摘要: Micro-supercapacitors hold great promise for powering the Internet of Things devices owing to their high power density and long cycling life. However, the limited energy density hinders their practical use. Electrode materials play an important role in the performance of micro-supercapacitors. With the advantages of a large specific surface area and a high electrical conductivity, graphene has been considered a good candidate for the electrode material of micro-supercapacitors. The two-dimensional surface of graphene is parallel to the direction of transport of the electrolyte ions for micro-supercapacitors with an in-plane structure, which helps improve the ion accessibility of the electrodes. Therefore, the construction of graphene-based in-plane micro-supercapacitors has aroused great interest among researchers. Here, we summarize the recent advances in graphene and graphene-based materials for in-plane micro-supercapacitors from the perspective of electrode material design. The electrode materials include graphenes produced by chemical vapor deposition, liquid-phase exfoliation, reduction of graphene oxide, laser induction and heteroatom doping, as well as graphene-based composites, such as carbon nanotube/graphene, transition metal oxide/graphene, conducting polymer/graphene and two-dimensional material/graphene composites. Challenges and opportunities in graphene-based in-plane micro-supercapacitors are discussed, and future research directions and development trends are proposed.
摘要: A silicon anode with a high specific capacity is one of the most promising candidates for developing advanced rechargeable lithium-ion batteries (LIBs). However, the problems of low electrical conductivity, severe volume changes during use and an unstable solid electrolyte interface seriously hinder their use in LIBs. Although using the carbon materials used to construct Si/C composite anodes have demonstrated their advantages in improving the performance of Si-based anodes, the binder, another key component of the electrode, also has a significant effect on the electrochemical performance of a battery. A self-healing binder uses non-covalent and reversible covalent bonds to effectively improve the cycling stability of LIBs by repairing the internal/external damage caused by the huge volume change of a Si-based anode. As for the solid-state polymer electrolytes (SPEs) of flexible lithium batteries, the use of self-healing polymers can also quickly repair the damages or cracks in the SPEs, and have a promising prospect in the development of flexible and wearable electronics. The paper gives an overview of the synthesis, characterization and self-healing mechanisms of the self-healing polymer binders for use in Si and Si/C anodes and their recent application in flexible lithium batteries is briefly summarized. The related technical challenges and design requirements for self-healing polymer binders used in the Si and Si/C anodes of LIBs are discussed.
摘要: The ever-growing demands for wearable devices has stimulated the development of advanced flexible energy storage devices. Aqueous rechargeable zinc ion batteries (ZIBs) have gained much attention due to their low cost and intrinsic safety. Carbon materials with excellent conductivity, high mechanical strength, and light weight, can be used to construct flexible ZIBs (FZIBs). Here, we summarize the recent advances in carbon materials (e.g., carbon nanotubes, carbon fibers, graphene) for high-performance FZIBs with one-dimensional cable-shaped, two-dimensional planar, and three-dimensional sandwich configurations. Ways for constructing different types of FZIBs for better electrochemical performance are emphasized. The vital roles of carbons as the conductive materials and current collectors of cathodes, the current collectors and host materials of anodes, and modifiers of functional separators are discussed. The challenges and prospects of advanced carbon materials for next-generation FZIBs are also briefly discussed.
摘要: With the rapid growth of the flexible and wearable electronics market, there have been big advances in flexible electrochemical energy storage technologies. Developing flexible electrodes with a low cost, superior safety, and high performance remains a great challenge. In recent years, potassium-based electrochemical energy storage devices have received much attention by virtue of their cost competitiveness and the availability of potassium resources. Carbon materials have been widely used as electrode materials or substrates for flexible energy storage devices due to their excellent properties, such as low weight, non-toxicity and abundance. Here, we summarize the recent advances in carbon materials (e.g. carbon nanofibers, carbon nanotubes, and graphene) for use in flexible electrochemical potassium storage devices, including potassium-ion batteries, potassium-ion hybrid capacitors, and K-S/Se batteries. Strategies for the synthesis of carbon-based flexible electrodes and their reported electrochemical performance are outlined. Finally, the challenges of future developments in this field are discussed.
摘要: The construction of flexible supercapacitors with high electrochemical performance and excellent mechanical properties to power flexible electronics and sensors is very important. Freestanding electrodes play a crucial role in flexible supercapacitors, and carbon has been widely used in this role because of its high electronic conductivity, tunable porosity, adjustable surface area, excellent mechanical properties, low density and easy functionalization. It is also abundant and cheap. Recent progress on the fabrication of freestanding carbon electrodes based on various carbon materials for use in flexible supercapacitors is summarized, and remaining challenges and future opportunities are discussed.
摘要: Next-generation wearable and portable devices require rechargeable microbatteries to provide energy storage. Three-dimensional (3D) printing, with its ability to build geometrically complex 3D structures, enables the manufacture of microbatteries of different sizes and shapes, and with high energy and power densities. Lightweight carbon materials have a great advantage over other porous metals as electrode materials for rechargeable batteries, because of their large specific surface area, superior electrical conductivity and high chemical stability. In recent years, a variety of rechargeable microbatteries of different types have been successfully printed using carbon-based inks. To optimize their electrochemical performance and extend their potential applications, it is important to analyze the design principles with respect to the 3D printing technique, printable carbon materials and promising applications. This paper provides a perspective on recent progress in the four major 3D printing techniques, elaborates on conductive carbon materials in addressing the challenging issues of 3D printed microbatteries, and summarizes their applications in a number of energy storage devices that integrate with wearable electronics. Current challenges and future opportunities for carbon-based microbattery fabrication by 3D printing techniques are discussed.
摘要: Along with the emergence of wearable electronic devices, green energy devices like Zn-ion hybrid supercapacitors (ZHSCs), which are extremely safe and cheap, and have excellent stability and high power energy densities, have received great attention. Carbonenes, mainly including graphene and carbon nanotubes (CNTs), are promising materials for ZHSCs because of their exceptional electrical conductivity and excellent mechanical stability. A comprehensive overview of strategies for the modification of carbonene-based materials for ZHSCs, and a brief summary of their energy storage mechanisms is given and topics for potential research are suggested.
摘要: 石墨烯基二维介孔材料能够有效耦合石墨烯基底、功能化材料和介孔结构的优势，被认为是一种理想的微型超级电容器电极材料。基于此，本文以苯胺为前驱体，氧化石墨烯为二维导向剂，二氧化硅纳米球为介孔模板，采用双模板界面诱导自组装法制备介孔氮掺杂炭/石墨烯（mNC/G）纳米片，并实现了其介孔孔径的精确调控和电化学性能的优化。研究表明，7 nm孔径的介孔氮掺杂炭/石墨烯（mNC/G-7）展现出267 F g−1的高比电容，且应用于准固态平面微型超级电容器表现出21.0 F cm−3的体积比电容和1.9 mWh cm−3的体积能量密度，证明了该二维介孔氮掺杂炭/石墨烯纳米片在微型超级电容器应用方面具有良好的前景。
摘要: A coaxial anode with a carbon fiber core encapsulated in nanocrystalline FeNiMnO4 with a nitrogen-doped carbon sheath was prepared using carbon fiber cloth as the core, FeNiMnO4 nanocrystallite arrays as the first coating layer and nitrogen-doped carbon derived from F127 (a kind of triblock copolymer)-resorcinol-melamine gel as the outer layer. After annealing at 600 °C it was used as the anode material of an all solid flexible lithium ion battery using LiFePO4 as the cathode material and boron nitride modified polyethylene oxide as the electrolyte. The battery had a large areal capacity of ~1.40 mAh cm−2 and satisfactory cycling stability under different bending and strain states. Annealing below 600 °C leads to incomplete carbonization of the nitrogen-doped carbon and thus a low electrical conductivity while above 600 °C aggregation of FeNiMnO4 nanocrystallites and their detachment during cycling are observed under bending and strain.
摘要: The rapid development of micro/nanomanufactured integrated microsystems in recent years requires high performance micro energy storage devices (MESDs). Li-ion microbatteries (LIMBs) are the most studied MESDs, but the low mass loading of active materials and the less-than-perfect energy density hinder their further application. A 3D printed ZnSe/N-doped carbon (ZnSe/NC) composite electrode was designed and fabricated by extrusion-based 3D printing and a post-treatment strategy for use as the anode of LIMBs. The high capacity ZnSe nanoparticles are confined in the NC, where the NC not only improves the conductivity but also acts as a buffer layer to reduce the volume expansion and provide additional active sites for electrochemical reactions. The interconnected design of the 3D printed electrode is good for fast mass transfer and ion transport. A freestanding 3D printed ZnSe/NC electrode with a high mass loading of 3.15 mg cm−2 was achieved by direct ink printing, which had a superior energy density and decent reversibility in high-power LIMBs. This strategy can be used for other high-performance electrodes to achieve a high-mass-loading of active materials for microbatteries, opening up a new way to construct advanced MESDs.
摘要: Following the fast growth of micro-energy storage devices, there is an urgent need to develop miniaturized electronic devices with excellent performance that are both green and safe. Planar interdigitated rechargeable Zn microbatteries (MBs) have gained widespread attention in recent years due to their ease of series-parallel integration, mechanical flexibility and no need for traditional separators. We prepared a patterned cathode of NiCo layered double hydroxide (LDH)@indium tin oxide (ITO) nanowires (NWs) @carbon cloth (CC) by the chemical vapor deposition of ITO NWs on the carbon fibers in a CC, laser patterning, and finally the electrodeposition of NiCo-LDH to coat the ITO NW@carbon fibers. The cathode was combined with a patterned Zn foil anode to form a planar MB. Because of the highly conductive ITO NWs@CC current collector, the interdigitated MB had a satisfactory performance. The planar MB has a high specific capacity of 453.5 mAh g−1 (corresponding to 0.56 mAh cm−2) in an alkaline water-based electrolyte at 1 mA cm−2. After 4 000 cycles the capacity increased to 216% of the initial value due to gradual penetration of electrolyte into the three-dimensional NiCo-LDH@ITO NW@CC network. It also had excellent energy (798.4 μWh cm−2, corresponding to 649.9 Wh kg−1) and power densities (4.1 mW cm−2, corresponding to 3 282.7 mW kg−1). Furthermore, MBs connected in series-parallel in lighting tests illustrate the excellent performance of the device. Therefore, these fast and simple Zn MBs with an in-plane interdigital structure provide a reference for next-generation high-performance, environmentally-friendly, and scalable planar micro-energy storage systems.
摘要: Three-dimensional carbon nanonetworks (3D CNNs) have interconnected conductive skeletons and accessible pore structures, which provide multi-level transport channels and thus have promising applications in many areas. However, the physical stacking of these network units to form long-range conductive paths is hard to accomplish, and the introduction of micropores and small mesopores is usually difficult. We report a simple yet efficient strategy to construct CNNs with a nitrogen-doped micro-meso-macroporous carbon nanonetwork using Schiff-base gelation followed by carbonization. Using a polyacrolein-grafted graphene oxide molecular brush as the building block and tetrakis (4-aminophenyl) methane as the crosslinking agent, the obtained molecular brush nanonetworks have a high carbon yield and largely retain the original morphology, leading to the formation of a 3D continuous nanonetwork after carbonization. The materials have a micro-meso-macroporous structure with a high surface area and a highly conductive N-doped carbon backbone. This unique structure has a large number of exposed active sites and excellent charge/mass transfer ability. When loaded on carbon cloth and used as the electrodes of a flexible supercapacitor, the CNN has a specific capacitance of 180 F g−1 at 1 A g−1 and a high capacitance retention of 91.4% after 10 000 cycles at 8 A g−1 .
摘要: Organic-inorganic hybrid perovskite films made by low-temperature solution processing offer promising opportunities to fabricate flexible solar cells while formidable challenges regarding their environmental and mechanical stability remain due to their ionic and fragile nature. This work explores the possibility of chemical crosslinking between adjacent grains by the interfacial embedding of laser-derived carbon dots with halogen-terminated surfaces to improve the flexibility and stability of the polycrystalline films. A series of halogen-terminated carbon dots was generated in halobenzene solvents by pulsed laser irradiation in the liquid, and were then placed in the surface and grain boundaries of the perovskite film by an antisolvent procedure, where an immiscible solvent was poured onto the coating surface with a suspension containing carbon dots and perovskite precursors to cause precipitation. Strong interaction between perovskite and the carbon dots results in effective defect passivation, lattice anchoring and a change in the carrier dynamics of the perovskite films. Because of this, unencapsulated flexible perovskite solar cells after the interfacial embedding have power conversion efficiencies up to 20.26%, maintain over 90% of this initial value for 90 days under a relative humidity of 40% and have a thermal stability of 200 h even at 85 °C. The flexible devices withstand mechanical deformation, retaining over 80% of their initial values after 500 bend cycles to a radius of curvature of 4 mm.
摘要: Due to the difference of energy storage mechanisms between the anode and cathode materials, the power density or rate performance of a lithium-ion capacitor is greatly limited by its anode material. Hard carbon is a promising anode material for lithium ion capacitors, and its modification is an important way to improve the electrochemical performance of lithium-ion capacitors. A commercial hard carbon from Kuraray Inc was modified by oxidation followed by intercalation with ZnCl2 (ZnCl2―OHC). The reversible capacity of a half-cell prepared using this material was 257.4 mAh·g−1 at 0.05 A·g−1, which is obviously higher than the unmodified one (172.5 mAh·g−1). The capacity retention of a full cell prepared using ZnCl2―OHC as the anode and activated carbon as the cathode reached 43.3% when the current density increased from 0.1 to 10 A·g−1, which is more than twice that of the untreated hard carbon. After 5 000 charge-discharge cycles at 1 A·g−1, the capacity retention of the full cell was about 98.4%. The modification of hard carbon by surface oxidation and intercalation is therefore a promising way to improve its anode performance for lithium ion capacitors.