Surface protection and Interfacial optimization By ALD-coatings on sulfide-based Solid Electrolytes (SE)

• Grant number: 22/07637-3
• Support Opportunities: Regular Research Grants
• Start date: February 01, 2024
• End date: January 31, 2026
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Agreement: M-ERA.NET
• Principal Investigator: Hellmut Eckert
• Grantee: Hellmut Eckert
• Principal researcher abroad: Henry Auer
• Institution abroad: Fraunhofer Institute for Ceramic Technologies and Systems, Germany
• Host Institution: Instituto de Física de São Carlos (IFSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil
• Associated researchers: Anuraag Gaddam ; Marcos de Oliveira Junior

Abstract

Sulfide solid electrolytes pose a high potential for application in all-solid-state batteries while they are compatible with conventional lithium-ion processing technology. Still, some obstacles regarding material degradation need to be overcome. Thus, the proposed project aims to a surface protection and interfacial optimization by ALD-coatings on sulfide-based solid electrolytes (SE) - ALD-SE. By proper surface design reactivity of the sulfides (i) against moisture, (ii) with polar solvents and (iii) at anodic as well as cathodic electrode potentials is suppressed. The former aspects (i) and (ii) are game changers for a sustainable production chain. Protection against moisture suppresses toxic H2S formation during battery manufacturing, cell damage and recycling processes. The decreased requirements towards a dry processing atmosphere thus safe energy and operational cost. Increased solvent compatibility allows to use established binder systems at low binder contents - a key requirement for high performing cells. The latter aspect (iii) increases cell performance by reducing detrimental side reactions. This also allows the manufacturing of long-lasting cells. To reach these targets, coatings applied by ALD are developed and optimized regarding composition and thickness. These developments are supported by atomistic, solid-state NMR and a macroscopic, electrochemical understanding of the effects of the applied surface layer on the material properties. The process technology is adapted to a powder (TRL 2 to TRL 3) and a sheet-based route (TRL 2 to TRL 4). Both strategies pose advantages and drawbacks regarding sulfide processing on material and component level, implementation and scalability of ALD technology within the battery manufacturing chain and functionality of the all-solid-state battery. These aspects are evaluated and updated throughout the project. Although the materials are located at the very beginning of the value chain, in battery business their impact on performance and price of the end-product is difficult to overestimate. The introduction of ALD-coatings supports the development of the whole value chain of all-solid-state batteries in Europe. By proper IP protection the added value due to coatings can become more important than the initial uncoated material. State-of-the-art (SoA) sulfide electrolytes cannot be directly processed into all-solid-state batteries due to interfacial issues. ALD-caoting technology and proper surface engineering can bridge this gap between SoA and desired properties. Trough the ALD-SE project we are getting closer to a scalable development of an intrinsically safe, high-energy all-solid-state battery. (AU)