H+‐Insertion Boosted α‐MnO2 for an Aqueous Zn‐Ion Battery

Rechargeable Zn/MnO₂ batteries using mild aqueous electrolytes are attracting extensive attention due to their low cost, high safety, and environmental friendliness. However, the charge‐storage mechanism involved remains a topic of controversy so far. Also, the practical energy density and cycling stability are still major issues for their applications. Herein, a free‐standing α‐MnO₂ cathode for aqueous zinc‐ion batteries (ZIBs) is directly constructed with ultralong nanowires, leading to a rather high energy density of 384 mWh g^?1 for the entire electrode. Greatly, the H⁺/Zn²⁺ coinsertion mechanism of α‐MnO₂ cathode for aqueous ZIBs is confirmed by a combined analysis of in situ X‐ray diffractometry, ex situ transmission electron microscopy, and electrochemical methods. More interestingly, the Zn²⁺‐insertion is found to be less reversible than H⁺‐insertion in view of the dramatic capacity fading occurring in the Zn²⁺‐insertion step, which is further evidenced by the discovery of an irreversible ZnMn₂O₄ layer at the surface of α‐MnO₂. Hence, the H⁺‐insertion process actually plays a crucial role in maintaining the cycling performance of the aqueous Zn/α‐MnO₂ battery. This work is believed to provide an insight into the charge‐storage mechanism of α‐MnO₂ in aqueous systems and paves the way for designing aqueous ZIBs with high energy density and long‐term cycling ability.     

Bi-MOF Modulating MnO2 Deposition Enables Ultra-Stable Cathode-Free Aqueous Zinc-Ion Batteries

The Mn-based materials are considered as the most promising cathodes for zinc-ion batteries (ZIBs) due to their inherent advantages of safety, sustainability and high energy density, however suffer from poor cyclability caused by gradual Mn²⁺ dissolution and irreversible structural transformation. The mainstream solution is pre-adding Mn²⁺ into the electrolyte, nevertheless faces the challenge of irreversible Mn²⁺ consumption results from the MnO₂ electrodeposition reaction (Mn²⁺ → MnO₂). This work proposes a “MOFs as the electrodeposition surface” strategy, rather than blocking it. The bismuth (III) pyridine-3,5-dicarboxylate (Bi-PYDC) is selected as the typical electrodeposition surface to regulate the deposition reaction from Mn²⁺ to MnO₂. Because of the unique less hydrophilic and manganophilic nature of Bi-PYDC for Mn²⁺, a moderate MnO₂ deposition rate is achieved, preventing the electrolyte from rapidly exhausting Mn²⁺. Simultaneously, the intrinsic stability of deposited R-MnO₂ is enhanced by the slowly released Bi³⁺ from Bi-PYDC reservoir. Furthermore, Bi-PYDC shows the ability to accommodate H⁺ insertion/extraction. Benefiting from these merits, the cathode-free ZIB using Bi-PYDC as the electrodeposition surface for MnO₂ shows an outstanding cycle lifespan of more than 10 000 cycles at 1 mA cm^-2. This electrode design may stimulate a new pathway for developing cathode free long-life rechargeable ZIBs.     

Triggering High Capacity and Superior Reversibility of Manganese Oxides Cathode via Magnesium Modulation for Zn//MnO2 Batteries

Aqueous zinc-ion batteries (ZIBs) have attracted extensive attention in recent years because of its high volumetric energy density, the abundance of zinc resources, and safety. However, ZIBs still suffer from poor reversibility and sluggish kinetics derived from the unstable cathodic structure and the strong electrostatic interactions between bivalent Zn²⁺ and cathodes. Herein, magnesium doping into layered manganese dioxide (Mg–MnO₂) via a simple hydrothermal method as cathode materials for ZIBs is proposed. The interconnected nanoflakes of Mg–MnO₂ possess a larger specific surface area compared to pristine δ-MnO₂, providing more electroactive sites and boosting the capacity of batteries. The ion diffusion coefficients of Mg–MnO₂ can be enhanced due to the improved electrical conductivity by doped cations and oxygen vacancies in MnO₂ lattices. The assembled Zn//Mg–MnO₂ battery delivers a high specific capacity of 370 mAh g⁻¹ at a current density of 0.6 A g⁻¹. Furthermore, the reaction mechanism confirms that Zn²⁺ insertion occurred after a few cycles of activation reactions. Most important, the reversible redox reaction between Zn²⁺ and MnOOH is found after several charge–discharge processes, promoting capacity and stability. It believes that this systematic research enlightens the design of high-performance of ZIBs and facilitates the practical application of Zn//MnO₂ batteries.     

Advanced In Situ Electrochemical Induced Dual-Mechanism Heterointerface toward High-Energy Aqueous Zinc-Ion Batteries

In situ electrochemical activation brings unexpected electrochemical performance improvements to electrode materials, while the mechanism behind is still needed to study deeply. Herein, an in situ electrochemically approach is developed for the activation of heterointerface MnO_x/Co₃O₄ by inducing Mn-defect, wherein the Mn defects are formed through a charge process that converts the MnO_x with poor electrochemical activities toward Zn²⁺ into high electrochemically active cathode for aqueous zinc-ion batteries (ZIBs). Guided by the coupling engineering strategy, the heterointerface cathode exhibits an intercalation/conversion dual-mechanism without structural collapse during storage/release of Zn²⁺. The heterointerfaces between different phases can generate built-in electric fields, reducing the energy barrier for ion migration and facilitating electron/ion diffusion. As a consequence, the dual-mechanism MnO_x/Co₃O₄ shows an outstanding fast charging performance and maintains a capacity of 401.03 mAh g⁻¹ at 0.1 A g⁻¹. More importantly, a ZIB based on MnO_x/Co₃O₄ delivered an energy density of 166.09 Wh kg⁻¹ at an ultrahigh power density of 694.64 W kg⁻¹, which outperforms those of fast charging supercapacitors. This work provides insights for using defect chemistry to introduce novel properties in active materials for highly for high-performance aqueous ZIBs.     

Nitrogen-Doped and Sulfonated Carbon Dots as a Multifunctional Additive to Realize Highly Reversible Aqueous Zinc-Ion Batteries

Aqueous zinc-ion batteries (ZIBs) using the Zn metal anode have been considered as one of the next-generation commercial batteries with high security, robust capacity, and low price. However, parasitic reactions, notorious dendrites and limited lifespan still hamper their practical applications. Herein, an eco-friendly nitrogen-doped and sulfonated carbon dots (NSCDs) is designed as a multifunctional additive for the cheap aqueous ZnSO₄ electrolyte, which can overcome the above difficulties effectively. The abundant polar groups (-COOH, -OH, -NH₂, and -SO₃H) on the CDs surfaces can regulate the solvation structure of Zn²⁺ through decreasing the coordinated active H₂O molecules, and thus redistribute Zn²⁺ deposition to avoid side reactions. Some of the negatively charged NSCDs are adsorbed on Zn anode surface to isolate the H₂O/SO₄^2- corrosion through the electrostatic shielding effect. The synergistic effect of the doped nitrogen species and the surface sulfonic groups can induce a uniform electrolyte flux and a homogeneous Zn plating with a (002) texture. As a result, the excellent cycle life (4000 h) and Coulombic efficiency (99.5%) of the optimized ZIBs are realized in typical ZnSO₄ electrolytes with only 0.1 mg mL^-1 of NSCDs additive.     

Layered Ca0.28MnO2·0.5H2O as a High Performance Cathode for Aqueous Zinc‐Ion Battery

Aqueous zinc‐ion batteries are promising candidates for grid‐scale energy storage because of their intrinsic safety, low cost, and high energy intensity. However, lack of suitable cathode materials with both excellent rate performance and cycling stability hinders further practical application of aqueous zinc‐ion batteries. Here, a nanoflake‐self‐assembled nanorod structure of Ca_0.28MnO₂·0.5H₂O as Zn‐insertion cathode material is designed. The Ca_0.28MnO₂·0.5H₂O exhibits a reversible capacity of 298 mAh g^?1 at 175 mA g^?1 and long‐term cycling stability over 5000 cycles with no obvious capacity fading, which indicates that the per‐insertion of Ca ions and water can significantly improve reversible insertion/extraction stability of Zn²⁺ in Mn‐based layered type material. Further, its charge storage mechanism, especially hydrogen ions, is elucidated. A comprehensive study suggests that the intercalation of hydrogen ions in the first discharge plat is controled by both pH value and type of anion of electrolyte. Further, it can stabilize the Ca_0.28MnO₂·0.5H₂O cathode and facilitate the following insertion of Zn²⁺ in 1 m ZnSO₄/0.1 m MnSO₄ electrolyte. This work can enlighten and promote the development of high‐performance rechargeable aqueous zinc‐ion batteries.     

A High‐Energy and Long‐Life Aqueous Zn/Birnessite Battery via Reversible Water and Zn2+ Coinsertion

Aqueous rechargeable Zn/birnessite batteries have recently attracted extensive attention for energy storage system because of their low cost and high safety. However, the reaction mechanism of the birnessite cathode in aqueous electrolytes and the cathode structure degradation mechanics still remain elusive and controversial. In this work, it is found that solvation water molecules coordinated to Zn²⁺ are coinserted into birnessite lattice structure contributing to Zn²⁺ diffusion. However, the birnessite will suffer from hydroxylation and Mn dissolution with too much solvated water coinsertion. Through engineering Zn²⁺ primary solvation sheath with strong‐field ligand in aqueous electrolyte, highly reversible [Zn(H₂O)₂]²⁺ complex intercalation/extraction into/from birnessite cathode is obtained. Cathode–electrolyte interface suppressing the Mn dissolution also forms. The Zn metal anode also shows high reversibility without formation of “death‐zinc” and detrimental dendrite. A full cell coupled with birnessite cathode and Zn metal anode delivers a discharge capacity of 270 mAh g^?1, a high energy density of 280 Wh kg^?1 (based on total mass of cathode and anode active materials), and capacity retention of 90% over 5000 cycles.     

Joint Charge Storage for High‐Rate Aqueous Zinc–Manganese Dioxide Batteries

Aqueous rechargeable zinc–manganese dioxide batteries show great promise for large‐scale energy storage due to their use of environmentally friendly, abundant, and rechargeable Zn metal anodes and MnO₂ cathodes. In the literature various intercalation and conversion reaction mechanisms in MnO₂ have been reported, but it is not clear how these mechanisms can be simultaneously manipulated to improve the charge storage and transport properties. A systematical study to understand the charge storage mechanisms in a layered δ‐MnO₂ cathode is reported. An electrolyte‐dependent reaction mechanism in δ‐MnO₂ is identified. Nondiffusion controlled Zn²⁺ intercalation in bulky δ‐MnO₂ and control of H⁺ conversion reaction pathways over a wide C‐rate charge–discharge range facilitate high rate performance of the δ‐MnO₂ cathode without sacrificing the energy density in optimal electrolytes. The Zn‐δ‐MnO₂ system delivers a discharge capacity of 136.9 mAh g^?1 at 20 C and capacity retention of 93% over 4000 cycles with this joint charge storage mechanism. This study opens a new gateway for the design of high‐rate electrode materials by manipulating the effective redox reactions in electrode materials for rechargeable batteries.     

Coupling Engineering of NH4+ Pre-Intercalation and Rich Oxygen Vacancies in Tunnel WO3 Toward Fast and Stable Rocking Chair Zinc-Ion Battery

Herein, for the first time, a pre-intercalated non-metal ion (NH₄⁺) with rich oxygen vacancies stabilized tunnel WO₃ is proposed as a new intercalation anode to construct Zn-metal-free rocking-chair ZIBs. With the ethylene glycol additive in the aqueous electrolyte, the Zn²⁺ solvation structure can be regulated and the side reaction of hydrogen evolution can also be suppressed. Owing to the integrated synergetic modification, a high-rate and ultra-stable aqueous Zn-(NH₄)_xWO₃ battery can be constructed, which exhibits an improved specific capacity (153 mAh g⁻¹ at 0.1 A g⁻¹), excellent rate performance (when the current density increases to 3 A g⁻¹, the specific capacitance is still 86 mAh g⁻¹), and a high cycle stability with 100% capacity retention after 2,200 cycles under 5 A g⁻¹. Ex situ X-ray diffraction and XPS reveal the reversible insertion/extraction of Zn²⁺ in (NH₄)_xWO₃. The assembled (NH₄)_xWO₃//MnO₂ rocking-chair ZIBs delivers excellent capacity of 82 mAh g⁻¹ at 0.1 A g⁻¹, impressive cyclic stability. Additionally, the flexible (NH₄)_xWO₃//MnO₂ ZIBs can power the electrochromic device-based PANI/WO₃ with high color contrast and fast response time. This study provides new insight for developing high-performance rechargeable aqueous ZIBs.     

A High-Voltage,Dendrite-Free,and Durable Zn–Graphite Battery

The intrinsic advantages of metallic Zn, like high theoretical capacity (820 mAh g⁻¹), high abundance, low toxicity, and high safety have driven the recent booming development of rechargeable Zn batteries. However, the lack of high-voltage electrolyte and cathode materials restricts the cell voltage mostly to below 2 V. Moreover, dendrite formation and the poor rechargeability of the Zn anode hinder the long-term operation of Zn batteries. Here a high-voltage and durable Zn–graphite battery, which is enabled by a LiPF₆-containing hybrid electrolyte, is reported. The presence of LiPF₆ efficiently suppresses the anodic oxidation of Zn electrolyte and leads to a super-wide electrochemical stability window of 4 V (vs Zn/Zn²⁺). Both dendrite-free Zn plating/stripping and reversible dual-anion intercalation into the graphite cathode are realized in the hybrid electrolyte. The resultant Zn–graphite battery performs stably at a high voltage of 2.8 V with a record midpoint discharge voltage of 2.2 V. After 2000 cycles at a high charge–discharge rate, high capacity retention of 97.5% is achieved with ≈100% Coulombic efficiency.     

Molecular-Crowding Effect Mimicking Cold-Resistant Plants to Stabilize the Zinc Anode with Wider Service Temperature Range

Growth of dendrites, the low plating/stripping efficiency of Zn anodes, and the high freezing point of aqueous electrolytes hinder the practical application of aqueous Zn-ion batteries. Here, a zwitterionic osmolyte-based molecular crowding electrolyte is presented, by adding betaine (Bet, a by-product from beet plant) to the aqueous electrolyte, to solve the abovementioned problems. Substantive verification tests, density functional theory calculations, and ab initio molecular dynamics simulations consistently reveal that side reactions and growth of Zn dendrites are restrained because Bet can break Zn²⁺ solvation and regulate oriented 2D Zn²⁺ deposition. The Bet/ZnSO₄ electrolyte enables superior reversibility in a Zn–Cu half-cell to achieve a high Coulombic efficiency >99.9% for 900 cycles (≈1800 h), and dendrite-free Zn plating/stripping in Zn–Zn cells for 4235 h at 0.5 mA cm⁻² and 0.5 mAh cm⁻². Furthermore, a high concentration of Bet lowers the freezing point of the electrolyte to −92 °C via the molecular-crowding effect, which ensures the stable operation of the aqueous batteries at −30 °C. This innovative concept of such a molecular crowding electrolyte will inject new vitality into the development of multifunctional aqueous electrolytes.     

A Multifunctional Organic Electrolyte Additive for Aqueous Zinc Ion Batteries Based on Polyaniline Cathode

The practical applications of aqueous zinc ion batteries are hindered by the formation of dendrites on the anode, the narrow electrochemical window of electrolyte, and the instability of the cathode. To address all these challenges simultaneously, a multi-functional electrolyte additive of 1-phenylethylamine hydrochloride (PEA) is developed for aqueous zinc ion batteries based on polyaniline (PANI) cathode. Experiments and theoretical calculations confirm that the PEA additive can regulate the solvation sheath of Zn²⁺ and form a protective layer on the surface of the Zn metal anode. This broadens the electrochemical stability window of the aqueous electrolyte and enables uniform deposition of Zn. On the cathode side, the Cl⁻ anions from PEA enter the PANI chain during charge and release fewer water molecules surrounding the oxidized PANI, thus suppressing harmful side reactions. When used in a Zn||PANI battery, this cathode/anode compatible electrolyte exhibits excellent rate performance and long cycle life, making it highly attractive for practical applications.     

Achieving Ultrahigh Energy Density and Long Durability in a Flexible Rechargeable Quasi‐Solid‐State Zn–MnO2 Battery

Advanced flexible batteries with high energy density and long cycle life are an important research target. Herein, the first paradigm of a high‐performance and stable flexible rechargeable quasi‐solid‐state Zn–MnO₂ battery is constructed by engineering MnO₂ electrodes and gel electrolyte. Benefiting from a poly(3,4‐ethylenedioxythiophene) (PEDOT) buffer layer and a Mn²⁺‐based neutral electrolyte, the fabricated Zn–MnO₂@PEDOT battery presents a remarkable capacity of 366.6 mA h g^?1 and good cycling performance (83.7% after 300 cycles) in aqueous electrolyte. More importantly, when using PVA/ZnCl₂/MnSO₄ gel as electrolyte, the as‐fabricated quasi‐solid‐state Zn–MnO₂@PEDOT battery remains highly rechargeable, maintaining more than 77.7% of its initial capacity and nearly 100% Coulombic efficiency after 300 cycles. Moreover, this flexible quasi‐solid‐state Zn–MnO₂ battery achieves an admirable energy density of 504.9 W h kg^?1 (33.95 mW h cm^?3), together with a peak power density of 8.6 kW kg^?1, substantially higher than most recently reported flexible energy‐storage devices. With the merits of impressive energy density and durability, this highly flexible rechargeable Zn–MnO₂ battery opens new opportunities for powering portable and wearable electronics.     

Interfacial Engineering Coupled Valence Tuning of MoO3 Cathode for High‐Capacity and High‐Rate Fiber‐Shaped Zinc‐Ion Batteries

Aqueous Zn‐ion batteries (ZIBs) have garnered the researchers' spotlight owing to its high safety, cost effectiveness, and high theoretical capacity of Zn anode. However, the availability of cathode materials for Zn ions storage is limited. With unique layered structure along the [010] direction, α‐MoO₃ holds great promise as a cathode material for ZIBs, but its intrinsically poor conductivity severely restricts the capacity and rate capability. To circumvent this issue, an efficient surface engineering strategy is proposed to significantly improve the electric conductivity, Zn ion diffusion rate, and cycling stability of the MoO₃ cathode for ZIBs, thus drastically promoting its electrochemical properties. With the synergetic effect of Al₂O₃ coating and phosphating process, the constructed Zn//P‐MoO_3?x@Al₂O₃ battery delivers impressive capacity of 257.7 mAh g^?1 at 1 A g^?1 and superior rate capability (57% capacity retention at 20 A g^?1), dramatically surpassing the pristine Zn//MoO₃ battery (115.8 mAh g^?1; 19.7%). More importantly, capitalized on polyvinyl alcohol gel electrolyte, an admirable capacity (19.2 mAh cm^?3) as well as favorable energy density (14.4 mWh cm^?3; 240 Wh kg^?1) are both achieved by the fiber‐shaped quasi‐solid‐state ZIB. This work may be a great motivation for further research on molybdenum or other layered structure materials for high‐performance ZIBs.     

Unravelling H+/Zn2+ Synergistic Intercalation in a Novel Phase of Manganese Oxide for High‐Performance Aqueous Rechargeable Battery

Aqueous Zn‐MnO₂ batteries using mild electrolyte show great potential in large‐scale energy storage (LSES) application, due to high safety and low cost. However, structure collapse of manganese oxides upon cycling caused by the conversion mechanism (e.g., from tunnel to layer structures for α‐, β‐, and γ‐phases) is one of the most urgent issues plaguing its practical applications. Herein, to avoid the phase conversion issue and enhance battery performance, a structurally robust novel phase of manganese oxide MnO₂H_0.16(H₂O)_0.27 (MON) nanosheet with thickness of ≈2.5 nm is designed and synthesized as a promising cathode material, in which a nanosheet structure combined with a novel H⁺/Zn²⁺ synergistic intercalation mechanism is demonstrated and evidenced. Accordingly, a high‐performance Zn/MON cell is achieved, showing a high energy density of ≈228.5 Wh kg^?1, impressive cyclability with capacity retention of 96% at 0.5 C after 300 cycles, as well as exhibiting rate performance of 115.1 mAh g^?1 at current rate of 10 C. To the best current knowledge, this H⁺/Zn²⁺ synergistic intercalation mechanism is first reported in an aqueous battery system, which opens a new opportunity for development of high‐performance aqueous Zn ion batteries for LSES.     

Atomic Engineering Catalyzed MnO2 Electrolysis Kinetics for a Hybrid Aqueous Battery with High Power and Energy Density

Research interest and achievements in zinc aqueous batteries, such as alkaline Zn//Mn, Zn//Ni/Co, Zn–air batteries, and near-neutral Zn-ion and hybrid ion batteries, have surged throughout the world due to their features of low-cost and high-safety. However, practical application of Zn-based secondary batteries is plagued by restrictive energy and power densities in which an inadequate output plateau voltage and sluggish kinetics are mutually accountable. Here, a novel paradigm high-rate and high-voltage Zn–Mn hybrid aqueous battery (HAB) is constructed with an expanded electrochemical stability window over 3.4 V that is affordable. As a proof of concept, catalyzed MnO₂/Mn²⁺ electrolysis kinetics is demonstrated in the HAB via facile introduction of Ni²⁺ into the electrolyte. Various techniques are employed, including in situ synchrotron X-ray powder diffraction, ex situ X-ray absorption fine structure, and electron energy loss spectroscopy, to reveal the reversible charge-storage mechanism and the origin of the boosted rate-capability. Density functional theory (DFT) calculations reveal enhanced active electron states and charge delocalization after introducing strongly electronegative Ni. Simulations of the reaction pathways confirm the enhanced catalyzed electrolysis kinetics by the facilitated charge transfer at the active O sites around Ni dopants. These findings significantly advance aqueous batteries a step closer toward practical low-cost application.     

Langmuir–Blodgett Nanowire Devices for In Situ Probing of Zinc‐Ion Batteries

In situ monitoring the evolution of electrode materials in micro/nano scale is crucial to understand the intrinsic mechanism of rechargeable batteries. Here a novel on‐chip Langmuir–Blodgett nanowire (LBNW) microdevice is designed based on aligned and assembled MnO₂ nanowire quasimonolayer films for directly probing Zn‐ion batteries (ZIBs) in real‐time. With an interdigital device configuration, a splendid Ohmic contact between MnO₂ LBNWs and pyrolytic carbon current collector is demonstrated here, enabling a small polarization voltage. In addition, this work reveals, for the first time, that the conductance of MnO₂ LBNWs monotonically increases/decreases when the ZIBs are charged/discharged. Multistep phase transition is mainly responsible for the mechanism of the ZIBs, as evidenced by combined high‐resolution transmission electron microscopy and in situ Raman spectroscopy. This work provides a new and adaptable platform for microchip‐based in situ simultaneous electrochemical and physical detection of batteries, which would promote the fundamental and practical research of nanowire electrode materials in energy storage applications.     

Fluorinated Interface Engineering toward Controllable Zinc Deposition and Rapid Cation Migration of Aqueous Zn-Ion Batteries

Metallic zinc (Zn) is a highly promising anode material for aqueous energy storage systems due to its low redox potential, high theoretical capacity, and low cost. However, rampant dendrites/by-products and torpid Zn²⁺ transfer kinetics at electrode/electrolyte interface severely threaten the cycling stability, which deteriorate the electrochemical performance of Zn-ion batteries. Herein, an interfacial engineering strategy to construct alkaline earth fluoride modified metal Zn electrodes with long lifespan and high capacity retention is reported. The compact fluoride layer is revealed to guide uniform Zn stripping/plating and accelerate the transfer/diffusion of Zn²⁺ via Maxwell-Wagner polarization. A series of in situ and ex situ spectroscopic studies verified that the fluoride layer can guide uniform Zn stripping/plating. Electrochemical kinetics analyses reveal that positive effect on the removal of Zn²⁺ solvation sheath provided by fluoride layer. Meanwhile, this fluoride coating layer can act as a barrier between the Zn electrode and electrolyte, providing a high electrode overpotential toward hydrogen evolution reaction to hold back H₂ evolution. Consequently, the fluoride-modified Zn anode exhibited a capacity retention of 88.2% after 4000 cycles under10 A g⁻¹. This work opens up a new path to interface engineering for propelling the exploration of advanced rechargeable aqueous Zn-ion batteries.     

Self-Assembled Protein Nanofilm Regulating Uniform Zn Nucleation and Deposition Enabling Long-Life Zn Anodes

Rechargeable zinc-ion batteries (RZIBs) have gained promising attention as a feasible alternative for large-scale energy storage by the virtue of their intrinsic security, environmental benignity, low cost, and high volumetric capacity (5849 mAh cm⁻³). Nevertheless, the deep-rooted issues of dendrite formation and side reactions in unstable Zn metal anode have impeded RZIBs from being dependably deployed in their proposed applications. Herein, silk fibroin (SF) and lysozyme (ly), as natural biomacromolecules with abundant polar groups arranged in polypeptide backbones, are in situ self-assembled on the Zn anode surface to construct a homogeneous and compact protein nanofilm. Such protein nanofilm protecting layer presents a negative charge surface and significantly regulates Zn²⁺ deposition behavior. Meanwhile, synergistic flexible and robust features of protein nanofilm function as artificial solid electrolyte interface (SEI), accommodates the dynamic volume deformation during deposition/dissolution, and blocks corrosion of side reactions. Consequently, the electrochemical stability of protein nanofilm-modified Zn anode is greatly improved, with an excellent extended lifespan of over 1100 h at a high current density of 10 mA cm⁻² and a high cycling capacity of 10 mAh cm⁻², corresponding to a high depth of discharge (83% DOD_Zn). Furthermore, the highly reversible Zn electrode remarkably improved the overall performance of MnO₂||Zn full-cells.     

Extended Electrochemical Window of Solid Electrolytes via Heterogeneous Multilayered Structure for High‐Voltage Lithium Metal Batteries

In response to the call for safer high‐energy‐density storage systems, high‐voltage solid‐state Li metal batteries have attracted extensive attention. Therefore, solid electrolytes are required to be stable against both Li anode and high‐voltage cathodes; nevertheless, the requirements still cannot be completely satisfied. Herein, a heterogeneous multilayered solid electrolyte (HMSE) is proposed to broaden electrochemical window of solid electrolytes to 0–5 V, through different electrode/electrolyte interfaces to overcome the interfacial instability problems. Oxidation‐resistance poly(acrylonitrile) (PAN) is in contact with the cathode, while reduction tolerant polyethylene glycol diacrylate contacts with Li metal anode. A Janus and flexible PAN@Li_1.4Al_0.4Ge_1.6(PO₄)₃ (80 wt%) composite electrolyte is designed as intermediate layer to inhibit dendrite penetration and ensure compact interface. Paired with LiNi_0.6Co_0.2Mn_0.2O₂ and LiNi_0.8Co_0.1Mn_0.1O₂ cathodes, which are rarely used in solid‐state batteries, the solid‐state Li metal batteries with HMSE exhibit excellent electrochemical performance including high capacity and long cycle life. Besides, the Li||Li symmetric batteries maintain a stable polarization less than 40 mV for more than 1000 h under 2 mA cm^?2 and effective inhibition of dendrite formation. This study offers a promising approach to extend the applications of solid electrolytes for high‐voltage solid‐state Li metal batteries.