Flexible Aqueous Lithium‐Ion Battery with High Safety and Large Volumetric Energy Density

A flexible and wearable aqueous lithium‐ion battery is introduced based on spinel Li_1.1Mn₂O₄ cathode and a carbon‐coated NASICON‐type LiTi₂(PO₄)₃ anode (NASICON=sodium‐ion super ionic conductor). Energy densities of 63 Wh kg^?1 or 124 mWh cm^?3 and power densities of 3 275 W kg^?1 or 11.1 W cm^?3 can be obtained, which are seven times larger than the largest reported till now. The full cell can keep its capacity without significant loss under different bending states, which shows excellent flexibility. Furthermore, two such flexible cells in series with an operation voltage of 4 V can be compatible with current nonaqueous Li‐ion batteries. Therefore, such a flexible cell can potentially be put into practical applications for wearable electronics. In addition, a self‐chargeable unit is realized by integrating a single flexible aqueous Li‐ion battery with a commercial flexible solar cell, which may facilitate the long‐time outdoor operation of flexible and wearable electronic devices.     

柔性电池的最新研究进展

柔性电池作为新型柔性电子设备的关键部件,得到越来越多的关注.近年来,柔性锂离子电池取得了实质性的发展,并在卷曲式显示器、触摸屏、可穿戴动力传感器和可植入医疗装置等方面得到应用.本文主要介绍柔性锂离子电池的发展现状,分别从集流体、电极材料和电解质三部分进行阐述,特别介绍拉伸性能的实现途径,根据其不同的结构特点,可以分为波形结构、点阵互联结构、纺织结构、折纸结构和电缆式结构,并提出将柔性材料与新型结构相结合可以促进柔性电池发展.同时,也对其他柔性电池体系,如锂硫电池、燃料电池和太阳能电池等的最新发展进行简单概述.最后,对目前柔性电池的发展过程中存在的问题进行了总结,并对其未来的发展方向与面临的挑战进行展望.     

Hydrophobic Organic-Electrolyte-Protected Zinc Anodes for Aqueous Zinc Batteries

Aqueous Zn batteries are promising energy-storage devices. However, their lifespan is limited by irreversible Zn anodes owing to water decomposition and Zn dendrite growth. Here, we separate aqueous electrolyte from Zn anode by coating a thin MOF layer on anode and filling the pores of MOF with hydrophobic Zn(TFSI)₂-tris(2,2,2-trifluoroethyl)phosphate (TFEP) organic electrolyte that is immiscible with aqueous Zn(TFSI)₂–H₂O bulk electrolyte. The MOF encapsulated Zn(TFSI)₂-TFEP forms a ZnF₂-Zn₃(PO₄)₂ solid electrolyte interphase (SEI) preventing Zn dendrite and water decomposition. The Zn(TFSI)₂-TFEP@MOF electrolyte protected Zn anode enables a Zn||Ti cell to achieve a high average Coulombic efficiency of 99.1 % for 350 cycles. The highly reversible Zn anode brings a high energy density of 210 Wh kg⁻¹ (of cathode and anode mass) and a low capacity decay rate of 0.0047 % per cycle over 600 cycles in a Zn||MnO₂ full cell with a low capacity ratio of Zn:MnO₂ at 2:1.     

A Deep‐Cycle Aqueous Zinc‐Ion Battery Containing an Oxygen‐Deficient Vanadium Oxide Cathode

Rechargeable aqueous zinc‐ion batteries are attractive because of their inherent safety, low cost, and high energy density. However, viable cathode materials (such as vanadium oxides) suffer from strong Coulombic ion–lattice interactions with divalent Zn²⁺, thereby limiting stability when cycled at a high charge/discharge depth with high capacity. A synthetic strategy is reported for an oxygen‐deficient vanadium oxide cathode in which facilitated Zn²⁺ reaction kinetic enhance capacity and Zn²⁺ pathways for high reversibility. The benefits for the robust cathode are evident in its performance metrics; the aqueous Zn battery shows an unprecedented stability over 200 cycles with a high specific capacity of approximately 400 mAh g^?1, achieving 95 % utilization of its theoretical capacity, and a long cycle life up to 2 000 cycles at a high cathode utilization efficiency of 67 %. This work opens up a new avenue for synthesis of novel cathode materials with an oxygen‐deficient structure for use in advanced batteries.     

Proton Insertion Chemistry of a Zinc–Organic Battery

Proton storage in rechargeable aqueous zinc‐ion batteries (ZIBs) is attracting extensive attention owing to the fast kinetics of H⁺ insertion/extraction. However, it has not been achieved in organic materials‐based ZIBs with a mild electrolyte. Now, aqueous ZIBs based on diquinoxalino [2,3‐a:2′,3′‐c] phenazine (HATN) in a mild electrolyte are developed. Electrochemical and structural analysis confirm for the first time that such Zn–HATN batteries experience a H⁺ uptake/removal behavior with highly reversible structural evolution of HATN. The H⁺ uptake/removal endows the Zn–HATN batteries with enhanced electrochemical performance. Proton insertion chemistry will broaden the horizons of aqueous Zn–organic batteries and open up new opportunities to construct high‐performance ZIBs.     

A Truxenone-based Covalent Organic Framework as an All-Solid-State Lithium-Ion Battery Cathode with High Capacity

All-solid-state lithium ion batteries (LIBs) are ideal for energy storage given their safety and long-term stability. However, there is a limited availability of viable electrode active materials. Herein, we report a truxenone-based covalent organic framework (COF-TRO) as cathode materials for all-solid-state LIBs. The high-density carbonyl groups combined with the ordered crystalline COF structure greatly facilitate lithium ion storage via reversible redox reactions. As a result, a high specific capacity of 268 mAh g⁻¹, almost 97.5 % of the calculated theoretical capacity was achieved. To the best of our knowledge, this is the highest capacity among all COF-based cathode materials for all-solid-state LIBs reported so far. Moreover, the excellent cycling stability (99.9 % capacity retention after 100 cycles at 0.1 C rate) shown by COF-TRO suggests such truxenone-based COFs have great potential in energy storage applications.     

Freestanding Carbon Nanotube Film for Flexible Straplike Lithium/Sulfur Batteries

Flexible lithium/sulfur (Li/S) batteries are promising to meet the emerging power demand for flexible electronic devices. The key challenge for a flexible Li/S battery is to design a cathode with excellent electrochemical performance and mechanical flexibility. In this work, a flexible strap-like Li/S battery based on a S@carbon nanotube/Pt@carbon nanotube hybrid film cathode was designed. It delivers a specific capacity of 1145 mAh g⁻¹ at the first cycle and retains a specific capacity of 822 mAh g⁻¹ after 100 cycles. Moreover, the flexible Li/S battery retains stabile specific capacity and Coulombic efficiency even under severe bending conditions. As a demonstration of practical applications, an LED array is shown stably powered by the flexible Li/S battery under flattened and bent states. We also use the strap-like flexible Li/S battery as a real strap for a watch, which at the same time provides a reliable power supply to the watch.     

柔性可穿戴传感器件与储能器件的发展现状与挑战

随着人们生活质量与对可穿戴监测设备需求的提高以及物联网、人工智能和人机交互等科技水平的发展,能够对人体生命体征信号采集、转化与识别的可穿戴柔性电子装置成为连接智能生物与非智能机械装置的桥梁. 可穿戴柔性电子器件对人体生命体征信号的采集包括人体脉搏、温度、皮肤应变、呼吸和心跳等指标. 本文总结概述了近年来可穿戴柔性传感器对人体生命信号采集的现状以及存在的问题和挑战,并对可穿戴柔性供能器件做了简要的总结和展望.     

Constructing a Super-Saturated Electrolyte Front Surface for Stable Rechargeable Aqueous Zinc Batteries

Rechargeable aqueous zinc batteries (RAZB) have been re-evaluated because of the superiority in addressing safety and cost concerns. Nonetheless, the limited lifespan arising from dendritic electrodeposition of metallic Zn hinders their further development. Herein, a metal–organic framework (MOF) was constructed as front surface layer to maintain a super-saturated electrolyte layer on the Zn anode. Raman spectroscopy indicated that the highly coordinated ion complexes migrating through the MOF channels were different from the solvation structure in bulk electrolyte. Benefiting from the unique super-saturated front surface, symmetric Zn cells survived up to 3000 hours at 0.5 mA cm⁻², near 55-times that of bare Zn anodes. Moreover, aqueous MnO₂–Zn batteries delivered a reversible capacity of 180.3 mAh g⁻¹ and maintained a high capacity retention of 88.9 % after 600 cycles with MnO₂ mass loading up to 4.2 mg cm⁻².     

水系锌离子电池研究进展和挑战

水系锌离子电池(AZIBs)作为一种新兴电池储能技术,具有安全性高、价格低廉、能量密度高、环境友好、易制造等优点,在大规模储能等领域具有良好的应用价值和前景,近年引起了人们的广泛关注且发展迅速.作者从目前AZIBs存在的科学问题出发,综述了AZIBs在正负极材料及电解液方面取得的重要进展,对己开发的多种正极材料的特点及...     

An Organic Coordination Manganese Complex as Cathode for High-Voltage Aqueous Zinc-metal Battery

Aqueous Zn−Mn battery has been considered as the most promising scalable energy-storage system due to its intrinsic safety and especially ultralow cost. However, the traditional Zn−Mn battery mainly using manganese oxides as cathode shows low voltage and suffers from dissolution/disproportionation of the cathode during cycling. Herein, for the first time, a high-voltage and long-cycle Zn−Mn battery based on a highly reversible organic coordination manganese complex cathode (Manganese polyacrylate, PAL−Mn) was constructed. Benefiting from the insoluble carboxylate ligand of PAL−Mn that can suppress shuttle effect and disproportionationation reaction of Mn³⁺ in a mild electrolyte, Mn³⁺/Mn²⁺ reaction in coordination state is realized, which not only offers a high discharge voltage of 1.67 V but also exhibits excellent cyclability (100 % capacity retention, after 4000 cycles). High voltage reaction endows the Zn−Mn battery high specific energy (600 Wh kg⁻¹ at 0.2 A g⁻¹), indicating a bright application prospect. The strategy of introducing carboxylate ligands in Zn−Mn battery to harness high-voltage reaction of Mn³⁺/Mn²⁺ well broadens the research of high-voltage Zn−Mn batteries under mild electrolyte conditions.     

A Low‐Cost and Environmentally Friendly Mixed Polyanionic Cathode for Sodium‐Ion Storage

Sodium‐ion batteries (NIBs) are the most promising alternatives to lithium‐ion batteries in the development of renewable energy sources. The advancement of NIBs depends on the exploration of new electrode materials and fundamental understanding of working mechanisms. Herein, via experimental and simulation methods, we develop a mixed polyanionic compound, Na₂Fe(C₂O₄)SO₄?H₂O, as a cathode for NIBs. Thanks to its rigid three dimensional framework and the combined inductive effects from oxalate and sulfate, it delivered reversible Na insertion/desertion at average discharging voltages of 3.5 and 3.1 V for 500 cycles with Coulombic efficiencies of ca. 99 %. In situ synchrotron X‐ray measurements and DFT calculations demonstrate the Fe²⁺/Fe³⁺ redox reactions contribute to electron compensation during Na⁺ desertion/insertion. The study suggests mixed polyanionic frameworks may provide promising materials for Na ion storage with the merits of low cost and environmental friendliness.     

Constructing a Super‐Saturated Electrolyte Front Surface for Stable Rechargeable Aqueous Zinc Batteries

Rechargeable aqueous zinc batteries (RAZB) have been re‐evaluated because of the superiority in addressing safety and cost concerns. Nonetheless, the limited lifespan arising from dendritic electrodeposition of metallic Zn hinders their further development. Herein, a metal–organic framework (MOF) was constructed as front surface layer to maintain a super‐saturated electrolyte layer on the Zn anode. Raman spectroscopy indicated that the highly coordinated ion complexes migrating through the MOF channels were different from the solvation structure in bulk electrolyte. Benefiting from the unique super‐saturated front surface, symmetric Zn cells survived up to 3000 hours at 0.5 mA cm^?2, near 55‐times that of bare Zn anodes. Moreover, aqueous MnO₂–Zn batteries delivered a reversible capacity of 180.3 mAh g^?1 and maintained a high capacity retention of 88.9 % after 600 cycles with MnO₂ mass loading up to 4.2 mg cm^?2.     

Highly Stable Aqueous Zinc‐Ion Storage Using a Layered Calcium Vanadium Oxide Bronze Cathode

Cost‐effective aqueous rechargeable batteries are attractive alternatives to non‐aqueous cells for stationary grid energy storage. Among different aqueous cells, zinc‐ion batteries (ZIBs), based on Zn²⁺ intercalation chemistry, stand out as they can employ high‐capacity Zn metal as the anode material. Herein, we report a layered calcium vanadium oxide bronze as the cathode material for aqueous Zn batteries. For the storage of the Zn²⁺ ions in the aqueous electrolyte, we demonstrate that the calcium‐based bronze structure can deliver a high capacity of 340 mA h g^?1 at 0.2 C, good rate capability, and very long cycling life (96 % retention after 3000 cycles at 80 C). Further, we investigate the Zn²⁺ storage mechanism, and the corresponding electrochemical kinetics in this bronze cathode. Finally, we show that our Zn cell delivers an energy density of 267 W h kg^?1 at a power density of 53.4 W kg^?1.     

Engineering Active Sites of Polyaniline for AlCl2+ Storage in an Aluminum-Ion Battery

The reversible capacity of AlCl₄⁻ intercalation/de-intercalation in conventional cathodes of aluminum-ion batteries (AIBs) is difficult to improve due to the large size of AlCl₄⁻ anions. Therefore, it is highly desirable to realize the intercalation/de-intercalation of smaller Al-based ions. Here, we fabricated polyaniline/single-walled carbon nanotubes (PANI/SWCNTs) composite films and protonated the PANI nanorods. The protonation endows PANI with more active sites and enhanced conductivity. Hyper self-protonated PANI (PANI(H⁺)) exhibits reversible AlCl₂⁺ intercalation/de-intercalation during the discharge/charge process. As a result, the discharge capacity of the Al/PANI(H⁺) battery is twice as high as that of the initial composite films. PANI(H⁺)@SWCNT electrodes also have a stable cycling life with only 0.003 % capacity decay per cycle over 8000 cycles. Owing to the excellent mechanical properties, PANI(H⁺)@SWCNT composite films can act as the electrodes of flexible AIBs.     

A Universal Organic Cathode for Ultrafast Lithium and Multivalent Metal Batteries

Low‐cost multivalent battery chemistries (Mg²⁺, Al³⁺) have been extensively investigated for large‐scale energy storage applications. However, their commercialization is plagued by the poor power density and cycle life of cathodes. A universal polyimides@CNT (PI@CNT) cathode is now presented that can reversibly store various cations with different valences (Li⁺, Mg²⁺, Al³⁺) at an extremely fast rate. The ion‐coordination charge storage mechanism of PI@CNT is systemically investigated. Full cells using PI@CNT cathodes and corresponding metal anodes exhibit long cycle life (>10000 cycles), fast kinetics (>20 C), and wide operating temperature range (?40 to 50 °C), making the low‐cost industrial polyimides universal cathodes for different multivalent metal batteries. The stable ion‐coordinated mechanism opens a new foundation for the development of high‐energy and high‐power multivalent batteries.     

高分子导电水凝胶的制备及在柔性可穿戴电子设备中的应用

水凝胶是具有高含水量、可变形性和良好生物相容性的材料,其中导电水凝胶具有良好的导电性、可调节的机械性及自黏附性等特征,逐渐成为制备柔性可穿戴电子设备的最佳候选材料。近年来,具有生物相容性、机械柔韧性和抗疲劳性的导电水凝胶得到广泛研究,能够实现多种生理信号和物理信号的监测及传输,促进了柔性可穿戴电子设备的发展。柔性可穿戴电子设备逐渐成为人机交互技术和人工智能领域的主要研究方向。导电水凝胶通过使用导电聚合物、导电填料、自由离子及其混合物来合成,根据导电机理,所制备的导电水凝胶可分为电子导电水凝胶、离子导电水凝胶和混合电子-离子导电水凝胶。本文讨论了导电水凝胶的制备方法,总结了导电水凝胶在可拉伸性、导电性、生物相容性和自修复性等功能方面的研究进展及其在柔性可穿戴电子设备中的应用,期望导电水凝胶可以取得更好的发展。     

Engineering Active Sites of Polyaniline for AlCl2+ Storage in an Aluminum‐Ion Battery

The reversible capacity of AlCl₄^? intercalation/de‐intercalation in conventional cathodes of aluminum‐ion batteries (AIBs) is difficult to improve due to the large size of AlCl₄^? anions. Therefore, it is highly desirable to realize the intercalation/de‐intercalation of smaller Al‐based ions. Here, we fabricated polyaniline/single‐walled carbon nanotubes (PANI/SWCNTs) composite films and protonated the PANI nanorods. The protonation endows PANI with more active sites and enhanced conductivity. Hyper self‐protonated PANI (PANI(H⁺)) exhibits reversible AlCl₂⁺ intercalation/de‐intercalation during the discharge/charge process. As a result, the discharge capacity of the Al/PANI(H⁺) battery is twice as high as that of the initial composite films. PANI(H⁺)@SWCNT electrodes also have a stable cycling life with only 0.003 % capacity decay per cycle over 8000 cycles. Owing to the excellent mechanical properties, PANI(H⁺)@SWCNT composite films can act as the electrodes of flexible AIBs.     

基于有机物电极的电化学能量存储与转化

由于高安全的特性,水系二次电池被认为是未来大型储能的有效解决方案之一. 然而,现有水系电池主要以含金属元素的无机化合物为电极活性材料,其在大型储能中的实际应用仍受到循环寿命、环境问题、原料成本或金属元素丰度的限制. 相较于无机电极材料,部分有机电极材料具有原料丰富、结构丰富、可持续及环境友好等优点. 此外,有机物材料分子内空间大,能够存储不同价态电荷,因此近年来被广泛关注. 本文综述了课题组近期在有机物电极方面的研究进展,内容聚焦含羰基有机物通过C=O/C-O-的可逆转化存储单价金属阳离子(Li⁺, Na⁺)、双价金属阳离子(Zn²⁺)、质子(H⁺)所涉及的电化学过程,及其在水系锂、钠离子电池、水系锌离子电池、质子电池以及分步电解水中的应用.     

Metal Oxide Nanostructures Generated from In Situ Sacrifice of Zinc in Bimetallic Textures as Flexible Ni/Fe Fast Battery Electrodes

An “in situ sacrifice” process was devised in this work as a room‐temperature, all‐solution processed electrochemical method to synthesize nanostructured NiO_x and FeO_x directly on current collectors. After electrodepositing NiZn/FeZn bimetallic textures on a copper net, the zinc component is etched and the remnant nickel/iron are evolved into NiO_x and FeO_x by the “in situ sacrifice” activation we propose. As‐prepared electrodes exhibit high areal capacities of 0.47 mA h cm⁻² and 0.32 mA h cm⁻², respectively. By integrating NiO_x as the cathode, FeO_x as the anode, and poly(vinyl alcohol) (PVA)‐KOH gel as the separator/solid‐state electrolyte, the assembled quasi‐solid‐state flexible battery delivers a volumetric capacity of 6.91 mA h cm⁻³ at 5 mA cm⁻², along with a maximum energy density of 7.40 mWh cm⁻³ under a power density of 0.27 W cm⁻³ and a maximum tested power density of 3.13 W cm⁻³ with a 2.17 mW h cm⁻³ energy density retention. Our room‐temperature synthesis, which only consumes minute electricity, makes it a promising approach for large‐scale production. We also emphasize the in situ sacrifice zinc etching process used in this work as a general strategy for metal‐based nanostructure growth for high‐performance battery materials.