Phase segregation and nanoconfined fluid O2 in a lithium-rich oxide cathode
The rechargeable lithium-ion battery has been instrumental in powering the global revolution in portable electronics. Indeed, many of you are reading this news piece on a mobile phone, laptop or tablet computer that relies on such technology. Now the need has never been greater for more powerful lithium batteries in electric vehicles (EVs) for a low carbon future.
One of the main avenues being explored is lithium-rich materials (so called O-redox cathodes) which can store additional charge on the oxygen ions, thus increasing energy density by up to 50%. These materials, however, lose energy density during cycling due to nanoscale structural changes, which are not fully understood.
This study* on an archetypal layered lithium-rich manganese oxide uses a powerful atomistic modelling approach to answer long-standing questions about such structural arrangements. At the top of the charge, the bulk structure locally phase segregates into manganese-rich regions and manganese-deficient nanovoids, which contain O2 molecules as a nonconfined fluid. These nanovoids are connected providing a link between bulk oxygen formation and surface oxygen gas.
These insights highlight directions for improving the performance of lithium-rich battery materials for electric vehicles.
The research is supported by a £4.2M Faraday Institution CATMAT project grant on lithium-ion cathode materials led by Professor Saiful Islam.
Read the full study in Nature Materials: 'Phase segregation and nanoconfined fluid O2 in a lithium-rich oxide cathode'.
