Porous carbon anchored titanium carbonitride for high-performance supercapacitor

Accepted Manuscript Porous carbon anchored titanium carbonitride for high-performance supercapacitor Hao Yan, Jianghong Wang, Yuan Fang, Muxuan Zhou, Xiaoya Guo, Hui-Qiong Wang, Yang Dai, Wenrong Li, Jin-Cheng Zheng PII:

S0013-4686(19)30376-7

DOI:

https://doi.org/10.1016/j.electacta.2019.02.109

Reference:

EA 33701

To appear in:

Electrochimica Acta

Received Date: 29 October 2018 Revised Date:

23 February 2019

Accepted Date: 26 February 2019

Please cite this article as: H. Yan, J. Wang, Y. Fang, M. Zhou, X. Guo, H.-Q. Wang, Y. Dai, W. Li, J.-C. Zheng, Porous carbon anchored titanium carbonitride for high-performance supercapacitor, Electrochimica Acta (2019), doi: https://doi.org/10.1016/j.electacta.2019.02.109. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

ACCEPTED MANUSCRIPT

Porous

Carbon

Anchored

Titanium

Carbonitride

for

high-performance Supercapacitor Hao Yan1∗, Jianghong Wang1, Yuan Fang1, Muxuan Zhou1, Xiaoya Guo1, Hui-Qiong

RI PT

Wang2, 3, Yang Dai1∗, Wenrong Li1*, Jin-Cheng Zheng2*, 3 1

Department of Chemical Engineering, School of Environmental and Chemical Engineering, and Institute for Sustainable Energy, Shanghai University, Shangda Road 99, Shanghai, 200444, China

2

Xiamen University Malaysia, 439000 Sepang, Selangor, Malaysia

M AN U

3

SC

Department of Physics, and Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient Devices, Xiamen University, Xiamen 361005, China

AC C

EP

TE D

Carbon anchored titanium carbonitride for supercapacitor electrode material was prepared by a direct semi-solid-sate carbonitridation method. The prepared sample is highly conductive and mesoporous (250 m2 g-1), enabling fast electron transfer and ion transport. As a result, a high capacitance of 360 F g-1 at 0.5 A g-1, and an impressive capacitance retention ratio 100Ag-1/1 A g-1 of 53%, as well as long cyclic capability (>10000 cycles) can be obtained in 1 M H2SO4. The thick electrode also presents a high area capacitance up to 1.77 F cm-2. A flexible H2SO4/PVA symmetric supercapacitor was fabricated to demonstrate its practicality. Remarkably, the supercapacitor presents high-rate performance (up to 25 KW kg-1) and long cyclic performance (>10000 cycles), illustrating its potential application in flexible integrated energy storage devices. This work provides a novel insight into designing and preparing carbonitride based materials for high performance supercapacitor.

Keywords Titanium carbonitride Solid state carbonitridation High-rate performance; Semi-solid state supercapacitor Flexible devices

∗

Address to corresponding authors: H.Y. ([email protected]), Y.D. ([email protected]), W.L. [email protected] and J.Z.([email protected])

ACCEPTED MANUSCRIPT

1. Introduction Bridging the gap between batteries and traditional capacitors, supercapacitors are considered as promising energy devices to provide high rate charge and discharge

RI PT

with long cyclic durability, and play an irreplaceable role in energy storage application [1-19]. Supercapacitors can be typically classified into electrical double layer capacitor and pseudocapacitor. The charge storage mechanism of the Electrical

SC

Double Layer Capacitor (EDLC) is based on ion adsorption, while the

M AN U

pseudocapacitor arises from surface redox reactions or fast ion intercalation [6]. As vital components of any supercapacitors, the electrode materials determine the overall performance [7]. Recently, efforts have been devoted to investigating new electrode materials for supercapacitor. Graphene based materials [8, 9], biomass carbon

TE D

materials [3, 7, 16-18], nanostructured metal oxides [2, 20], conducting polymers [21, 22], transition-metal dichalcogenides [23], metal-organic frameworks based materials [24], carbide/nitride [1, 4-6, 26-28] based materials and other materials are developed

EP

as potential electrode materials for supercapacitors. Among the candidates, the

AC C

carbide/nitride-based materials have attracted much attention, due to their high electrical conductivity, high density, excellent chemical stability, and outstanding capacitive performance [4]. MXenes and their composites (most typical Ti3C2Tx) are explored as promising electrode materials for supercapacitors with high volumetric and rate performances [1, 11-14, 26-28]. A distinct capacitance of 1500F cm-3 can be achieved in the specially designed Ti3C2Tx MXene hydrogels, demonstrating that these materials can be further employed in next-generation flexible power sources 2

ACCEPTED MANUSCRIPT [28]. However, the top-down synthetic methods described in these reports require high temperature (>1000 °C) and multistep processes, which would hamper their large-scale application [26-28]. Another way to prepare carbide/nitride based

RI PT

materials is bottom-up. The most studied and attractive material is titanium based carbide/nitride. Micro/nanostructure carbide/nitride based materials have been prepared by carbon template reduction [4], carbon thermal reduction [29, 30] and

SC

chemical vapor deposition [31, 32] for application in electrode material for

M AN U

supercapacitor. Although various materials have been synthesized using these methods, a direct conversion of titanium carbonitride from Titania by a direct solid state carbonitridation of Titania nanotube has not been well documented. Compared to the carbide/nitride (TixCy/TixNy) based materials, the heteroatoms (C, N) with

TE D

different sizes and electronegativity in the carbonitride (titanium carbonitride) may introduce more reactive sites on the surface, beneficial to fast surface reaction [33]. In this work, we report a direct solid state carbonitridation of Titania nanotube to

EP

prepare carbon anchored titanium carbonitride (C- Titanium carbonitride) as electrode

AC C

materials for supercapacitor. Compared to other methods, this method is simple and high efficient to prepare carbonitride based porous electrode material at a lower reacting temperature. The prepared sample is highly conductive and porous, in favor of fast electron transfer and ion transport. Therefore, the carbon anchored titanium carbonitride based electrode shows an outstanding capacitive performance, achieving a high capacitance of 360 F g-1 at 0.5 A g-1, and an impressive capacitance of 126 F g-1 even at ultrahigh-rate of 150A g-1, as well as long cyclic capability (>10000 cycles) in 3

ACCEPTED MANUSCRIPT 1 M H2SO4. The titanium carbonitride based electrode also presents a high area capacitance up to 1.77 F cm-2. Further, a flexible H2SO4/PVA solid-state symmetric supercapacitor was fabricated to demonstrate its practicality. With excellent flexibility,

RI PT

it can deliver a distinct high-rate performance of 25000 W kg-1, as well as excellent cyclic capability (~90 % capacitance retention after 10000 cycles).

2.1 Preparation of Samples

M AN U

SC

2. Experimental

Titanium nanotube was prepared by a typical hydrothermal method. Briefly, 2 g TiO2 (40 nm, Aladdin) and 140 ml 10mol L-1 NaOH mixture were blended by

TE D

ultra-sonication for 10 min. Then, the mixture was transferred to a 200 mL Teflon-lined autoclave and kept at 180°C for 48 h. After that, the autoclave was naturally cooled, and the sample was filtered and rinsed throughout with ultrapure

EP

water for several times. Finally, the titanium nanotube was obtained by drying at

AC C

100 °C for 24 hours.

C- Titanium carbonitride (S1) was synthesized by mixing 0.5 g titanium

nanotube with 5 g guanidine hydrochloride (Aladdin) by an agate mortar. Then, the mixture was heated at 10°C min-1 in a tube furnace for 2 h at 900°C under the flowing N2 condition. The as-prepared sample was ground and rinsed with 0.3 M HNO3/H2O2 solution and ultrapure water for several times. For comparison, another sample (S2) 4

ACCEPTED MANUSCRIPT was also prepared by mixing 0.5 g TiO2 (40 nm, Aladdin) with 5 g guanidine hydrochloride following the method mentioned above.

RI PT

2.2 Characterization

The surface morphologies of the samples were visualized by a Hitachi S4800

SC

microscope (SEM). Elemental analysis was performed by energy dispersive

M AN U

spectroscopy by means of XFlash® 6, with the Bruker detector connected to the SEM. The microstructures of samples were investigated on a JEOL JEM-2100F microscope (TEM). The overall structure of the samples was examined by a Rigaku D/max-2600PC diffractometer (XRD) with nickel-filtered Cu Kα radiation (λ=1.5418

TE D

Å). The mean crystallite size was calculated from the full width at half maximum (FWHW) of (111) peaks using Scherrer’s formula by Jade 6.5. Raman spectra were collected by a Renishaw Reflex with laser excitation (λ = 532.5 nm). Nitrogen

AC C

EP

isotherm was obtained by a Micromeritics ASAP 2020 at 77K.

The sample was outgassed at 300 °C for 12 h. X-ray photoelectron spectroscopy

(XPS) was performed using a Thermo Fisher Scientific ESCALAB 250Xi XPS System. A Shirley background was removed from the spectra before deconvolution.

To measure the electrical conductivity of the sample, 90 wt% of the sample and 10 wt% Polytetrafluoroethylene (PTFE) were mixed and pressed at 20 MPa to form discs with a diameter of 30 mm and a thickness of 50 µm. For comparison, the 5

ACCEPTED MANUSCRIPT commercial carbon YP-50 is also evaluated using this method. The electrical conductivity was determined by a four point probe meter (SX1944, Suzhou Telecommuication Instrument). Three discs for each sample were made and tested for

2.3 Electrochemical evaluation in three-electrode cell

RI PT

three times. And then the nine results for each were averaged.

SC

The electrode was prepared by mechanical pressing of the pre-mixed slurry,

including the sample powder (80 wt %), super-p conductive carbon (10 wt %), and

M AN U

PTFE binder (10 wt %, 60 wt % in H2O, Aldrich) to form a disc. The resulting electrode was pressed on a stainless mesh (400 mesh) as the work electrode and measured in a conventional three-electrode cell with 1M H2SO4 electrolyte. The Ag/AgCl and Pt foils (4 cm2) were used as the reference electrode and counter

TE D

electrode, respectively. Unless otherwise specified, the mass loading is 1.00-2.00 mg cm-2. For comparison, a thick electrode with a mass loading of 13.25 mg cm-2 was

EP

also prepared.

AC C

2.4 Fabrication of flexible two-electrode symmetric supercapacitor To form a uniform slurry, the S1 (80 wt%) powder, conducting carbon (super-p,

10%) and Polyvinylidene fluoride (PVDF) binder (10 wt%, Kynar 761) were blended in N-methyl-2-pyrrolidone with vigorous stirring. The electrodes were prepared by cast coating the slurry onto the carbon nanotube (CNT) cloth (~0.5×1.5 cm, 18 µm thick). The mass loading was set about 1-2 mg cm-2 after drying and rolling depression. The Poly(vinyl alcohol) PVA (Mowiol® PVA-117, Mw~145000)/H2SO4 6

ACCEPTED MANUSCRIPT sol gel electrolyte was coated onto the upper surface of the electrodes. The flexible semi-solid state symmetric supercapacitor was fabricated by combining two gel-electrolyte coated electrodes face to face to form a sandwiched structure.

RI PT

Afterwards, the supercapacitor was well prepared after the solidifying of the gel-electrolyte.

SC

Cyclic Voltammetry (CV) at various scan rate, galvanostatic charge-discharge

M AN U

(GCD) at different current density, and electrochemical impedance spectroscopy (EIS) at a frequency range (1 mHz -100 KHz) were performed on a potentiostat–galvanostat (CHI 660C) instrument.

TE D

2.5 Calculations

The capacitance was calculated from the CVs or the GCD curves, according to the equations [23]:

C=‫ܸ݀ܫ ׬‬/(‫)ܸ݉ݒ‬

EP

AC C

or

(1)

C=It/(mV)

(2)

where C denotes gravimetric capacitance (Fg-1), I denotes current (A), ν denotes scan rate (V/s), m denotes mass (g) , V denotes potential range, and t denotes discharging time. The energy density E (Wh kg-1), and power density P (W kg-1) of the symmetric two-electrode cell were calculated based on the GCD curve by the following 7

ACCEPTED MANUSCRIPT equations: (3)

E= Cs ∆V2/3.6*8

(4)

P=3600E/td

(5)

RI PT

Cs=It/(m∆V)

where Cs is the single electrode capacitance of the two-electrode cell, I is the applied current density based on the single electrode, m is mass based on a single electrode,

3. Results and Discussion

M AN U

SC

∆V is the effective potential range during discharge, and td is the discharging time (s).

3.1 Material preparation and characterization

As illustrated in Fig. 1, the schemes (a)-(c) present the preparation procedure of

TE D

the sample (S1). The as-prepared titania nanotubes (Fig. 1d) exhibit tube bundle shaped structure, containing nanotubes with a diameter of 50-100 nm and a length of 500-1000nm. The benefit of employing the titania nanotube as the precursor is that it

EP

can provide more reactive sites for carbonitridation. During the carbonitridation

AC C

process, the nanotube bundles break down. The guanidine hydrochloride acts as the carbon and nitride sources, producing a certain amount of gases to form a porous structure [24]. After reaction, the open and porous ‘nest’ shaped structure is generated (Fig. 1c, e). The rinsing process will eliminate the impurities, such as the residual TiO2 and sodium ions, ensuring the relatively pure phase of the sample. In addition, the surface species will be generated during the procedure. The porous ‘nest’ structure will facilitate electrolyte permeating, acting as an efficient ion-saving container for 8

ACCEPTED MANUSCRIPT fast reaction. Further confirmed by the TEM images (Fig. 1f-g), the formed titanium carbonitride nanoparticles are anchored on the carbon network (Fig. 1f). And the fast Fourier transformed (FFT) pattern of the small particle region (Fig. 1g) matched well

RI PT

with the (200) facet. [19] For comparison, the SEM image of the sample directly using TiO2 as the precursor (S2) is shown in Fig. S1a. As can be seen from the image, solid polyhedral-shaped particles can be obtained after carbonitridation. Compared to

SC

the TiO2 precursor, the more porous nanotubes, the more reactive sites and

M AN U

dimensional restriction will be provided for carbonitridation, generating smaller particles and more pores. Fig. S3 and Table SI show the EDX results and elemental composition of the sample S1. The presence of both nitrogen and carbon in the composition indicates the sample is not pure carbide or nitride, confirming the

partially oxidized.

TE D

formation of carbonitride. In addition, the result also indicates the particles are

EP

The S1 sample is further examined by XRD, Raman, N2 adsorption and XPS, as

AC C

indicated in Fig.2. XRD (Fig. 2a) shows five clear peaks of (111), (200), (220), (311) and (222), corresponding to TiC0.3N0.7 (PDF#42-1488) with a FCC structure (Fm-3m (225)) [4]. The mean crystallite size was calculated from the FWHM of (111) peaks according to Scherrer’s formula. The particle size is estimated to be 83 nm. The broad peak at 26°C can be assigned to amorphous carbon phase [4]. For comparison, XRD pattern of S2 sample (TiO2 powder precursor) is also presented in Fig. S1b. It also shows the similar FCC structure with sharper peaks. However, the broad peak at 26°C 9

ACCEPTED MANUSCRIPT is not as obvious, suggesting lower carbon content. In this study, the surrounding of guanidine hydrochloride can provide enough sources for both C and N at high temperature, leading to the formation of FCC phase. This is also confirmed by the

RI PT

XPS results (Fig. 2b and Fig. S2). The peak at 456.6 eV in the Ti2p spectra can be assigned to the Ti (C, N) bond [35]. The other peaks at 459.1 eV (2p3/2) and 464.4 eV (2p1/2) arise from the titanium oxidized species (Fig. 2a) [35, 36], which may

SC

originate from the rinsing process using the HNO3/H2O2 solution. As shown in Fig. S

M AN U

2a, there are three peaks corresponding to Ti-O (530.6 eV), N-O (532.1 eV), and carbon (533.3 eV) for O1s. The oxidized species on the surface can provide pseudocapacitive behavior through fast surface reaction. And the N1s region presents two peaks at 397.5 and 400.2 eV, which can be ascribed to the N-(Ti, C) and N-C

TE D

bond, respectively. Owing to the titanium carbonitride particles anchored in the carbon network, the C1s (Fig. S2c) only shows two species of sp2 (284.5 eV) and sp3 (285.5 eV) [35-37]. The Ti related region could not be detected in the Raman

EP

spectrum within the shift range of 400-800 cm-1 (Fig. 2c). The characteristics for the

AC C

D (1360 cm-1) and G (1585 cm-1) bands are exhibited in the Raman spectrum, with an integral intensity ratio (IG/ID) of 1.07 [4, 26]. It is well accepted that the integral intensity ratio partially depends on the graphitization degree [3, 7]. Therefore, the sample contains partial graphite carbon. The nitrogen adsorption isotherm is presented in Fig. 2d. The shape of the isotherm (type IV, with a hysteresis loop), and the pore size distribution (Fig. S3) demonstrate that the sample S1 exhibits both of the micropore and mesopore characters [38, 39]. The contribution of the meso-pores for 10

ACCEPTED MANUSCRIPT supercapacitor application is rather significant, since they can function as pathways for ion transport. The sample also exhibits a relatively high value of Brunauer– Emmett–Teller (BET) specific surface area (251 m2 g-1). More importantly, the

RI PT

material indicates an electrical conductivity as high as 18 S cm-1 determined by the four probe point method, compared to 1.4 S cm-1 of commercial YP-50 carbon (Fig. S 1d) measured under the same conditions. The prepared material possesses high

SC

surface area with abundant mesopores, together with high electrical conductivity.

M AN U

Therefore, the superior capacitive performance is anticipated [4].

3.2 Capacitive performances in three-electrode cell

TE D

Firstly, the capacitive performances were evaluated in a three-electrode cell with 1 M H2SO4 aqueous electrolyte. We choose the H2SO4 based electrolyte for its outstanding ionic conductivity, stable and small size nature of proton to facilitate fast

EP

surface redox reaction [6, 27]. Fig. 3a presents the cyclic voltammetry (CV) curves of

AC C

C- Titanium carbonitride (S1) based electrode at various scan rates. The CVs indicate rectangular shape, revealing capacitive performance in H2SO4 electrolyte. However, the deviation from the ideal capacitive behaviour as depicted in Fig. 3a somehow suggests that pseudocapacitance contributes to the total capacitance. At a low scan rate of 2 mVs-1, the capacitance reaches 302 F g-1, and a good rate capability can be obtained. Even at a high scan rate of 200 mV s-1, the CV curve can still keep rectangular-shaped with a capacitance of 205 F g-1. For comparison, the CVs of 11

ACCEPTED MANUSCRIPT Sample S2 are also measured and displayed in Fig. S5. The CVs also present a rectangular shape. However, the capacitances are only approximately half of that from the Sample S1 based electrode at corresponding scan rates. The result shows the

RI PT

precursor and the morphology will strongly affect the electrochemical performance. Based on the calculation, the specific capacitances are much higher (>100F g-1) than the merely double-layer capacitance calculated from the relatively low specific area

SC

(< 1000 m2g-1), suggesting the contribution of pseudocapacitance [6]. For a close

M AN U

packing FCC structure, it seems hard for ions to fast intercalate into lattice. Thus, the surface fast redox reaction could be responsible for the main charge storage mechanism. As shown in Fig. 3b, the galvanostatic charge-discharge (GCD) curves at different current densities exhibit almost symmetric with quasi-linear shops [40]. The

TE D

nonlinearity of the GCD curve at low current density also illustrates pseudocapacitive behavior. The GCDs display a high capacitance of 367 F g-1 at 0.5 A g-1. It should be mentioned that an impressive high specific capacitance of 125 Fg-1 can also be

EP

obtained at an ultrahigh high-rate of 150 A g-1, highlighting the faster ion-transport.

AC C

The outstanding capacitive performance can be attributed to the unique porous structure as well as high electrical conductivity, benefiting fast ion transport and electron transfer [41]. To further elucidate the mechanism of charge storage, the relationship between peak current (at 0.15 V vs. Ag/AgCl) and the sweep rate was also investigated based on the power-law relationship [20]: i= avb

6

where i represents the current at a particular potential (A), v is the scan rate (mV s-1) 12

ACCEPTED MANUSCRIPT and a and b are adjustable constants. When b=0.5, the process is determined by diffusion, indicating the battery behavior. While b=1, the current is capacitive or surface controlled. Fitting from the curves of Fig. 3c, the b values for cathodic and

RI PT

anodic are 0.92 and 0.93, respectively, further supporting the mechanism of fast surface redox reaction. During the reaction, the surface titanium oxide species provide the active sites and the bulk act as the highly conductive core. In addition, the N,

SC

O-doped carbon matrix also contributes to the total capacitance.

M AN U

For wearable electronic applications, the geometric areal capacitance is another important metric to evaluate the capacitive performance of the electrode. Our results (Fig. 3d, Fig. S6) show that the fairly high mass loading electrode (Sample S1, 13.25 mg cm-2) can reach a relatively high areal capacitance of 1.77, 0.98 F cm-2, at 2 and

TE D

100 mV s-1 (7s discharge response), respectively, proving the formation of efficient conducting network in the electrode for ion transport and electron transfer [2]. The result is better than the recently reported values from WO3 2H2O (0.25 F cm-2, 5s),

EP

MnO2/graphene (0.25 F cm-2, 4s), WO3-x/ MoO3-x (0.16 F cm-2, 5.9 s), and Ti3C2Tx

AC C

(1.37 F cm-2, 7s) [2, 27].

To gain a better understanding of the capacitive performance, EIS measurement

was conducted. As shown in Fig. 4e, the Nyquist plot at open circuit voltage (OCV) contains two parts, including a straight lines in the low-frequency region, and a small depressed semicircle in the high-frequency region. The straight line represents low ion diffusion and Warburg impedance. The small depressed semicircle stands for the 13

ACCEPTED MANUSCRIPT interfacial charge transfer resistance, implying low charge transfer resistance. It can be observed from the plot that, the line is not all vertical to the x-axis, suggesting the pseudocapacitive behavior rather than the electrical double layer capacitive behavior.

RI PT

This phenomenon can also be found in other pseudocapacitive systems, such as two-dimensional h-MoO3 nanosheet [20]. The electrode also presents excellent cyclic performance. It delivers no measurable capacitance variation even after 10000 cycles

M AN U

SC

at 10 Ag-1 (Fig. 4f), with a coulombic efficiency close to 100% [6].

3.3 Flexible symmetric cell performances

In the above section, we have demonstrated the excellent performance of the

TE D

porous carbon anchored titanium carbonitride electrode based on PTFE binder process, which is widely used for material evaluation in supercapacitor with an aqueous electrolyte. However, the PTFE binder based electrode is not flexible enough and

EP

compatible with the PVA based solid state electrolyte. Thus, to prepare the flexible

AC C

supercapacitor electrode, a slurry coating may be more suitable. In order to verify the practicality of this material for a flexible energy-storage system [41], a symmetric semi-solid state supercapacitor (PVA/H2SO4 electrolyte based) was fabricated. To ensure the flexibility, we employ the highly bendable and robust CNT cloth (18 µm) as the current collector. The potential window can be extended to 1 V in the two-electrode system. The contribution of the current collector is trivial enough to be neglected and has been deducted. As indicated in Fig. 4a (inset) [42, 43], the flexible 14

ACCEPTED MANUSCRIPT supercapacitor can be easily bent without damaging the integrality. The CV curves in Fig. 4 display rectangular shape with a little variation under different bending angles, revealing excellent capacitive behavior. GCD measurements at various current

RI PT

densities were also conducted (Fig.4b). The GCD curves show nearly symmetric shape with linear slopes at all current densities, suggesting a low polarization. The

cell can reach a high capacitance value (based on one electrode active material) of 248

SC

F g-1. Indeed, the value is slightly lower than the three-electrode based capacitance at

M AN U

1 A of 306 F g-1. The electrode coupling in pseudocapacitive system and relative slower kinetic in PVA/H2SO4 based electrolyte could be responsible for this. Remarkably, the prepared supercapacitor can deliver at an ultrahigh current density of 100 A g-1 (based on one electrode) with a high capacitance retention ratio 100A/1A of

TE D

66% in the form of PVA/H2SO4 based solid electrolyte [42]. The outstanding performances could be due to the formation of an efficient conducting network. It can be seen from Fig. S7a that, the active material layer has an intimate contact with the

EP

high conductive CNT cloth. As shown in the schematic illustration (Fig. S 7b), the

AC C

way of carbon-to-carbon contact may decrease the resistance for electron transfer, providing more electronic paths in the electrode [44, 45]. More importantly, the open and porous structure can effectively incorporate PVA/H2SO4 based electrolyte, benefiting fast ions transport. Thus, an efficient electron and ion conducting network can be formed. The Ragone plot in Fig. 4c shows the high power-energy performance of the symmetric supercapacitor. A high energy density of 8.6 Wh kg-1 at 160.5 W kg-1, and 4.9 Wh kg-1 at a high power density of 25000 W kg-1 can be obtained. Long cyclic 15

ACCEPTED MANUSCRIPT capability is another vital feature for supercapacitor. Indeed, the semi-solid state supercapacitor can maintain over 90.3 % of its initial capacity after 10,000 cycles at 10 Ag-1. Compared with other flexible symmetric supercapacitor systems (Table S2),

RI PT

the superb power capability and long cyclic ability are exhibited in our supercapacitor. The performance can be further improved by optimizing the fabricating process or

SC

asymmetric design.

M AN U

4 Conclusions

In summary, we develop a simple bottom-up method to prepare carbon anchored titanium carbonitride by a direct solid state carbonitridation of titania nanotubes. The as-prepared material is highly conductive and porous with open porous ‘nest’ shaped

TE D

structure, enabling fast electron transfer and ion transport for the surface redox reaction. When applied as the electrode material for supercapacitor, the carbon anchored titanium carbonitride based electrode displays a high capacitance of 360 F

EP

g-1 at 0.5 A g-1, and an impressive capacitance of 126 F g-1 at ultrahigh-rate of 150A

AC C

g-1, as well as long cyclic capability (>10000 cycles) in 1 M H2SO4. Moreover, the thick electrode also exhibits a high area capacitance up to 1.77 F cm-2. Owing to carbon-to-carbon contact and highly efficient conducting network, our fabricated flexible H2SO4/PVA semi-solid state symmetric supercapacitor delivers a high power density up to 25000 W kg-1, as well as long cyclic performance with ~90 % capacitance retention after 10000 cycles. We believe that this work may not only pave the way for designing and preparing materials for high performance supercapacitor, 16

ACCEPTED MANUSCRIPT but also open new opportunities in emerging flexible and integrated energy storage devices [26, 28]. Furthermore, the method presented in this work provides a general procedure to generate carbonitride/carbon composite materials for other applications

RI PT

such as fuel cells and air batteries. Acknowledgements

Financial support from the National Natural Science Foundation of China (No.

SC

21103109, No. 21176152, No. 21373137, No. 51661135011), the support provided by

M AN U

China Scholarship Council (CSC) during a visit of Yang Dai (CSC No. 201806895011) to Brookhaven National Laboratory is acknowledged. The beam time and technical supports at the beamline stations BL14B1 and BL14W1, at the Shanghai Synchrotron

TE D

Radiation Facility (SSRF) (Shanghai, China) are appreciated.

References

EP

[1] M.R. Lukatskaya, B. Dunn, Y. Gogotsi, Multidimensional materials and device

AC C

architectures for future hybrid energy storage, Nat. Commun. 7 (2016) 12647. [2] J. B. Mitchell, W. C. Lo, A. Genc, J. LeBeau, V. Augustyn, Transition from Battery to Pseudocapacitor Behavior via Structural Water in Tungsten Oxide, Chem. Mater. 29 (2017) 3928−3937.

[3] J. Liu, Y. Deng, X. Li, L. Wang, Promising Nitrogen-Rich Porous Carbons Derived from One-Step Calcium Chloride Activation of Biomass-Based Waste for High Performance Supercapacitors, ACS Sustainable Chem. Eng.4 (2016) 177−187. 17

ACCEPTED MANUSCRIPT [4] X. Xia, Y. Zhang, D. Chao, Q. Xiong, Z. Fan, X. Tong, J. Tu, Tubular TiC fibre nanostructures as supercapacitor electrode materials with stable cycling life and wide-temperature performance, Energy Environ. Sci. 8 (2015) 1559-1568.

RI PT

[5] P. Yang, D. Chao, C. Zhu, X. Xia, Y. Zhang, Y. Wang, P. Sun, P. K. Tay, Z. X. Shen, W. Mai, H. Fan, Ultrafast-Charging Supercapacitors Based on Corn-Like Titanium Nitride Nanostructures, Adv. Sci. 3 (2016), 1500299.

SC

[6] M.R. Lukatskaya, C.E. Ren, O. Mashtalir, Y.DallAgnese, M.W. Barsoum, Y.

M AN U

Gogotsi, P.Simon,Cation Intercalation and High Volumetric Capacitance of Two-Dimensional Titanium Carbide, Science 341 (2013) 1502-1505. [7] Y. Gong, D. Li, C. Luo, Q. Fu, C. Pan, Highly porous graphitic biomass carbon as advanced electrode materials for supercapacitors, Green Chem. 17 (2017) 4132-4140.

TE D

[8] C. Liu, Z. Yu, D. Neff, A. Zhamu, B. Z. Jang, Graphene-based supercapacitor with an ultrahigh energy density, Nano Lett. 10 (2010), 4863-4868. [9] R. Singh, C. C. Tripathi, Electrochemical Exfoliation of Graphite into Graphene

AC C

1125-1130.

EP

for Flexible Supercapacitor Application, Materials Today: Proceedings, 5 (2018)

[10] H. Yan, Y. Li, X. Guo, M. Zhou, H. Q. Wang, Y. Dai, J. C. Zheng, Synergistic Supercritical Water ‘Wet’ Activated Biomass Carbon as High Performances Electrode Materials for Supercapacitor, J. Electrochem. Soc. 165 (2018) A2075-A2083. [11] C. Zhang, V. Nicolosi, Graphene and MXene-based transparent conductive electrodes and supercapacitors, Energy Storage Materials 16 (2019) 102-125. [12] C. Zhang, B. Anasori, A. S.-Ascaso, S.-H. Park, N. McEvoy, A. Shmeliov, G. S. 18

ACCEPTED MANUSCRIPT Duesberg, J. N. Coleman, Y. Gogotsi, V. Nicolosi, Transparent, flexible, and conductive 2D titanium carbide (MXene) films with high volumetric capacitance, Adv. Mater. 29 (2017) 1702678.

RI PT

[13] L. Kong, C. Zhang, J. Wang, D. Long, W. Qiao, L. Ling, Ultrahigh intercalation pseudocapacitance of mesoporous orthorhombic niobium pentoxide from a novel cellulose nanocrystal template, Materials Chemistry and Physics 149-150 (2015)

SC

495-504.

M AN U

[14] F. Du, H. Tang, L. Pan, T. Zhang, H. Lu, J. Xiong, J. Yang, C. Zhang, Environmental Friendly Scalable Production of Colloidal 2D Titanium Carbonitride MXene with Minimized Nanosheets Restacking for Excellent Cycle Life Lithium-Ion Batteries, Electrochimica Acta 235 (2017) 690-699.

TE D

[15] C. Zhang, K. B. Hatzell , M. Boota, B. Dyatkin, M. Beidaghi, D. Long, W. Qiao, E. C. Kumbur, Y. Gogotsi, Highly porous carbon spheres for electrochemical capacitors and capacitive flowable suspension electrodes, Carbon 77 (2014) 155-164.

EP

[16] J. Niu, R. Shao, J. Liang, M. Dou, Z. Li, Y. Huang, F. Wang, Biomass-derived

AC C

mesopore-dominant porous carbons with large specific surface area and high defect density as high performance electrode materials for Li-ion batteries and supercapacitors, Nano Energy 36 (2017) 322–330. [17] R. Shao, J. Niu, J. Liang, M. Liu, Z. Zhang, M. Dou, Y. Huang, F. Wang, Mesopore- and Macropore-Dominant Nitrogen-Doped Hierarchically Porous Carbons for High-Energy and Ultrafast Supercapacitors in Non-Aqueous Electrolytes, ACS Appl. Mater. & Interfaces, 49 (2017) 42797-42805. 19

ACCEPTED MANUSCRIPT [18] M. Liu, J. Niu, Z. Zhang, M. Dou, F. Wang, Potassium compound-assistant synthesis of multi-heteroatom doped ultrathin porous carbon nanosheets for high performance supercapacitors, Nano Energy, 51 (2018) 366-372.

RI PT

[19] J. Huang, A. S. Poyraz, S.-Y. Lee, L. Wu, Y. Zhu, A. C. Marschilok, K. J. Takeuchi, E. S. Takeuchi, Silver-Containing α-MnO2 Nanorods : Electrochemistry in Na-Based Battery Systems, ACS Appl. Mater. Interfaces 9 (2017) 4333 4342.

SC

[20]Xiao,H.Song,S.Lin,Y.Zhou,X.Zhan,Z.Hu,Q.Zhang,J.Sun,B.Yang,T.Li,L.Jiao,J.Zh

M AN U

ou,J.Tang, Y. Gogots, Scalable salt-templated synthesis of two-dimensional transition metal oxides, Nat. Commun. 4 (2016) 22.

[21] Q. Meng, K. Cai, Y. Chen, L. Chen, Research progress on conducting polymer based supercapacitor electrode materials, Nano Energy 36 (2017) 268-285.

(2017) 86-107.

TE D

[22] A. Eftekhari, L. Li, Y. Yang, Polyaniline supercapacitors, J. Power Sources. 347

[23] M. Acerce, D. Voiry, M. Chhowalla, Metallic 1T phase MoS2 nanosheets as

EP

supercapacitor electrode materials, Nature Nanotech. 10 (2015), 313-318.

AC C

[24] D. Feng, T. Lei, M. R. Lukatskaya, J. Park, Z. Huang, M. Lee, L. Shaw, S. Chen, A. A. Yakovenko, A. Kulkarni, J. Xiao, K. Fredrickson, J. B. Tok, X. Zou, Y. Cui, Z. Bao, Robust and conductive two-dimensional metal organic frameworks with exceptionally high volumetric and areal capacitance, Nature Energy 3 (2018) 30-36. [25] D. Sheberla, J. C. Bachman, J. S. Elias, C. J. Sun, Y. Shao-Horn, M. Dincă, Conductive MOF electrodes for stable supercapacitors with high areal capacitance, Nature Mater. 16 (2017) 220–224. 20

ACCEPTED MANUSCRIPT [26] Y. Yan, C. E. Ren, K. Maleski, C. B. Hatter, B. Anasori, P. Urbankowski, A. Sarycheva, Y. Gogotsi, Flexible MXene/Graphene Films for Ultrafast Supercapacitors with Outstanding Volumetric Capacitance, Adv. Funct. Mater. 27 (2017) 1701264.

RI PT

[27] M. Ghidiu, M. R. Lukatskaya, M. Q. Zhao, Y. Gogotsi, M. W. Barsoum, Conductive two-dimensional titanium carbide ‘clay’ with high volumetric capacitance, Nature. 576 (2014) 78-U71.

SC

[28] M. R. Lukatskaya, S. Kota, Z. Lin, M-Q. Zhao, N. Shpigel, M. D. Lev, J. Halim,

M AN U

P-L. Taberna, M. Barsoum, P. Simon, Y. Gogotsi,Ultra-high-rate pseudocapacitive energy storage in two-dimensional transition metal carbides, Nature Energy 8 (2017)17105.

[29] H. L. Jia, Z. H. Zhang, Z. Qi, G. D. Liu, X. F. Bian, Formation of nanocrystalline

TE D

TiC from titanium and different carbon sources by mechanical alloying, J. Alloys. Compd. 472 ( 2009) 97-103.

[30] X. Y. Tao, Y. P. Li, J. Du, Y. Xia, Y. C. Yang, H. Huang, Y. P. Gan, W. K. Zhang,

EP

X. D. Li, Generic bamboo-based carbothermal method for preparing carbide (SiC,

AC C

B4C, TiC, TaC, NbC, TixNb1−xC, and TaxNb1−xC) nanowires, J. Mater. Chem. 21(2011) 9095-9102.

[31] S. R. Qi, X. T. Huang, Z. W. Gan, X. X. Ding, Synthesis of titanium carbide nanowires, J. Cryst. Growth. 219 (2000) 485-488. [32] C. H. Liang, G. W. Meng, W. Chen, Y. W. Wang, L. D. Zhang, Growth and characterization of TiC nanorods activated by nickel nanoparticles, J. Cryst. Growth. 220 (2000) 296-300. 21

ACCEPTED MANUSCRIPT [33] T. Panja, D. Bhattacharjya, J-S. Yu, Nitrogen and phosphorus co-doped cubic ordered mesoporous carbon as a supercapacitor electrode material with extraordinary cyclic stability, J. Mater. Chem. A. 3 (2015) 18001-18009.

for effective water cleaning, Nat. Commun. 4 (2013) 1777.

RI PT

[34]W. Lei, D. Portehault, D. Liu, S. Qin, Y. Chen, Porous boron nitride nanosheets

[35] J. N. He, Y. Zhang, P. Mi, Y. F. Qin, K. Chen, Y. C. Yang, J. X. Zhang, F. X. Yin,

SC

Microstructure and wear behavior of nano C-rich TiCN coatings fabricated by

305 (2016) 215–222.

M AN U

reactive plasma spraying with Ti-graphite powders, Surface & Coatings Technology.

[36] T. Miller, J. M. Lin, L. Pirolli, L. Coquilleau, R. Luharuka, A.V. Teplyakov, Investigation of thin titanium carbonitride coatings deposited onto stainless steel, Thin

TE D

Solid Films. 522 (2012) 193-198.

[37] P. K. Ajikumarn, M. Kamruddin, T. R. Ravindran, S. Kalavathi, A. K. Tyagi, Oxidation behavior of TiCxN1-x coatings as a function of C/N ratio, Ceramics

EP

International. 40 (2014) 10523-10529.

AC C

[38] K. Fic, G. Lota, M. Meller, E. Frackowiak, Novel insight into neutral medium as electrolyte for high-voltage supercapacitors, Energy Environ. Sci. 5 (2012) 5842. [39] M. P. Bichat, E. Raymundo-Pinero, F. Be´guin, High voltage supercapacitor built with seaweed carbons in neutral aqueous electrolyte, Carbon 48 (2010) 4351–4361. [40] H. Cui, G. Zhu, X. Liu, F. Liu, Y. Xie, C. Yang, T. Lin, H. Gu, F. Huang, Niobium Nitride Nb4N5 as a New High-Performance Electrode Material for Supercapacitors, Adv. Sci. 2 (2015) 1500126. 22

ACCEPTED MANUSCRIPT [41] J. T. Mefford, W. G. Hardin, S. Dai, K. P. Johnston, K. J. Stevenson, Anion charge storage through oxygen intercalation in LaMnO3 perovskite pseudocapacitor electrodes, Nature Materials. 13 (2014) 726-732.

RI PT

[42] D. P. Dubal, N. R. Chodankar, D-H. Kim, P. Gomez-Romero, Towards flexible solid-state supercapacitors for smart and wearable electronics, Chem. Soc. Rev. 47 (2018) 2065-2129.

SC

[43] J. Li, J. Lu, J. Yan, T-W. Chou, High performance solid-state flexible

Chem. A. 5 (2017) 11271–11277.

M AN U

supercapacitor based on Fe3O4/carbon nanotube/polyaniline ternary films, J. Mater.

[44] P. F. Smith, K. J. Takeuchi, A. C. Marschilok, E. S. Takeuchi, Holy Grails in Chemistry: Investigating and Understanding Fast Electron/Cation Coupled Transport

TE D

within Inorganic Ionic Matrices, ACCOUNTS Chem. Res. 50 (2017) 544 548. [45] Y. Dai, S. Cai, L. Wu, W. Yang, J. Xie, W. Wen, J-C. Zheng, Y. Zhu, Surface modified CFx cathode material for ultrafast discharge and high energy density, J.

AC C

EP

Mater. Chem. A, 2 (2014) 20896–20901.

23

ACCEPTED MANUSCRIPT

AC C

EP

TE D

M AN U

SC

RI PT

Figures

Fig.1 Schematic of the preparing process of carbon anchored titanium carbonitride (a)-(c). SEM images of the prepared titania nanotube (d) porous ‘nest’ shaped carbon anchored titanium carbonitride (e). TEM (f) and HRTEM (g) of the carbon anchored titanium carbonitride. The inset in (g) is fast Fourier transformed (FFT) patterns of the selected square area HRTEM image.

24

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

TE D

Fig.2 Structural characterization of the carbon anchored titanium carbonitride, (a) XRD pattern (b) XPS spectrum of Ti 2p (c) Raman spectrum (d) Isothermal curve of

AC C

EP

N2 adsorption.

25

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

AC C

Fig. 3 Electrochemical performance of titanium carbonitride based electrode in 1 M H2SO4 electrolyte. (a) CV profiles at various scan rates. (b) GCD curves at different current densities. (c) Plot of b values for the cathodic and anodic peaks (0.15V vs. Ag/AgCl). (d) Areal capacitance versus scan rate of the high mass loading (13.25 mg cm-2). (e) Electrochemical impedance spectrum (EIS) of the electrode (inset is magnified region at high frequency). (f) Capacitance retention test (galvanostatic cycling at 10 A g-1). 26

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

Fig. 4 CV curves at 10 mV s-1 for the semi-solid-state symmetric flexible

EP

supercapacitor subjected to 0°, 90°, 150°, and 180° bending (inset is the optical

AC C

photograph of bended flexible supercapacitor). (b) GCD curves at different current densities. (c) Ragone plot. (d) Cyclic performance of the flexible supercapacitor at 10 Ag-1. The inset is the GCD curve at 10 A g-1. The blue and red discs denote capacitance retention and columbic efficiency, respectively.

27

ACCEPTED MANUSCRIPT

Highlights anchored

carbonitridation

titanium

carbonitride

is

prepared

by

a

bottom-up

TE D

1. Carbon

M AN U

SC

RI PT

Graphitic abstract

2. As the electrode material for ultrafast supercapacitor

EP

3. A high capacitance of 360 F g-1 at 0.5 A g-1, with a retention 100/1 A g-1 of 53% 4. Thick electrode can present a high area capacitance up to 1.77 F cm-2

AC C

5. Flexible solid state symmetric supercapacitor delivers 4.9 Wh kg-1 at 25000 W kg-1

28