Materials scientists discover new method to manufacture cathodes for Na ion battery


Ali Nunes

A new study from the Braun Group demonstrates a generalized electrochemical method to grow thick  
energy   dense   cathodes   for   Na   ion   batteries.   This   is   the   first   demonstration  
of electrodeposition of thick ceramic oxide  films of importance for sodium-based electrochemical
energy storage.

The  research  team  at  the  University  of  Illinois  includes  Materials  Science  and 
Engineering Professor Paul V. Braun;   P.hD. student Arghya Patra and undergraduate student Jerome
Davis III;  and  collaborators  Professor Daniel  P. Shoemaker and Professor Jian  Min Zuo,  along 
with members of their respective groups. All are researchers in the Materials Research Laboratory.

The  new  manufacturing  method  is  of  interest  to  both  the  basic materials  science
community given  the  new  growth  method  demonstrated,  and  companies  interested  in  new 
cathodes  for sodium-ion based energy storage - in particular, companies interested in grid energy
storage. The grown materials exhibit nearly ideal electrochemical properties, and can be grown to
thicknesses of relevance for industry.

“Sodium-ion based batteries have the potential to be much more cost effective for energy storage
than lithium-based systems if new electrode materials and electrode growth technologies can be
developed,” said Paul Braun.

“Prior  to  our  demonstration, only  atmosphere stable thin oxide  films could  be synthesized by
electrodeposition  technique,”   said  Patra.  “Also,   our  work  is  the  first  demonstration 
of  a fabrication  method  that  can  synthesize  binder and  additive free sodium  ion cathodes 
that can perform similar to the solid-state synthesized slurry cast analogs.”

The electrochemically grown cathodes have  higher volumetric and gravimetric capacities than
classically made slurry-based electrodes due to the absence of low-density binder and conductive
additives. One important feature of  this  electrodeposition process is  that the  orientation of
the crystals can be controlled  such that  the fast  Na ion conducting directions in the crystal
can be preferentially oriented perpendicular to the current collector. This enables the materials
to charge and discharge quickly, even for very thick electrodes.

“Our    molten    hydroxide-based    electrodeposition    method    allows    access    to   
multiple electrochemically important polytypes across different transition metal chemistries in the
sodium transition metal oxide class of materials,” the team adds.

The next steps for this research is to further enhance the performance, in particular of the lowest
cost chemistries. Doing so  would minimize the performance gap between this new class of Na ion
systems and classical, and more expensive, Li ion chemistries.

[cr][lf]<p style="margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: Calibri, sans-serif;"><span style="font-size: 11.0pt; font-family: Arial, sans-serif;">Scanning electron micrograph showing ~60 &mu;m thick Na</span><span style="font-size: 7.0pt; font-family: Arial, sans-serif;">x</span><span style="font-size: 11.0pt; font-family: Arial, sans-serif;">CoO</span><span style="font-size: 7.0pt; font-family: Arial, sans-serif;">2 </span><span style="font-size: 11.0pt; font-family: Arial, sans-serif;">on a nickel foil (nickel foil is the brighter band at the bottom of the image). [Image courtesy : Arghya Patra]</span></p>[cr][lf]

Scanning electron micrograph showing ~60 μm thick NaxCoO2 on a nickel foil (nickel foil is the brighter band at the bottom of the image). [Image courtesy : Arghya Patra]










Colorized scanning electron microscope images of the electrodeposited Na-ion battery cathode materials [Image<br />courtesy : Arghya Patra, colorized by Marley Dewey]
Colorized scanning electron microscope images of the electrodeposited Na-ion battery cathode materials [Image
courtesy : Arghya Patra, colorized by Marley Dewey]











The paper, Electrodeposition of atmosphere-sensitive ternary sodium transition metal oxide films
for sodium-based electrochemical energy storage, is published in PNAS.

Significant aspects of the characterization were performed using the shared user facilities of the
University of Illinois Materials Research Laboratory.

Funding for the project was provided by  the Office of Naval Research (ONR) through the Navy and
Marine Corps Department of Defense University Research-to-Adoption (DURA) Initiative, the U.S. Army
Construction Engineering Research Laboratory, and the National Science Foundation Engineering
Research Center for Power Optimization of Electro Thermal Systems