The poor Zn reversibility has been criticized for limiting applications of aqueous Zn‐ion batteries (ZIBs); however, its behavior in aqueous media is not fully uncovered yet. Here, this knowledge gap is addressed, indicating that Zn electrodes face a O2‐involving corrosion, besides H2 evolution and dendrite growth. Differing from aqueous Li/Na batteries, removing O2 cannot enhance ZIB performance because of the aggravated competing H2 evolution. To address Zn issues, a one‐off electrolyte strategy is reported by introducing the triple‐function C3H7Na2O6P, which can take effects during the shelf time of battery. It regulates H+ concentration and reduces free‐water activity, inhibiting H2 evolution. A self‐healing solid/electrolyte interphase (SEI) can be triggered before battery operation, which suppresses O2 adsorption corrosion and dendritic deposition. Consequently, a high Zn reversibility of 99.6% is achieved under a high discharge depth of 85%. The pouch full‐cell with a lean electrolyte displays a record lifespan with capacity retention of 95.5% after 500 cycles. This study not only looks deeply into Zn behavior in aqueous media but also underscores rules for the design of active metal anodes, including Zn and Li metals, during shelf time toward real applications.

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/adma.202206963

Triple‐Function Electrolyte Regulation toward Advanced Aqueous Zn‐Ion Batteries

The ever-increasing demand for flexible and portable electronics has stimulated research and development in building advanced electrochemical energy devices which are lightweight, ultrathin, small in size, bendable, foldable, knittable, wearable, and/or stretchable. In such flexible and portable devices, semi-solid/solid electrolytes besides anodes and cathodes are the necessary components determining the energy/power performances. By serving as the ion transport channels, such semi-solid/solid electrolytes may be beneficial to resolving the issues of leakage, electrode corrosion, and metal electrode dendrite growth. In this paper, the fundamentals of semi-solid/solid electrolytes (e.g., chemical composition, ionic conductivity, electrochemical window, mechanical strength, thermal stability, and other attractive features), the electrode-electrolyte interfacial properties, and their relationships with the performance of various energy devices (e.g., supercapacitors, secondary ion batteries, metal-sulfur batteries, and metal-air batteries) are comprehensively reviewed in terms of materials synthesis and/or characterization, functional mechanisms, and device assembling for performance validation. The most recent advancements in improving the performance of electrochemical energy devices are summarized with focuses on analyzing the existing technical challenges (e.g., solid electrolyte interphase formation, metal electrode dendrite growth, polysulfide shuttle issue, electrolyte instability in half-open battery structure) and the strategies for overcoming these challenges through modification of semi-solid/solid electrolyte materials. Several possible directions for future research and development are proposed for going beyond existing technological bottlenecks and achieving desirable flexible and portable electrochemical energy devices to fulfill their practical applications. It is expected that this review may provide the readers with a comprehensive cross-technology understanding of the semi-solid/solid electrolytes for facilitating their current and future researches on the flexible and portable electrochemical energy devices.

Opportunities of Flexible and Portable Electrochemical Devices for Energy Storage: Expanding the Spotlight onto Semi-solid/Solid Electrolytes.

Fundamental study on Zn corrosion and dendrite growth in gel electrolyte towards advanced wearable Zn-ion battery

Flexibility and multifunctionality are now becoming inevitable worldwide tendencies for electronic devices to meet modern life's convenience, efficiency, and quality demand. To that end, developing flexible and wearable energy storage devices is a must. Recently, aqueous zinc-ion batteries (ZIBs) and zinc-ion capacitors (ZICs) stand out as two of the most potent candidates for wearable electronics due to their excellent electrochemical performance, intrinsic safety, low cost, and functional controllability. Simultaneously, polymer electrolytes' introduction and rational design, especially various hydrogels, have endowed conventional ZIBs and ZICs with colorful functions, which has been regarded as a perfect answer for energy suppliers integrated into those advanced wearable electronic devices. This review focuses on the functional hydrogel electrolytes (HEs) and their application for ZIBs and ZICs. Previously reported HEs for ZIBs and ZICs were classified and analyzed, from the flexibility to mechanical endurance, temperature adaptability, electrochemical stability, and finally cell-level ZIBs and ZICs based on multifunctional HEs. Besides introducing the diverse and exciting functions of HEs, working principles were also analyzed. Ultimately, all the details of these examples were summarized, and the related challenges, constructive solutions, and futural prospects of functional ZIBs and ZICs were also dedicatedly evaluated. 

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/eem2.12464

Polymer hydrogel electrolytes for flexible and multifunctional zinc‐ion batteries and capacitors

A review of self-healing electrolyte and their applications in flexible/stretchable energy storage devices

Poor room-temperature ionic conductivities and narrow electrochemical stable windows severely hinder the application of conventional poly(ethylene oxide)-based (PEO-based) solid polymer electrolytes (SPEs) for high-energy-density lithium metal batteries (LMBs). Herein, we designed and synthesized a PEO-based self-healing solid polymer electrolyte (SHSPE) via dynamically cross-linked imine bonds for safe, flexible solid LMBs. The constructed dynamic networks endow this SPE with fascinating intrinsic self-healing ability and excellent mechanical properties (extensibility > 500% and stress >130 kPa). More importantly, this SHSPE exhibits ultrahigh ionic conductivity (7.48 × 10-4 S cm-1 at 25 °C) and wide ESW (5.0 V vs Li/Li+). As a result, Li||Li symmetrical cells with the SHSPE showed reliable stability in a >1200 h cycling test under room temperature. The assembled Li|SHSPE|LiFePO4 cell maintained a discharge capacity of 126.4 mAh g-1 after 300 cycles (0.1C, 27 °C). This work highlights a promising strategy for next-generation room-temperature solid-state LMBs.

Self-Healing Solid Polymer Electrolyte for Room-Temperature Solid-State Lithium Metal Batteries.

The rechargeable aqueous Zn battery is promising for next-generation wearable energy storage devices, due to its outstanding safety and low cost. Herein, we report a high-performance dual-ion Zn battery with both cations and anions hosted in the polyaniline (PANI) cathode. Of special interest is that a polyzwitterionic hydrogel electrolyte is specifically designed to regulate both the anion and cation transport, which originates from the strong electrostatic interaction between polyzwitterions with counter free ions. The ion-conducting and mechanical properties are then optimized by adjusting the polyzwitterionic content in the hydrogel networks. The intrinsic regulated anion/cation transport channels result in stable and uniform plating/stripping behaviors of the Zn metal anode, and meanwhile promote the cation/anion hosting reaction in the PANI cathode. These synergistic effects provide the Zn/PANI battery with excellent electrochemical performances, achieving a capacity of 102.5 mA h g−1 and a high retention rate of 87.5% after 600 cycles at 5 A g−1. Furthermore, a solid-state pouch cell is prepared for wearable devices with demonstrated excellent electrochemical performances, high flexibility and safety.

High-performance dual-ion Zn batteries enabled by a polyzwitterionic hydrogel electrolyte with regulated anion/cation transport and suppressed Zn dendrite growth

Research on identification and active vibration control of cantilever structure based on NARX neural network

Highly sensitive soft sensors play key roles in flexible electronics, which therefore have attracted much attention in recent years. Herein, we report a flexible capacitive pressure sensor with high sensitivity by using engineered micro-patterned porous polydimethylsiloxane (PDMS) dielectric layer through an environmental-friendly fabrication procedure. The porous structure is formed by evaporation of emulsified water droplets during PDMS curing process, while the micro-patterned structure is obtained via molding on sandpaper. Impressively, this structure renders the capacitive sensor with a high sensitivity up to 143.5 MPa−1 at the pressure range of 0.068 ∼ 150 kPa and excellent anti-fatigue performance over 20 000 cycles. Meanwhile, the sensor can distinguish different motions of the same person or different people doing the same action. Our work illustrates the promising application prospects of this flexible pressure sensor for the security field or human motion monitoring area.

Flexible capacitive pressure sensors with micro-patterned porous dielectric layer for wearable electronics

Correction for ‘High-performance dual-ion Zn batteries enabled by a polyzwitterionic hydrogel electrolyte with regulated anion/cation transport and suppressed Zn dendrite growth’ by Longwei Li et al., J. Mater. Chem. A, 2021, 9, 24325–24335, https://doi.org/10.1039/D1TA08127F.

Correction: High-performance dual-ion Zn batteries enabled by a polyzwitterionic hydrogel electrolyte with regulated anion/cation transport and suppressed Zn dendrite growth

Lanshuang Zhang

Papers

Self-Healing Solid Polymer Electrolyte for Room-Temperature Solid-State Lithium Metal Batteries.

High-performance dual-ion Zn batteries enabled by a polyzwitterionic hydrogel electrolyte with regulated anion/cation transport and suppressed Zn dendrite growth

Research on identification and active vibration control of cantilever structure based on NARX neural network

Flexible capacitive pressure sensors with micro-patterned porous dielectric layer for wearable electronics

Correction: High-performance dual-ion Zn batteries enabled by a polyzwitterionic hydrogel electrolyte with regulated anion/cation transport and suppressed Zn dendrite growth