轉化型負極材料應用於鈉離子電池之電化學分析

Electrochemical Analyses of Conversion-type Anode Materials for Sodium-Ion Batteries

馬艾莉(Irish Maggay)

指導教授 ： 劉偉仁

中原大學/工學院/化學工程研究所/博士(2018年)

https://doi.org/10.6840/cycu201900006

摘要

隨著行動裝置與除能設備的需求上升，鈉離子電池系統成為了新一代能源材料的主流，與鋰離子電池相比，鈉的豐富來源與其低成本的優點，成為了可取代鋰離子電池重要因素，因此本研究中開發了一種簡單製備方法製備轉化型負極材料，透過溶劑熱與水熱法來製備 ZnV2O4、FeV2O4、ZnMn2O4 和 ZnIn2S4，並研究材料在鈉離子電池的電化學特性表現。
第一章針對鈉離子電池進行簡單的介紹，第二章針對鈉離子電池近幾年相關文獻介紹與其反應機制，第三章是ZnV2O4的電化學特性進行分析。在電化學測試下，ZnV2O4的第一圈電容量為537 mAh∙g-1，在100 mA∙g-1的電流測試下，30圈循環後還保有113 mAh∙g-1的可逆電容量。通過理論計算，可以得知ZnV2O4的能隙為0.314 eV，這也證實了ZnV2O4有較低的RCT與電阻率
第四章我們開發了一種新型負極材料FeV2O4，並針對此材料進行電化學測試，本章節還探討了PVdF與CMC和SBR作為黏著劑的探討與比較，其電化學結果得知，經過200次的循環後，由於材料從Cu箔上剝離，PVdF配方下的電極僅27mAh•g-1。 同時，使用SBR / CMC的電極獲得穩定的循環壽命測試並且在200次循環後保持容量97mAh•g-1。 此外，透過拆解電池後的極版，並利用XRD分析可得知在充電和放電過程中Fe和V的轉化並不完全。
第五章我們將介紹了不同煅燒溫度對ZnV2O4電化學性能的影響。 透過燒結溫度700℃且在2℃∙min -1的低加熱速率慢慢升溫，使ZnV2O4¬生成多孔結構並提高顆粒的表面積。 在700℃煅燒下的ZnV2O4的BET分析下，孔徑、孔體積與表面積分別為275.08 Å，0.1663 cm3∙g-1和26.62 m2∙g-1，其結果遠高於500°C和600°C煅燒後的結果。透過電化學測試下，在700℃的燒結條件下，ZnV2O4經過400次循環後的保留率為64％，其結果來至其多孔結構和高表面積，透過高表面積與多孔結構增
第六章內容包含了煅燒過程中不同加熱速率對ZnMn2O4的電化學性能的影響。 透過緩慢的加熱速率讓材料有足夠的時間能夠緩慢釋放氣體，在微球表面上生成孔洞。 實際上在電化學測試下，在1℃∙min-1的升溫速率下，微球獲得了最大的孔徑和表面積，其結果改善了電解質與電極界面中的電荷轉移速度，並讓電極中的Na+擴散加快，讓材料有高度穩定的循環壽命和116 mAh∙g-1的可逆電容量，其測試結果也沒有明顯的電容量衰減
第七章是對ZnIn-2S4的電化學特性進行了初步分析。 透過CTAB作為表面活性劑，ZnIn2S4的表面形貌從不規則形狀的層狀顆粒塊變為花狀微球。在循環壽命測試下，兩種表面形貌皆有較大的電容量衰減，並且在100次循環測試後，其可替電容量百分比僅為36％和49％。為了解決此問題，我們將會透過碳塗層或將顆粒嵌入碳基質中可以減少體積膨脹。
第八章我們將針對以上的實驗成果進行總結，並且針對本論文研究中提出一些改進方法

關鍵字

鈉離子電池 ； 負極材料 ； 轉化型材料

並列摘要

The need to sustain the demands of portable devices and stationary energy storage devices have opened new opportunities for sodium-ion battery systems (SIBs). The abundant sources and low-cost of sodium compared to lithium made it a viable alternative for lithium-ion batteries (LIBS). This dissertation provides a simple preparation of conversion type anode materials such ZnV2O4, FeV2O4, ZnMn2O4 and ZnIn2S4 using solvothermal or hydrothermal methods and investigates their electrochemical properties as viable electrode materials for sodium-ion batteries.
Chapter 1 describes a brief introduction about SIBs and chapter 2 provides some of the most recent related literatures on SIBs and the principles that governs it. Chapter 3 focuses on the preliminary electrochemical analyses of ZnV2O4. An initial capacity of 537 mAh∙g-1 is obtained and reversible capacity of 113 mAh∙g-1 is maintained after 30 cycles at a constant current rate of 100 mA∙g-1. Through theoretical calculations the band gap of ZnV2O4 is determined to be 0.314 eV which verifies the low RCT of the electrode and generates low electrical resistivity.
Chapter 4 presents the electrochemical performance of FeV2O4 as a novel anode material. This chapter also explores the comparison between PVdF a non-aqueous binder and CMC and SBR as aqueous binders for the electrode preparations. The electrochemical results reveal that after 200 cycles of sodiation and de-sodiation, PVdF-based electrode obtained only 27 mAh∙g-1 due to the detachment of the electrode from the Cu foil. Meanwhile, SBR/CMC based electrodes obtained a stable cycle life test and retained a capacity 97 mAh∙g-1 after 200 cycles. Furthermore, the ex-situ XRD analyses of the electrode unveil the incomplete conversion of the Fe and V during charge and discharge process.
Chapter 5 puts an emphasis on the effect of different calcination temperature on the electrochemical performance of ZnV2O4. Increasing the calcination to 700°C at a low heating rate of 2°C∙min-1 induced the formation of porous structure and increased the surface area of the particles. the BET analysis of ZnV2O4 calcined at 700°C has pore size, pore volume and surface area of 275.08Å, 0.1663 cm3∙g-1 and 26.62 m2∙g-1, respectively which are considerably higher than 500°C and 600°C. The electrochemical tests reveal that the retention rate after 400 cycles of ZnV2O4 calcined at 700°C is 64% which is attributable to its porous structure and high surface which enhanced the kinetics of Na+ ions during charge and discharge and increased the charge-transfer at the electrode-electrolyte interface.
Chapter 6 involves the study of different heating rates during the calcination method on the electrochemical performance of ZnMn2O4. Slow heating rate permitted the slow release of gas which in turn induced pores on the surface of the microspheres. In fact, the electrochemical results divulge at 1°C∙min-1 the microspheres obtained the highest pore size and surface area which facilitated the increased charge-transfer in the electrolyte-electrode interface and permitted fast Na+ diffusion in the electrode, generating a highly stable cycle life and a reversible capacity of 116 mAh∙g-1 with no obvious capacity fade.
Chapter 7 provides a preliminary analysis on the electrochemical properties of ZnIn¬2S4. Using CTAB as a surfactant, the morphology of ZnIn2S4 is changed from an irregularly shaped block of layered particle to a flower-like microsphere. Cycle life test revealed that both morphologies suffer from huge capacity fading and only delivered 36% and 49% retention rates after 100 cycles. In order to resolve this, carbon coating or embedding the particles on a carbon matrix can reduce the volume expansion.
Chapter 8 provides an overall conclusion of all the experimental findings and also imparts a few strategies on the future work of the studies conducted in this dissertation

並列關鍵字

Sodium-ion batteries, anode materials, conversion materials.

參考文獻

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