Double Layer Polymer Electrolytes as strategy for improved performance high-voltage solid-state Li-metal batteries
Mikel Arrese-Igor a b, María Martinez-Ibañez a, Erwan Dumont c, Ekaterina Pavlenko c, Michel Armand a, Frédéric Aguesse a, Pedro López-Aranguren a
a CIC energiGUNE, Albert Einstein 48, Miñano, Spain
b University of the Basque Country (UPV/EHU), Barrio Sarriena, S/N, Leioa, Spain
c SAFT, Boulevard Alfred Daney, 111, Bordeaux, France
Materials for Sustainable Development Conference (MATSUS)
Proceedings of Materials for Sustainable Development Conference (MAT-SUS) (NFM22)
#BATTERIES - Solid State Batteries: Advances and challenges on materials, processing and characterization
Barcelona, Spain, 2022 October 24th - 28th
Organizers: Alex Morata, Albert Tarancón and Ainara Aguadero
Contributed talk, Mikel Arrese-Igor, presentation 235
Publication date: 11th July 2022

Solid-state batteries with polymer electrolytes (PEs) are at the forefront of candidates to boost energy density and improve the safety of conventional Li-ion batteries. PEs require a wide electrochemical stability window to withstand high-voltage positive electrodes (i.e. LiNi0.6Mn0.2Co0.2O2, NMC622) and offer stability with the negative electrode (typically Li-metal).1 However, solid PEs still suffer from low electrochemical stability against highly oxidative and reductive potentials simultaneously. The Double Layer Polymer Electrolyte (DLPE) approach overcomes this issue from the choice of appropriate polymers for the positive electrode and separator respectively, combining them within the same electrochemical device. In this work, polyethylene oxide (PEO), offering stability against Li metal, and polypropylene carbonate (PPC), offering stability at high potentials, were used to prepare DPLE cells with NMC622 and Li-metal electrodes. Nevertheless, the use of a conventional dual-ion conductor lithium-salt (e.g. lithium bis(trifluoromethanesulfonyl)imide, LiTFSI) was found to play a key role on the thermodynamical compatibility between the polymer phases due to ion diffusion from PPC to the more solvating PEO, leading ultimately to cell failure. By modifying the lithium-ion conductive salt we successfully overcome those hurdles and provide guidelines on the design of improved performance cells with DLPE technology.2 Ultimately, this allows to assemble cells with high loading NMC622 (1 mAh cm–2) delivering 160 mAh g–1 and overcoming the performance of ethylene oxide -based cells, which rapidly degrade in the presence of high cut-off voltage active materials.3 This study provides a detailed understanding on the transport properties and ageing mechanisms taking place in SSLMBs, inspiring further the rational design of new DLPE technology with robust electrochemical performance.

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