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

Daniel – ORNL
V.E.3 Intercalation Kinetics and Ion Mobility in Electrode Materials (ORNL)
(a)
(a)
(b)
(b)
(c)
Figure V - 195: Effect of mechanical damage on the ESM activity: a) 400
nm deep indentation; b) 200 nm deep indentation. The indented areas are
marked with circles.
Samples with the NCM cathode material
(Li 1.05 (Ni 1/3 Co 1/3 Mn 1/3 ) 0.95 O 2 ) were prepared using a new
technique for uniformly spreading active material particles
over the current collector (as opposed to traditional
composite electrode samples made from slurry) which is
suitable for ESM studies. The results (Figure V - 196) show
significant dependence of electrochemical activity on the
crystallographic features of the sample. Bias induced strain
amplitude from BE-line measurements is a function of
location of pulse application. In addition, the amplitude of
normal strain in the direction of the cantilever deflection
(out-of-plane) can be very different from that in the inpane
direction (corresponding to cantilever torsion), which
is evident in Figure V - 196b and Figure V - 196c. It can be seen
that the same area of the material produces either very high
or nearly zero strains depending on which of the
orthogonal directions is considered. It should be noticed
that some of the grain boundaries are highly active while
others remain inactive under in-plane measurements (Figure
V - 196c).
(a)
(d)
Figure V - 194: ESM study of the indented thin film LiCoO2 cathode: a)
indented region; b) analyzed area; c) loop opening; d) corresponding loops
(b)
(c)
Figure V - 196: ESM of NCM grains: a) deflection; b) out-of-plane amplitude;
c) in-plane amplitude
FY 2011 Annual Progress Report 639 Energy Storage R&D