Ionic conductor glass-ceramics sintering with concurrent crystallisation using flash sintering

• Grant number: 21/06509-9
• Support type: Scholarships in Brazil - Post-Doctorate
• Effective date (Start): August 01, 2021
• Effective date (End): July 31, 2023
• Field of knowledge: Engineering - Materials and Metallurgical Engineering - Nonmetallic Materials
• Principal researcher: Ana Candida Martins Rodrigues
• Grantee: João Vitor Campos
• Home Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil
• Associated research grant: 13/07793-6 - CEPIV - Center for Teaching, Research and Innovation in Glass, AP.CEPID

Abstract

Materials with NASICON structure (an acronym for "Na Superionic Conductor") have shown potential for application as electrolytes for next-generation batteries. This is because Solid-State Electrolytes (SSE) allow the use of high-voltage cathodes and metallic anodes, which result in a battery with higher energy density and are safer to use when compared with the ones currently in use (flammable liquid electrolytes batteries). Among the main challenges for the use at the scale of all-solid-state batteries, the high electrical resistance at the electrolyte/electrode interface stands out. This high interface resistance can be related to several factors such as low interfacial contact, interfacial degradation due to mutual diffusion, and mechanical failures in the contacts (e.g., cracks and pores). The synthesis route via glass-ceramics (fusion of precursor glass, followed by thermal treatment for controlled crystallization) is promising in obtaining materials with NASICON structure with high densification and ionic conduction. However, another alternative still little explored for these materials is the flash-sintering technique. Flash-sintering consists of applying an electric field directly to the sample, forcing the passage of an electric current through it; quickly warming it up by the Joule effect. Recent works have shown an increase in the ionic conductivity of flash sintered materials and also the possibility of joining two ceramics in a multilayer system applying the so-called flash-joining (a variation of the Flash-Sintering technique for joining/bonding materials). With this in mind, it is hypothesized that sintering with concurrent crystallization using flash-sintering can optimize the ionic conductivity of NASICON and that the flash-joining technique can be used to optimize the interface between the cathode material (e.g., LiFePO4 and LiCoO2) and the electrolyte. It is proposed to study the following compounds Na2AlTi(PO4)3 (NATP), Na1,8Al0,8Ge1,2(PO4)3 (NAGP), Na1+xTi2SixP3-xO12 (NATSP), and Li1,3Al0,3Ti1.7(PO4)3 (LATP) individually, and also, it is proposed to study the application of flash-joining in multilayer systems containing electrode material/NASICON/electrode material (the composition of the electrodes can be varied). For this, samples of the afore mentioned compounds will be prepared, for the first time, via the glass-ceramic route using flash-sintering as a sintering method with concurrent crystallization. In addition, multilayer systems will be sintered and joined via flash-joining. (AU)