V. Focused Fundamental Research - EERE - U.S. Department of ...

V.C.4 Nano-structured Materials as Anodes (Binghamton U.) Whittingham – Binghamton U.
Figure V - 83a shows the lithium insertion curve,
which is the charging of the battery using this material as
an anode. Figure V - 83b shows the capacity as a
percentage of the capacity at 0.1 mA/cm 2 ; for each data
point, the lithium was first removed at the low rate of 0.1
mA/cm 2 . It can be immediately seen that at the high rates
used, the capacity falls off very rapidly. At a rate of 2
mA/cm 2 50% of the capacity is lost. In contrast, the
capacity on lithium removal is maintained even at high
rates; for example, around 70% of the capacity is retained
at 10 mA/cm 2 (2.5C rate). Thus, this anode material can
sustain high discharge rates (lithium delivery), and
probably meets the technical needs of PHEV and EV. It is
more limited on charging, Figure V - 83c and Figure V - 83d,
and in this respect is comparable to carbon anodes, and
might create problems with the fast charging needs of
HEV batteries.
Bulk Tin Foil Anodes. In contrast to nanoamorphous
tin, bulk tin foil loses capacity after about 10 to
12 deep cycles (or equivalent shallow cycles). This is due
to a resistance build-up caused by the continuous
formation of the SEI layer as the tin expands and contracts
on reaction with the lithium. Robert Kostecki at LBNL has
shown that the SEI layer formed on tin in the carbonate
electrolytes is non-protective.
Other Anode Materials We are exploring other
metal-based anode materials under our new project
V.C.10.
Conclusions and Future Directions
A clear result from our study of understanding the
cycling behavior of tin anode materials is that
nano/amorphous materials work, and that bulk materials
with their high expansion on lithium reaction do not and
are therefore unsuitable for batteries. This project is now
complete.
FY 2011 Publications/Presentations
1. Presentation to the 2011 DOE Annual Peer Review
Meeting.
2. Ruigang Zhang and M. Stanley Whittingham
“Electrochemical Behavior of the Amorphous Tin–
Cobalt Anode”, Electrochem. Solid State Letters,
2010, 13: A184-A187
3. Many invited presentations, incl.:
o ECS, MRS, PPS
o ORNL
Energy Storage R &D 550 FY 2011 Annual Progress Report