Ceramic electrolyte design mitigating dendrites and voids at the Li anode

对储能设备的需求从未如此之大。锂离子电池由于其高能量密度而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，并使交通运输充分节能，将需要新材料和电池技术。例如，固态电解质使锂金属阳极的使用成为可能，显著提高了能源安全性，即延长了驱动范围。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，则仍然需要解决重要的挑战。在具有锂金属阳极的固态电池的循环期间，锂金属被电镀和剥离。这在锂-固体电解质界面处产生了挑战：如何减轻在放电（剥离）时界面处空隙的形成以及如何抑制在充电（电镀）时枝晶的形成。我们已经表明了空洞的有害影响，并在理解锂枝晶生长方面取得了重要进展，这最终导致电池失效。这种基本的理解提出了控制陶瓷电解质的表面和本体形态作为抑制空隙和枝晶的手段的可能性，关键是在实际的电流密度和压力下。这是这些主题，本研究将调查。首先，与锂接触的固体电解质的表面将被改性以防止空隙化并显著增加剥离电流密度。其次，将利用对锂枝晶穿透的新理解来控制固体电解质形态，以实现更高的电流密度而不产生枝晶生长和短路。控制硫化物基固体电解质的表面和体相形态，并了解这些因素与锂负极性能之间的关系，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，将其分散并制造电池并研究其性能。这些结果将用于产生优化的形态。该项目将涉及许多技术来控制形态，如3D打印，热压，放电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和测试，如循环和EIS将被用来评估性能的变化。扫描电子显微镜和断层扫描将提供补充数据。该项目福尔斯EPSRC物理科学和能源与脱碳研究领域。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。这是为期4年的法拉第机构助学金（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)