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Fabrication of perovskite-based porous nanotubes as efficient bifunctional catalyst and application in hybrid lithium–oxygen batteries

Gong, Hao, Wang, Tao, Guo, Hu, Fan, Xiaoli, Liu, Xiao, Song, Li, Xia, Wei, Gao, Bin, Huang, Xianli, He, Jianping
Journal of materials chemistry 2018 v.6 no.35 pp. 16943-16949
annealing, batteries, catalysts, cathodes, chemical bonding, cobalt, electrochemistry, electrolytes, electron transfer, energy, heat treatment, nanotubes, oxygen, porous media, surface area
The design of efficient oxygen electrocatalysts is extremely important and urgent for much energy storage and conversion equipment. Among these, the high energy densities of lithium–oxygen batteries (LOBs) have driven us to explore bifunctional catalysts. Compared with non-aqueous LOBs, which have been blamed for poor cycling stability due to their undesirable side reaction, hybrid LOBs have been considered an alternative solution due to their high electrochemical reversibility and safeness. Here, one-dimensional hierarchical mesoporous/macroporous LaMn₀.₇Co₀.₃O₃₋ₓ nanotubes were synthesized through an electrospinning method combined with an annealing treatment. With the suitable heat treatment and rational doping with elemental Co, the LMCO-800 sample shows a well-designed hierarchical porous nanotube structure and possess great bifunctional electrocatalytic performance. The linear sweep voltammetry (LSV) curves show that the half-wave potential (E₁/₂) of the LMCO-800 sample is 0.72 V (vs. RHE) and the average electron transfer number (n) is calculated to be 3.8. Moreover, the successful doping of elemental Co into the LMCO-800 nanotubes can shorten the average distance of the Mn–Mn atoms and promote the formation of O–O bonds, contributing to the enhanced OER performance. The high specific surface area and one-dimensional nanotubes can greatly benefit oxygen diffusion, facilitate electrolyte infiltration and improve electron transfer. Consequently, the as-assembled hybrid lithium–oxygen batteries with an LMCO-800 cathode exhibit superior cycling stability.