One of the ambitions of Science Robotics is to deeply root robotics research in science while developing novel robotic platforms that will enable new scientific discoveries. Of our 10 grand challenges, the first 7 represent underpinning technologies that have a wider impact on all application areas of robotics. For the next two challenges, we have included social robotics and medical robotics as application-specific areas of development to highlight the substantial societal and health impacts that they will bring. Finally, the last challenge is related to responsible innovation and how ethics and security should be carefully considered as we develop the technology further.

The grand challenges of Science Robotics

Organic electrode materials are very attractive for electrochemical energy storage devices because they can be flexible, lightweight, low cost, benign to the environment, and used in a variety of device architectures. They are not mere alternatives to more traditional energy storage materials, rather, they have the potential to lead to disruptive technologies. Although organic electrode materials for energy storage have progressed in recent years, there are still significant challenges to overcome before reaching large-scale commercialization. This review provides an overview of energy storage systems as a whole, the metrics that are used to quantify the performance of electrodes, recent strategies that have been investigated to overcome the challenges associated with organic electrode materials, and the use of computational chemistry to design and study new materials and their properties. Design strategies are examined to overcome issues with capacity/capacitance, device voltage, rate capability, and cycling stability in order to guide future work in the area. The use of low cost materials is highlighted as a direction towards commercial realization.

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The rise of organic electrode materials for energy storage

Covalent organic frameworks (COFs) have attracted growing interest by virtue of their structural diversity and tunability. Herein, we present a novel approach for the development of organic rechargeable battery cathodes in which three distinct redox-active COFs were successfully prepared and delaminated into 2D few-layer nanosheets. Compared with the pristine COFs, the exfoliated COFs with shorter Li+ diffusion pathways allow a significant higher utilization efficiency of redox sites and faster kinetics for lithium storage. Unlike diffusion-controlled manners in the bulk COFs, the redox reactions in ECOFs are mainly dominated by charge transfer process. The capacity and potential are further engineered by reticular design of COFs without altering the underlying topology. Specifically, DAAQ-ECOF exhibits excellent rechargeability (98% capacity retention after 1800 cycles) and fast charge–discharge ability (74% retention at 500 mA g–1 as compared to at 20 mA g–1). DABQ-ECOF shows a specific capacity of 210 ...

Exfoliation of Covalent Organic Frameworks into Few-Layer Redox-Active Nanosheets as Cathode Materials for Lithium-Ion Batteries

Organic materials have attracted much attention for their utility as lithium-battery electrodes because their tunable structures can be sustainably prepared from abundant precursors in an environmentally friendly manner. Most research into organic electrodes has focused on the material level instead of evaluating performance in practical batteries. This Review addresses this by first providing an overview of the history and redox of organic electrode materials and then evaluating the prospects and remaining challenges of organic electrode materials for practical lithium batteries. Our evaluations are made according to energy density, power density, cycle life, gravimetric density, electronic conductivity and other relevant parameters, such as energy efficiency, cost and resource availability. We posit that research in this field must focus more on the intrinsic electronic conductivity and density of organic electrode materials, after which a comprehensive optimization of full batteries should be performed under practically relevant conditions. We hope to stimulate high-quality applied research that might see the future commercialization of organic electrode materials. Organic materials can serve as sustainable electrodes in lithium batteries. This Review describes the desirable characteristics of organic electrodes and the corresponding batteries and how we should evaluate them in terms of performance, cost and sustainability.

Prospects of organic electrode materials for practical lithium batteries

The development of various redox-flow batteries for the storage of fluctuating renewable energy has intensified in recent years because of their peculiar ability to be scaled separately in terms of energy and power, and therefore potentially to reduce the costs of energy storage. This has resulted in a considerable increase in the number of publications on redox-flow batteries. This was a motivation to present a comprehensive and critical overview of the features of this type of batteries, focusing mainly on the chemistry of electrolytes and introducing a thorough systematic classification to reveal their potential for future development.

The Chemistry of Redox-Flow Batteries.

Spatial separation of the electrolyte and electrode is the main characteristic of flow-battery technologies, which liberates them from the constraints of overall energy content and the energy/power ratio. The concept of a flowing electrolyte not only presents a cost-effective approach for large-scale energy storage, but has also recently been used to develop a wide range of new hybrid energy storage and conversion systems. The advent of flow-based lithium-ion, organic redox-active materials, metal–air cells and photoelectrochemical batteries promises new opportunities for advanced electrical energy-storage technologies. In this Review, we present a critical overview of recent progress in conventional aqueous redox-flow batteries and next-generation flow batteries, highlighting the latest innovative alternative materials. We outline their technical feasibility for use in long-term and large-scale electrical energy-storage devices, as well as the limitations that need to be overcome, providing our view of promising future research directions in the field of redox-flow batteries. Flow-battery technologies open a new age of large-scale electrical energy-storage systems. This Review highlights the latest innovative materials and their technical feasibility for next-generation flow batteries.

Material design and engineering of next-generation flow-battery technologies

Recent studies on all-vanadium redox flow batteries (VRFBs) have focused on carbon-based materials for cost-effective electrocatalysts to commercialize them in grid-scale energy storage markets. We report an environmentally friendly and safe method to produce carbon-based catalysts by corn protein self-assembly. This new method allows carbon black (CB) nanoparticles to be coated with nitrogen-doped graphitic layers with oxygen-rich functionalities (N-CB). We observed increased catalytic activity of this catalyst toward both V2+/V3+ and VO2+/VO2+ ions, showing a 24% increased mass transfer process and ca. 50 mV higher reduction onset potential compared to CB catalyst. It is believed that the abundant oxygen active sites and nitrogen defects in the N-CB catalyst are beneficial to the vanadium redox reaction by improving the electron transfer rate and giving faster vanadium ion transfer kinetics.

Corn protein-derived nitrogen-doped carbon materials with oxygen-rich functional groups: a highly efficient electrocatalyst for all-vanadium redox flow batteries

Aluminum-air batteries are considered as next-generation batteries owing to their high energy density with the abundant reserves, low cost, and lightweight of aluminum. However, there are several hurdles to be overcome, such as the sluggish rate of the oxygen reduction reaction (ORR) at the air electrode, precipitation of aluminum hydroxides and oxides at the anode, and severe hydrogen evolution problems at the interface of the anode and the electrolyte. Here, recent advances in silver metal and metal-nitrogen-carbon-based ORR electrocatalysts, aluminum anodes, electrolytes, and the requirements of future research directions are mainly summarized.

Advanced Technologies for High-Energy Aluminum–Air Batteries

DOI: 10.1002/aenm.201401550 Recently, vanadium redox reactions were extensively studied to improve their catalytic activity for better electron conductivity and mass-transfer kinetics. The investigation of various electrocatalysts for the VRFBs can be categorized into metal-based [ 6–9 ] and carbon-based [ 10–14 ] nanomaterials. In the latter case, the carbon-based catalysts such as carbon nanotube (CNT), carbon nanofi ber (CNF), and graphene are considered promising candidates due to their large surface area, high conductivity, and stability under concentrated acidic conditions. [ 11,14 ] These nanomaterials are usually used by coating them onto a carbon-felt or carbonpaper electrode. Recently, nitrogen-doped CNT, [ 13 ] multi-walled CNT, [ 15 ] and CNT/CNF hybrid-coated [ 10 ] carbon-felt electrodes were reported, in which oxygen or nitrogen atoms within the carbon structure help the vanadium redox reactions. In particular, graphene-based nanomaterials have demonstrated improved catalytic properties in VRFB systems. [ 12 ]

Jaechan Ryu

Papers

Material design and engineering of next-generation flow-battery technologies

Corn protein-derived nitrogen-doped carbon materials with oxygen-rich functional groups: a highly efficient electrocatalyst for all-vanadium redox flow batteries

Advanced Technologies for High-Energy Aluminum–Air Batteries

Exploration of the Effective Location of Surface Oxygen Defects in Graphene‐Based Electrocatalysts for All‐Vanadium Redox‐Flow Batteries

Edge-halogenated graphene nanoplatelets with F, Cl, or Br as electrocatalysts for all-vanadium redox flow batteries