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Infiltrated and isostatic laminated NCM and LTO electrodes with plastic crystal electrolyte based on succinonitrile for lithium-ion solid state batteries

 
: Coeler, Matthias; Laack, Vanessa van; Langer, Frederieke; Potthoff, Annegret; Höhn, Sören; Reuber, Sebastian; Koschek, Katharina; Wolter, Mareike

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Fulltext ()

Batteries 7 (2021), No.1, Art. 11, 15 pp.
ISSN: 2313-0105
Fraunhofer-Gesellschaft FhG
MAVO; 836915; Kobibatt
English
Journal Article, Electronic Publication
Fraunhofer IKTS ()
Fraunhofer IFAM ()
solid state battery; lithium ion battery; polymer electrolyte; plastic crystal; Bipolar

Abstract
We report a new process technique for electrode manufacturing for all solid-state batteries. Porous electrodes are manufactured by a tape casting process and subsequently infiltrated by a plastic crystal polymer electrolyte (PCPE). With a following isostatic lamination process, the PCPE was further integrated deeply into the porous electrode layer, forming a composite electrode. The PCPE compromises the plastic crystal succinonitrile (SN), lithium conductive salt LiTFSI and polyacrylonitrile (PAN) and exhibits suitable thermal, rheological (ƞ = 0.6 Pa s @ 80°C 1 s-1) and electrochemical properties (σ > 10-4 S/cm @ 45 °C). We detected a lowered porosity of infiltrated and laminated electrodes through Hg porosimetry, showing a reduction from 25.6 % to 2.6 % (NCM infiltrated to laminated) and 32.9 to 4.0 % (LTO infiltrated to laminated). Infiltration of PCPE into the electrodes was further verified by FESEM images and EDX mapping of sulfur content of the conductive salt. Cycling tests of full cells with NCM and LTO electrodes with PCPE separator at 45 °C showed up to 165 mAh/g at 0.03C over 20 cycles, which is about 97 % of the total usable LTO capacity, with a coulomb efficiency of between 98 and 99 %. Cycling tests at 0.1C showed a capacity of ~128 mAh/g after 40 cycles. The C-rate of 0.2C showed a mean capacity of 127 mAh/g. In summary, we could manufacture full cells using a plastic crystal polymer electrolyte, suitable for NCM and LTO active material, which is easily to be integrated into porous electrodes and which is being able to be used in future cell concepts like bipolar stacked cells.

: http://publica.fraunhofer.de/documents/N-633797.html