Bio-inspired synthesis of nanomaterials and smart structures for electrochemical energy storage and conversion

Traditional synthetic methodologies are confronted with great challenges to fabricate complex nanomaterials with delicate design,high efficiency and excellent sustainability.During the past decade,bio-inspired synthesis has been extensively applied as an effective and efficient strategy for the fabrication of nanomaterials and nanostructures.Mimicking electrode materials at nanoscale in the aspect of either structure or functionality has been receiving surging interest because of their incomparable advantages and outperforming properties.In this review,we summarize the recent progresses on bio-inspired synthesis of nanomaterials and smart structures in the field of energy storage and conversion.Firstly,an overall introduction of bio-inspired synthetic strategies will be presented,with focus on the biotemplates and bio-resources.Following that,a library of complex mimicking structures featured by high-order,hierarchical porosity,or bionic function are introduced,with discussion on their chemical and physical properties associated with the structure.The enhanced electrochemical properties such as energy density,cycling stability,etc.in different electrochemical systems will be also discussed.At last,we will expand the perspectives regarding the advantages and limitations of bioinspired strategy and possible solutions in the future.

Biphenyl-lithium-TEGDME solution as anolyte for high energy density non-aqueous redox flow lithium battery

Non-aqueous redox flow batteries, because of larger operating voltage, have attracted considerable at- tention for high-density energy storage applications. However, the study of the anolyte is rather limited compared with the catholyte due to the labile properties of redox mediators at low potentials. Here, we report a new strategy that exploits high concentration organic lithium metal solution as a robust and energetic anolyte. The solution formed by dissolving metallic lithium with biphenyl （BP） in tetraethylene glycol dimethyl ether （TEGDME） presents a redox potential of 0.39V versus Li/Li＋, and a concentration up to 2 M. When coupled with a redox-targeted LiFePO4 catholyte system, the constructed redox flow lithium battery full cell delivers a ceil voltage of 3.0V and presents reasonably good cycling performance.

Recent advances in multifunctional metal-organic frameworks for lithium metal batteries

In view of novel materials in the field of lithium metal batteries(LMBs), metal-organic frameworks(MOFs) have attracted extensive research interest owing to their controllable pore size, unsaturated metal sites and multifunctional organic groups. A variety of MOFs have been elaborately calculated and synthesized to be applied as separator coating, electrolyte modulators and solid-state electrolyte fillers in LMBs. In this mini-review, we summarize the mechanism of MOFs to limit the migration of anions, improve the Li-ion transference number and prolong the lifespan of LMBs. Suitable pore structure of MOFs can physically restrict the movement of Li^(+). Unsaturated metal sites can adsorb anions by electrostatic interaction. In addition,multifunctional organic functional groups that limit the migration of anions are discussed. Finally, the key challenges and perspectives in the development direction of MOFs-based separators and electrolytes are further elaborated.

新型半固态液流储能电池研究进展

发展大规模储能技术是促进可再生能源高效利用及保证国家能源安全的关键。半固态液流电池兼具传统锂离子电池和均相液流电池的优点,拥有能量密度高、易放大、环境适应性强、功率/容量解耦等优点。半固态液流电池的电极液由固体活性颗粒和液态电解液构成,导致其循环稳定性差。本文将分析典型半固态液流电池储能技术的研究进展、面临的挑战,并就其未来发展趋势进行展望。

Catholyte engineering to release the capacity of iodide for high-energy-density iodine-based redox flow batteries

Due to the high solubility,high reversibility,and low cost of iodide,iodine-based redox flow batteries(RFBs)are considered to have great potential for upscaling energy storage.However,their further development has been limited by the low capacity of I−as one-third of the I−is used to form I3−(I2I−)during the charging process.Herein,we have demonstrated that the pseudohalide ion,thiocyanate(SCN−),is a promising complexing agent for catholyte of iodinebased RFBs to free up the I−by forming iodine-thiocyanate ions([I2SCN]−)instead of I3−,unlocking the capacity of iodide.Applying this strategy,we have demonstrated iodine-based RFBs with full utilization of iodide to achieve high capacity and high energy density.Both the zinc/iodine RFB and polysulfide/iodine RFB with SCN−complex agent achieve their theoretical capacity of around 160 A h Lposolyte^(−1)(6.0MI−in catholyte).Therefore,the zinc/iodine RFB delivers a high energy density of 221.34Wh Lposolyte^(−1),and the polysulfide/iodine RFB achieves a highenergy density of 165.62Wh Lposolyte^(−1).It is believed that this effective catholyte engineering can be further generalized to other iodine-based RFBs,offering new opportunities to unlock the capacity of iodide and achieve high energy density for energy storage.

Research progress on ecological protection technology of highway slope: status and challenges

Slope protection has always been a major concern in highway construction and later operation.Ecological protection technology is widely used in highway slope,which takes into account functions of protection,ecology,and landscape.Ecological protection technology is mainly to improve the stability of the slope through the combination of supporting structure and plants,and vegetation restoration can reduce the negative impact of highway construction.In this paper,the latest research progress of ecological protection technology was first reviewed to identify the main construction process and types,which revealed the protection mechanism of ecological protection technology.The comprehensive benefits of ecological slope protection technology were analysed from the aspects of air,water circulation,landscape and biodiversity.It has found that ecological protection technology of highway slope mainly forms the atmosphere-plant-soil system.Ecological protection technology of highway slope improved the stability of the slope through the supporting structure and the anchoring effect of plant roots.And the restoration of the surface vegetation on the slope promoted the photosynthesis and transpiration of plants and purifies the air quality along the highway.Ecological protection technology of highway slope could quickly restore the ecological balance,overall landscape and biodiversity of the region.

Large scale preparation of 20 cm×20 cm graphene modified carbon felt for high performance vanadium redox flow battery

Vanadium redox flow batteries(VRFBs)are widely applied in energy storage systems(e.g.,wind energy,solar energy),while the poor activity of commonly used carbon-based electrode limits their large-scale application.In this study,the graphene modified carbon felt(G/CF)with a large area of 20 cm×20 cm has been successfully prepared by a chemical vapor deposition(CVD)strategy,achieving outstanding electrocatalytic redox reversibility of the VRFBs.The decorating graphene can provide abundant active sites for the vanadium redox reactions.Compared with the pristine carbon felt(CF)electrode,the G/CF composite electrode possesses more defective sites on surface,which enhances activity toward VO^(2+)/VO^(2+)couple and electrochemical performances.For instance,such G/CF electrode delivered remarkable voltage efficiency(VE)of 88.4%and energy efficiency(EE)of 86.4%at 100 mA·cm^(-2),much higher than CF electrode by 2.1%and 3.78%,respectively.The long-term cycling stability of G/CF electrode was further investigated and a high retention value of 47.6%can be achieved over 600 cycles.It is demonstrated that this work develops a promising and effective strategy to synthesize the large size of carbon electrode with high performances for the next-generation VRFBs.

Cost-Effective Membrane and Advanced Electrode for Stable Polysulfide-Ferricyanide Flow Battery

Based on inexpensive,safe,and environmentally friendly active redox species,neutral polysulfide-ferrocyanide redox flow batteries(PFRFBs)have attracted much attention for large-scale energy storage.However,the development of PFRFBs is undermined by the expensive commercial membrane materials as well as the sluggish polysulfide redox reactions.This work attempts to solve these critical problems by combining the economical membrane with the highly catalytic electrode.In specific,K^(+)-exchanged sulfonated polyether ether ketone(SPEEK-K)membranes have been investigated in PFRFBs to replace the costly Nafion membrane.SPEEK-K with optimized degree of sulfonation enables the PFRFB high average coulombic efficiency of 99.80%and superior energy efficiency of 90.42%at a current density of 20mAcm^(-2).Meanwhile,to overcome the kinetic limitations of polysulfide redox reactions,a CuS-modified carbon felt electrode is demonstrated with excellent catalytic performance,enabling the PFRFB higher and more stable energy efficiency over cycling.The combination of the cost-effective membrane with the catalytic electrode in one cell leads to a capacity retention of 99.54%after 1180 cycles and an outstanding power density(up to 223mWcm^(-2)).The significant enhancements of electrochemical performance at reduced capital cost will make the PFRFB more promising for large-scale energy storage systems.