Realizing Two-Electron Transfer in Ni(OH)₂ Nanosheets for Energy Storage

Journal Article · Mon May 02 00:00:00 EDT 2022 · Journal of the American Chemical Society

DOI:https://doi.org/10.1021/jacs.1c13523· OSTI ID:1906370

Kang, Jianxin ^[1]; Xue, Yufeng ^[2]; Yang, Jie ^[2]; Hu, Qi ^[3]; Zhang, Qinghua ^[4]; Gu, Lin ^[4]; Selloni, Annabella ^[5]; Liu, Li-Min ^[2]; Guo, Lin ^[2]

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1. Beihang University, Beijing (China); Princeton University
2. Beihang University, Beijing (China)
3. Beijing Computational Science Research Center (China)
4. Chinese Academy of Sciences (CAS), Beijing (China)
5. Princeton Univ., NJ (United States)

The theoretical capacity of a given electrode material is ultimately determined by the number of electrons transferred in each redox center. The design of multi-electron transfer processes could break through the limitation of one–electron transfer and multiply the total capacity, but is difficult to achieve because multiple electron transfer processes are generally thermodynamically and kinetically more complex. In this work, we report the discovery of two-electron transfer in monolayer Ni(OH)₂ nanosheets, which contrasts with the traditional one-electron transfer found in multilayer materials. The first-principles calculations predict that the first oxidation process from Ni²⁺→Ni³⁺ occurs easily, whereas the second electron transfer from Ni³⁺→Ni⁴⁺ is strongly hindered in multilayer materials by both the interlayer hydrogen bonds and the domain H structure induced by the Jahn-Teller distortion of the Ni³⁺ (t_2g⁶e_g¹) centered octahedra. In contrast, the second electron transfer can easily occur in monolayers because all H’s are fully exposed. Experimentally, the as-prepared monolayer is found to deliver an exceptional redox capacity of ~ 576 mAh/g, nearly two times the theoretical capacity of one-electron processes. In-situ experiments demonstrate that monolayer Ni(OH)₂ can transfer two electrons and mostly transform to Ni⁴⁺ in the charging process, while bulk Ni(OH)₂ can be partially transformed . Our work reveals a new redox reaction mechanism in atomically thin Ni(OH)₂ nanosheets, and suggests a promising path towards tuning the electron transfer numbers to multiply the capacity of the relevant energy storage materials.

• Research Organization: Princeton Univ., NJ (United States)
• Sponsoring Organization: National Natural Science Foundation of China (NSFC); USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences & Biosciences Division
• Grant/Contract Number: SC0007347
• OSTI ID: 1906370
• Journal Information: Journal of the American Chemical Society, Journal Name: Journal of the American Chemical Society Journal Issue: 20 Vol. 144; ISSN 0002-7863
• Publisher: American Chemical Society (ACS)
• Country of Publication: United States
• Language: English

Related Subjects

25 ENERGY STORAGE
Charge transfer
Electrodes
Ions
Layered materials
Monolayers