Helis. High energy lithium sulphur cells and batteries. Dr. Marian Cristian Stan a, Prof. Dr. Martin Winter a,b

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1 Helis High energy lithium sulphur cells and batteries Dr. Marian Cristian Stan a, Prof. Dr. Martin Winter a,b a MEET Battery Research Center, University of Muenster b Helmholtz-Institute Muenster (HI MS), IEK-12, Forschungszentrum Juelich GmbH Contact Dr. Marian Cristian Stan MEET Battery Research Center Corrensstraße , Muenster marian.stan@uni-muenster.de Tel.:

2 Helis: facts and figures 14 partners from 7 countries 2 large enterprises, 3 SMEs, 3 knowledge transfer institutions and 6 research laboratories 2

3 Helis: About the project EC Call NMP : Post-lithium ion batteries for electric automotive applications Type of action CP collaborative project Project budget EU Funding Project Start-End 7.97 M 7.97 M 1 st June st May 2019 Partners Target & Deliverables SAFT SAS, PSA, Solvionic, Picosun, Accurec, INERIS, CNRS, IREQ, Chalmers University, Fraunhofer, Tel Aviv University, Munster University, Max Planck, NIC - Energy density, power, durability, ageing, safety, battery packs, recycling, modeling, scale up of components from EUROLIS 3

4 Interdependency between WPs 4

5 Helis: road map June 2016 October 2018 M1. Kick off meeting M2. Prototypes for ageing study M3. Improved prototypes (separator) M4.Improved prototypes (protected lithium) June 2015 October 2017 Developing ideas able to frog leap from lab scale to the market should be provided by the end of the project Lithium surface protection with an artificial SEI (Solid Electrolyte Interphase) is still in ist infancy (expected TRL < 3) 5

6 WP5: Lithium anode and separators Objectives The main objective of WP 5 concerns with R&D on the protection of the Li-metal electrode against the continuous degradation due to the formation of an unstable SEI and against the PSs reaction during the redox shuttle process The metallic lithium and separator, more precisely engineering of the anode and its composition including possible coatings on the lithium surface. It also deals with the development and scale-up of the ion-selective separators Approach - Lithium surface protected with artificial SEI - Ion selective separators (blocking polysulphides) 6

7 Barriers to efficient Li-electrodes Continuous electrolyte decomposition Lithium - + Electrolyte Cathode HSAL (dendrite) formation Loss of Li Low Coulombic Efficiency Impedance increase Inhomogeneous deposition-dissolution 3862 mah/g Light weight Low redox potential (-3.04 V vs. SHE) Safety Low energy density Poor cycling performance Xu et al., Energy Environ. Sci., 2014, 7, 513 Eichinger et al., J. Electroanal. Chem., 1976, 72, 1 Winter et al., Monatsh. Chem., 2001, 132, 473 Winter et al., Z. Phys. Chem., 2009, 223,

8 Challenges of Li Metal: Inhomogeneous Dissolution-Deposition (1st cycle) (2) Dissolution (1) Pristine (3) Deposition 10µm 0,4 0,3 Li symmetric cell (2) Deposition Voltage / V 0,2 0,1 0,0-0, (3) Dissolution -0,2-0,3-0, Time / h Electrolyte: 1M LiTFSI in DEGBEE:DOL 1:1 (by v.) Electrodes: Li (Foil) vs. Li (2-Electrode, symmetric cells) Currentdensity: 0.25 ma/cm 2, 3h deposition and3h dissolution 20 C, 1 st cycle 8

9 Solutions to overcome the barriers Mechanical modification Li-morphology Protection layer Roll-press Micro-patterning Li-metal powder Electrolyte additives Inorganic coatings Li overpotentials Li deposit homogeneity (HSAL) Controlled Li deposition (dendrites) Current density Li overpotentials Li overpotentials Li morphology (HSAL) Chemical reactivity Coulombic efficiency Becking et al., Adv. Mat. Interfaces, 2017, 4(16), Ryou et al., Adv. Funct. Mater., 2014, 25, 834. Bieker et al., Adv. Energy Mater., 2014, 4, Heine et al., J. Electrochem. Soc., 2015, 162, A

10 Increasing the reactivity of the Li-surface As received Li-foil Roll-pressed Li-foil Voltage / V Voltage / V Time / h Time / h Mechanical surface modification reduces and stabilizes the extent of overvoltages Electrolyte: 1M LiTFSI in TEGDME:DOL 1:1 (by v.) Electrodes: Li (Foil) vs. Li (2-Electrode, symmetric cells) Current density: 0.1 ma/cm 2, 1h deposition and 1h dissolution 20 C, 50 cycles Becking et al., Adv. Mat. Interfaces, 2017, 4 (16),

11 Electrochem. performances of Li after cementation Improved Li cycling performances after the cementation process Stan et al., in preparation 11

12 Acknowledgements Horizon 2020 This project receives funding from the European Union s Horizon 2020 research and innovation program under the Grant Agreement no Dipl. Chem. Jens Becking Dipl. Chem. Albert Gröbmeyer 12