| 原位构建富氟SEI的凝胶电解质用于金属锂二次电池 |
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| 引用本文： | 李文涛,林慧娟,钟海. 原位构建富氟SEI的凝胶电解质用于金属锂二次电池[J]. 化工学报, 2022, 73(7): 3240-3250. DOI: 10.11949/0438-1157.20220316 |
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| 作者姓名： | 李文涛 林慧娟 钟海 |
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| 作者单位： | 暨南大学新能源技术研究院,广东广州510632 |
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| 基金项目： | 国家自然科学基金项目(21805113);广东省基础与应用研究基金项目(2019A1515011656) |
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| 摘 要： | 以六氟磷酸锂（LiPF6）为四氢呋喃的聚合引发剂制备凝胶电解质，同时作为氟源在金属锂负极表面原位构建富含LiF的固态电解质界面层（solid electrolyte interface，SEI）来抑制锂枝晶的生长以及金属锂/电解液之间的副反应。所制备的凝胶电解质具有较高的室温离子电导率（1.33 mS·cm-1）和较宽的电化学稳定窗口（4.5 V）。原位聚合方式组装金属锂对称电池循环后，锂负极表面没有明显的锂枝晶和被损毁的形貌出现；XPS结果表明锂负极表面生成了富含LiF的SEI。组装的LiFePO4全电池在1 C的电流密度下，稳定循环400周后仍保持118.7 mAh·g-1的放电比容量。得益于四氢呋喃在开环聚合反应过程中，促进了LiPF6分解反应平衡的正向移动，在锂负极表面形成稳定的富含LiF的SEI，能够抑制锂枝晶的生长并防止其被持续性的腐蚀破坏。
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| 关 键 词： | 氟化锂 固态电解质界面层 原位聚合 凝胶聚合物电解质 金属锂电池 |
| 收稿时间： | 2022-03-02 |
LiF-rich SEI generated by in-situ gel polymer electrolyte process for lithium metal rechargeable batteries |
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| Wentao LI,Huijuan LIN,Hai ZHONG. LiF-rich SEI generated by in-situ gel polymer electrolyte process for lithium metal rechargeable batteries[J]. Journal of Chemical Industry and Engineering(China), 2022, 73(7): 3240-3250. DOI: 10.11949/0438-1157.20220316 |
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| Authors: | Wentao LI Huijuan LIN Hai ZHONG |
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| Affiliation: | Institute of New Energy Technology, Jinan University, Guangzhou 510632, Guangdong, China |
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| Abstract: | A gel electrolyte was prepared by using lithium hexafluorophosphate (LiPF6) as the polymerization initiator of tetrahydrofuran, and at the same time as a fluorine source, a LiF-rich solid electrolyte interface (SEI) was constructed in-situ on the surface of the lithium metal anode to suppress the growth of lithium dendrites and side reactions between metallic lithium/electrolyte. The as-prepared gel polymer electrolyte presents an ionic conductivity of 1.33 mS·cm-1 at room temperature and shows a high electrochemical stability up to 4.5 V. Compared with linear sweep voltammetry in 335C electrolyte, lower reduction current is observed at the range of 0—1.5 V (vs Li/Li+) in the cell with gel polymer electrolyte, which indicates that gel polymer electrolyte can mitigate the side reaction of metallic lithium with electrolyte. The lithium metal anode in the symmetric-cell with in-situ polymerization gel polymer electrolyte exhibits no obvious lithium dendrite and damaged morphology. X-Ray photoelectron spectroscopy results further reveal that the lithium metal anode in gel polymer electrolyte is formed a stable SEI with LiF-rich compound, which is much enhanced than that of in 335C electrolyte. Consequently, the Li|LiFePO4 cells with gel polymer electrolyte exhibits a long-term cycling stability, which can release a reversible capacity 118.7 mAh·g-1 after 400 cycles at a current density of 1 C, as well as coulombic efficiency of 99.5%. Benefit from the ring opening polymerization process of tetrahydrofuran, PF5 participates the formation reaction of intermediate product [(THF)+(PF5)-], which caused the equilibrium of the decomposition reaction shift to the right and therefore increase the formation of LiF on the surface of lithium metal anode. This process results in a great enhancement of the cyclability due to LiF-rich formed in the SEI. Therefore, the growth of lithium dendrite can be prevented by the stable SEI, as well as the side reaction between lithium metal and electrolyte. |
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| Keywords: | LiF SEI in-situ polymerization gel polymer electrolyte lithium mental batteries |
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