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In order to improve the critical issues of Zn dendritic in zinc-ion batterie, we investigate herein a hybrid electrolyte with PAN-DMSO-H2O. With the synergistic effects of PAN and DMSO, a uniform, smooth and dendrite-free Zn anode could be obtained.

Efficient bifunctional OER/ORR catalysts are crucial for the further development of zinc-air battery. From a sustainable point of view, it is important that electrocatalysts are efficient, low cost, and composed of abundant resources instead of scarce metals. Due to their good conductivity, low cost, and strong durability, carbon-based materials are considered a promising alternative in the field of commercial zinc-air battery catalysts. Herein, we briefly introduce the zinc-air battery and then summarize recent progress in the development of carbon-based bifunctional catalysts by defect engineering, heteroatom doping and metal doping. Finally, we discuss the main challenges and prospects for the future development of carbon-based bifunctional oxygen catalysts.

The introduction of P heteroatoms into NiO constructed abundant Ni–P coordination groups as emerging catalytic sites, which improved adsorption capacity to the intermediate product LiO2, ensuring effective formation/decomposition of conformal Li2O2.

The structure–function relationships between heterostructures and their catalytic properties were discussed in detail, and the challenges and improvement strategies for heterostructure based cathodes towards Li–O2 catalysis were also summarized.

As anodes for sodium-ion batteries, calcium terephthalate flakes possess fast kinetics and display superior cycling capacity and high-rate capability.

This work advances on the microstructure design and the growth mechanism of porous-shell hollow CaWO4 microspheres with a deep discussion on the origin of enhanced photoluminescence.

Sodium-ion batteries are considered to be a future alternative to lithium-ion batteries because of their low cost and abundant resources. In recent years, the research of sodium-ion batteries in flexible energy storage systems has attracted widespread attention. However, most of the current research on flexible sodium ion batteries is mainly focused on the preparation of flexible electrode materials. In this paper, the challenges faced in the preparation of flexible electrode materials for sodium ion batteries and the evaluation of device flexibility is summarized. Several important parameters including cycle-calendar life, energy/power density, safety, flexible, biocompatibility and multifunctional intergration of current flexible sodium ion batteries will be described mainly from the application point of view. Finally, the promising current applications of flexible sodium ion batteries are summarized.

High electrochemical-performance and cost-efficient cathodes are crucial for the development of grid-scale sodium-ion batteries (SIBs). Prussian blue analogs (PBAs) are generally regarded as promising cathode candidates for SIBs, although their practical application has been limited by low capacity or poor cycling ability caused by their poor crystallinity and reversibility. Herein, a series of low-cost and high-quality ternary PBAs are prepared by structural regulation to simultaneously achieve high capacity, stable cyclability, and wide temperature suitability. The prepared CuHCF-3 sample has delivered a high specific capacity of 132.4 mAh g-1 with 73.3% capacity retention over 1000 cycles when applied as a cathode material for SIBs. A highly reversible three phase (monoclinic to cubic to tetragonal) sodium-ion storage mechanism is revealed via multiple in-situ techniques. Density functional theory calculations indicate that the key for achieving high capacity and long lifespan lies in the synergistic effect of Mn and Cu in the crystal structure of PBAs. The presence of Mn could enhance electronic conductivity, improve the operating voltage, and provide more possible redox centers while the presence of Cu-ions can restrain the Jahn-Teller distortions and buffer huge volume expansion during cycling. Furthermore, the wide-temperature suitability of these materials and Na-ion full cells are investigated based on kilogram-scale production as a demonstration for their practical application. We hope that this work can provide new insights into designing high-performance and low-cost electrode materials for practical grid-scale energy storage systems.

Sodium-ion batteries (SIBs) with fast-charge capability and long lifespan could be applied in various sustainable energy storage systems, from personal devices to grid storage. Inspired by the disordered Rubik's cube, here, we report that the high-entropy (HE) concept can lead to a very substantial improvement in the sodium storage properties of hexacyanoferrate (HCF). An example of HE-HCF has been synthesized as a proof of concept, which has achieved impressive cycling stability over 50 000 cycles and an outstanding fast-charging capability up to 75 C. Remarkable air stability and all-climate performance are observed. Its quasi-zero-strain reaction mechanism and high sodium diffusion coefficient have been measured and analyzed by multiple in situ techniques and density functional theory calculations. This strategy provides new insights into the development of advanced electrodes and provides the opportunity to tune electrochemical performance by tailoring the atomic composition.

Metal phosphides have shown great potential for potassium-ion batteries because of their high theoretical specific capacity. Nevertheless, most of the metal phosphide anodes are plagued by rapid capacity decay (caused by the large volume changes during the discharge/charge process), which would restrict their further practical application. Herein, a chemically bonded CuP2/C composite was prepared by a facile high-energy ball milling method. A potassium bis(trifluoromethanesulfonyl)imide (KFSI)-based electrolyte was adopted instead of a conventional KPF6-based electrolyte for the CuP2/C composite anode. Benefiting from the synergistic effects of the formation of strong P–O–C chemical bonds and the KFSI-based electrolyte, the CuP2/C composite anode exhibited high reversible capacity (451.4 mAh g−1 at 50 mA g−1), excellent rate performance (123.5 mAh g−1 at 1000 mA g−1), and superior cycling stability (300 mAh g−1 after 100 cycles). This work paves the way for the development of high-performance CuP2 anode for potassium-ion batteries.

p-Benzoquinone (BQ) is a promising candidate for next-generation sodium-ion batteries (SIBs) because of its high theoretical specific capacity, good reaction reversibility, and high resource availability. However, practical application of BQ faces many challenges, such as a low discharge plateau (∼2.7 V) as cathode material or a high discharge plateau as anode material compared with inorganic materials for SIBs and high solubility in organic electrolytes, resulting in low power and energy densities. Here, tetrahydroxybenzoquinone tetrasodium salt (Na4C6O6) is synthesized through a simple neutralization reaction at low temperatures. The four −ONa electron-donating groups introduced on the structure of BQ greatly lower the discharge plateau by over 1.4 V from ∼2.70 V to ∼1.26 V, which can change BQ from cathode to anode material for SIBs. At the same time, the addition of four −ONa hydrophilic groups inhibits the dissolution of BQ in the organic electrolyte to a certain extent. As a result, Na4C6O6 as the anode displays a moderate discharge capacity and cycling performance at an average work voltage of ∼1.26 V versus Na/Na+. When evaluated as a Na-ion full cell (NIFC), a Na3V2(PO4)3 ‖ Na4C6O6 NIFC reveals a moderate discharge capacity and an average discharge plateau of ∼1.4 V. This research offers a new molecular structure design strategy for reducing the discharge plateau and simultaneously restraining the dissolution of organic electrode materials.

Increasing generation of permanent magnet waste has resulted in an urgent need to preserve finite resources. Reforming these wastes as feedstock to produce renewables is an ideal strategy for addressing waste and energy challenges. Herein, our work reports a smart and sustainable strategy to convert iron in magnet wastes into Prussian blue analogues that can serve as cathode materials for sodium-ion batteries. Moreover, a method to control feed rates is proposed to generate high-quality materials with fewer [Fe(CN)

Manganese-based Prussian Blue, Na2-δ Mn[Fe(CN)6 ] (MnPB), is a good candidate for sodium-ion battery cathode materials due to its high capacity. However, it suffers from severe capacity decay during battery cycling due to the destabilizing Jahn-Teller distortions it undergoes as Mn2+ is oxidized to Mn3+ . Herein, the structure is stabilized by a thin epitaxial surface layer of nickel-based Prussian Blue (Na2-δ Ni[Fe(CN)6 ]). The one-pot synthesis relies on a chelating agent with an unequal affinity for Mn2+ and Ni2+ ions, which prevents Ni2+ from reacting until the Mn2+ is consumed. This is a new and simpler synthesis of core-shell materials, which usually needs several steps. The material has an electrochemical capacity of 93 mA h g-1 , of which it retains 96 % after 500 charge-discharge cycles (vs. 37 % for MnPB). Its rate capability is also remarkable: at 4 A g-1 (ca. 55 C) it can reversibly store 70 mA h g-1 , which is also reflected in its diffusion coefficient of ca. 10-8 cm2 s-1 . The epitaxial outer layer appears to exert an anisotropic strain on the inner layer, preventing the Jahn-Teller distortions it normally undergoes during de-sodiation.

Mn-based layered oxides are very attractive as cathodes for potassium-ion batteries (PIBs) due to their low-cost and environmentally friendly precursors. Their transfer to practical application, however, is inhibited by some issues including consecutive phase transitions, sluggish K+ deintercalation/intercalation, and serious capacity loss. Herein, Mg-Ni co-substituted K1/2Mn5/6Mg1/12Ni1/12O2 is designed as a promising cathode material for PIBs, with suppressed phase transitions that occurred in K1/2MnO2 and improved K+ storage performance. Part of Mg2+ and Ni2+ occupies the K+ layer, playing the role of a "nailed pillar", which restrains metal oxide layer gliding during the K+ (de)intercalation. The "Mg-Ni pinning effect" not only suppresses the phase transitions but also reduces the cell volume variation, leading to the improved cycle performance. Moreover, K1/2Mn5/6Mg1/12Ni1/12O2 has low activation barrier energy for K+ diffusion and high electron conductivity as demonstrated by first-principles calculations, resulting in better rate capability. In addition, K1/2Mn5/6Mg1/12Ni1/12O2 also delivers a higher reversible capacity owing to the participation of the Ni element in electrochemical reactions and the pseudocapacitive contribution. This study provides a basic understanding of structural evolution in layered Mn-based oxides and broadens the strategic design of cathode materials for PIBs.

Bismuth is a promising anode for potassium-ion batteries (PIBs) due to its suitable redox potential, large theoretical capacity, and superior electronic conductivity. Herein, we report a Bi@C (Bi nanoparticles uniformly embedded in a carbon skeleton) composite anode which delivers a superior rate performance of 244.3 mA h g

The shuttling of soluble lithium polysulfides (LiPS) and the sluggish Li-S conversion kinetics are two main barriers toward the practical application of lithium-sulfur batteries (LSBs). Herein, we propose the addition of copper selenide nanoparticles at the cathode to trap LiPS and accelerate the Li-S reaction kinetics. Using both computational and experimental results, we demonstrate the crystal phase and concentration of copper vacancies to control the electronic structure of the copper selenide, its affinity toward LiPS chemisorption, and its electrical conductivity. The adjustment of the defect density also allows for tuning the electrochemically active sites for the catalytic conversion of polysulfide. The optimized S/Cu1.8Se cathode efficiently promotes and stabilizes the sulfur electrochemistry, thus improving significantly the LSB performance, including an outstanding cyclability over 1000 cycles at 3 C with a capacity fading rate of just 0.029% per cycle, a superb rate capability up to 5 C, and a high areal capacity of 6.07 mAh cm-2 under high sulfur loading. Overall, the present work proposes a crystal phase and defect engineering strategy toward fast and durable sulfur electrochemistry, demonstrating great potential in developing practical LSBs., The authors thank the support from the projects ENE2016-77798-C4-3-R and NANOGEN (PID2020-116093RB-C43), funded by MCIN/AEI/10.13039/501100011033/and by “ERDF A way of making Europe”, by the “European Union”. D.Y., M.L., X.H., and C.Z. thank the China Scholarship Council for the scholarship support. ICN2 acknowledges the support from the Severo Ochoa Programme (MINECO, grant no. SEV-2017-0706). IREC and ICN2 are both funded by the CERCA Program/Generalitat de Catalunya. This project received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No. 823717-ESTEEM3. Calculations at UT Austin were supported by the Welch Foundation (F-1841) and the Texas Advanced Computing Center. Part of the present work has been performed in the framework of Universitat Autònoma de Barcelona Materials Science PhD program. J.L. is a Serra Húnter Fellow and is grateful to MICINN/FEDER RTI2018-093996-B-C31, GC 2017 SGR 128, and to the ICREA Academia program.