Ultrathin Manganese-Based Metal–Organic Framework Nanosheets: Low-Cost and Energy-Dense Lithium Storage Anodes with the Coexistence of Metal and Ligand Redox Activities

5 years ago

Ultrathin Manganese-Based Metal–Organic Framework Nanosheets: Low-Cost and Energy-Dense Lithium Storage Anodes with the Coexistence of Metal and Ligand Redox Activities

Xiaoshi Hu, Ming Shen, Xiaobing Lou, Bingwen Hu, Wei Tong, Wensheng Yan, Chao Li

We herein demonstrate the fabrication of Mn- and Ni-based ultrathin metal–organic framework nanosheets with the same coordination mode (termed “Mn-UMOFNs” and “Ni-UMOFNs”, respectively) through an expedient and versatile ultrasonic approach and scrutinize their electrochemical properties as anode materials for rechargeable lithium batteries for the first time. The obtained Mn-UMOFNs with structure advantages over Ni-UMOFNs (thinner nanosheets, smaller metal-ion radius, higher specific surface area) exhibit high reversible capacity (1187 mAh g^–1 at 100 mA g^–1 for 100 cycles), excellent rate capability (701 mAh g^–1 even at 2 A g^–1), rapid Li⁺ diffusion coefficient (2.48 × 10^–9 cm² s^–1), and a reasonable charge–discharge profile with low average operating potential at 0.4 V. On the grounds of the low-cost and environmental benignity of Mn metals and terephthalic acid linkers, our Mn-UMOFNs show alluring promise as a low-cost high-energy anode material for future LIBs. Furthermore, the lithiation–delithiation chemistry of Mn-UMOFNs was unequivocally studied by a combination of magnetic measurements, electron paramagnetic resonance, and synchrotron-based soft X-ray spectroscopy (O K-edge and Mn L-edge) experiments, the results of which substantiate that both the aromatic chelating ligands and the Mn²⁺ centers participate in lithium storage.

Publisher URL: http://dx.doi.org/10.1021/acsami.7b09363

DOI: 10.1021/acsami.7b09363