Ceramic electrolyte design mitigating dendrites and voids at the Li anode

对能量存储设备的需求从未像现在这么大。锂离子电池由于其高能量密度，在便携式电子产品的发展中发挥了重要作用。它们是实现运输电气化和摆脱内燃机的关键技术。为了支持向可再生能源的过渡并使交通完全电气化，将需要新的材料和电池技术。例如，固态电解质使锂金属阳极的使用成为可能，大大提高了能源安全性，即延长了行驶里程。然而，如果要实现具有锂阳极和陶瓷电解质的实用固态电池，还需要解决一些重要的挑战。在有锂金属阳极的固态电池的循环过程中，锂金属被镀和剥离。这给锂-固体电解质界面带来了挑战：如何在放电（剥离）时减轻界面上空洞的形成，以及如何在充电（电镀）时抑制枝晶的形成。我们已经证明了排空的有害影响，并在理解锂枝晶生长方面取得了重要进展，锂枝晶生长最终导致细胞衰竭。这种基本的理解提高了控制陶瓷电解质的表面和体形态作为抑制空洞和枝晶的手段的可能性，这在实际电流密度和压力下至关重要。本研究将研究这些主题。首先，对与锂接触的固体电解质表面进行改性，防止空化，显著提高剥离电流密度。其次，将利用对锂枝晶渗透的新认识来控制固体电解质的形态，以实现更高的电流密度，而不会导致枝晶生长和短路。这也将有助于理解硫化物基电解质的机制。控制硫化物基固体电解质的表面和体积形态，并了解这些因素与锂阳极性能之间的关系，在科学和技术上都具有挑战性。该项目将涉及设计和开发新技术，以制备具有不同体积和表面形态的固体电解质，表征它们，制造电池并研究它们的性能。这些结果将用于产生优化的形态学。该项目将涉及许多技术来控制形貌，如3D打印、热压、火花等离子烧结和其他材料加工方法。电解质将被纳入电化学电池，循环和EIS等测试将用于评估性能的变化。扫描电子显微镜和断层扫描将提供补充数据。该项目属于EPSRC物理科学、能源和脱碳研究领域。该奖学金是法拉第研究所固态电池项目SOLBAT的一部分，并将与参与该项目的其他合作伙伴合作。这是一项为期4年的法拉第研究所奖学金（部分课程费用由牛津材料基金支付）

The demand for energy storage devices has never been greater. Lithium ion batteries have played an important role in the development of portable electronics due to their high energy densities. They are a key technology in enabling the electrification of transport and the move away from the internal combustion engine. In order to support the transition to renewable energy sources and to fully electrify transport, new materials and battery technologies will be needed. For example, solid state electrolytes make the use of a lithium metal anode possible, significantly increasing the energy safety, i.e. extending driving range. However important challenges remain to be solved if practical solid-state batteries with a lithium anode and ceramic electrolyte are to be realised. During cycling of a solid-state battery with a lithium metal anode, lithium metal is plated and stripped. This give rise to challenges at the lithium-solid electrolyte interface: how to mitigate the formation of voids at the interface on discharge (stripping) and how to suppress dendrite formation on charging (plating). We have shown the detrimental effects of voiding and have made important progress in understanding lithium dendrite growth, which ultimately leads to cell failure. This fundamental understanding has raised the possibility of controlling both the surface and bulk morphology of the ceramic electrolyte as a means of suppressing voids and dendrites, crucially at practical current densities and pressures. It is these topics that this studentship will investigate. Firstly, the surface of the solid electrolyte in contact with lithium will be modified to prevent voiding and significantly increase the stripping current density. Secondly new understanding of lithium dendrite penetration will be exploited to control the solid electrolyte morphology to realise higher current densities without dendrite growth and short-circuiting. This will also contribute to the understanding of the mechanics of sulphide-based electrolytes.Controlling the surface and bulk morphology of sulphide-based solid electrolytes and understanding the relationship between these factors and the performance of the lithium anode is scientifically and technically challenging. This project will involve designing and developing new techniques to prepare solid electrolytes with different bulk and surface morphologies, to characterise them and to fabricate cells and investigate their performance. These results will be used to produce optimised morphologies. This project will involve a number of techniques to control the morphology, such as 3D printing, hot pressing, spark plasma sintering and other materials processing methodologies. The electrolytes will be incorporated in electrochemical cells and testing such as cycling and EIS will be will be used to assess changes in performance. Scanning electron microscopy and tomography will provide complementary data.This project falls within the EPSRC Physical Sciences and Energy and decarbonisation research areas.The studentship is funded as part of the Faraday Institution's solid-state battery project, SOLBAT, and will collaborate with the other partners involved in the project. This is a 4-year Faraday Institution Studentship (part of the course fee paid from Oxford Materials funds)