不同結構的二硫化錫對鈉離子電池影響之研究
Abstract
錫、二氧化錫、二硫化錫是非常有潛力的陽極材料在鈉離子電池應用上，因為有較高的電容量、價格便宜、對環境沒有汙染。錫雖然擁有較高的理論電容量，但是循環穩定性不佳，而二氧化錫主要的問題就是第一圈不可逆電容量很大，造成電容量不高，通常硫化物的不可逆電容量都比氧化物來得小，另外硫的原子量較錫輕且所形成的二硫化錫可減緩體積膨脹的問題，所以二硫化錫的第一圈不可逆電容量較小且循環穩定性較佳，因此本研究選擇用二硫化錫。
本研究主要是先探討不同形狀的二硫化錫在電池表現上有無差別，包括花型結構(Flower-shape)、奈米板狀(Nanoplates)、奈米粒子(Nanoparticles)，同時也與Bulk二硫化錫做比較。在經過不同的形狀結構測試下，花型(Flower-shape)的二硫化錫表現上較佳，不過約在充放電30圈後，電容量衰退很快，因此為了解決循環穩定性不佳的這個問題，之後用花型二硫化錫來分別進行不同黏著劑及電解液的探討，試圖改善循環穩定性的問題，黏著劑包括Polyvinylidene fluoride (PVDF)、Sodium carboxymethyl cellulose(Na-CMC)、Polyacrylic acid (PAA)，而電解液包括NaClO4/EC+PC、NaClO4/EC+DEC、NaClO4/PC、NaClO4/5% FEC+EC+PC，結果在黏著劑方面使用Sodium carboxy- methyl cellulose(Na-CMC)、電解液使用NaClO4/5% FEC+EC+PC分別有較佳的表現。
在最佳條件測試下，花型二硫化錫經過充放電50圈後電容量約還有400 mAhg-1左右，因此花型二硫化錫在鈉離子電池未來開發應用上或許是一個合適的材料。
Tin compounds such as Sn, SnO2, and SnS2 are promising anode materials for sodium ion battery, due to their high theoretical gravimetric capacity, low cost, and eco-friendliness. However, Sn has poor cyclic stability and SnO2 have intrinsic problem such as low first cycle efficiency (30-40%). Moreover, sulphides formation is typically more reversible than oxides, resulting in higher first cycle efficiency than oxide materials. Thus, SnS2 has chosen suitable material for improved first cycle efficiency that can give higher capacity at higher current because of light weight of the S atoms and expected improvement in mechanical stability due to smaller volume change during charge/discharge. In our study, first time explore the distinct morphologies of SnS2 including flower, nanoplate, nanoparticle and bulk SnS2 for comparative study of sodium storage properties. During investigation, the SnS2 microflower sample shows best performance compare with others, but SnS2 microflower has problem of fast capacity decay after 30 cycles. Hence, in order to avoid the poor cyclic stability, our courses have been extent to studies of different binders and electrolytes for better performance of SnS2 microflower in sodium ion battery. The different binders and electrolytes are polyvinylidene fluoride (PVDF), sodium carboxymethyl cellulose (Na-CMC), polyacrylic acid (PAA), and NaClO4 contains of EC + PC, EC + DEC, PC, 5% FEC + EC + PC, respectively used here. We found that among them, Na-CMC and NaClO4 contains in 5% FEC + EC+ PC best binders and electrolytes. Under optimum conditions, microflower-shaped SnS2 showed capacity of 400 mAhg-1 remained up to 50 cycles; hence, microflower- shaped SnS2 are good candidate anode material for sodium ion battery in commercial exploitation.
Tin compounds such as Sn, SnO2, and SnS2 are promising anode materials for sodium ion battery, due to their high theoretical gravimetric capacity, low cost, and eco-friendliness. However, Sn has poor cyclic stability and SnO2 have intrinsic problem such as low first cycle efficiency (30-40%). Moreover, sulphides formation is typically more reversible than oxides, resulting in higher first cycle efficiency than oxide materials. Thus, SnS2 has chosen suitable material for improved first cycle efficiency that can give higher capacity at higher current because of light weight of the S atoms and expected improvement in mechanical stability due to smaller volume change during charge/discharge. In our study, first time explore the distinct morphologies of SnS2 including flower, nanoplate, nanoparticle and bulk SnS2 for comparative study of sodium storage properties. During investigation, the SnS2 microflower sample shows best performance compare with others, but SnS2 microflower has problem of fast capacity decay after 30 cycles. Hence, in order to avoid the poor cyclic stability, our courses have been extent to studies of different binders and electrolytes for better performance of SnS2 microflower in sodium ion battery. The different binders and electrolytes are polyvinylidene fluoride (PVDF), sodium carboxymethyl cellulose (Na-CMC), polyacrylic acid (PAA), and NaClO4 contains of EC + PC, EC + DEC, PC, 5% FEC + EC + PC, respectively used here. We found that among them, Na-CMC and NaClO4 contains in 5% FEC + EC+ PC best binders and electrolytes. Under optimum conditions, microflower-shaped SnS2 showed capacity of 400 mAhg-1 remained up to 50 cycles; hence, microflower- shaped SnS2 are good candidate anode material for sodium ion battery in commercial exploitation.
Description
Keywords
鈉離子電池, 陽極材料, 二硫化錫, Sodium ion battery, Anode material, Tin(IV) sulfide