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The increased focus on green energy storage devices and the related rapid advancement in biomedical technologies makes the investigation of biocompatible integrated systems with medical relevance increasingly important. Peptides and their assembled morphologies with their innate biocompatibility and biodegradability are emerging as promising candidates in this respect due to their structural attributes which can be easily tuned to form supramolecular 3D architectures with extended pathways for ionic mobility. However, to comprehend their applicability in energy storage devices, it is crucial to explore their self‐assembling characteristics, charge‐storage mechanisms, and coating efficacies. Herein, all these aspects are compiled with specific emphasis on peptide‐based systems for supercapacitor applications. The electrochemical charge storage mechanisms that are used for categorizing conventional supercapacitors with the theories and mechanisms outlining biological electron transfer, such as tunneling, hopping, superexchange, and flickering resonance, are collated. Furthermore, the characterization techniques solely pertaining to the study of such systems and their role in predicting the morphology of self‐assembly patterns which could directly impact the overall electrochemical properties are also addressed. Finally, some of the critical challenges associated with these systems while realizing their future potential in the field of sustainable energy storage devices are highlighted.

HighlightsFundamental principles and advantages of electrochemical proton storage are briefly reviewed.Research progresses and strategies to promote the development of electrochemical proton storage based on various charge storage mechanisms, electrode materials, and devices are discussed and summarized.Challenges and perspectives of the next-generation electrochemical proton storage technology are discussed.Simultaneously improving the energy density and power density of electrochemical energy storage systems is the ultimate goal of electrochemical energy storage technology. An effective strategy to achieve this goal is to take advantage of the high capacity and rapid kinetics of electrochemical proton storage to break through the power limit of batteries and the energy limit of capacitors. This article aims to review the research progress on the physicochemical properties, electrochemical performance, and reaction mechanisms of electrode materials for electrochemical proton storage. According to the different charge storage mechanisms, the surface redox, intercalation, and conversion materials are classified and introduced in detail, where the influence of crystal water and other nanostructures on the migration kinetics of protons is clarified. Several reported advanced full cell devices are summarized to promote the commercialization of electrochemical proton storage. Finally, this review provides a framework for research directions of charge storage mechanism, basic principles of material structure design, construction strategies of full cell device, and goals of practical application for electrochemical proton storage.

The ever‐growing demands for green and sustainable power sources for applications in grid‐scale energy storage and portable/wearable devices have enabled the continual development of advanced aqueous electrochemical energy storage (EES) systems. Aqueous batteries and supercapacitors made of iron‐based anodes are one of the most promising options due to the remarkable electrochemical features and natural abundance, pretty low cost and good environmental friendliness of ferruginous species. Though impressive advances in developing the state‐of‐the‐art ferruginous anodes and designing various full‐cell aqueous devices have been made, there still remain key issues and challenges on the way to practical applications, which urgently need discussing to put forwards possible solutions. In this review, rather than focusing on the detailed methods to optimize the iron anode, electrolyte, and device performance, we first give a comprehensive review on the charge storage mechanisms for ferruginous anodes in different electrolyte systems, as well as the newly developed iron‐based aqueous EES devices. The deep insights, involving the inherent failure mechanisms and corresponding modification/optimization strategies toward iron anodes for the development of high‐performance aqueous EES devices, will then be discussed. The advances in applying iron‐based aqueous EES devices for emerging fields such as flexible/wearable electronics and functionalized building materials will be further outlined. Last, future research trends and perspectives for maximizing the potential of current iron anodes and devices as well as exploiting brand‐new iron‐based aqueous EES systems are put forward. A comprehensive overview of charge‐storage mechanisms for ferruginous anodes in different aqueous electrolytes, and newly developed iron‐based electrochemical energy storage devices is presented. The iron anode failure mechanisms and corresponding optimization strategies are discussed. Future research trends and perspectives for maximizing the potential of current iron anodes and devices are proposed.

Supercapacitors have emerged as a promising energy storage technology due to their high‐power density, fast charging/discharging capabilities, and long cycle life. Moreover, innovative electrode materials are extensively explored to enhance the performance, mainly the energy density of supercapacitors. Among the two‐dimensional (2D) supercapacitor electrodes, borocarbonitride (BCN) has sparked widespread curiosity owing to its exceptional tunable properties concerning the change in concentration of the constituent elements, along with an excellent alternative to graphene‐based electrodes. BCN, an advanced nanomaterial, possesses excellent electrical conductivity, chemical stability, and a large specific surface area. These factors contribute to supercapacitors' overall performance and reliability, making them a viable option to address the energy crisis. This review provides a detailed survey of BCN, its structural, electronic, chemical, magnetic, and mechanical properties, advanced synthesis methods, factors affecting the charge storage mechanism, and recent advances in BCN‐based supercapacitor electrodes. The review embarks on the scrupulous elaboration of ways to enhance the electrochemical properties of BCN through various innovative strategies followed by critical challenges and future perspectives. BCN, as an eminent electrode material, holds great potential to revolutionize the energy landscape and support the growing energy demands of the future. The review article embarks on the scrupulous elaboration of ways to enhance the electrochemical properties of borocarbonitride (BCN) through various innovative strategies followed by critical challenges and future perspectives. BCN as an eminent electrode material holds great potential to revolutionize the energy landscape and support the growing energy demands of the future.

Aqueous zinc‐manganese (Zn–Mn) batteries have promising potential in large‐scale energy storage applications since they are highly safe, environment‐friendly, and low‐cost. However, the practicality of Mn‐based materials is plagued by their structural collapse and uncertain energy storage mechanism upon cycling. Herein, this work designs an amorphous manganese borate (a‐MnBOx) material via disordered coordination to alleviate the above issues and improve the electrochemical performance of Zn–Mn batteries. The unique physicochemical characteristic of a‐MnBOx enables the inner a‐MnBOx to serve as a robust framework in the initial energy storage process. Additionally, the amorphous manganese dioxide, amorphous ZnxMnO(OH)2, and Zn4SO4(OH)6·4H2O active components form on the surface of a‐MnBOx during the charge/discharge process. The detailed in situ/ex situ characterization demonstrates that the heterostructure of the inner a‐MnBOx and surface multicomponent phases endows two energy storage modes (Zn2+/H+ intercalation/deintercalation process and reversible conversion mechanism between the ZnxMnO(OH)2 and Zn4SO4(OH)6·4H2O) phases). Therefore, the obtained Zn//a‐MnBOx battery exhibits a high specific capacity of 360.4 mAh g−1, a high energy density of 484.2 Wh kg−1, and impressive cycling stability (97.0% capacity retention after 10 000 cycles). This finding on a‐MnBOx with a dual‐energy storage mechanism provides new opportunities for developing high‐performance aqueous Zn–Mn batteries. A conceptual amorphous manganese borate material for AZIBs is designed via a disordered coordination strategy. The unique physicochemical characteristic of a‐MnBOx can form the a‐MnO2, ZnxMnO(OH)2, and Zn4SO4(OH)6·4H2O phases, realizing multiple energy storage modes for enhancing the charge storage ability.

HighlightsA unique dual-ion adsorption mechanism for zinc ion capacitor is enabled by a carbon cathode with defect-rich tissue, dense heteroatom dopant and immense surface area.The active sites on carbon surface for reversible dual-ion adsorption are identified by in-depth characterizations and DFT simulations.The zinc ion capacitor delivers unrivaled combination of high energy and power characteristics. The superb energy, power and cyclability are achieved in multiple cell configurations including coin cell and flexible solid-state pouch-/cable-type cells.Aqueous zinc-based batteries (AZBs) attract tremendous attention due to the abundant and rechargeable zinc anode. Nonetheless, the requirement of high energy and power densities raises great challenge for the cathode development. Herein we construct an aqueous zinc ion capacitor possessing an unrivaled combination of high energy and power characteristics by employing a unique dual-ion adsorption mechanism in the cathode side. Through a templating/activating co-assisted carbonization procedure, a routine protein-rich biomass transforms into defect-rich carbon with immense surface area of 3657.5 m2 g−1 and electrochemically active heteroatom content of 8.0 at%. Comprehensive characterization and DFT calculations reveal that the obtained carbon cathode exhibits capacitive charge adsorptions toward both the cations and anions, which regularly occur at the specific sites of heteroatom moieties and lattice defects upon different depths of discharge/charge. The dual-ion adsorption mechanism endows the assembled cells with maximum capacity of 257 mAh g−1 and retention of 72 mAh g−1 at ultrahigh current density of 100 A g−1 (400 C), corresponding to the outstanding energy and power of 168 Wh kg−1 and 61,700 W kg−1. Furthermore, practical battery configurations of solid-state pouch and cable-type cells display excellent reliability in electrochemistry as flexible and knittable power sources.

Transition metal high‐entropy oxides (HEOs) are an attractive class of anode materials for high‐performance lithium‐ion batteries (LIBs). However, owing to the multiple electroactive centers of HEOs, the Li+ storage mechanism is complex and debated in the literature. In this work, operando quick‐scanning X‐ray absorption spectroscopy (XAS) is used to study the lithiation/delithiation mechanism of the Cobalt‐free spinel (CrMnFeNiCu)3O4 HEO. A monochromator oscillation frequency of 2 Hz is used and 240 spectra are integrated to achieve a 2 min time resolution. High‐photon‐flux synchrotron radiation is employed to increase the XAS sensitivity. The results indicate that the Cu2+ and Ni2+ cations are reduced to their metallic states during lithiation but their oxidation reactions are less favorable compared to the other elements upon delithiation. The Mn2+/3+ and Fe2+/3+ cations undergo two‐step conversion reactions to form metallic phases, with MnO and FeO as the intermediate species, respectively. During delithiation, the oxidation of Mn occurs prior to that of Fe. The Cr3+ cations are reduced to CrO and then Cr0 during lithiation. A relatively large overpotential is required to activate the Cr reoxidation reaction. The Cr3+ cations are found after delithiation. These results can guide the material design of HEOs for improving LIB performance. The charge‐storage mechanism of Cobalt‐Free high‐entropy oxide is studied using a novel operando quick‐scanning X‐ray absorption spectroscopy (XAS) technique. High‐photon‐flux synchrotron radiation is employed to increase XAS sensitivity.XAS data are acquired in on‐the‐fly mode using a monochromator oscillation frequency of 2 Hz. Valence/coordination state variations and multiple transition steps of the constituent species upon charging/discharging are investigated in detail.

Aqueous rechargeable ammonium-ion (NH 4 + ) batteries (AAIBs) with ammonium ions as charge carriers possess many advantages, yet the relatively low discharge capacities (e.g., < 200 mAh·g −1 ) of the reported NH 4 + host materials hinder the development of AAIBs. Herein, we study the NH 4 + storage properties of an electrochemically activated NiCo double hydroxide (A-NiCo-DH) in neutral ammonium acetate electrolyte for the first time. The activation process extracts the interlayer anions (NO 3 − ) from the host material, providing additional cation accommodation sites for charge storage. The introduced H vacancies in A-NiCo-DH could activate the O sites, leading to the enhanced cation adsorption capability for the electrode. Therefore, A-NiCo-DH exhibits a high discharge capacity of 280.6 mAh·g −1 at 0.72 A·g −1 with good rate capability. Spectroscopy studies suggest A-NiCo-DH experiences a NH 4 + /H + coinsertion mechanism. A NH 4 + -Zn hybrid cell is assembled using A-NiCo-DH as the cathode and Zn foil as the anode, respectively. The device delivers an energy density of 306 Wh·kg −1 at the power density of 745.8 W·kg −1 (based on the active mass of A-NiCo-DH). This work provides a new NH 4 + storage material and would push forward the development of aqueous NH 4 + -based batteries.

The NASICON-type Na 3 V 2 (PO 4 ) 3 (NVP) material was synthesized through the sol–gel route and characterized as cathode in sodium-ion battery by the cyclic voltammetry (CV), galvanostatic intermittent titration technique (GITT) as well as electrochemical impedance spectroscopy (EIS) methods. Scan rate-dependent CV demonstrates an approximate diffusion-type behaviour and gives the diffusion coefficient value 5.24 × 10 –11  cm 2  s –1 for Na + in NVP. Both GITT and EIS tests demonstrate the U-shape diffusion coefficients for Na + correlated to stoichiometry ranging from 10 –16 to 10 –11  cm 2  s –1 , where bottom of the diffusion rate corresponding the plateau voltage well matches with CV data. The strong interaction between the main skeleton and Na + during the two-phase reaction as demonstrated by the X-ray diffraction results was believed as the reason that reduces the diffusion rate of Na + at the plateau voltage.

Regulation of the composition and microstructure of nanoelectrode materials is an effective way to improve the electrochemical property of supercapacitor electrode materials. In this paper, NiCo-MOF nanorods prepared by simple solution immersion method were used as precursors, which were subjected to alkalization, and hollow fries-like NiCo-LDH layered double hydroxide consisting of two-dimensional nanosheets was fabricated when the molar ratio of Ni 2+ /Co 2+ was 1:1. This unique hollow fries structure of NiCo-LDH electrode material can provide more electrochemical reaction sites and improve its electrochemical performance. The analysis revealed the NiCo-LDH material derived from MOF has a specific capacity of 1491 F g −1 at 1 A g −1 and still has a capacity retention rate of 88% after 4000 cycles at 20 A g −1 . The mechanisms of charge storage were discussed by kinetic analysis. The assembled NiCo-LDH//AC ASC device has a high energy density of 30.3 Wh kg −1 (power density of 806.7 W kg −1 ), and a capacitance retention of 78% after 2000 cycles at 5 A g −1 . In this research, the hollow fries-like NiCo-LDH electrode materials derived from NiCo-MOF have the characteristics of a fast electron/ion transfer rate and a high utilization rate of active materials, which provides a new idea for MOF-derived nanoelectrode materials.