Ion transport in solid electrolyte interphases

固体电解质界面中的离子传输

• 批准号: 2887685
• 金额: --
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2887685
• 关键词: Ion; transport; solid; electrolyte; interphases

Lithium Metal Batteries (LMBs), with lithium metal as the anode, have recently garnered significant interest as a higher energy density alternative to conventional lithium-ion batteries (LIBs) for high-end electric vehicles and novel applications, including electric flight. However, the successful commercialisation of LMBs will require batteries with high specific energies (above 500 Wh/kg) at a low cost of US $100/kWh. Additionally, batteries must retain 80-90% of their capacity over 1000 cycles, necessitating a coulombic efficiency (CE) of over 99.99%. Achieving these targets also demands the implementation of high-energy cathodes and the development of novel electrolytes compatible with both electrodes. Liquid electrolytes are ideal, as they ensure good electrode contact and compatibility with existing manufacturing routes established for LIBs.Nevertheless, lithium metal anodes operate outside of the electrochemical stability window of any electrolyte, leading to spontaneous electrolyte reduction when the electrochemical potential of the anode exceeds the lowest unoccupied molecular orbital (LUMO) of the electrolyte. Kinetic stability is achieved through the formation of a surface layer composed of insoluble reaction products, first named the solid electrolyte interphase (SEI) by Peled in 1979.Currently, the cycle life of LMBs is limited by inhomogeneous lithium plating/stripping, which exposes additional lithium to the electrolyte and results in 'active' lithium loss due to the formation of SEI and electrochemically isolated 'dead' lithium. This reduces the CE, requiring the use of excess lithium in the form of lithium foil to extend cycle life to practical values, thus reducing specific energy. This non-uniform lithium plating and stripping behavior is influenced by the fundamental properties of the liquid electrolyte and metallic lithium. Electrolyte transport and thermodynamic properties govern the development of salt concentration gradients and overpotentials during cell operation. In extreme cases, the electrolyte can be entirely depleted of salt at the anode surface during charge, leading to the nucleation of fractal lithium dendrites and associated safety concerns. Recent studies have also shown that charge-transfer kinetics influence deposition morphology, with fast interfacial charge-transfer observed to positively correlate with CE. Additionally, the microstructure and anisotropic nanomechanical properties of lithium metal affect cycling behaviour. In fact, inhomogeneous stripping is influenced by crystallographic texture, and more uniform deposition morphologies are achieved under applied stack pressures.However, the degradation phenomena observed in LMBs cannot be fully described by the properties of lithium and the electrolyte alone. Ultimately, it is the SEI that controls cycling performance by regulating lithium morphology and 'dead' lithium formation. This demands a better understanding of the properties of the SEI and their influence on cycling performance, enabling the rational design of SEIs to guide future electrolyte development.This project aims to first examine the nanostructure of the SEI through surface/interfacial characterisation techniques, including atomic force microscopy, x-ray photoelectron spectroscopy, electron microscopy, and electrochemical impedance spectroscopy. Knowledge of SEI nanostructure alone is inadequate to predict cell performance, as it is not yet understood how SEI properties are affected by its structure and composition. Therefore, the second objective of the project is to investigate the structure-property relationships to facilitate rational SEI design and guide future electrolyte development.This project falls within the EPSRC Energy research area. The goal of this theme is for the UK to meet its environmental and energy targets.

锂金属电池（LMB）以矿石为阳极，最近引起了高端电动汽车和新型应用（包括电动飞行）的传统锂离子电池（LIBS）的更高能量密度替代品。但是，LMB的成功商业化将需要具有高能量（高于500 WH/kg）的电池，价格低于100美元/千瓦时。此外，电池必须将其容量的80-90％保留在1000个周期以上，因此需要库仑效率（CE）超过99.99％。实现这些目标还需要实施高能阴极，并开发与两个电极兼容的新型电解质。液体电解质是理想的，因为它们确保了良好的电极接触和兼容性与为Libs建立的现有制造途径的兼容性。不过，锂金属阳极在任何电解质的电化学稳定窗口外运行，从而导致自发的电解质降低，从而导致ANODE的电化学潜力超过了低瓶电源溶液的电源溶液或lumecupiel colecupiel colecupiel Moleculit（Lumecupile Molecortal）。通过形成由不溶性反应产物组成的表面层来实现动力学稳定性，该表面层首先通过1979年用骨头命名为固体电解质对称相（SEI）。锂。这减少了CE，需要以锂箔形式使用过量的锂，以将循环寿命延长至实际值，从而减少特定的能量。这种不均匀的锂镀层和剥离行为受液体电解质和金属锂的基本特性的影响。电解质运输和热力学特性控制细胞运行过程中盐浓度梯度和过电势的发展。在极端情况下，电解质可以在电荷过程中完全耗尽盐表面的盐，从而导致分形锂树突的成核和相关的安全问题。最近的研究还表明，电荷转移动力学会影响沉积形态，观察到快速的界面电荷转移与CE正相关。另外，锂金属的微观结构和各向异性纳米力学影响循环行为。实际上，不均匀的剥离受晶体学质地的影响，并且在应用的堆栈压力下实现了更多均匀的沉积形态。最终，是通过调节锂形态和“死亡”锂形成来控制循环性能的SEI。 This demands a better understanding of the properties of the SEI and their influence on cycling performance, enabling the rational design of SEIs to guide future electrolyte development.This project aims to first examine the nanostructure of the SEI through surface/interfacial characterisation techniques, including atomic force microscopy, x-ray photoelectron spectroscopy, electron microscopy, and electrochemical impedance spectroscopy.仅对SEI纳米结构的知识就不足以预测细胞性能，因为尚未了解SEI特性如何受其结构和组成的影响。因此，该项目的第二个目标是调查结构性关系，以促进合理的SEI设计并指导未来的电解质开发。该项目属于EPSRC能源研究领域。该主题的目的是使英国实现其环境和能源目标。