to improve the ionic conductivity of sulfide electrolyte and improve the stability of sulfide electrolyte to lithium. The main research contents are as follows: (1) 75Li _ 2S 路25p _ 2S_5 glass material was prepared by high energy ball milling, and 75Li _ 2S 路25p _ 2S_5 glass-ceramic material was prepared by proper heat treatment. When the ratio of ball to material is 45 脳 1 and the speed of ball milling is 500 rpm, the optimum milling time is 12 h, the optimum heat treatment temperature is 270 鈩，

本文編號：2478614