Potassium nucleation and growth on substrates of disparate potassiophilicity
Typ
Examensarbete för masterexamen
Program
Publicerad
2022
Författare
Chrobak, Wojciech
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
The increasing demand for batteries in combination with the limited lithium (Li)
reserves has motivated the search for alternatives to the conventional Li-ion battery
chemistry. Batteries based on potassium (K) have been proposed due to its greater
abundance compared to Li in the Earth’s crust. However, the larger weight of
K compared to Li necessitates the use of K metal anodes to attain competitive
energy densities in K batteries. Metallic anodes are problematic pertaining to
rechargeability, as a result of their tendency to form dendritic morphology during
cycling. The dendrites are detrimental to the coulombic efficiency of the cells and
even hazardous, as they can grow through the separator to the other electrode,
causing a short circuit. To control the morphology of K metal, it is imperative to
build a fundamental understanding of the electrochemical deposition of K.
This work focuses on studying electrochemical deposition of K metal onto various
substrates by method of constant current cycling. With this technique, the voltage
response is recorded and the peaks during deposition correspond to the nucleation
process. The substrate onto which the metal is deposited affects the nucleation and
ostensibly the emerging morphology as a consequence. A surprising result is the
similarity in depth of the nucleation peaks for the substrates tungsten (W), previously
predicted to be superpotassiophobic and gold (Au), expected to be potassiophilic.
Another is the both deeper and wider peak for copper (Cu) as compared to W, even
though Cu was theoretically estimated to be over 4 times less potassiophobic.
Beskrivning
Ämne/nyckelord
potassium , metal anode , three-electrode , nucleation , overpotential , constant current cycling