連續式可量產低溫破碎法製備石墨烯導電添加劑應用於鋰離子電池

Scalable and Facile Production of Few-Layer Graphene and its Application as Conductive Additives for Lithium Ion Battery

吳兆益(Jhao-Yi Wu)

指導教授 ： 劉偉仁

中原大學/工學院/化學工程研究所/碩士(2018年)

https://doi.org/10.6840/cycu201800310

摘要

本研究以簡單快速且環保的低溫破碎法製備石墨烯導電添加劑並應用於鋰離子電池中。研究中分為三個部分，分別為導電添加劑組成、導電添加劑添加方式與導電添加劑添加比例進行研究探討。
第一部分，我們成功的利用低溫破碎法對人造石墨與天然石墨進行脫層，製備出石墨烯微片(MoCPCB與Mo8)，在AFM分析中，兩種石墨烯都有大於80 %的層數是小於5奈米，約為十層，而拉曼分析中，MoCPCB的缺陷比為0.24，Mo8的缺陷比為0.19，這比一般Hummers法所製備出的石墨烯缺陷還要低，接著我們將石墨烯或是石墨烯與導電碳黑複合作為導電添加劑添加至電池中，其中以添加MoCPCB 7% SP 3%的電池(在0.1 C時平均電容量約為144.6 mAh/g，在1 C時平均電容量約為131.0 mAh/g)與添加Mo8 3% SP 7%的電池(在0.1 C時平均電容量有154.0 mAh/g，在1 C時平均電容量有142.1 mAh/g)有最佳的C-rate電性表現。
第二部分，我們探討不同的導電添加劑方式對電池C-rate電性表現的影響，添加液相導電添加劑的電池在0.1 C時平均電容量約為149.8 mAh/g，在1 C時平均電容量約為142.9 mAh/g，在10 C時電容量更還有91.8 mAh/g，電容量保留率有61.2 %，比原來固相方式添加導電添加劑還要有更佳的效果。
第三部分，我們探討以不同的導電添加劑添加量對電池電性表現的影響，發現添加4 %液相導電添加劑，可以提升單位極片重量下的電容量，在0.1 C時添加Mo(8+SP) 4%的電池單位極片重量平均電容量為137.3 mAh/g(electrode)，在1 C為125.3 mAh/g(electrode)，而在10 C單位極片重量下的平均電容量為56.2 mAh/g(electrode)，電容量保留率還有41.0 %。
本研究實現可連續式量產石墨烯導電添加劑，並應用於提升鋰離子電池電性表現，在未來極具商業應用價值。

關鍵字

石墨烯、低溫破碎、導電添加劑、鋰電池

並列摘要

In this study, a green, facile, low-cost and scalable industrial method using jet cavitation (JC) is utilized to prepare graphene conductive additive and applied to a lithium-ion battery. The study is divided into three parts.
In the first part, delamination of artificial graphite and natural graphite by jet cavitation to prepare few layer graphene (MoCPCB and Mo8) is studied. According to AFM analysis, more than 80% the layer of few layer graphene is less than 5 nm (10 layers). In the Raman analysis, the D/G ratio of MoCPCB is 0.24, and the D/G ratio of Mo8 is 0.19, which is lower than the graphene produced by Hummers method. Next, the as-prepared graphene is applied as conductive additive for lithium ion battery. Graphene is also mixed with commercial conductive carbon black for comparison. The battery with MoCPCB 7% SP 3% has an average capacity of 144.6 mAh/g at 0.1 C and 131.0 mAh/g at 1 C. The battery with Mo8 3% SP 7 % has an average capacity 154.0 mAh/g at 0.1 C and 142.1 mAh/g at 1 C. These two conductive additive ratios deliver the best C-rate performance compared to commercial KS6.
In the second part, the effects of different methods to add conductive additives to improve the C-rate performance is investigated. The battery with liquid-phase conductive additives has an average capacity 149.8 mAh/g at 0.1 C, 142.9 mAh/g at 1 C and 91.8 mAh/g at 10 C with a retention of 61.2%. This method is found to be more effective than using solid-phase method to prepare the conductive additive.
Lastly, the effect of different amount conductive additives on the C-rate performance through liquid-phase method is examined. It is found that the optimum electrochemical performance of the battery is achieved by adding 4% conductive additive. An average capacity of 137.3 mAh/g(electrode) and 125.3 mAh/g(electrode) are obtained at 0.1C and 1C, respectively. At 10 C, the average capacity is 56.2 mAh/g(electrode) with a capacity retention of 41.0 %.
A continuous, facile and scalable approach to prepare graphene for conductive additive applications is successfully obtained through jet-cavitation technique. It is effectively applied as conductive additives for the cathode in lithium-ion batteries. The obtain results showed potential commercial applications in the future.

並列關鍵字

graphene, jet cavitation, conductive additive, lithium battery

參考文獻

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