【Article Information】
The interlayer conversion reaction enables aqueous batteries
First Author: Gui Qiuyue
Contact: LIU Jinping*, LI Yuanyuan*
Unit: Wuhan University of Technology; Hust
【Background】
In the context of the global active promotion to reduce carbon emissions and find sustainable energy, aqueous batteries, as a high-safety, environmentally friendly and low-cost energy storage technology, are gradually becoming the focus of research. Compared with traditional lithium-ion batteries, the water-based electrolyte used in aqueous batteries has no risk of combustion and explosion, offers significant safety advantages, and is inexpensive to manufacture and environmentally friendly, making them extremely attractive for large-scale applications in the future. However, among the many anode anodes of aqueous batteries, although the conversion anode material can provide higher capacity and lower redox potential, which can significantly improve the battery performance in theory, it often encounters the problem of poor cycle stability in practical applications. Factors such as volume expansion, dendrite growth, and passivation of the electrode surface caused by hydrogen evolution side reactions will cause the capacity of the battery to decay rapidly after repeated charging and discharging. Therefore, it is urgent to solve these key problems faced by converting anode materials to ensure that aqueous batteries can operate stably and efficiently for a long time and better meet future energy needs.
【Introduction】
Recently, Professor Liu Jinping's team published an article entitled "Confining Conversion Chemistry in Intercalation Host for Aqueous Batteries" in the internationally renowned journal Angewandte Chemie International Edition. In this paper, a novel iron-based hydroxyl oxide column-supported sodium titanate (FeNTO) anode was successfully synthesized by using a simple hydrothermal synthesis method to limit the conversion reaction to the layered body. The anode uses the high stability of the stable two-dimensional plate layer and the spatial effect of sub-nanometer to solve the key problem of iron-based conversion anode.
Figure 1. FeNTO theoretical calculations and structural characterization. (a) Formation energies of possible locations of iron in the host (including interlayers, sodium locations in NTO, and interstitial locations in TiO6), (b) a-axis HAADF-STEM plots along FeNTO nanosheets, bottom left is an enlarged HAADF-STEM plot, upper right panel is an atomic column intensity distribution map, (c) EELS (up) and elemental signal intensity distribution (down) at the red arrows in (b) figure, (d) HAADF-STEM diagram and element distribution diagram of cross-sectional FeNTO@Ti. (e) Fe K-edge X-ray absorption near-edge structure spectra of FeNTO, embedding plot showing the Fourier transform of k3-weighted Fe K-edge EXAFS spectra, (f) FT-EXAFS wavelet conversion spectra of FeNTO and Fe2O3, and (g) 1H MAS NMR spectra of FeNTO experiments and fittings.
Figure 2. Characterization of the working conditions, energy storage mechanism and electrochemical properties of FeNTO anode in Na2SO4 electrolyte. (a) Schematic diagram of the operating system of the optical microscope, (b) Optical images of the degree of hydrogen evolution of the Fe3O4 (up) and FeNTO (down) electrodes at a CV sweep speed of 1 mV s-1, (c) CV curves of FeNTO scanning from state 0 to state 3, (d-e) real-time Raman profile and selected Raman spectra of the FeNTO electrode when testing the CV curve, (f-g) STEM and FTIR plots of the electrodes in states 2 and 3, (h) Cyclic comparison of the electrode and the reported iron-based anode. Insert the table for the Fe content in the electrolyte for initial and post-cycle ICP-AES testing. Note that for the original electrolyte, trace amounts of Fe come from the Na2SO4 reagent.
Figure 3. Kinetic analysis. (a) CV curves of FeNTO electrode in Na2SO4 electrolyte, (b) Plot of electrode peak current vs. scan rate, (c) Non-diffusion control and diffusion control capacity contribution of FeNTO electrode, (d) Non-diffusion control and diffusion control capacity contribution at different sweep speeds, (e-f) Na+ migration path in NTO and FeNTO, (g) Na+ migration energy.
Figure 4. Electrochemical performance of FeNTO electrodes in neutral and basic electrolytes. (a-b) CV curve and rate performance in Li2SO4/Na2SO4/K2SO4 electrolytes, (c) the relationship between the charge capacity of the electrode and the hydrated ionic radius of Li+/Na+/K+, (d) Schematic diagram of the adjacent TiO6 layer of hydrated ion intercalation, showing the magnitude order of the ions at the bottom, (e) plot of the real part of the impedance (Z′) with the reciprocal (ω-1/2) of the square root of the angular frequency in the Li2SO4/Na2SO4/K2SO4 electrolyte, The inset shows the cation diffusion coefficient, (f-g) CV curves and rate performance in LiOH/NaOH/KOH electrolytes, and (h) CV potential polarization between oxidation and reduction peaks of various iron-based anodes.
Figure 5. Electrochemical performance of FeNTO-based neutral/alkaline aqueous batteries. (a) Schematic diagram of the structure of the two cells and associated redox reactions, (b) GCD curves of a neutral whole cell using Li2SO4-PAM hydrogel, (c) rate performance of a neutral/alkaline cell, (d) Ragone plot of the mass-energy density versus power density of the cell, (e) Cycling performance and polarization of the alkaline cell compared to previously reported device performance.
Figure 6. Large-scale preparation of FeNTO anode and its battery application scenarios. (a) GCD pattern of aqueous cells assembled by 1-3 tandem cells at a current density of 1.6 A g-1, (b) Extended FeNTO film, (c) Schematic diagram of large-scale synthesis of FeNTO@Ti film and FeNTO powder, (d) Pouch cell powering common wearable electronic devices and schematic diagram, (e) Infrared thermal image of pouch cell under mechanical damage.
【Main points of the text】
Point 1: The transformation reaction is fast and stable
In this sub-nanometer space and stable two-dimensional layered structure, the two-dimensional embedded body is activated, and the conversion reaction (Fe3+⇌Fe0) initiated by the transport of electrons through the TiO6 laminate has higher reversibility, which greatly shortens the ion transport path and reduces the redox polarization, so that the conversion reaction is carried out before water electrolysis and hydroxide deposition, while the volume expansion is completely limited. Based on this, the electrode can still maintain more than 87% of its initial capacity after 8700 cycles of neutral electrolyte. It has the smallest CV polarization in alkaline solutions (scan rate 5 mV s-1).
Point 2: The universality of the embedding-transformation chemical anode
It is worth noting that the cations in the electrolyte can be embedded in the layered body for charge compensation during the transformation reaction of iron-based compounds, so that FeNTO can work well in other neutral (K2SO4, Na2SO4), basic (LiOH, NaOH, KOH) and even divalent cation (Mg2+, Ca2+) electrolytes.
Point 3: Large-scale preparation of FeNTO anode and its application and demonstration
Further demonstrates the large-scale synthesis of FeNTO films and powders, as well as the rationally designed quasi-solid-state, high-pressure aqueous pouch battery, which can be integrated into clothing to power wearable electronics and resist extreme mechanical damage. This work provides an effective confinement method for the development of electrode materials for a new generation of aqueous batteries.
【Article Link】
Confining Conversion Chemistry in Intercalation Host for Aqueous Batteries
https://onlinelibrary.wiley.com/doi/10.1002/anie.202409098
【About the Corresponding Author】
Professor Liu Jinping's profile: Professor and doctoral supervisor of Wuhan University of Technology, selected into the National High-level Talent Program, Fellow of the Royal Society of Chemistry, Fellow of the International Association for Advanced Materials, winner of the Hubei Outstanding Youth Fund, and core member of the innovation team in key areas of the Ministry of Science and Technology's Innovative Talent Promotion Program. He has been engaged in research in the field of electrochemical energy materials and devices for a long time. In recent years, he has presided over more than 10 national high-level talent projects, sub-projects of the National Key R&D Program, projects of the National Natural Science Foundation of China and horizontal projects. In Nature Commun., Adv. Mater., Angew. Chem. Int. Ed.、Energy Environ. He has published more than 200 SCI papers in journals such as Sci., which have been cited 23,000 times by Nature Energy and others, and one paper has been awarded "China's 100 Most Influential International Academic Papers".
More than 20 invention patents have been authorized, and 3 monographs (chapters) in Chinese and English have been published. He has won the Hubei Provincial Natural Science Award, the China Science and Technology Emerging Talent Award, the Clarivate Analytics Global Highly Cited Researcher, the Elsevier China Highly Cited Researcher (for 10 consecutive years), the Nano Research Emerging Young Scientist Award, and the SCOPUS Young Scientist Star. He served as the founding associate editor of Energy & Environmental Materials (Zone 1), the academic editor of Interdisciplinary Materials (Zone 1), the editorial board member of several SCI English journals, and a reviewer for top journals such as Science.
Associate Professor Li Yuanyuan: He graduated from Central China Normal University in June 2009 with a Ph.D. degree. From July 2009 to April 2010, he served as an assistant researcher in the State Key Laboratory of New Materials Composite Technology of Wuhan University of Technology (Prof. Yu Jiaguo's research group); In April 2010, he joined Huazhong University of Science and Technology and is currently an associate professor/doctoral supervisor. From December 2017 to December 2018, he was a visiting researcher at the University of Wollongong, Australia (Prof. Zaiping Guo's group). He has been engaged in the research of energy storage materials and devices for a long time. It has been published in Adv. He has published more than 80 papers in international SCI journals such as Mater., Nano Lett., and has been cited more than 10,000 times by SCI. He has presided over 4 projects of the National Natural Science Foundation of China, 1 general project of the Natural Science Foundation of Hubei Province and nearly 10 related scientific research projects.