Haoran Xu

Bio: Haoran Xu is an academic researcher from Zhejiang University. The author has contributed to research in topics: Solid oxide fuel cell & Anode. The author has an hindex of 23, co-authored 72 publications receiving 1676 citations. Previous affiliations of Haoran Xu include Loughborough University & Heriot-Watt University.

Flexible Zn– and Li–air batteries: recent advances, challenges, and future perspectives

Abstract: The demand for flexible power sources with high energy density and durability has increased rapidly with the development of flexible and wearable electronic devices. Metal–air batteries are considered as the most promising candidates for these applications due to their excellent theoretical energy densities. In particular, rechargeable zinc–air and lithium–air batteries have attracted much attention because of their potential to offer high energy density while maintaining a long operational life. Although significant progress has been made in enhancing the electrochemical performance of these batteries, many technical challenges still remain to achieve the mechanical flexibility required for wearable electronic devices while maintaining high performance. This article describes the most recent advances and challenges in the development of flexible zinc–air and lithium–air batteries. We start with an overview of the latest innovations in the exploration of various battery configurations to effectively accommodate stresses and strains associated with the use of flexible electronic devices. This is followed by a detailed review of the advancements made in the design of flexible battery components: the metal electrode, the electrolyte membrane, and the air electrode. Furthermore, the effects of operating conditions on battery performance characteristics and durabilities are discussed, including the effect of the operating temperature and the contaminants commonly encountered in ambient air (e.g., carbon dioxide and moisture). Finally, challenges facing the development of a new generation of flexible metal–air batteries are highlighted, together with further research directions and perspectives.

In-situ growth of Co3O4 nanowire-assembled clusters on nickel foam for aqueous rechargeable Zn-Co3O4 and Zn-air batteries

Abstract: With the urgent requirements for advanced energy storage systems, rechargeable Zn-based batteries attract research interest due to the remarkable theoretical capacity, low cost, and environmental benignity Hence, developing effective battery materials are in great need In this work, an electrode composed of Co3O4 nanowire-assembled clusters is developed The porous Co3O4 nanowires are directly coupled to the underlying nickel foam to form clusters, avoiding the use of additional binders and conductive carbons This hierarchical structure not only provides large active surfaces and facilitates species transport, but also favors the structural stability In an alkaline solution, this electrode exhibits high activity toward both oxygen reduction and evolution reactions and large specific capacitance, indicating the excellent electrochemical performance A Zn-Co3O4 battery using this electrode delivers an energy density up to 239 Wh kg−1 on the basis of the Co3O4 loading and the theoretical capacity of zinc, and the capacity retention reaches 841% after 1000 cycles Moreover, a hybrid Zn-Co3O4/air battery fitted with the present electrode exhibits a high capacity of 771 mAh gZn−1 and excellent cycling stability for over 1000 cycles (over 333 h) at 10 mA cm−2 with a fixed capacity of 167 mA cm−2 while maintaining the energy efficiency of ∼70% The results show that the nickel foam coated with Co3O4 nanowire-assembled clusters is a promising electrode for high-performance rechargeable Zn-based batteries with high energy density, energy efficiency, and cycling stability

Co3O4 Nanosheets as Active Material for Hybrid Zn Batteries

Abstract: The rapid development of electric vehicles and modern personal electronic devices is severely hindered by the limited energy and power density of the existing power sources. Here a novel hybrid Zn battery is reported which is composed of a nanostructured transition metal oxide-based positive electrode (i.e., Co3 O4 nanosheets grown on carbon cloth) and a Zn foil negative electrode in an aqueous alkaline electrolyte. The hybrid battery configuration successfully combines the unique advantages of a Zn-Co3 O4 battery and a Zn-air battery, achieving a high voltage of 1.85 V in the Zn-Co3 O4 battery region and a high capacity of 792 mAh gZn-1 . In addition, the battery shows high stability while maintaining high energy efficiency (higher than 70%) for over 200 cycles and high rate capabilities. Furthermore, the high flexibility of the carbon cloth substrate allows the construction of a flexible battery with a gel electrolyte, demonstrating not only good rechargeability and stability, but also reasonable mechanical deformation without noticeable degradation in performance. This work also provides an inspiring example for further explorations of high-performance hybrid and flexible battery systems.

Energy storage: The future enabled by nanomaterials

Abstract: Lithium-ion batteries, which power portable electronics, electric vehicles, and stationary storage, have been recognized with the 2019 Nobel Prize in chemistry. The development of nanomaterials and their related processing into electrodes and devices can improve the performance and/or development of the existing energy storage systems. We provide a perspective on recent progress in the application of nanomaterials in energy storage devices, such as supercapacitors and batteries. The versatility of nanomaterials can lead to power sources for portable, flexible, foldable, and distributable electronics; electric transportation; and grid-scale storage, as well as integration in living environments and biomedical systems. To overcome limitations of nanomaterials related to high reactivity and chemical instability caused by their high surface area, nanoparticles with different functionalities should be combined in smart architectures on nano- and microscales. The integration of nanomaterials into functional architectures and devices requires the development of advanced manufacturing approaches. We discuss successful strategies and outline a roadmap for the exploitation of nanomaterials for enabling future energy storage applications, such as powering distributed sensor networks and flexible and wearable electronics.

Advanced Carbon for Flexible and Wearable Electronics.

Abstract: Flexible and wearable electronics are attracting wide attention due to their potential applications in wearable human health monitoring and care systems. Carbon materials have combined superiorities such as good electrical conductivity, intrinsic and structural flexibility, light weight, high chemical and thermal stability, ease of chemical functionalization, as well as potential mass production, enabling them to be promising candidate materials for flexible and wearable electronics. Consequently, great efforts are devoted to the controlled fabrication of carbon materials with rationally designed structures for applications in next-generation electronics. Herein, the latest advances in the rational design and controlled fabrication of carbon materials toward applications in flexible and wearable electronics are reviewed. Various carbon materials (carbon nanotubes, graphene, natural-biomaterial-derived carbon, etc.) with controlled micro/nanostructures and designed macroscopic morphologies for high-performance flexible electronics are introduced. The fabrication strategies, working mechanism, performance, and applications of carbon-based flexible devices are reviewed and discussed, including strain/pressure sensors, temperature/humidity sensors, electrochemical sensors, flexible conductive electrodes/wires, and flexible power devices. Furthermore, the integration of multiple devices toward multifunctional wearable systems is briefly reviewed. Finally, the existing challenges and future opportunities in this field are summarized.

Advanced Architectures and Relatives of Air Electrodes in Zn-Air Batteries.

Abstract: Zn-air batteries are becoming the promising power sources for portable and wearable electronic devices and hybrid/electric vehicles because of their high specific energy density and the low cost for next-generation green and sustainable energy technologies. An air electrode integrated with an oxygen electrocatalyst is the most important component and inevitably determines the performance and cost of a Zn-air battery. This article presents exciting advances and challenges related to air electrodes and their relatives. After a brief introduction of the Zn-air battery, the architectures and oxygen electrocatalysts of air electrodes and relevant electrolytes are highlighted in primary and rechargeable types with different configurations, respectively. Moreover, the individual components and major issues of flexible Zn-air batteries are also highlighted, along with the strategies to enhance the battery performance. Finally, a perspective for design, preparation, and assembly of air electrodes is proposed for the future innovations of Zn-air batteries with high performance.

Durability Investigation of Carbon Nanotube as Catalyst Support for Proton Exchange Membrane Fuel Cell Electrode

Abstract: Abstract Electrochemical surface oxidation of carbon black Vulcan XC-72 and multiwalled carbon nanotube (MWNT) has been compared following potentiostatic treatments up to 168 h under condition simulating PEMFC cathode environment (60 °C, N2 purged 0.5 M H2SO4, and a constant potential of 0.9 V). The subsequent electrochemical characterization at different treatment time intervals suggests that MWNT is electrochemically more stable than Vulcan XC-72 with less surface oxide formation and 30% lower corrosion current under the investigated condition. As a result of high corrosion resistance, MWNT shows lower loss of Pt surface area and oxygen reduction reaction activity when used as fuel cell catalyst support.