Effect of Sheet Morphology on the Scalability of Graphene-Based Ultracapacitors

Luo, Jiayan; Jang, Hee Dong; Huang, Jiaxing

doi:10.1021/nn3052378

Cited by 502 publications

(419 citation statements)

References 39 publications

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“…Recently, CG has drawn increasing attention due to its threedimensional (3D) hollow structure and excellent stability in aqueous solutions. [25][26][27] Furthermore, due to its highly conductive nature and large specific surface area, the CG is a promising substrate for loading active materials into energy devices, that is, supercapacitors 24,28,29 and batteries, [30][31][32][33][34] and as a catalyst support in fuel cells. 23 As shown in Figure 1, the GO suspension was first mixed with precursors (titanium (IV) bis(ammonium lactato) dihydroxide and LiOH) and then nebulized to generate aerosol droplets, which flowed through a tube furnace.…”

Section: Results and Discussion Lto/cg Composite Synthesis Through Aementioning

confidence: 99%

One-step, continuous synthesis of a spherical Li4Ti5O12/graphene composite as an ultra-long cycle life lithium-ion battery anode

et al. 2015

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We report, for the first time, a one-step, continuous synthesis of spherical lithium titanate (Li 4 Ti 5 O 12 , LTO)/graphene composites through direct aerosolization of a graphene oxide (GO) suspension mixed with Li and Ti precursors. The resulting crumpled graphene-sphere-supported LTO nanocrystals has a three-dimensional structure with a high electrical conductivity, a high surface area and good stability in electrolyte. The LTO/CG composite, as an anode in LIBs, exhibited excellent rate capability (for example, at a high current density of 5000 mA g − 1 it delivered 60% of the capacity obtained at 12.5 mA g − 1 ) and an outstanding cycling performance (a capacity retention of 88% after 5000 cycles at 1,250 mA g − 1 ). The one-step, continuous synthesis of the LTO/graphene composite offers a high-producing efficiency compared with conventional multi-step preparations, and can be generally applied for synthesizing lithium metal oxides/graphene (cathode or anode) materials for lithium-ion batteries. NPG Asia Materials (2015) 7, e224; doi:10.1038/am.2015.120; published online 6 November 2015 INTRODUCTION Lithium-ion batteries (LIBs) have a high-rate capacity and long cycle life, and thus are critical for many important applications, such as electric vehicles (EVs) and portable electronic devices. 1-3 The use of combustible graphite (especially in lithiated states) is highly risky in the application of EVs and hybrid EVs (HEVs); therefore, alternative anode materials with a higher power density, better stability, and higher safety performance are greatly needed and deserve greater scientific exploration.Compared with graphitic carbon, spinel lithium titanate Li 4 Ti 5 O 12 (LTO) exhibits a relatively high lithium insertion/extraction voltage of 1.55 V (vs Li + /Li), which prevents the formation of the solid electrolyte interphase (SEI) and suppresses lithium dendrite deposition on the surface of the anode (most electrolyte materials or solvents are reduced below 1 V), thereby greatly decreasing the short-circuit risk of the battery. [4][5][6][7][8] In addition, LTO possesses excellent Li ion insertion and removal reversibility with almost zero volume change during the charge/discharge process. 9,10 However, as demonstrated in previous studies, it is still a challenge to achieve good battery performance at high charge/discharge rates using LTO as the anode material because of the low electrical conductivity (o10 − 13 S cm − 1 ) of LTO,11,12 and thus there have been many efforts to improve the rate capability and the cycling performance of LTO-based batteries. Commonly applied strategies include engineering the proper LTO structure to reduce the transport path length of Li ions and enhancing the electrical conductivity by surface coating or forming composites with

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Section: Results and Discussion Lto/cg Composite Synthesis Through Aementioning

confidence: 99%

One-step, continuous synthesis of a spherical Li4Ti5O12/graphene composite as an ultra-long cycle life lithium-ion battery anode

et al. 2015

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“…The highest capacitance of 275 F g À1 were achieved for the PRGO films at scan rate of 10 mV s À1 , which are exceptionally higher than the values of the GO films (103 F g À1 ), the CCG films (146 F g À1 ) and those reported previously for graphene. 23,28,31 Furthermore, on increasing the scan rate up to 1000 mV s À1 , the specific capacitance remain stable at 167 F g À1 , highlighting the excellent rate capability of PRGO films. We compared the capacitance performances of the PRGO films with those of recent research works focused on graphene-based films for supercapacitors by examining the data presented in Supplementary Tables S2 and S3.…”

Section: Fabrication Of Prgo Films Y Shao Et Almentioning

confidence: 88%

Fabrication of large-area and high-crystallinity photoreduced graphene oxide films via reconstructed two-dimensional multilayer structures

et al. 2014

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Graphene, the last representative sp 2 carbon material to be isolated, acts as an ideal material platform for constructing flexible electronic devices. Exploring a new method to fabricate high-quality graphene films with high throughput is essential for achieving greater performance with flexible electronic devices. Here, we report a facile coating and subsequent illumination method for mass-fabricating highly crystalline photoreduced graphene oxide (PRGO) films directly onto conductive substrates. The direct fabrication of PRGO films onto Cu foils with partial oxygenated groups, an intensive stacked highly crystalline structure, and reduced graphene oxide regions enable significant performance enhancements when used as supercapacitor electrodes compared with other graphene-only devices, exhibiting high specific capacitances of 275 F g À1 at a scan rate of 10 mV s À1 and 167 F g À1 at 1 V g À1 with excellent rate capability. The as-established all-solid-state flexible supercapacitors exhibit superior flexibility and robust mechanical stability, resulting in a capacitance delay of only 2% after performing 100 bending cycles. The demonstrated PRGO films provide a promising material platform to realize a broad range of applications related to flexible electronics devices. INTRODUCTIONFlexible electronic devices have garnered considerable attention because of the benefits enabled by large-area, lightweight, flexible electrode films, which have the potential to enable unique advances in future mobile applications, such as wearable displays, roll-up solar cells, electronic skin and flexible energy storage. 1,2 Graphene films containing a few layers or multiple layers of two-dimensional graphene sheets are prominent contenders as attractive components for use in flexible electronic devices due to their high conductivity, chemical stability and mechanical flexibility. 3,4 For the practical applications of graphene in these fields, scalable production of macroscopic-scale graphene films is required rather than the current micrometer-sized graphene sheets. To date, the synthesis of large-scale flexible graphene films has mainly been demonstrated by two approaches. One approach is the 'bottom-up' synthesis strategy, by which high-quality graphene can be prepared using chemical vapor deposition to grow graphene at high temperature, followed by a transfer procedure to place graphene films onto flexible substrates; 5 however, this method is not sufficiently cost-and time-effective to be commercially viable for mass production and requires a difficult post-functionalization step to produce the appropriate graphene films. Another approach is the 'top-down' method, that is, solution

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“…Moreover, the srGOS shows folded layers with extensive wrinkles, maybe which can prevent them from forming strong aggregation. [50] A further exfoliation induced graphenic networks can be seen in the HPG. TEM images of HPG also reveal a highly interconnected structure, which is in good agreement with SEM results (Figure 4c-f).…”

Section: Figure 1amentioning

confidence: 92%

“…More specifically, when the precursor concentration is increased, there is an isotropic to nematic orientation transition for GO sheets in the solution. [50] Similarly, HPG-10 sample derived from GOS-10 yields a less porosity ( Figure S15, Supporting Information). Accordingly, a definite precursor concentration-dependent capacitance is observed (Figure 5e; Table S2, Supporting Information).…”

Section: Figure 1amentioning

confidence: 96%

“…Naturally, these delaminated GO sheets distribute very differently in the solution compared to their 2D packed form in small NANObulk solid-state. [49,50] The abundant oxygen-containing surface functional groups, such as epoxides, hydroxyls, and carboxyls ( Figure S1, Supporting Information), make the GO highly hydrophilic, thus easily producing a homogeneous GO dispersion. Subsequently, the GO solution was dropped into liquid nitrogen (77 K) with a 2 mm diameter pipette.…”

Section: Figure 1amentioning

confidence: 99%

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Design of 3D Graphene‐Oxide Spheres and Their Derived Hierarchical Porous Structures for High Performance Supercapacitors

Gadipelli

Yang

et al. 2017

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Graphene‐oxide (GO) based porous structures are highly desirable for supercapacitors, as the charge storage and transfer can be enhanced by advancement in the synthesis. An effective route is presented of, first, synthesis of three‐dimensional (3D) assembly of GO sheets in a spherical architecture (GOS) by flash‐freezing of GO dispersion, and then development of hierarchical porous graphene (HPG) networks by facile thermal‐shock reduction of GOS. This leads to a superior gravimetric specific capacitance of ≈306 F g−1 at 1.0 A g−1, with a capacitance retention of 93% after 10 000 cycles. The values represent a significant capacitance enhancement by 30–50% compared with the GO powder equivalent, and are among the highest reported for GO‐based structures from different chemical reduction routes. Furthermore, a solid‐state flexible supercapacitor is fabricated by constructing the HPG with polymer gel electrolyte, exhibiting an excellent areal specific capacitance of ≈220 mF cm−2 at 1.0 mA cm−2 with exceptional cyclic stability. The work reveals a facile but efficient synthesis approach of GO‐based materials to enhance the capacitive energy storage.

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Effect of Sheet Morphology on the Scalability of Graphene-Based Ultracapacitors

Cited by 502 publications

References 39 publications

One-step, continuous synthesis of a spherical Li4Ti5O12/graphene composite as an ultra-long cycle life lithium-ion battery anode

One-step, continuous synthesis of a spherical Li4Ti5O12/graphene composite as an ultra-long cycle life lithium-ion battery anode

Fabrication of large-area and high-crystallinity photoreduced graphene oxide films via reconstructed two-dimensional multilayer structures

Design of 3D Graphene‐Oxide Spheres and Their Derived Hierarchical Porous Structures for High Performance Supercapacitors

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