MSGID: 1:317/3 627201e4   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    Dual membrane offers hope for long-term energy storage    
      
     Date:   
         May 3, 2022   
     Source:   
         Imperial College London   
     Summary:   
         A new approach to battery design could provide the key to low-cost,   
         long- term energy storage, according to researchers.   
      
      
      
   FULL STORY   
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   A new approach to battery design could provide the key to low-cost,   
   long-term energy storage, according to Imperial College London   
   researchers.   
      
      
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   The team of engineers and chemists have created a polysulfide-air redox   
   flow battery (PSA RFB) with not one, but two membranes. The dual membrane   
   design overcomes the main problems with this type of large-scale battery,   
   opening up its potential to store excess energy from, for example,   
   renewable sources such as wind and solar. The research is published in   
   Nature Communications.   
      
   In redox flow batteries, energy is stored in liquid electrolytes which   
   flow through the cells during charge and discharge, enabled through   
   chemical reactions. The amount of energy stored is determined by the   
   volume of the electrolyte, making the design potentially easy to scale   
   up. However, the electrolyte used in conventional redox flow batteries   
   -- vanadium -- is expensive and primarily sourced from either China   
   or Russia.   
      
   The Imperial team, led by Professors Nigel Brandon and Anthony Kucernak,   
   have been working on alternatives that use lower cost materials which   
   are widely available. Their approach uses a liquid as one electrolyte and   
   a gas as the other -- in this case polysulfide (sulphur dissolved in an   
   alkaline solution) and air. However, the performance of polysulfide-air   
   batteries is limited because no membrane could fully enable the chemical   
   reactions to take place while still preventing polysulfide crossing over   
   into the other part of the cell.   
      
   Dr Mengzheng Ouyang, from Imperial's Department of Earth Science and   
   Engineering, explained: "If the polysulfide crosses over into the air   
   side, then you lose material from one side, which reduces the reaction   
   taking place there and inhibits the activity of the catalyst on the   
   other. This reduces the performance of the battery -- so it was a problem   
   we needed to solve."  The alternative devised by the researchers was   
   to use two membranes to separate the polysulfide and the air, with a   
   solution of sodium hydroxide between them.   
      
   The advantage of the design is that all materials, including the   
   membranes, are relatively cheap and widely available, and that the design   
   provides far more choice in the materials that can be used.   
      
      
      
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   When compared with the best results obtained to date from a   
   polysulfide-air redox flow battery, the new design was able to provide   
   significantly more power, up to 5.8 milliwatts per centimetre squared.   
      
   As cost is a critical factor for long-term and large-scale storage,   
   the team also carried out a cost analysis. They calculated the energy   
   cost -- the price of the storage materials in relation to the amount of   
   energy stored -- to be around $2.5 per kilowatt hour.   
      
   The power cost -- the rate of charge and discharge achieved in relation   
   to the price of the membranes and catalysts in the cell -- was found   
   to be around $1600 per kilowatt. This is currently higher than would be   
   feasible for large- scale energy storage, but the team believe further   
   improvements are readily achievable.   
      
   Professor Nigel Brandon, who is also Dean of the Faculty of Engineering,   
   said: "Our dual-membrane approach is very exciting as it opens up many   
   new possibilities, for both this and other batteries. To make this cost   
   effective for large-scale storage, a relatively modest improvement in   
   performance would be required, which could be achieved by changes to   
   the catalyst to increase its activity or by further improvements in the   
   membranes used."  Work in this area is already underway within the team,   
   through the catalyst expertise of Professor Anthony Kucernak, from the   
   Department of Chemistry, and research into membrane technology by Dr   
   Qilei Song from the Department of Chemical Engineering.   
      
   The spin-out company RFC Power Ltd, established to develop long-duration   
   storage of renewable energy based on the team's research, is set to   
   commercialise this new design should the improvements be made.   
      
   CEO of RFC Power Ltd, Tim Von Werne, said: "There is a pressing need   
   for new ways to store renewable energy over days, weeks or even months   
   at a reasonable cost. This research shows a way to make that possible   
   through improved performance and low-cost materials."  The research is   
   funded through the UK Research and Innovation Engineering and Physical   
   Sciences Research Council, and the European Research Council.   
      
      
   ==========================================================================   
   Story Source: Materials provided by Imperial_College_London. Original   
   written by Hayley Dunning. Note: Content may be edited for style and   
   length.   
      
      
   ==========================================================================   
   Journal Reference:   
      1. Yuhua Xia, Mengzheng Ouyang, Vladimir Yufit, Rui Tan, Anna Regoutz,   
      Anqi   
         Wang, Wenjie Mao, Barun Chakrabarti, Ashkan Kavei, Qilei Song,   
         Anthony R.   
      
         Kucernak, Nigel P. Brandon. A cost-effective alkaline   
         polysulfide-air redox flow battery enabled by a dual-membrane   
         cell architecture. Nature Communications, 2022; 13 (1) DOI:   
         10.1038/s41467-022-30044-w   
   ==========================================================================   
      
   Link to news story:   
   https://www.sciencedaily.com/releases/2022/05/220503141342.htm   
      
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