Sugar-based polymers for renewable, degradable and efficient battery electrolytes

Context of Research:
As the world transitions towards a low carbon economy, storing the energy generated by intermittent renewable
sources is crucial. Rechargeable lithium-based batteries are promising technologies due to their high energy
capacity. However, the liquid electrolytes employed in lithium-ion batteries (LIBs) currently available on the market
pose safety issues including flammability and release of toxic products when damaged. Using a polymer doped with
ion salts as a Solid Polymer Electrolyte (SPE) is a safer and lightweight alternative, which has also been shown to
increase battery life. Poly(ethylene oxide) (PEO) mixed with ion salts is the most popular and researched SPE.
However, it has many shortcomings including poor ionic conductivity and mechanical strength but no major
altenatives exist.
The Buchard group has previously developed a platform of functionalisable sugar-based polymers, which are
hypothesised to be suitable to develop novel high-performance SPEs:
1. The high oxygen content of these sugar-based polymers will promote coordination and therefore solubility of ion
salts.
2. The structure and properties of these polymers can be varied to explore a large chemical space relevant to several
ion mobility mechanisms.
3. These polymers are renewable, (bio)degradable and non-toxic.
Aims and objectives of research project:
The aim of this PhD research project is to develop a range of novel SPEs based upon polymers derived from natural
sugars.
The objectives of this project are: 1) Synthesise a series of sugar-based polymers targeted towards cation transport.
This will be carried out using a range of established methodologies to prepare various cyclic monomers with different
linkages and diverse functional groups. These monomers will be polymerised using controlled polymerisation
techniques and analysis of the resulting materials will be performed to establish their structure/properties relationship.
2) Prepare solid polymer electroly tes by combining these polymers with ion salts via solvent casting from solution.
The SPEs will be characterised with various techniques including thermogravimetric analysis and differential
scanning calorimetry. Electrochemical performance of the SPEs will be investigated by electron impedance
spectroscopy to assess the SPE's suitability as a battery electrolyte material.
Potential applications and benefits:
The main potential application of this research is as a replacement to liquid electrolytes traditionally using in
commercial lithium-ion batteries. This is beneficial as by replacing liquid electrolytes with SPEs the safety of the
batteries will be improved due to the reduced flammability and no leakage of toxic by-products if the battery is
damaged. SPEs hold great potential for the next generation of rechargeable batteries, including those based on
multivalent and abundant metal anodes (Mg, Ca). Furthermore, another benefit is that these polymers are renewable,
(bio)degradable and non-toxic, which would minimise the carbon footprint of the batteries and facilitate recycling of
the precious elements involved in their manufacture. Without legitimising a thrown-away culture, biodegradable SPEs
could also find a place in short-lived devices, that are not retrieved from the environment.
The second supervisor to this project is Prof. Frank Marken who has expertise in electrochemistry and will be able to
provide support in electrochemical analysis of SPEs.