The conventional fabrication of electrodes for sodium-ion
batteries
(SIB) involves mixing of the active material with additives and tape-casting
on metallic current collectors. Herein, an electrophoretic deposition
(EPD) method has been developed to fabricate composite electrodes
without using volatile and toxic solvents as well as binders. The
approach is based on the EPD of amorphous FePO4 and multiwall
carbon nanotube (MWCNT) from aqueous suspensions. The fabrication
of FePO4 suspensions containing MWCNT and the controlled
co-deposition of both materials are pivotal for the EPD of composites.
Multiple dispersants with different properties are investigated as
the charging, dispersing, and film-forming agents. The deposition
yield of EPD films is measured under various conditions. The atomic
force microscopy analysis, engaged with thermogravimetric tests, provides
evidence for the formation of adhesive and conductive FePO4/MWCNT films. The dispersant concentration is optimized in order
to achieve high capacity. The composite electrode, prepared by EPD,
delivers a discharge capacity of 142.2 mA h g–1 at
a current of 10 mA g–1. Another important finding
is the possibility to fabricate full-cell SIBs, containing presodiated
hard carbon as the anode and a deposited FePO4/MWCNT cathode.
The deposited films show adequate capacitance retention as the charge–discharge
current increased and stable cycling performance.