Ứng dụng graphene cho điện cực âm của pin lithium ion dẻo

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Tác giả: Đức Anh Đinh

Ngôn ngữ: Vie

Ký hiệu phân loại: 570.285 Life sciences Biology

Thông tin xuất bản: Tạp chí Khoa học và Công nghệ - Đại học Nguyễn Tất Thành, 2021

Mô tả vật lý: 15-24

Bộ sưu tập: Metadata

ID: 416149

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Thiết bị điện tử dẻo (dụng cụ đeo tay, máy tính, TV... với màn hình có thể uốn cong) đòi hỏi phải có pin lithium ion dẻo (flexible lithium ion battery - FLIB), pin này có thể uốn cong theo thiết bị. Điện cực của FLIB phải có độ bền cơ lí và điện hóa. Graphene với những tính chất cơ lí, hóa học ưu việt là loại vật liệu tiềm năng cho điện cực của FLIB. Nhóm tác giả đã sử dụng phương pháp tách lớp pha lỏng (liquid phase exfoliation - LPE) để tổng hợp vật liệu graphene với kích thước ~ 150 nm và độ dày ~ 5 nm. Kết quả các phân tích điện hóa cho thấy điện lượng riêng của điện cực dẻo (flexible graphene electrode - FGE) đạt giá trị ổn định (~ 520 mAh g-1 khi uốn cong và ~ 530 mAh g-1 ở trạng thái phẳng) sau 100 chu kì nạp/xả với mật độ dòng điện 100 mA g-1 và hiệu suất Coulomb đạt 98 %. Với mật độ dòng điện cao (200, 500 và 1000) mA g-1 sau nhiều chu kì nạp/xả, điện lượng riêng của FGE (ở trạng thái uốn cong) suy giảm, nhưng khi tiếp tục được nạp/xả với mật độ dòng điện thấp ~ 100 mA g-1 thì điện lượng riêng được phục hồi (~ 520 mAh g-1 ) với hiệu suất phục hồi đạt 93 %. Các kết quả này cho thấy cấu trúc cơ lí và độ bền điện hóa của FGE uốn cong được bảo toàn như khi ở trạng thái phẳng, gợi mở các nghiên cứu đầy đủ hơn về ứng dụng graphene và vật liệu hai chiều trong chế tạo điện cực của FLIB, Tóm tắt tiếng anh, The development of flexible electronics (flexible/foldable displays of watches, laptops, TV, etc.) has drawn a great attention in the research field of flexible lithium-ion batteries (FLIB). FLIB is an energy storage system capable of bending according to the shapes of the electronic devices. The fabrication of FLIBs requires advance materials which have extreme mechanical and chemical properties. In this circumstance, graphene, thanks to its novel mechanical, physical and electrochemical properties, has been concerned as a potential material for FLIB electrode. In this work, we deployed the liquid phase exfoliation (LPE) method to produce graphene and utilize it for the anode of FLIBs. Graphene nanoflakes produced via LPE, has the average lateral size of ~ 150 nm and the thickness of ~ 5 nm. The electrochemical analysis shown that the flexible graphene anode at bending state and at flat state delivered a similar specific capacity of (~ 520 and 530) mAh g-1 , respectively, after 100 cycles at current density of 100 mA g-1 with Coulombic Efficiency ~ 98 %. Besides, although the flexible graphene electrode at bending state revealed the decrease in specific capacities at the test with high current density (200, 500 and 1 000) mA g-1 in plenty of charge/discharge cycles, it still delivered a capacity of 520 mAh g-1 in the consecutive charge/discharge cycles at 100 mA g-1 . The capacity retention of flexible graphene electrode reached 93 %. These results proved that the mechanical and electrochemical properties of flexible graphene electrode at bending state is stable during the charge/discharge cycle test, prompting further research directions in the field of graphene and related two dimensional materials for flexible electrode of FLIB.

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