Chinese Science Bulletin, Volume 64, Issue 5-6: 514-531(2019) https://doi.org/10.1360/N972018-01105

Design, preparation and assembly of flexible electrode based on carbon materials

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  • ReceivedNov 10, 2018
  • AcceptedDec 10, 2018
  • PublishedJan 17, 2019


Flexible electronics as an innovative technology to bring huge changes in people's daily lives have greatly stimulated the research and development of flexible energy storage devices. Among them, flexible lithium ion batteries (LIBs) are attracting remarkable interests due to their significant advantages. Flexibility of electrode has an important role on the electrochemical performance and stability of flexible LIBs. It requires that active particles can keep tightly in touch with their flexible substrate during the whole charge/discharge process, even though the batteries are bended, rolled, stretched or compressed. Carbon materials, such as carbon nanotubes, carbon fibers, graphene, carbon cloth, carbon paper and so on, as free-standing substrates are very popular owe to their deformability, excellent thermal and chemical stability, high conductivity and a wide potential window. In order to overcome the fundamental mismatch in mechanics and form between "rigid" active materials and "flexible" substrate, it is necessary to design the structure of composite electrode, increase the bonding strength and develop the novel fabrication route.

Here, we review the progress and synthesis strategies of flexible electrodes based on carbon materials. It is described the effect of structure characteristic on electrochemical performance. According to this review, the self-standing flexible electrodes composed of active materials and carbon materials are commonly 3D porous network structures with various forms, such as sandwich structure. Currently, in-situ growth is standing out from the abundant synthesis methods because the bonding strength between active materials and carbon substrates can be obviously increased. Several typical prototypes and electrochemical performance of flexible LIBs are discussed briefly. The facing challenge and some perspectives of flexible electrodes in the future are also concluded. It can be sure that the advance in flexible electrodes with the combination of softness and hardness can promote the development of not only lithium-ion batteries, but also other energy storage devices.

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表S1 典型的碳基柔性锂离子电池及其性能

本文以上补充材料见网络版csb.scichina.com. 补充材料为作者提供的原始数据, 作者对其学术质量和内容负责.


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  • Figure 1

    Hierarchical assemblies of carbon nanotubes and full flexible cell with a CNT cone anode and cathode. (a) Electrode architectures (top) and their deformation when bent (bottom). (b) Schematic representation of the full cell with a CNT cone anode and cathode. (c) Flexible CNT cone battery connected to a 3 V white-light LED[34]

  • Figure 2

    (Color online) Carbon nanotube fiber springs and coaxial fiber full batteries with aligned CNT composite yarns. (a) SEM images of a CNT/LTO hybrid fiber and a spring-like fiber at 0, 50%, 100% strains, and evolution of specific capacitance with strain and stretch cycles[48]. (b) Schematic illustration to the fabrication, electrochemical performance and photograph of the coaxial fiber full LIB[49]

  • Figure 3

    (Color online) Some examples of CNTs flexible electrodes by in-situ growth. (a) Schematic illustration and SEM image of the solvothermal procedure with an SWCNT film as substrate for the preparation of stable 1T-MoSe2/SWCNTs hybrids[50]. (b) Schematic and SEM image of the preparation process of PI/SWNT film[51]. (c) Schematic illustration of the formation and SEM image and TEM image of carbon coated α-Fe2O3 hollow nanohorns on the CNT backbone[52]

  • Figure 4

    (Color online) Stable 1T-MoSe2 and carbon nanotube hybridized flexible electrode and properties in LIBs. (a) Schematic illustration showing the electrochemical process in a 1T-MoSe2/SWCNTs electrode. (b) Photographs of a flat and bent flexible full cell. (c) C K-edge and (d) O K-edge X-ray absorption near-edge structures (XANES) of the SWCNTs film and 1T-MoSe2/SWCNTs hybrids. (e) Cyclic voltammogram (CV) curves of LiFePO4/(1T-MoSe2/SWCNTs) flexible full cell cycled between 0.01 and 3 V at a scan rate of 0.5 mV/s. (f) Charge and discharge curves of the flexible full cell at a current density of 60 mA/g (the mass of the 1T-MoSe2/SWCNTs hybrids is 0.5 mg)[50]

  • Figure 5

    (Color online) Preparation and electrochemical performances of self-standing Fe2O3@CNFs@MoS2 film. (a) Schematic illustration of the preparation of the self-standing Fe2O3@CNFs@MoS2 film. (b) SEM images of Fe2O3@CNFs and Fe2O3@CNFs@MoS2 fabric films prepared at hydrothermal times of 24 h, and the inset is a photograph of the flexible Fe2O3@CNFs@MoS2 film. (c) The transport pathway of Li ions and electrons in the Fe2O3@CNFs@MoS2. (d) Cycling performance at a current density of 0.2 A/g and rate capability at various current densities in half-cel. (e) Electrochemical performance of the full flexible LIB[65]

  • Figure 6

    (Color online) Graphene foams and properties in LIBs. (a) Synthesis of a GF and integration with PDMS. (b) Electrical-resistance change of GF/PDMS composites under mechanical deformation[87]. (c) Schematic of a flexible battery containing a cathode and an anode made from 3D interconnected GF. (d) Photograph of a bent battery lighting a red LED device under bending. (e) Cyclic performance of the battery under flat and bent states[88]

  • Figure 7

    (Color online) HsGDY thin film as flexible electrode in LIBs. (a) Schematic diagram of the synthesis of the HsGDY. (b) The SEM image of HsGDY and inset is the photograph of free-standing HsGDY films. (c) The rate performance of the flexible electrode for LIBs. (d) The cycle performance of flexible electrode at the current density of 0.1A/g. (e) The mechanism of Li storage. (f) A bendable transparent LIB is made up of HsGDY[101]

  • Figure 8

    (Color online) Flexible graphene-wrapped carbon nanotube/graphene@MnO2 3D multilevel porous film. (a) Schematic illustration for the synthesis and energy storage characteristics of the freestanding GCMP film. (b)–(e) Photograph (inset) and SEM images of porous films. (f) Schematic illustration of microstructure evolutions after cycling[106]

  • Figure 9

    (Color online) Synthesis process and electrode design of the 3D FSiGCNFs. (a) Illustration of the synthesis process of the 3D FSiGCNFs. (b) Schematic diagram of the 3D FSiGCNF electrode design. Illustration of (c) electron transmission and (d) Li+ storage in the 3D FSiGCNF film[107]

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