Trapped O2 and the origin of voltage fade in layered Li-rich cathodes

Abstract Oxygen redox cathodes, such as Li 1.2 Ni 0.13 Co 0.13 Mn 0.54 O 2 , deliver higher energy densities than those based on transition metal redox alone. However, they commonly exhibit voltage fade, a gradually diminishing discharge voltage on extended cycling. Recent research has shown that, on the first charge, oxidation of O 2− ions forms O 2 molecules trapped in nano-sized voids within the structure, which can be fully reduced to O 2− on the subsequent discharge. Here we show that the loss of O-redox capacity on cycling and therefore voltage fade arises from a combination of a reduction in the reversibility of the O 2− /O 2 redox process and O 2 loss. The closed voids that trap O 2 grow on cycling,…

• DL
  Diamond Light Source
• HR
  Henry Royce Institute

  Awards: EP/R00661X/1, EP/R010145/1, EP/S019367, EP/R010145, EP/L019469/1, EP/S019367/1, EP/R00661X
• RA
  Royal Academy of Engineering
• EA
  Engineering and Physical Sciences Research Council

  Awards: EP/L019469/1, EP/R010145/1, EP/R010145/1, EP/R00661X/1, EP/L019469, EP/S019367/1, EP/R00661X, EP/S019367/1, EP/S032622/1, EP/R010145, EP/R00661X/1, EP/L019469/1, FIRG016