Search

High rate tolerance and long cycle life represent the critical demand of the market for energy storage devices, known as one of major challenges for the development of rechargeable aqueous batteries. Herein, a layered Mo4/3B2T2 (where "T" denotes ‐O, ‐OH, and ‐F terminations) MBene (a transition metal boride) with in‐plane ordered metal vacancies is first proposed as an iodine species host of an aqueous Zn‖I2 battery, delivering a discharge capacity of 106.8 mAh g−1 at 25 A g−1 after 230 000 cycles and 80 mAh g−1 at 100 A g−1, far exceeding those of all Zn‖I2 batteries ever reported. The high performance is attributed to the strong affinity with iodine species and accelerated the redox kinetics by the conductive MBene with metal vacancies, as evidenced by the one‐step conversion of I‒/I0 without the generation of I3‒ ions. This work unlocks a new route for the construction of other halide or sulfur electrode batteries with superior durability and kinetics. [ABSTRACT FROM AUTHOR]

Potassium-ion batteries (KIBs) are considered a promising candidate for energy storage owing to their low cost and similar "rocking chair" mechanism to lithium-ion batteries. However, there is a great lack of suitable and high working performance electrode materials for KIBs. Herein, first principles calculations based on density functional theory (DFT) are applied to evaluate the potential of the B7N5 monolayer as an anode material for KIBs. It is found that B7N5 shows negative adsorption energies for Li/Na/K on its surface. Besides, the B7N5 monolayer can effectively achieve double-layer adsorption for K atoms on both sides of the monolayer surface, while one-layer adsorption for Li and Na. Thus, B7N5 exhibits an ultra-high theoretical capacity of 1471.5 mA h g−1 for KIBs, which is almost the highest value for the anode materials reported in the literature. And the attractive capacity for KIBs is mainly contributed by the multiple empty electron orbitals of the constituting elements of B7N5 and the small distance mismatch. In addition, K atoms display high diffusivities on B7N5 with low energy barriers of 0.10 eV, and the open circuit voltages of 0.14 V for KIBs are also smaller compared with previous research. It is also shown that after adsorbing K, the semiconducting B7N5 monolayer is transformed to a metallic state with good conductivity. Furthermore, despite the large size of K+, the maximum change in the lattice constant of B7N5 is only 1.32%, indicating structural stability and ensuring good cycling stability for KIBs. The above-mentioned results suggest that B7N5 is a potential anode material for KIBs. [ABSTRACT FROM AUTHOR]

The storage time of Zn‐air batteries (ZABs) for practical implementation have been neglected long‐lastingly. ZABs based on organic solvents promise long shelf lives but suffer from sluggish kinetics. Here, we report a longly storable ZAB with accelerated kinetics mediated by I3−/I− redox. In the charge process, the electrooxidation of Zn5(OH)8Cl2⋅H2O is accelerated by I3− chemical oxidation. In the discharge process, I− adsorbed on the electrocatalyst changes the energy level of oxygen reduction reaction (ORR). Benefitting from these advantages, the prepared ZAB shows remarkably improved round‐trip efficiency (56.03 % vs. 30.97 % without the mediator), and long‐term cycling time (>2600 h) in ambient air without replacing any components or applying any protective treatment to Zn anode and electrocatalyst. After resting for 30 days without any protection, it can still directly discharge continuously for 32.5 h and charge/discharge very stably for 2200 h (440 cycles), which is evidently superior to aqueous ZABs (only 0/0.25 h, and 50/25 h (10/5 cycles) by mild/alkaline electrolyte replenishment). This study provides a strategy to solve both storage and sluggish kinetics issues that have been plaguing ZABs for centuries, opening up a new avenue to the industrial application of ZABs. [ABSTRACT FROM AUTHOR]

The development of novel high specific capacity anode materials is urgently needed for rechargeable metal ion batteries. Herein, S-functionalized V2B as the electrode material for Li/Na/K ion batteries are comprehensively investigated using first-principles calculations. Specifically, V2BS2 was verified with good electrical conductivity via band structure and density of states calculations. Phonon dispersion and ab initio molecular dynamic simulations were performed and confirmed the dynamic and thermal stability of V2BS2. The use of V2BS2 with a high theoretical specific capacity of 606 mA h g−1 for lithium ion batteries (LIBs) due to the bilayer adsorption of Li atoms is encouraging, which is attributed to the double empty orbitals of the S atoms and small lattice mismatch (1.5%) between the Li layers and substrate. Furthermore, dendrite formation would be well prohibited and safety issues for battery operation would be ensured for V2BS2 as electrode materials because of the low open circuit voltage with 0.37 V. The high charge/discharge rate for LIBs is also achievable owing to the high mobility of adatoms on the surface of V2BS2. Our work not only finds use as a promising material for the field of energy storage, but also provides constructive design strategies for developing high performance anode materials for rechargeable metal ion batteries. [ABSTRACT FROM AUTHOR]

Strain engineering is an effective strategy to tune the catalytic performance of catalysts. Herein, the strain effects on the catalytic performance of Pt-doped Ti2CF2 (Pt-VF-Ti2CF2) for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) were systematically studied using first principles calculations. Firstly, Pt-VF-Ti2CF2 exhibits metallic conductivity and good stability under strain in a range of −14% to 14%. Moreover, Pt-VF-Ti2CF2 under a compressive strain of 14% and tensile strain of 4% shows the highest ORR and OER catalytic performance with an overpotential of 0.45 V and 0.43 V, respectively. The overpotential of the ORR and OER can be reduced by 0.28 V and 0.03 V when a specific strain was applied. Additionally, Pt-VF-Ti2CF2 under a specific strain shows a higher selectivity by significantly suppressing the hydrogen evolution reaction (HER). Furthermore, we analyzed the reasons behind this performance boost. The enhanced catalytic performance of Pt-VF-Ti2CF2 by strain engineering can be attributed to the shift of the d-band center and work function. Overall, our work demonstrated that strain engineering can effectively improve the catalytic efficiency and selectivity of Pt-VF-Ti2CF2 and may provide insightful guidance for the design and development of other high-performance two-dimensional catalysts. [ABSTRACT FROM AUTHOR]

The unique structural, electronic and magnetic properties of intrinsic defect in tetragonal ultrathin BaTiO3 nanotube (u-BTONT) have been investigated by first-principle calculations. The zigzag (9,0) u-BTONTs with two different terminations (TiO2 and BaO) can be formed by rolling up one monolayer BTO along a certain crystallographic axis, and the BaO-terminated NT is more stable than TiO2 terminated due to its lower binding energy. The oxygen vacancies on the tube are more stable than cation vacancies, and their magnetic coupling is related not only to the kinds of oxygen vacancies but also to the distance of vacancies. Moreover, both Ba and Ti vacancies also can introduce the ferromagnetism in u-BTONT, which is different from the origin of magnetism in BTO bulk and (001) surface. It is indicated that one-dimensional structure with high surface area can make it easier to form more useful vacancies which prefer ferromagnetism. Our work offers a possible route to fabricate the multiferroic materials. [ABSTRACT FROM AUTHOR]

The formation and stability of the solid electrolyte interphase (SEI) play a crucial role in determining the performance and lifespan of lithium-ion batteries (LIBs) at evaluated temperatures. Electrolyte additives have emerged as promising candidates for modulating the formation kinetics and stability of the SEI layer. In this study, molecular dynamics (MD) and ab initio molecular dynamics (AIMD) simulations were employed to investigate the influences of P-toluenesulfonyl isocyanate (PTSI) as an electrolyte additive in the LiPF 6 /EC/DMC electrolyte on the SEI formation process on the graphite anode under high temperatures. MD simulations revealed that PTSI induces modifications in the solvation structure, resulting in two ethylene carbonate (EC) and two dimethyl carbonate (DMC) molecules in the first solvation shell of Li + . Furthermore, the PTSI additive suppressed the decomposition of solvent molecules and PF6 anions in the LiPF 6 /EC/DMC/PTSI electrolyte under high temperatures according to the AIMD simulations, contributing to a more stable SEI layer. Moreover, this suppression can be attributed to the reduced reactivity of solvent molecules and salt anions, as evidenced by the enhanced bond strength and decreased bond length. These microscopic insights provide a multi-faceted understanding of the functionality of PTSI additives, facilitating the rational design of novel additives., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Inc.)

Electrocatalytic reduction of dinitrogen to ammonia has attracted significant research interest. Herein, it reports the boosting performance of electrocatalytic nitrogen reduction on Ti 2 CO 2 MXene with an oxygen vacancy through biaxial tensile strain engineering. Specifically, tensile strain modified electronic structures and formation energy of oxygen vacancy are evaluated. The exposed Ti atoms with additional electron states near the Fermi level serve as active site for intermediate adsorption, leading to superior catalytic performance (U limit = -0.44 V) under 2.5% biaxial tensile strain through a distal mechanism. However, the two sides of the "Sabatier optimum" in volcano plot are not limited by two different electronic steps, but are induced by the diverse adsorption behaviors of intermediates. Crucially, the "Sabatier optimum" results from the different response speeds of the adsorption energy for *N 2 and *NNH to strains. Moreover, the authors observe conventional d-band adsorption for *N 2 and *NNH, non-linear adsorption for *NNH 2 , and abnormal d-band adsorption for *N, *NH, *NH 2 , and *NH 3 , which can be explained by the competition between attractive orbital hybridization and repulsive orbital orthogonalization with the spin-polarized d-band model, which further clarifies the contributions of 3σ → d z2 and d xz /d yz → 2π* to the overall population of bonding and anti-bonding states., (© 2023 Wiley-VCH GmbH.)

Potassium-ion batteries (KIBs) are considered a promising candidate for energy storage owing to their low cost and similar "rocking chair" mechanism to lithium-ion batteries. However, there is a great lack of suitable and high working performance electrode materials for KIBs. Herein, first principles calculations based on density functional theory (DFT) are applied to evaluate the potential of the B 7 N 5 monolayer as an anode material for KIBs. It is found that B 7 N 5 shows negative adsorption energies for Li/Na/K on its surface. Besides, the B 7 N 5 monolayer can effectively achieve double-layer adsorption for K atoms on both sides of the monolayer surface, while one-layer adsorption for Li and Na. Thus, B 7 N 5 exhibits an ultra-high theoretical capacity of 1471.5 mA h g -1 for KIBs, which is almost the highest value for the anode materials reported in the literature. And the attractive capacity for KIBs is mainly contributed by the multiple empty electron orbitals of the constituting elements of B 7 N 5 and the small distance mismatch. In addition, K atoms display high diffusivities on B 7 N 5 with low energy barriers of 0.10 eV, and the open circuit voltages of 0.14 V for KIBs are also smaller compared with previous research. It is also shown that after adsorbing K, the semiconducting B 7 N 5 monolayer is transformed to a metallic state with good conductivity. Furthermore, despite the large size of K + , the maximum change in the lattice constant of B 7 N 5 is only 1.32%, indicating structural stability and ensuring good cycling stability for KIBs. The above-mentioned results suggest that B 7 N 5 is a potential anode material for KIBs.

The storage time of Zn-air batteries (ZABs) for practical implementation have been neglected long-lastingly. ZABs based on organic solvents promise long shelf lives but suffer from sluggish kinetics. Here, we report a longly storable ZAB with accelerated kinetics mediated by I 3 - /I - redox. In the charge process, the electrooxidation of Zn 5 (OH) 8 Cl 2 ⋅H 2 O is accelerated by I 3 - chemical oxidation. In the discharge process, I - adsorbed on the electrocatalyst changes the energy level of oxygen reduction reaction (ORR). Benefitting from these advantages, the prepared ZAB shows remarkably improved round-trip efficiency (56.03 % vs. 30.97 % without the mediator), and long-term cycling time (>2600 h) in ambient air without replacing any components or applying any protective treatment to Zn anode and electrocatalyst. After resting for 30 days without any protection, it can still directly discharge continuously for 32.5 h and charge/discharge very stably for 2200 h (440 cycles), which is evidently superior to aqueous ZABs (only 0/0.25 h, and 50/25 h (10/5 cycles) by mild/alkaline electrolyte replenishment). This study provides a strategy to solve both storage and sluggish kinetics issues that have been plaguing ZABs for centuries, opening up a new avenue to the industrial application of ZABs., (© 2023 Wiley-VCH GmbH.)

Calcium ion batteries (CIBs) are considered as promising candidates for the next-generation large-scale energy storage technologies, due to the abundant resources and bivalent properties of calcium. Herein, based on first principles calculations, we systematically explore the performance of B 5 N 3 as an electrode material for chargeable CIBs. Specifically, the adsorption of the Ca atom effectively reduces the band gap of B 5 N 3 , leading to good electrical conductivity. Additionally, the B 5 N 3 monolayer can achieve an effective double-layered adsorption of Ca atoms on both sides of the monolayer surface, thus exhibiting an ultra-high theoretical capacity of 4463 mA h g -1 (Ca) compared with the capacities of Na (2231 mA h g -1 ), Li (1116 mA h g -1 ) and K (558 mA h g -1 ). The high capacity is attributed to the multiple empty electron orbitals of the constituent elements of B 5 N 3 and low distance mismatch which can exhibit excellent adsorption properties for multivalent atoms. Furthermore, the low diffusion energy barriers and satisfactory thermal stability ensure the reliability of B 5 N 3 as a CIB electrode material. Our work not only develops an excellent candidate for the electrode materials of CIBs, but may also inspire the rational design and synthesis of electrode materials towards high-performance CIBs.