Abstract
Tin-based oxide Li2SnO3 has attracted considerable interest as a promising cathode material for potential use in rechargeable lithium batteries due to its high- capacity. Static atomistic scale simulations are employed to provide insights into the defect chemistry, doping behaviour and lithium diffusion paths in Li2SnO3. The most favourable intrinsic defect type is Li Frenkel (0.75 eV/defect). The formation of anti-site defect, in which Li and Sn ions exchange their positions is 0.78 eV/defect, very close to the Li Frenkel. The present calculations confirm the cation intermixing found experimentally in Li2SnO3. Long range lithium diffusion paths via vacancy mechanisms were examined and it is confirmed that the lowest activation energy migration path is along the c-axis plane with the overall activation energy of 0.61 eV. Subvalent doping by Al on the Sn site is energetically favourable and is proposed to be an efficient way to increase the Li content in Li2SnO3. The electronic structure calculations show that the introduction of Al will not introduce levels in the band gap.
Highlights
We have used atomistic simulation techniques to provide detailed insights into intrinsic defects, lithium ion mobility and trivalent doping, which are relevant to the general electrochemical behaviour of layered Li2SnO3 as a lithium battery cathode material
We have considered the solution energies of R2O3 (R = Al, Sc, In, Y, Gd and La) to create extra lithium in this material and found that Al2O3 have the lowest solution
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Summary
We have constructed long range paths connecting local Li hops with lower overall activation energy. The first long range path exhibits a zig-zag pattern (A → B → C → B → ttincluding a local Li hop with lower activation energy of migration of 0.16 eV (local hop C) but with overall activation energy of 0.65 eV (refer to Table 2). There are different possible long range Li diffusion paths can be constructed along the c-axis. Our examination reveals that the lower activation energy long range path along the c-axis plane is L → L → L (refer to Fig. 3) with overall activation energy of 0.61 eV. Other long range paths will have activation energies greater than 0.61 eV in this direction as their local Li hops show higher energies.
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