Zinc-ion batteries built on water-based electrolytes featuring compelling price-points, competitive performance, and enhanced safety represent advanced energy storage chemistry as a promising alternative to current lithium-ion battery systems. Attempts to develop rechargeable aqueous zinc-ion batteries (ZIBs) can be traced to as early as the 1980s; however, since 2015, the research activity in this field has surged throughout the world. Despite the achievements made in exploring electrode materials so far, significant challenges remain at the material level and even on the whole aqueous ZIBs system, leading to the failure of ZIBs to meet commercial requirements. This review aims to discuss how to pave the way for developing aqueous ZIBs. The current research efforts related to aqueous ZIBs electrode materials and electrolytes are summarized, including an analysis of the problems encountered in both cathode/anode materials and electrolyte optimization. Some concerns and feasible solutions for achieving practical aqueous ZIBs are discussed in detail. We would like to point out that merely improving the electrode materials is not enough; synergistic optimization strategies toward the whole battery system are also deeply needed. Finally, some perspectives are provided on the subsequent optimization design for further research efforts in the aqueous ZIB field.

Issues and opportunities facing aqueous zinc-ion batteries

https://www.cell.com/joule/pdf/S2542-4351(20)30094-5.pdf

Scientific Challenges for the Implementation of Zn-Ion Batteries

Aqueous zinc ion batteries (ZIBs) are truly promising contenders for the future large-scale electrical energy storage applications due to their cost-effectiveness, environmental friendliness, intri...

Active Materials for Aqueous Zinc Ion Batteries: Synthesis, Crystal Structure, Morphology, and Electrochemistry

To keep pace with the increasing pursuit of portable and wearable electronics, it is urgent to develop advanced flexible power supplies. In this context, Zn-ion batteries (ZIBs) have garnered increasing attention as favorable energy storage devices for flexible electronics, owing to the high capacity, low cost, abundant resources, high safety, and eco-friendliness. Extensive efforts have been devoted to developing flexible ZIBs in the last few years. This work summarizes the recent achievements in the design, fabrication, and characterization of flexible ZIBs. Representative structures, such as sandwich and cable type, are particularly highlighted. Special emphasis is put on the novel design of electrolyte and electrode, which aims to endow reliable flexibility to the fabricated ZIBs. Moreover, current challenges and future opportunities for the development of high-performance flexible ZIBs are also outlined.

Flexible Zn-Ion Batteries: Recent Progresses and Challenges.

The development of low-cost and high-safety zinc-ion batteries (ZIBs) has been extensively discussed and reviewed in recent years, but the work on the comprehensive discussion and perspectives in developing zinc-ion electrolytes is still relatively lacking. Faced with critical challenges and bottlenecks practically, the viability of ZIBs critically depends on the development of suitable electrolytes and their practical considerations. In this review, a systematic summary with regard to the basic characteristics of zinc-ion electrolytes facing different issues from optimization strategies to the fundamental science of electrolyte/electrode interfaces (EEIs), particularly in the feasible modifications and advanced characterizations of EEIs, has been put forward. Due to the lack of consideration of the practical issues in major academic studies, we have particularly highlighted aspects that mainly focus on the choice of the electrolyte system, dosage of liquid and fluid electrolytes, status of gel and all-solid electrolytes, together with other concerns related to the electrolytes. The final section proposes significant perspectives to guide and promote the development of zinc-ion electrolytes.

Fundamentals and perspectives in developing zinc-ion battery electrolytes: a comprehensive review

Flexible and stable quasi-solid-state zinc ion battery with conductive guar gum electrolyte

Flexible Zn–MnO2 batteries as wearable electronic power source have attracted much attention in recent years due to their low cost and high safety. To promote the practical application of flexible Zn–MnO2 batteries, it is imperative to develop flexible, mechanically robust and high performance solid state electrolyte. Herein, we construct a rechargeable quasi-solid-state zinc ion battery using kappa-carrageenan bio-polymer electrolyte. The kappa-carrageenan electrolyte is eco-friendly, low cost, and highly conductive (3.32 × 10−2 S cm−1 at room temperature). The mechanical robustness of kappa-carrageenan electrolyte is further reinforced by using a rice paper as scaffold. Benefiting from high ionic conductivity of the bio-polymer electrolyte, our zinc ion battery delivers a significant high energy density and power density (400 W h kg−1 and 7.9 kW kg−1, respectively), high specific capacity (291.5 mA h g−1 at 0.15 A g−1), fast charging and discharging capability (120.0 mA h g−1 at 6.0 A g−1). The zinc ion battery with bio-polymer electrolyte also shows excellent cycling stability and high bending durability. This work brings new research opportunities in developing low-cost flexible solid-state zinc ion batteries using green natural polymer.

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Flexible quasi-solid-state zinc ion batteries enabled by highly conductive carrageenan bio-polymer electrolyte

We demonstrate a rechargeable zinc-ion battery with high energy density and cyclability using MnO2 and reduced graphene oxide (MnO2/rGO) electrode. The flexible and binder free electrode, with high MnO2 mass ratio (80 wt% of MnO2), is fabricated using vacuum filtration without any additional additives other than rGO. Compared to batteries with conventional MnO2 electrodes, the Zn–MnO2/rGO battery shows a significant enhanced capacity (332.2 mAh g-1 at 0.3 A g-1), improved rate capability (172.3 mAh g-1 at 6 A g-1) and cyclability. The capacity retention remains 96% after 500 charge/discharge cycles at 6 A g-1. The high MnO2 mass ratio makes MnO2/rGO electrode advantageous when the capacity is normalized to the whole electrode, particularly at high rates. The calculated gravimetric energy density of Zn–MnO2/rGO battery is 33.17 W h kg-1, which is comparable to the existing commercial lead-acid batteries (30–40 W h kg-1). Furthermore, the discharge profile and capacity of our Zn–MnO2/rGO battery shows no deterioration during bending test, indicating good flexibility. As a result, zinc-ion battery is believed to be a promising technology for powering next generation flexible electronics. Simple carbon materials are shown to modify the MnO2 electrodes and greatly enhance the capacity and cyclability for zinc-ion batteries. An international team led by Prof Hang Zhou from Peking University Shenzhen Graduate School, China developed high performance flexible zinc-ion batteries with MnO2 and reduced graphene-oxide composites as the electrodes. The electrodes are prepared by vacuum filtering the suspension of the mixture of reduced graphene oxide and hydrothermal synthesized MnO2 nanosheets. The incorporation of reduced graphene oxide not only enhances the battery capacity by improving the conductivity and increasing the specific surface area, but also reduces the production cost by saving the trouble to use other binders or additives. Due to above advantages, this approach is competitive for wearable energy storage devices.

/pdf/flexible-high-energy-density-zinc-ion-batteries-enabled-by-5c41xxlgzo.pdf

Flexible high energy density zinc-ion batteries enabled by binder-free MnO2/reduced graphene oxide electrode

Identifying lithium fluorides for promising solid-state electrolyte and coating material of high-voltage cathode

The invention provides a composite flexible electrode as well as a preparation method and application thereof. The composite flexible electrode comprises a flexible current collector, flaky manganesedioxide compounded on the flexible current collector, and graphene. The composite flexible electrode as well as the preparation method and the application thereof provided by the invention have the benefits that the flaky manganese dioxide is mainly taken as an active substance, and the grapheme is taken as an electrical conductive agent, so that the electrical conductivity of the electrode can beimproved, the contact area of an electrolyte with the electrode is increased at the same time, and the diffusion distance of ions is reduced; therefore, the specific capacity and the rate performanceof a battery are improved. The invention further provides a flexible zinc ion battery and a preparation method thereof; the battery comprises the electrode and has good application and development prospects in aspects of portable foldable flexible electronics and energy devices. According to the embodiment of the invention, the flaky manganese dioxide and grapheme composite electrode is preparedby using a vacuum filtration method, a bonding agent is not required to be added, and the mass proportion of the active substance in the whole electrode is favorably improved, so that the energy density of the battery is improved. The preparation method provided by the invention is simple and is favorable for reduction in manufacturing cost.

Jiuwei Liu

Papers

Flexible and stable quasi-solid-state zinc ion battery with conductive guar gum electrolyte

Flexible quasi-solid-state zinc ion batteries enabled by highly conductive carrageenan bio-polymer electrolyte

Flexible high energy density zinc-ion batteries enabled by binder-free MnO2/reduced graphene oxide electrode

Identifying lithium fluorides for promising solid-state electrolyte and coating material of high-voltage cathode

Composite flexible electrode as well as preparation method and application thereof