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6. Highly crystalline monolayer transition metal chalcogenid

Time:2021/02/02 丨 source:未知 丨 visit count:

Lithium Battery Nat. Energy
Nature Energy: Compatibility of existing lithium-ion battery manufacturing equipment and post-lithium battery manufacturing
Considering both performance and cost, lithium-ion batteries are currently the most advanced electrochemical energy storage system. And as the electric vehicle market grows, the production capacity of lithium-ion batteries is also increasing. However, the demand for energy storage technologies with higher energy density and cheaper prices is becoming increasingly urgent. Recently, Fabian Duffner and Richard Schmuch of the University of Münster discussed the manufacturing process of different battery equipment based on the existing lithium-ion battery production technology and equipment, starting from market prospects and technical route analysis, and evaluated the existing lithium-ion battery equipment. The compatibility of battery production equipment with various types of battery production and the impact on processing costs.
Key points of this article:
1) The author takes sodium-ion batteries, lithium-sulfur batteries, lithium metal solid-state batteries and lithium-air battery systems as examples;
2) The author discusses the characteristics of the above-mentioned battery systems from the aspects of negative electrode manufacturing, positive electrode manufacturing, battery assembly, production environment requirements, and impact on prices;
3) The author summarized the difficulties faced in the process of industrialization of lithium-ion batteries after the advancement, and made an outlook for its future development. The author believes that no matter which battery system wants to become a marketable alternative to lithium-ion batteries, it must have significant advantages in parameters such as energy density, power density, safety, service life, and cost. Therefore, it is necessary for the further development and improvement of new electrochemical energy storage systems.

F. Duffner et al. Post-lithium-ion battery cell production and its compatibility with lithium-ion cell production infrastructure, Nat. Energy, 2021DOI: 10.1038/s41560-020-00748-8
2. Nature Nanotechnology: LiH and LiF in the electrolyte interface structure of lithium batteries
An in-depth understanding of the composition of the solid electrolyte interface structure (SEI) is particularly important for the development of lithium metal-related high-energy batteries. The more controversial point in this issue is the existence of LiH at the solid electrolyte interface. In view of this, Enyuan Hu and Xiao-Qing Yang of Brookhaven National Laboratory, and Jie Xiao of Pacific Northwest National Laboratory in the United States have reported the use of X-ray neutron diffraction and pair distribution function analysis (PDF) methods for Li metal anodes. LiH and LiF on the SEI interface are analyzed.
Key points of this article:
1) Analytical experiments have been carried out in carbonate and ether electrolytes, and in a variety of conditions with lower/higher salt concentration, and it is found that the content of LiH on the SEI interface in the lower/higher salt concentration conditions is all Very high, it is a major component. The chemical composition was further verified by exposure to humid atmosphere, and the phenomenon that it was mistaken for LiF in the literature was discussed (LiH (4.084 Å) and LiF (4.026 Å) have similar lattice parameters, The XRD data is similar. LiH is very sensitive to the ambient atmosphere, and exposure to air for ~1 s can cause LiH to decompose, so it is difficult to detect).
2) The LiF on the interface is different from the LiF of the bulk structure, showing larger lattice parameters and smaller grain size (<3 nm), which may be caused by the formation of LiHxF1-x on the interface. Quantitative characterization in high-concentration electrolyte conditions revealed that the content of interfacial LiF is more and less dead Li than in low electrolyte conditions, resulting in higher electrochemical performance and higher coulombic efficiency.

Shadike, Z., Lee, H., Borodin, O. et al. Identification of LiH and nanocrystalline LiF in the solid–electrolyte interphase of lithium metal anodes. Nat. Nanotechnol. (2021).DOI: 10.1038/s41565-020-00845-5
3. Nature Commun.: O2-/O- cycle in Na2-xMn3O7 battery cycle
In rechargeable batteries, electrode reactions that can occur in a reversible form are very important for long-life batteries. Additional oxidation-reduction reactions have become an important area for people to study to increase battery capacity. However, most oxidation-reduction electrodes are in charge and discharge cycles. The process faces a large voltage hysteresis (>0.5 V), which results in unacceptably low energy efficiency. This hysteresis is generally believed to be due to the formation of peroxide O22-dimer species during the redox reaction. Therefore, it is believed that preventing the formation of O-O dimer species is the most critical point.
In view of this, the University of Tokyo Atsuo Yamada et al. reported on the Na2-xMn3O7 material. This recent discovery exhibits a high reversible redox capacity while the polarization is only 0.04 V. Through spectroscopy and magnetic testing, the author found that there are stable O- species in Na2-xMn3O7 materials. Through theoretical calculations, the author found that due to the (σ+π) multiple orbitals in the Mn-O bond, this O-· species is thermodynamically more stable than the O22- species of the peroxy structure.
Key points of this article:
1) In the Na2-xMn3O7 redox electrode reaction process, O2-/O-·reversible cycle. In the low-concentration O-·condition, the formation of O22- has no advantage in thermodynamics, because the (σ+π) orbital effect makes the Mn-O bond very stable.
2) The work in this paper first revealed the electrode reaction of O2-/O- as a reduction pair at the redox electrode.

Tsuchimoto, A., Shi, XM., Kawai, K. et al. Nonpolarizing oxygen-redox capacity without O-O dimerization in Na2Mn3O7. Nat Commun 12, 631 (2021). 
DOI: 10.1038/s41467-020-20643-w
4. AFM: An inverse perovskite (Ni0.3Pd0.7) NNi3 used as a highly efficient ORR electrocatalyst
Among platinum group metals, Pd is considered to be the most effective catalyst to replace Pt. Although the electrochemical activities of Pd and Pd-metal alloys are equivalent, they are susceptible to the influence of liquid acid electrolytes, resulting in a decrease in catalytic activity. Pd-Ni alloys have been used to enhance catalytic activity because the electronic structure of Pd can be easily changed by adding Ni. In other studies, N atoms were introduced into the more stable M-Ni catalyst by inducing the formation of Ni4N species. However, the structural analysis and role of nitrogen are not yet fully understood.
In view of this, Sung Jong Yoo of the Korean Academy of Science and Technology, Pil Kim of Chonbuk National University and Docheon Ahn of Pohang Accelerator Laboratory have developed a simple synthesis method to obtain Pd-doped Ni3N nanoparticles (the chemical formula is ( Ni0.3Pd0.7)NNi3), with an inverse perovskite structure (ABX3), where Ni cations occupy the A position, and X and N anions occupy the B position. In this material, Pd is replaced by Ni in 70% of the A-site in the inverse perovskite structure. In electrochemical reactions, palladium has superior ORR activity and acid resistance conditions, which stems from the unique crystal structure of ordered intermetallic nitrides.
Key points of this article:
1) An intermetallic nitride alloy is proved by the high molar ratio of precursor and post-treatment. The anion-stabilized ae-PdNNi overcomes the difficulties in Pd-based electrocatalytic acidic media. The completely different crystal structure significantly changes the intrinsic properties of ae-PdNNi, thereby promoting excellent electrocatalytic activity and durability. Nitride PdNi nanoparticles have a new overall anti-perovskite structure with the chemical formula (PdxNi1−x)NNi3.
2) DFT calculations and experimental results show that the ORR activity and durability of ae-PdNNi can be improved by proper d-band center offset and operando catalytic surface. In addition, by introducing various components for the target electrochemical reaction, an atomically engineered electrocatalyst can be adjusted to a multifunctional electrocatalyst.
3) The unique anti-perovskite crystal (PdxNi1−x)NNi3 has superior ORR activity and stability, which originates from the downward shift of the d-band center on the surface of the Pd/anti-perovskite monolayer and the anti-perovskite core The lower formation energy of nanocrystals. Therefore, (PdxNi1−x)NNi3, as a platinum-free Pd-based electrocatalyst, overcomes the stability problem of Pd under acidic conditions, and its mass activity is 99 times higher than commercial Pd/C.

Sehyun Lee et al. Anion Constructor for Atomic‐Scale Engineering of Antiperovskite Crystals for Electrochemical Reactions. Advanced Functional Materials, 2021.
DOI: 10.1002/adfm.202009241
5. Nano Energy: Research progress of rechargeable potassium batteries
The future renewable energy integrated grid system requires low-cost, high-safety, and long-cycle life rechargeable batteries. The abundance of sodium and potassium in the earth's crust is much higher than that of lithium, indicating that rechargeable sodium and potassium batteries are ideal substitutes for lithium-ion batteries. In the past decade, rechargeable potassium batteries have received great attention. However, the development of rechargeable potassium batteries is still in its infancy.
In view of this, King Abdullah University of Science and Technology Husam N. Alshareef and others reviewed the research progress of rechargeable potassium batteries in recent years.
Key points of this article:
1) First, summarize the latest achievements in active material design, mechanism understanding and exploration of new active materials in recent years. A new direction for adjusting the structure to improve the electrochemical performance of the anode and cathode is proposed. Secondly, the research progress of new configurations of rechargeable potassium battery systems (potassium ion capacitors, potassium double ion batteries, potassium sulfur batteries and potassium oxygen batteries) are reviewed. Finally, the future development direction and design strategy of the commercial application of rechargeable potassium batteries are proposed.
2) In recent years, a variety of rechargeable potassium battery systems using potassium ions as carriers have been rapidly developed, for example, potassium ion batteries, potassium ion capacitors, potassium double ion batteries, potassium sulfur batteries, and potassium oxygen batteries. Compared with mature lithium battery systems, rechargeable potassium batteries face many opportunities and challenges due to the larger ion radius of potassium ions and the more active chemical properties of potassium metal. The large-scale preparation of high-capacity, high-stability positive and negative electrode materials, electrode materials, regulation of electrode/solution interface, mechanism research and simulation, and development of rechargeable potassium full batteries are the focus of future research.

Wenli Zhang et al. Status of Rechargeable Potassium Batteries. Nano Energy, 2021.
DOI: 10.1016/j.nanoen.2021.105792
6. ACS Nano: Highly crystalline monolayer transition metal chalcogenide film for wafer-level electronic products
Chemical vapor deposition (CVD) using liquid precursors has become a feasible technology for preparing uniform large-area transition metal dichalcogenide (TMD) films. However, the liquid-phase precursor-assisted growth process usually has smaller crystal grains and unreacted transition metal precursor residues, resulting in lower quality of the prepared TMD. In addition, it is quite challenging to synthesize large area TMD films with a single layer thickness. Recently, Joohoon Kang of Sungkyunkwan University in South Korea and Hyesung Park of the National Ulsan Institute of Science and Technology in South Korea reported that a simple and universal CVD method was proposed through the accelerator-assisted liquid phase CVD process to make the growth of high-quality single-layer TMD films become may.
Key points of this article:
1) The transition metal ammonium oxide and the alkali metal halide are uniformly mixed in the liquid phase and uniformly deposited on the substrate, and a volatile transition metal halide with higher reactivity is generated under mild annealing conditions. Alkali metals effectively lower the sulfidation energy barrier for the growth of TMDs. Based on these synergistic effects, the researchers successfully prepared a single layer of high-quality molybdenum diselenide (MoSe2) film with good uniformity and thickness on a 3 cm×3 cm sapphire substrate.
2) The researchers used the synthesized MoSe2 thin film to fabricate a back gate field effect transistor (FET) to study its electrical transport performance. The results showed that the FET has an electron mobility as high as 2.5 cm2V−1 s−1, and the current on-off ratio is 105, which is one of the highest values ​​of TMDs grown by CVD based on liquid precursors currently reported. In addition, the researchers demonstrated the versatility of the proposed liquid-phase CVD technology in other TMD families, including molybdenum disulfide (MoS2), tungsten disulfide (WS2) and tungsten diselenide (WSe2).
This CVD method provides better insights for the uniform and large-scale synthesis of high-quality single-layer TMDs films and their practical applications in various next-generation electronics and optoelectronics.

Minseong Kim, et al, High-Crystalline Monolayer Transition Metal Dichalcogenides Films for Wafer-Scale Electronics, ACS Nano
DOI: 10.1021/acsnano.0c09430
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