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SUMMARY:On the Role of Mechanics in the Design and Performance of Electrod
 e Materials for Energy Storage
DTSTART:20120522T131500
DTEND:20120522T141500
DTSTAMP:20260916T044001Z
UID:d0b8f2cc4e67f575aa2539f03d91e1bdc72498b5aecabe20c4652678
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. Pradeep Guduru\, Brown University\, USA\nThe increasing 
 interest in employing alternative energy sources\, especially for transpor
 tation applications\, led to a large scale national effort in recent years
  towards developing electrochemical energy storage systems (batteries) wit
 h significantly higher energy density and cycle-life compared to the preva
 iling technologies. The performance of the new classes of materials being 
 developed/considered is severely limited by the mechanical degradation tha
 t accumulates during operation\, which is a main impediment that needs to 
 be overcome. This talk focuses on the mechanics issues in silicon\, which 
 is considered to be a promising anode material to increase the specific en
 ergy of lithium-ion batteries by as much as 30%. For accurate modeling of 
 battery performance\, cycle life and reliability\, there is a need to unde
 rstand the failure modes and how mechanical fields influence electrochemic
 al response. Our experiments show that lithiated silicon is capable of und
 ergoing large plastic deformation in constrained geometries\; the ability 
 to undergo plastic deformation underpins the failure behavior in all silic
 on anode architectures. An analysis of the dependence of electric potentia
 l on the state of stress of a lithiated-silicon electrode is also presente
 d. Based on the Larche and Cahn chemical potential for a solid solution\, 
 a thermodynamic argument is made for the existence of a stress-potential c
 oupling in lithiated-silicon\, the magnitude of which is estimated to be ~
  60 mV/GPa. The analysis was validated by an accompanying experimental inv
 estigation that measured the coupling to be around 100 mV/GPa. The implica
 tions of the stress-potential coupling to Li plating and safety are discus
 sed. We also present an experimental method to measure average stress fiel
 ds in practical electrode microstructures during electrochemical cycling.
LOCATION:ME B3 31 http://plan.epfl.ch/?lang=fr&room=ME+B3+31
STATUS:CONFIRMED
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