NiCo2 O4 -Based Nanosheets with Uniform 4 nm Mesopores for Excellent Zn-Air Battery Performance

Jie Yin; Jing Jin; Hongbo Liu; Bolong Huang; Min Lu; Jianyi Li; Hanwen Liu; Hong Zhang; Yong Peng; Pinxian Xi; Chun-Hua Yan

doi:10.1002/adma.202001651

NiCo₂ O₄ -Based Nanosheets with Uniform 4 nm Mesopores for Excellent Zn-Air Battery Performance

Adv Mater. 2020 Oct;32(39):e2001651. doi: 10.1002/adma.202001651. Epub 2020 Aug 26.

Authors

Jie Yin¹, Jing Jin¹, Hongbo Liu², Bolong Huang³, Min Lu¹, Jianyi Li¹, Hanwen Liu¹, Hong Zhang⁴, Yong Peng⁴, Pinxian Xi¹, Chun-Hua Yan^{1

5}

Affiliations

¹ State Key Laboratory of Applied Organic Chemistry, Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, China.
² Petroleum Engineering School, Southwest Petroleum University, Chengdu, 610000, China.
³ Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hum, Kowloon, Hong Kong SAR, China.
⁴ Key Laboratory of Magnetism and Magnetic Materials of Ministry of Education, School of Physical Science and Technology, Lanzhou University, Lanzhou, 730000, China.
⁵ Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, PKU-HKU Joint Laboratory in Rare Earth Materials and Bioinorganic Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China.

PMID: 32844534
DOI: 10.1002/adma.202001651

Abstract

Herein, a strategy is reported for the fabrication of NiCo₂ O₄ -based mesoporous nanosheets (PNSs) with tunable cobalt valence states and oxygen vacancies. The optimized NiCo_2.148 O₄ PNSs with an average Co valence state of 2.3 and uniform 4 nm nanopores present excellent catalytic performance with an ultralow overpotential of 190 mV at a current density of 10 mA cm^-2 and long-term stability (700 h) for the oxygen evolution reaction (OER) in alkaline media. Furthermore, Zn-air batteries built using the NiCo_2.148 O₄ PNSs present a high power and energy density of 83 mW cm^-2 and 910 Wh kg^-1 , respectively. Moreover, a portable battery box with NiCo_2.148 O₄ PNSs as the air cathode presents long-term stability for 120 h under low temperatures in the range of 0 to -35 °C. Density functional theory calculations reveal that the prominent electron exchange and transfer activity of the electrocatalyst is attributed to the surface lower-coordinated Co-sites in the porous region presenting a merging 3d-e_g -t_2g band, which overlaps with the Fermi level of the Zn-air battery system. This favors the adsorption of the *OH, and stabilized *O radicals are reached, toward competitively lower overpotential, demonstrating a generalized key for optimally boosting overall OER performance.

Keywords: Zn-air batteries; mesoporous nanosheets; oxygen evolution reaction; oxygen vacancies; valence electron regulation.

Abstract

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