Zn metal anode suffers from dendrite issues and passive byproducts, which severely plagues the practical application of aqueous Zn metal batteries. Herein, a polyzwitterionic cross-linked double network hydrogel electrolyte composed of physical crosslinking (hyaluronic acid) and chemical crosslinking (synthetic zwitterionic monomer copolymerized with acrylamide) is introduced to overcome these obstacles. On the one hand, highly hydrophilic physical network provides an energy dissipation channel to buffer stress and builds a H₂O-poor interface to avoid side reactions. On the other hand, the charged groups (sulfonic and imidazolyl) in chemical crosslinking structure build anion/cation transport channels to boost ions’ kinetics migration and regulate the typical solvent structure [Zn(H₂O)₆]²⁺ to R-SO₃⁻ [Zn(H₂O)₄]²⁺, with uniform electric field distribution and significant resistance to dendrites and parasitic reactions. Based on the above functions, the symmetric zinc cell exhibits superior cycle stability for more than 420 h at a high current density of 5 mA·cm⁻², and Zn||MnO₂ full cell has a reversible specific capacity of 150 mAh·g⁻¹ after 1000 cycles at 2 C with this hydrogel electrolyte. Furthermore, the pouch cell delivers impressive flexibility and cyclability for energy-storage applications.

Li-S batteries (LSBs) have been considering as new and promising energy storage systems because of the high theoretical energy density and low price. Nevertheless, their practical application is inhibited by several factors, including poor electrical conductivity of electrode materials, greatly volumetric variation, as well as the polysulfide formation upon the cycling. To address these problems, it is imperative to develop and design effective and suitable sulfur host anode materials. Metal organic frameworks (MOFs)-based cathode materials, possessing their good conductivity and easy morphology design, have been extensively studied and exhibited enormously potential in LSBs. In this review, a comprehensive overview of MOFs-based sulfur host materials is provided, including their electrochemical reaction mechanisms, related evaluation parameters, and their performances used in LSBs in the past few years. In particular, the recent advances using in-situ characterization technologies for investigating the electrochemical reaction mechanism in LSBs are presented and highlighted. Additionally, the challenges and prospects associated with future research on MOF-related sulfur host materials are discussed. It is anticipated to offer the guidance for the identification of suitable MOFs-based sulfur cathode materials for high-performance LSBs, thereby contributing for the achievement of a sustainable and renewable society.

Conjugated polymers of organic carbonyl compounds are promising electrode materials for energy storage devices owing to the renewable development prospects, structural variability, and better insolubility in electrolyte. However, the synthesis methods in solution are cumbersome and complicated in separation and purification, and require the introduction of functional groups and use of expensive catalysts. In this work, a novel conjugated poly(3,4,9,10-perylenetetracarboxylic diimide) (PPI) with superior thermal stability and lower solubility was prepared successfully by a green facile mechanical ball milling strategy. The PPI exhibits enhanced electrochemical dynamics performance, preferable rate capability, higher discharge capacity, and excellent cycling stability of 450 cycles at 0.2 C with higher capacity retention of 85.7% when used as cathode material for sodium-ion battery. Furthermore, the in-situ X-ray diffraction (XRD) and in-situ Raman investigations combined with the Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) were carried out to investigate the sodium storage mechanism. The results indicate that only two sodium ions are bound to two opposite carbonyl groups of PPI monomer to form sodium enolates during normal charging and discharging and to deliver available reversible capacity.

The urgent need for highly safe and sustainable large-scale energy storage systems for residential buildings has led to research into aqueous zinc ion batteries. However, when zinc is used in aqueous zinc ion batteries, it suffers from severe irreversibility due to its low Coulombic efficiency, dendrite growth, and side reactions. To address these challenges, we take advantage of organic cation to induce trifluoromethanesulfonate decomposition to build zinc fluoride/zinc sulfide-rich solid electrolyte interphase (SEI) that not only can adapt to a high areal capacity of deposition/stripping disturbance but also adjust zinc ion deposition path to eliminate dendrite. As a result, the unique interface can promote the Zn battery to achieve excellent electrochemical performance: high levels of plating/stripping Coulombic efficiency (99.8%), stability life (6,600 h), and cumulative capacity (66,000 mAh·cm⁻²) at 68% zinc utilization (20 mAh·cm⁻²). More importantly, the SEI significantly enhances the cyclability of full battery under limited Zn, lean electrolyte, and high areal capacity cathode conditions.

Spinel LiMn₂O₄ is a widely utilized cathode material for Li-ion batteries. However, its applications are limited by its poor energy density and power density. Herein, a novel hierarchical porous onion-like LiMn₂O₄(LMO) was prepared to shorten the Li⁺ diffusion pathway with the presence of uniform pores and nanosized primary particles. The growth mechanism of the porous onion-like LiMn₂O₄ was analyzed to control the morphology and the crystal structure so that it forms a polyhedral crystal structure with reduced Mn dissolution. In addition, graphene was added to the cathode (LiMn₂O₄/graphene) to enhance the electronic conductivity. The synthesized LiMn₂O₄/graphene exhibited an ultrahigh-rate performance of 110.4 mAh·g^-1 at 50 C and an outstanding energy density at a high power density, maintaining 379.4 Wh·kg^-1 at 25, 293 W·kg^-1. Besides, it shows durable stability, with only 0.02% decrease in the capacity per cycle at 10 C. Furthermore, the (LiMn₂O₄/graphene)/graphite full-cell exhibited a high discharge capacity. This work provides a promising method for the preparation of outstanding, integrated cathodes for potential applications in lithium ion batteries.

Low-cost and easily obtainable electrode materials are crucial for the application of supercapacitors. Nickel hydroxides have recently attracted intensive attention owning to their high theoretical specific capacitance, high redox activity, low cost, and eco-friendliness. In this study, novel three-dimensional (3D) interspersed flower-like nickel hydroxide was assembled under mild conditions. When ammonia was used as the precipitant and inhibitor and CTAB was used as an exfoliation agent, the obtained exfoliated ultrathin Ni(OH)₂ nanosheets were assembled into 3D interspersed flower-like nickel hydroxide. In this novel 3D structure, the ultrathin Ni(OH)₂ nanosheets not only provided a large contact area with the electrolyte, reducing the polarization of the electrochemical reaction and providing more active sites, but also reduced the concentration polarization in the electrode solution interface. Consequently, the utilization efficiency of the active material was improved, yielding a high capacitance. The electrochemical performance was improved via promoting the electrical conductivity by mixing the as-synthesized Ni(OH)₂ with carbon tubes (N-4-CNT electrode), yielding excellent specific capacitances of 2, 225.1 F·g^–1 at 0.5 A·g^–1 in a three-electrode system and 722.0 F·g^–1 at 0.2 A·g^–1 in a two-electrode system. The N-4-CNT//active carbon (AC) device exhibited long-term cycling performance (capacitance-retention ratio of 111.4% after 10, 000 cycles at 5 A·g^–1) and a high specific capacitance of 180.5 F·g^–1 with a high energy density of 33.5 W·h·kg^–1 and a power density of 2, 251.6 W·kg^–1.