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SUMMARY:'Supercharged - using oxygen redox to store more energy in recharg
 eable batteries' - Dr Robert House (University of Oxford)
DTSTART;VALUE=DATE-TIME:20221117T160000Z
DTEND;VALUE=DATE-TIME:20221117T170000Z
UID:https://talks.ox.ac.uk/talks/id/4edcab55-4978-4648-a43d-50bd50be827b/
DESCRIPTION:Increasing the energy density of Li-ion batteries is a critica
 l challenge if we are to improve the driving range of EVs. One of the grea
 test barriers to achieving this is the cathode material. \n\nWhen conventi
 onal Li-ion cathodes are charged\, Li+ ions are removed\, and charge is co
 mpensated by oxidising the transition metal ions (i.e. in LiCoO2\, Co3+ is
  oxidized to Co4+). In these materials\, transition metal redox limits the
  capacity to store charge and hence the energy density. To increase the en
 ergy density of Li-ion batteries further\, it is possible in certain Li-ri
 ch compositions (i.e. Li1.2Ni0.2Mn0.6O2) to store additional charge by oxi
 dising the oxide ions. However\, this oxygen redox reaction involves compl
 ex structural changes\, and the mechanism has proved difficult to understa
 nd.\n\nIn this talk I will show\, using high resolution RIXS\, 17O NMR\, n
 eutron PDF\, that O2- ions are oxidized to form molecular O2 trapped insid
 e the structure. These O2 molecules are accommodated within voids formed i
 n the bulk by reorganization of transition metal ions. During discharge\, 
 the trapped molecular O2 can be reduced back to O2-\, but this process occ
 urs at a lower voltage compared to the first charge\, giving rise to volta
 ge hysteresis. To overcome these challenges\, it is necessary to suppress 
 the formation of O2 and trap hole states on O2-. I shall show that this is
  possible with careful control of superstructure ordering leading to the f
 ormation of delocalised electron hole states and reversible\, high voltage
  charge storage using oxygen redox.\n\nSpeakers:\nDr Robert House (Univers
 ity of Oxford)
LOCATION:Hume-Rothery Building (Hume-Rothery Lecture Theatre)\, Parks Road
  OX1 3PH
TZID:Europe/London
URL:https://talks.ox.ac.uk/talks/id/4edcab55-4978-4648-a43d-50bd50be827b/
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DESCRIPTION:Talk:'Supercharged - using oxygen redox to store more energy i
 n rechargeable batteries' - Dr Robert House (University of Oxford)
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