1. All Silicon Lithium-ion Battery Chao Xu Department of Chemistry-Ångström Uppsala University

2. Project info. Projektets namn: Nästa generation litium-jon batterier; kisel och silikat Start- och sluttid för projektet: 2011-06-01 – 2014-12-31 Huvudstödmottagare samt andra parter i projektet: Torbjörn Gustafsson, UU Inom vilket program projektet fått stöd: Energieffektiva vägfordon, period 2011-2014 Stödsumma: 4920000 kr

3. Background 1. Tarascon, J. M. and M. Armand (2001). "Issues and challenges facing rechargeable lithium batteries." Nature 414(6861): 359-367.

4. Criteria for different systems Portable devices Electric vehicle Grid energy storage Energy density Safety Lifetime Safety, lifetime Power density &Energy density Cost Lifetime Cost Up-scale capability Novel materials Material modification New electrolyte, additives Battery system engineering

5. All Silicon Battery Battery configuration CathodeElectrolyteAnode Lithium metal silicate e.g. Li 2 FeSiO 4 Liqiud electroyte, polymer electrolyte Silicon

6. Why ”all silicon”?  Silicate materials: stable crystal-structure  Earth abundant elements - Si, (Fe) - Low cost - Capable of large-scale production  High specific capacity Li 2 FeSiO 4 166 mAh/g (LiCoO 2 140 mAh/g ) Silicon 3600 mAh/g (Graphite 372 mAh/g )  Environmentally friendly, compare to toxic LiCoO 2

7. Problems to be solved Cathode side (Li 2 FeSiO 4 ):  Poor electronic conductivity  Low temperature performance  Extracting second Li from Li 2 FeSiO 4 Anode side (Si):  Volume change during cycling (4 times larger when fully discharged)  Large irreversible capacity  Low coulombic efficiency  Capacity fading

8. Silicon anode Significantly increased capacity rentation and coulombic efficiency 10 wt% electrolyte additive (fluoroethylene carbonate, FEC) added in the electrolyte LP40 0.12 V – 0.9 V, 500 mA/g

9. Silicon anode  Solid electrolyte interphase (SEI) study using X-ray photoelectron spectroscopy (XPS)  After 85 cycles C1s FEC/LP40 LP40

10. Lithium iron silicate Combustion synthesis of Li 2 FeSiO 4 (LFS) by Dr. Mohammed Dahbi 2. Dahbi, M., S. Urbonaite, et al. (2012). "Combustion synthesis and electrochemical performance of Li 2 FeSiO 4 /C cathode material for lithium-ion batteries." Journal of Power Sources 205(0): 456-462.

11. All silicon battery  Preliminary results on silicate-silicon battery with different cycling conditions

12. Conclusion and Outlook Safe and long lifetime battery systems needed for EV application Electrolyte additive FEC can significantly increase the performance of silicon anode Improve the electronic and ionic conductivity of Li 2 FeSiO 4 electrode Improve the all silicon battery performance

13. Acknowledgements Torbjörn Gustafsson Kristina Edström Mohammed Dahbi Fredrik Lindgren Bertrand Philippe

14. Comments and questions are appreciated!