Aqueous Metal-ion Batteries: Safe and Sustainable by Design

Doctoral thesis, 2024

Aqueous metal-ion batteries (AMIBs) are promising candidates for technically low-to-medium-demanding electrical applications and could in principle be used in tandem with high-performant lithium-ion batteries (LIBs) to save resources and invested capital. By using organic materials and avoiding the scarce, costly, and toxic transition metals found in LIBs (e.g. Ni/Co/Cu), the technology may become lower cost, more environmentally benign, and safer than today's alternatives, which altogether rhymes well with EU’s critical raw materials directive highlighting risks of shortages and price spikes for traditional LIB materials.

In this thesis we explore the possibility of assembling unconventional AMIBs and hybrid supercapacitors by considering both the active and passive materials of the electrochemical cell. Sodium based technologies are the starting point, the materials used are primarily organic, and there is a pervading theme of finding remedies for the active material dissolution issue of aqueous electrolytes. The latter is addressed without resorting to common routes e.g. saturating the electrolyte with expensive fluorinated/perchlorate salts or incorporating organic co-solvents. Instead, other types of electrolyte concepts are suggested – with the intention to maintain the low-cost and sustainable aspects of aqueous batteries, new kinds of electrodes are made, and novel electrochemical full cells are created and studied with a wide range of analytical techniques to assess the behaviour, interplay, and performance of the cells and their constituents.