Journal
CHEMISTRY OF MATERIALS
Volume 28, Issue 18, Pages 6656-6663Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acs.chemmater.6b02870
Keywords
-
Funding
- EPSRC for the Supergen Energy Storage Hub grant [EP/H019596]
- EPSRC [EP/L000202/1] Funding Source: UKRI
- Engineering and Physical Sciences Research Council [EP/L000202/1] Funding Source: researchfish
Ask authors/readers for more resources
Lithium-rich oxide electrodes with layered structures have attracted considerable interest because they can deliver high energy densities for lithium-ion batteries. However, there is significant debate regarding their redox chemistry. It is apparent that the mechanism of lithium extraction from lithium-rich Li2MnO3 is not fully understood, especially in relation to the observed O-2 evolution and structural transformation. Here, delithiation and kinetic processes in Li2MnO3 are investigated using ab initio simulation techniques employing high level hybrid functionals as they reproduce accurately the electronic structure of oxygen hole states. We show that Li extraction is charge-compensated by oxidation of the oxide anion, so that the overall delithiation reaction involves lattice oxygen loss. Localized holes on oxygen (O-) are formed as the first step but are not stable leading to oxygen dimerization (with O-O similar to 1.3 angstrom) and eventually to the formation of molecular O-2. Oxygen dimerization facilitates Mn migration onto octahedral sites in the vacated lithium layers. The results suggest that reversible oxygen redox without major structural changes is only possible if the localized oxygen holes are stabilized and oxygen dimerization suppressed. Such an understanding is important for the future optimization of new lithium-rich cathode materials for high energy density batteries.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available