富锂反钙钛矿材料用于安全高能量密度锂电池研究

EXPLORING LITHIUM-RICH ANTIPEROVSKITES MATERIALS FOR SAFE AND HIGH-ENERGY-DENSITY LITHIUM BATTERIES

冯东宇

11849286

硕士

材料工程领域工程

邓永红

2020-05-30

2020-07-20

哈尔滨工业大学

深圳

锂离子电池已被广泛应用于消费电子、电动汽车和大规模储能等诸多领域。随着科技的发展和储能需求的日益增加，人们对锂电池在安全性和高能量密度性能方面提出更多的要求。其中以锂金属作为负极的锂硫电池和锂-空气电池为代表的高能量密度储能体系，是下一代锂电池的发展方向。锂硫电池具有高达1167 mAh g-1 的理论比容量和2600 Wh kg-1 的理论能量密度。现阶段锂硫电池发展主要面临两方面的问题：1 负极锂金属枝晶生长带来的安全隐患；2 正极硫化物存在导电性差、多硫化物穿梭和巨大体积变化大大降低了锂硫电池实际容量和循环性能。考虑到一些无机固态电解质具备高离子电导、低电子电导、致密均匀等特性，使其有望在上述两方面提高锂硫电池性能。在锂金属负极表面修饰一层固态电解质膜，为界面电荷转移提供良好的通路并同时作为隔绝多硫化物的屏障，是一种解决上述问题行之有效的思路。因此，选择合适的固态电解质和恰当的成膜工艺成为关键所在。本论文中合成制备了以Li3OCl 为代表的具有优异性能的富锂反钙钛矿型(Li-RAP)固态电解质。通过熔融涂覆法结合电化学沉积方式将其修饰到锂金属表面作为人造SEI 膜，保护锂负极。得到的复合锂负极库伦效率得到明显改善，在0.5 mAcm-2 电流密度下循环超过1500 圈，平均库伦效率达到99.5%。将此复合锂负极组装成锂硫全电池，在最高11.5 mA cm-2 的电流密度下循环3000 圈后仍具有70 %的容量保持率。文中通过SEM、XPS、原位XRD、原位光学显微镜表征手段研究并探索了Li-RAP 人造SEI 膜在充放电过程中结构变化和抑制锂枝晶机制。指出其具有较高离子电导率是保护锂金属负极的关键因素，并对研究内容做了展望。

Lithium-ion batteries have been widely used in consumer electronics, electric vehicles, large-scale energy storage and many other areas. With the growing needs for energy storage, people put forward more requirements for the safety and high-energy density of lithium batteries. Lithium sulfur and lithium-air battery systems based on lithium metal anode, have the potential to be the next generation lithium batteries.Lithium-sulfur batteries have a theoretical capacity of up to 1167 mAh g-1 and a theoretical energy density of up to 2600 Wh kg-1. At present, the development of lithium sulfur battery is mainly inhibited with two problems: one is safety hazard caused by lithium dendrite growth, another is the existence of poor conductivity, polysulfide shuttlethrough and huge volume variation of positive sulfide greatly reduces the actual capacity and cycling performance of lithium sulfur batteries. Considering that some inorganic solid electrolytes have the characteristics of high ionic conductivity, low electron conductivity and uniform density, it is expected that they can improve the performance of lithium sulfur batteries in the above two aspects. It is considered to be an effective way to modify a solid electrolyte membrane on the negative surface of lithium metal by different means to provide a good path for the interfacial charge transfer and act as a barrier against polysulfide. Therefore, the choice of the appropriate solid electrolyte and the appropriate film-forming process are the key point.In this paper, Li-RAP solid electrolyte with excellent properties represented by Li3OCl was synthesized. It was modified to the surface of lithium metal by means of molten-coating and electrochemical deposition as an artificial SEI film protecting lithiummetal anode. The lithium metal anode obtained by this method got great improved in columbic efficiency, it was showed that the Li|Cu half-cell could cycle for over 1500 cycles at an average CE of 99.5%, and the Li-S battery using this anode could still have a capacity retention rate of 70% after 3000 cycles at the current density of 11.5mA cm-2. Furthermore, the author explored the structure change and specific dendrites suppressing mechanism of the Li-RAP artificial SEI during the electrochemical cycle of lithium sulfur batteries by different characterization methods such as SEM, XPS in-situ XRD and in-situ optical microscope observation of electrochemical cycling. It was pointed out that high ionic conductivity is the crucial reason for Li-RAP to protect lithium metal anode from dendrites. Finally, the author made some outlooks into future experiments and development.

锂硫电池 固态锂电池 固态电解质 人造SEI 膜 反钙钛矿

lithium sulfur battery solid lithium battery solid state electrolyte artificial SEI anti-perovskites

中文

联合培养

南方科技大学

冯东宇. 富锂反钙钛矿材料用于安全高能量密度锂电池研究[D]. 深圳. 哈尔滨工业大学,2020.