Using Mn-Co containing compounds formed through biological processes as precursors for development of electrode materials for energy storage applicat

Currently, Mn-Co containing oxides are used as cathode materials in commercial lithium ion batteries. Further research into the Co-Mn-O-H system is investigating phases that have potential in other energy storage applications such as supercapacitor materials or as electrode materials in Na-ion batteries. Development of new electroactive materials involves controlling the composition, particle size and morphology to optimise their electrochemical characteristics.
Materials formed though microbial processes would be a novel route to produce Mn-Co phases. It is known that Shewanella oneidensis MR-1 can precipitate dissolved Mn2+ from mixed-metal leachates produced from end-of-life lithium ion batteries. The precipitate formed was confirmed as MnCO3, a known pre-cursor material used for production of electrode materials in lithium ion batteries. For the most part, Mn removal is highly selective but 'impurities', such as Co-containing precipitates have been observed. The impurities may in fact be beneficial to the future use of the material and their variation investigated and controlled through genetic manipulation of the microbe. Furthermore, S. oneidensis is able to reduce a range of metal ions with the production of metal nanoparticles under anaerobic conditions. This dual action suggests the possibility that this bacterium could be used for the production of mixed metal materials influenced by conditions such as oxygen availability and metal ion concentrations. Separately, or in combination, these avenues of study will provide access to microbially-synthesised cathode materials.
The phases formed though microbial processes will be characterised by a range of techniques including X-ray Powder Diffraction to identify the crystalline phases present, Scanning Electron Microscopy to investigate particle size and morphology, crucial for energy storage applications and electrochemical characterisation to investigate the electroactive properties. Once materials with good electrochemical properties have been identified, methods to develop devices for energy applications, such as supercapacitors or batteries will be established. These devices will then be tested for their long term stability.
Monitoring structural changes as a function of potential, i.e. any changes that may occur on using the device, gives key information on the performance of the material whilst in-service. With the new state-of-the-art X-ray Powder Diffraction Facility recently established in the Centre for Science at Extreme Conditions (CSEC), development of electrochemical cells that can couple with the X-ray Powder diffractometer will allow these changes to be investigated.
The project proposed will cover both the biological synthesis of the material, the structural and electrochemical characterisation of the materials and development of prototype devices.