A study of electrolytes for rechargeable zinc-metal batteries
Typ
Examensarbete för masterexamen
Program
Publicerad
2022
Författare
Engblom, Alexander
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
Today batteries can be found in a large variety of products and the use of batteries increases
every year. However, current battery technologies are approaching their limit and will likely
struggle to keep up with future demands. Due to this, battery technology must take a leap
forward and explore new chemistries and concepts. One promising candidate for this is the
zinc-metal battery, which is made out of more environmentally friendly and safer materials and
could offer high energy density. However, the disadvantage of zinc-metal batteries is their short
cycle life which is caused by the growth of zinc dendrites, inducing short circuiting. There have
been several approaches to suppress the growth of zinc dendrites and electrolyte design is one
of the most promising approaches.
In this project electrolyte design, including salt concentration and exploration of additives,
was studied with the aim to stabilize the zinc anode in a zinc-metal battery. The salt chosen
was zinc sulfate heptahydrate, which was added at different concentration to water to create
aqueous electrolytes. Their physical properties such as ion conductivity, viscosity, density, and
their infrared and Raman spectrum were then measured. The effect of salt concentration on
the stability and Coulombic efficiency of coin cells were also investigated. To explore the effects
of additives sulfated cellulose nanocrystals (CNC) and sodium carboxymethyl cellulose (CMC)
were added to the electrolyte and the characterization was performed once again on these new
electrolytes. How the salt concentration and the additives affected the zinc deposition was
studied through the use of scanning electron microscopy (SEM).
The results of this project show that a molar ratio of water and zinc ions between 25:1-50:1 is
the most suitable for the stability and Coulombic efficiency of coin cells. The additives did not
affect the physical properties of the electrolyte notably, apart from the viscosity. However, they
did affect the electrochemical performance, CNC improved the Coulombic efficiency and CMC
improved the stability. The SEM images showed that the salt concentration and the additives
do affect the morphology of the deposited zinc.