Industrial electrochemical processes that use electrodes to produce fuels and chemical products are hampered by the formation of bubbles that block parts of the electrode surface, reducing the area available for the active reaction. Such blockage reduces the performance of the electrodes by anywhere from 10–25%.

It has long been assumed that the entire area of the electrode shadowed by each bubble would be effectively inactivated. However, new research has revealed out that only a much smaller area – roughly the area where the bubble actually contacts the surface – is blocked from its electrochemical activity. The new insights, reported in the journal Nanoscale, could lead directly to new ways of patterning the surfaces to minimise the contact area and improve overall efficiency.

The research team from the Massachusetts Institute of Technology (MIT), University of Chicago and Argonne National Laboratory developed a new way to quantify the bubble passivation effects on an electrode or catalyst surface. They devised a new performance metric called BECSA (bubble-induced electrochemically active surface), as opposed to ECSA (electrochemically active surface area) that is used in the field.  

Following their studies, the research team has made available an open-source, AI-based software tool to automatically recognise and quantify bubbles formed on a given surface, as a first step toward controlling an electrode material’s properties.

The knowledge that the area under bubbles can be significantly active ‘ushers in a new set of design rules for high-performance electrodes’, say the researchers. ‘This means that electrode designers should seek to minimise bubble contact area rather than simply bubble coverage, which can be achieved by controlling the morphology and chemistry of the electrodes.’ They say engineering surfaces to control bubbles could improve the overall efficiency of the processes and thus reduce energy use. They could also save on upfront materials costs, as many gas-evolving electrodes are coated with catalysts made of expensive metals like platinum or iridium.

Gas-evolving electrodes, often with catalytic surfaces that promote chemical reactions, are used in a wide variety of processes. These include the production of green hydrogen without the use of fossil fuels, carbon-capture processes that can reduce greenhouse gas (GHG) emissions, aluminium production, and the chlor-alkali process that is used to make popular chemical products.

These are very common processes. The chlor-alkali process alone accounts for 2% of all US electricity usage; aluminium production accounts for 3% of global electricity; and both carbon capture and hydrogen production are likely to grow rapidly in coming years as the world strives to meet GHG reduction targets. So, the new findings could make a real difference, say the researchers.

New research to improve battery performance

Meanwhile, UK battery specialist Integrals Power claims to have made a ‘breakthrough’ in lithium manganese iron phosphate (LMFP) cathode active materials for battery cells, developing a process that overcomes the drop in specific capacity that typically occurs as the percentage of manganese is increased.  

By overcoming this trade-off, the company says its new cathode active materials combine the best attributes of the lithium iron phosphate (LFP) chemistries – relatively low cost, long cycle life and good low-temperature performance – with energy density comparable to more expensive nickel cobalt manganese (NCM) chemistries. This could allow the range of electric vehicles (EVs) to increase by up to 20%, or – for a given range – allow battery packs to become smaller and lighter, it suggests.

The LMFP materials feature 80% manganese, instead of the 50–70% typically found in competing materials, and have higher specific capacity: 150mAh/g, while delivering a voltage of 4.1V (versus 3.45V for LFP). Third-party testing by experts at the Graphene Engineering Innovation Centre (GEIC) have been completed on coin cells and now being evaluated in EV-representative pouch cells.  

The company produced the high-performance LMFP cathode active materials at its new UK facility, alongside its proprietary LFP chemistry.

Establishing manufacturing in the UK will also enhance supply chain security and transparency, and mitigate geopolitical issues such as import tariffs on EVs and their components. Integrals Power says it sources all its raw materials from European and North American suppliers ‘which ensures a purer, higher performance LFP and LMFP cathode materials with greater energy density compared to the Chinese-manufactured cathode materials which currently account for around 90% of production worldwide’.