Hexaazatrinaphthylene-Based Porous Organic Polymers as Organic

Subscriber access provided by READING UNIV

Article

Hexaazatrinaphthylene-based porous organic polymers as organic cathode materials for lithium ion battery Jinquan Wang, Chung Shou Chen, and yugen zhang ACS Sustainable Chem. Eng., Just Accepted Manuscript • DOI: 10.1021/ acssuschemeng.7b03165 • Publication Date (Web): 09 Dec 2017 Downloaded from http://pubs.acs.org on December 11, 2017

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

ACS Sustainable Chemistry & Engineering is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Sustainable Chemistry & Engineering

Hexaazatrinaphthylene-based porous organic polymers as organic cathode materials for lithium ion battery Jinquan Wang, Chung Shou Chen, and Yugen Zhang* Institute of Bioengineering and Nanotechnology, 31 Biopolis Way, The Nanos #04-01, Singapore 138669 (Singapore). Email: [email protected].

ABSTRACT

Incorporating small organic molecules with redox active sites into a suitable porous organic framework could enhance both ion diffusion rate and electronic conductivity while reducing its solubility in electrolytes. Principles for the construction of redox-active porous organic framework should not sacrifice the theoretical capacity and should balance various important parameters such as specific capacity, cycling stability, rate capability as well as scalability. Herein, we designed two new porous organic frameworks as cathode materials for lithium ion battery (LIB) using hexaazatrinaphthalene (HATN) cores which show high theoretical capacities. The polymer materials were synthesized in a facile and scalable manner with different structural features ranging from a rigid conjugated framework (HATNPF1) to a flexible non-conjugated framework (HATNPF2). HATNPF polymers demonstrated a high specific capacity (309 mAh g-

ACS Paragon Plus Environment

1

ACS Sustainable Chemistry & Engineering 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

1

Page 2 of 26

), excellent long-term cycling stability (92 % capacity retention after 1200 cycles) and rate

capability (65 % capacity retention at 2 A g-1 as compared to capacity at 0.2 A g-1), which is an improvement over previously reported porous organic polymers and the HATN monomer. The structure-property-relationships of these porous frameworks were also studied using computational modelling.

KEYWORDS: organic cathode, hexaazatriphenylene, porous organic polymer, rechargeable battery, lithium ion, high performance, long cycling

INTRODUCTION Although organic electrode materials were conceived as early as their inorganic counterparts, progress in the development of organic electrode materials for rechargeable battery applications has been slow.1,2 Due to such advantages as low cost, high abundance, environmental benignity, high theoretical capacity, and excellent structural versatility and flexibility, there has been a resurgence of interest in organic electrode materials in rechargeable batteries.3-10 Various organic materials, including traditional conducting polymers,7 organic radical compounds,11-13 organosulfur compounds,14 organic carbonyl compounds,15 and organic carbon/nitrogen compounds,16,17 have been investigated as electrode materials. Despite the above-mentioned advantages, low redox stability, high solubility in electrolyte and low electronic conductivity remain crucial limitations to the application of these compounds.18-33 A common strategy for solving the solubility issue of small molecular organic electrode materials is the use of polymeric materials. Embedding redox active sites in a porous organic framework could improve the ion diffusion rate, while a porous organic conjugated framework


2

Page 3 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


could enhance both ion diffusion rate and electronic conductivity. However, a high extent of conjugation and a narrow energy band gap may also lead to rapid capacity decay and low cycling stability.34-36 It is therefore important to understand underlying structure-property relationships and achieve a balance between various parameters in a battery device. Current efforts toward utilizing porous organic polymers in energy storage applications are more focused on the development of supercapacitors.37, 38 There have been some recent examples on the use of porous organic polymers as organic cathode materials,36, 39-53 but most of these approaches work towards improving only one or two parameters of electrode materials, limiting the overall performance of the battery. In addition, the construction of redox-active porous organic polymers generally incorporates redox-inactive linkers, which significantly limits their theoretical specific capacities. Hexaazatrinaphthalene (HATN) is a derivative of hexaazatriphenylene (HAT),54 which is an electron-deficient, rigid and planar, aromatic discotic system. It can be easily synthesized from low-cost chemicals. This type of molecule has been used to build large conjugated frameworks which have also been studied as energy storage materials in many cases.54 HATN, which possesses high theoretical capacity up to 418 mA h g-1, has been studied as an organic cathode material in lithium ion batteries; however, due to its high solubility in electrolyte, poor cycling stability was observed.55,

56

A highly conjugated framework with HATN core and 1,4-

bisethynylbenzene linker was also developed (HATN-CMP) and tested as organic cathode material in lithium ion batteries.36 Though these conjugated porous polymers possess high porosity and high electronic conductivity, HATN-CMP exhibits a moderate cycling stability (62% capacity retention after 50 cycles) and rate capability (44% capacity retention at 500 mA g1

vis 100 mA g-1).


3


Page 4 of 26

To further explore the potential of HATN materials in lithium ion batteries, we designed two new porous organic frameworks incorporating HATN cores. These materials are designed with no (HATNPF1) or small (HATNPF2) additional linker. As shown in Figure 1, HATNPF1 and HATNPF2 have very high theoretical capacities with different structural features (rigid and conjugated HATNPF1 vs flexible and non-conjugated HATNPF2). The polymers were synthesized with easily available starting materials under mild conditions. Excellent electrochemical performance of HATNPF1 in specific capacity (309 mAh g-1, ~72% of theoretical capacity), cycling stability (92 % capacity retention after 1200 cycles) and rate capability (65 % capacity retention at 2 A g-1 vs 0.2 A g-1) was obtained. HATNPF2 showed relatively low cycling stability (66 % capacity retention after 1200 cycles) due to its different structural composition.

Figure 1. Structures, theoretical capacities and abbreviations of related materials.


4

Page 5 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


EXPERIMENTAL SECTION

General Considerations. All reagents were purchased from Scientific Resources Pte Ltd. and used as received. Electrolytes were purchased from Zhangjiagang Guotai-Huarong New Chemical Materials Co., Ltd. Battery capacities and C-rates were calculated based on the mass of active material in the cathode. Synthesis of HATNPF1. Cyclohexanehexone octahydrate (0.193 g, 0.6 mmol) and 3, 3'diaminobenzidine (0.195 g, 0.9 mmol) were charged in a 20 mL two-necked flask under argon and cooled in an ice bath. Deoxygenated NMP (5 mL) with two drops of sulfuric acid was slowly added. The reaction mixture was warmed to room temperature over 3 h, before being transferred to an oil bath and heated to 60 oC overnight. Then, the flask was cooled to room temperature and water was added. The solid precipitate was collected by centrifugation. The resultant dark solid underwent further Soxhlet extraction with methanol, and was dried at 60 oC under vacuum for 12 h to give HATNPF1 in almost quantitative yield. Elemental analysis result of HATNPF1, found: C, 57.64, H, 4.21, N, 16.51%. Synthesis of HATNPF2. Cyclohexanehexone octahydrate (0.193 g, 0.6 mmol) and 3,3’,4,4’Tetraaminodiphenylmethane (0.205 g, 0.9 mmol) were charged in a 20 mL two-necked flask under argon and cooled in an ice bath. Deoxygenated NMP (5 mL) with two drops of sulfuric acid was slowly added. The reaction mixture was warmed up to room temperature for 3 h. The ice bath was replaced with oil bath and heated to 60 oC for overnight. Then, the flask was cooled to room temperature and water was added. The solid precipitate was collected by centrifugation. The resultant dark solid underwent further Soxhlet extraction with methanol, and was dried at 60 o

C under vacuum for 12 h to give HATNPF2 in quantitative yield. Elemental analysis result of

HATNPF2, found: C, 60.32, H, 4.41, N, 16.29%.


5


Page 6 of 26

Characterization. Solid-13C NMR experiments were conducted in a Bruker Avance 400 (DRX400) with CP/MAS. N2 sorption analysis was performed on a Micromeritics ASAP 2020 (77 and 273 K, respectively). TEM experiments were conducted using an FEI Tecnai G2 F20 electron microscope (200 kV). The SEM experiment was conducted using a field emission SEM (JEOL JSM-7400F) operated at an accelerating voltage of 5 keV. Thermal gravimetric analysis (TGA) was performed on a Perkin-Elmer Pyris-1 thermogravimetric analyzer. Elemental analysis (CHNS) was performed on an Elementar vario MICRO cube. FT-IR experiments were performed on a Perkin Elmer Spectrum 100. XPS data were taken on Kratos Axis Ultra DLD (Kratos Analytical Ltd., UK), the data were converted into VAMAS file format and imported into CasaXPS software package, calibrated by the C 1s signal (284.8 eV) and further processed. Cyclic voltammograms (CVs) were taken using a CHI 760C electrochemical workstation (CH Instruments, Inc.). The battery testing system (CT2001A, Wuhan LAND electronics Co., Ltd) was used to evaluate the electrochemical performance. Coin Cell Assembly. The synthesized polymer materials were evaluated as cathode materials for lithium batteries. Cathodes were prepared by mixing active material with graphene oxide (sheet, from Scientific Resources Pte Ltd, made by the Staudenmaier method) and polyvinylidene fluoride (PVDF) as a binder (ratio of 4:5:1 in weight) (see Figure S1 for different ratio). These materials were mixed with NMP (N-methyl-2-pyrrolidone) solvent, and the thusobtained paste was coated on aluminum foil using a coater. NMP was then removed under vacuum at 80 °C for 12 h. Hermetically sealed two-electrode cells (CR2032) were used for electro-chemical experiments. The cathode was separated from the lithium anode by a polyethylene porous film (Celgard) wetted with an equimolar LiCF3SO3/G4 (tetraglyme) salt (see Figure S2 for details on the different electrolytes used). The three layers were pressed


6

Page 7 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


between two current collectors, one in contact with the cathodic material and the other in contact with the lithium disk. All cells were assembled in an argon-filled glovebox. The cathode had a diameter of 12.7 mm and an active material loading of ~0.32 mg/cm2. The capacity contributions of GO was around 25 mA h/g, as found from tests using a control under current conditions at 50 mA/g (Figure S3). Density Functional Theory (DFT) calculation. The calculations were carried out by DFT using the B3PW91functional and the 6-31G (d) basis set as implemented in Gaussian 09 program package. Vibrational frequency calculations, from which the zero-point energies were derived, were performed for each optimized structure at the same level to identify the natures of all stationary points. RESULTS AND DISCUSSION

Polymer materials HATNPF1 and HATNPF2 were synthesized using a modified literature method (Figure 2).57 The starting materials, cyclohexanehexone and amines, were condensed in the presence of several drops of H2SO4 at 60 oC to yield HATNPF1, HATNPF2 or HATN with near quantitative yield. In the framework of HATNPF1, HATN cores are linked via a carboncarbon bond between two phenyl rings. For HATNPF2, HATN cores are linked via the sp3 carbon of the methylene group. Thermal gravimetric analysis shows that the degradation of polymers starts at ~200 oC (Figure S4). XRD spectra indicate that these materials are amorphous (Figure S5). The morphologies of the synthesized polymers were also revealed by scanning electron microscopy (SEM, Figure S6) and transmission electron microscopy (TEM, Figure S7).


7


Page 8 of 26

Figure 2. Synthesis of polymers HATNPF1 and HATNPF2. Successful polymer synthesis was confirmed by Fourier Transform-Infrared Spectroscopy (FT-IR) (Figure S8a) and solid-state nuclear magnetic resonance (NMR) (Figure S9). In the FTIR spectra, the strong peak around 1495 cm-1 can be assigned to C=N stretching. For solid-state 13

C NMR of HATNPF1 and HATNPF2, peaks around 130 and 142 ppm correspond to the

aromatic carbons in benzene ring and aza ring, which was further confirmed by the 13C NMR of HATN (131, 132 and 143 ppm).54 There is a very weak peak observed at 175 ppm in HATNPF1 and HATNPF2, indicating unreacted C=O bond. The peak observed at 42 ppm for HATNPF2 corresponds to methylene group. HATNPFs were further characterized with X-ray photoelectron spectroscopy (XPS) (Figure 3). In the N 1s XPS profiles, HATNPF1 and HATNPF2 display a peak at 399.6 and 399.8 eV respectively, which is close to the N 1s peak observed in HATN (399.3 eV).54 The small peak of two final polymers (HATNPF1 and HATNPF2) and HATN beside the –C=N- in Figure S8 attributes to small amount of unreacted Ar-NH2, which is also confirmed in FT-IR (N-H stretch at 3500 cm-1 and NH2 scissoring at 1600 cm-1) (Figure S8a). The porosity of the synthesized polymers was evaluated by N2 adsorption-desorption isotherms (Figure S10). The BET (Brunauer, Emmett and Teller) surface areas for HATNPF1 and HATNPF2 are about 384 and 288 m2 g-1, and the total pore volumes are about 0.27 and 0.20 cm3


8

Page 9 of 26

g-1, respectively. A broad hysteresis down to low pressure is indicative of trapping effect at cryogenic temperature, which is related to the micropore.58

30000 Original Data Fit Curve Baseline C=N PeaK

20000

HATN

15000

Intensity (a.u.)

20000

399.3

25000

Intensity (a.u.)

10000 5000

399.6 15000

HATNPF1

388

5000 388

392 396 400 404 Binding Energy (eV)

399.8

15000

HATNPF2

Original Data Fit Curve Baseline C=N Peak

10000

0

Intensity (a.u.)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


392 396 400 Binding Energy (eV)

404

Original Data Fit Curve Baseline C=N Peak

10000

5000 388

392 396 400 Binding Energy (eV)

404

Figure 3. XPS spectra (N 1s) of HATN, HATNPF1 and HATNPF2. It was reported that the HATN cathode for LIBs could attain 100% theoretical capacity, although this value decreased during cycling due to the solubility of HATN in electrolyte.55,56 HATN-CMP, an insoluble highly conjugated porous framework gave 71% theoretical capacity in initial run when used as cathode for LIB and the capacity also decreased significantly during cycling.36 In contrast, in our two new porous polymer systems, HATNPF1 has a limited conjugation system due to the twisted adjacent phenyl rings while HATNPF2 is non-conjugated as the basic HATN units are separated by sp3 methylene group. To understand the properties of these new materials, energy profiles and LUMO/HOMOs of HATN, HATNPF12 and HATNPF22 (two-unit model) were calculated by using density functional theory (DFT, 6-31G (d)) method (Figure 4). In theory, the LUMO energy level correlates to the reduction potential


9


Page 10 of 26

and a lower LUMO energy level corresponds to a higher reduction potential.59-61 The LUMO energy levels of HATNPF12 and HATNPF22 are -2.79 eV and -2.64 eV respectively, implying a higher reduction potential of HATNPF1 as correlated to its conjugated framework structure (Figure 4a). The LUMO energy level of HATNPF22 is close to that of HATN (-2.63 eV), corresponding to the localized HATN units in its network structure. The different reduction potentials are in agreement with the results of electrochemical tests (Figure 5). In addition, the energy band gap between LUMO and HOMO of HATNPF12 (3.38 eV) is smaller than that of HATNPF22 (3.66 eV) and HATN (3.76 eV), which indicates higher electrical conductivity of HATNPF1. The smaller band gap of HATNPF1 also reflects its conjugated framework structure.

Figure 4. (a) Molecular structure and HOMO/LUMO energy levels of HATN, HATNPF12 and HATNPF22. (b) HOMO plots with different extents of reduction.


10

Page 11 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


The electronic stabilities of the new materials were examined by studying the highest occupied molecular orbitals (HOMO) (Figure 4).18,62 As shown in Figure 4b, HOMO plots of HATN, HATNPF12 and HATNPF22 present the distribution of electron clouds on molecule and reflect their electronic structures. Although only two-unit model structures were calculated, the results could indicate the qualitative trend of the properties of polymer materials. Electron cloud is well delocalized over the whole molecule of HATN, HATN-3Li and HATN-6Li, indicating HATN can undergo six-electron reduction and the electrons are stabilized by effective conjugation with the aromatic benzene groups. For HATNPF12, electron cloud is well delocalized over the entire conjugated structure. Interestingly, electron cloud is well delocalized in HATNPF12-6Li and relatively centralized in HATNPF12-12Li which indicates a very stable 6electron reduction (two-unit) and relatively less stable 12-electron reduction (two-unit) processes. For HATNPF22, electron cloud is well delocalized within the HATN unit and similar HOMO plots were observed in HATNPF12-6Li as well as HATNPF12-12Li, which indicates the rather stable 6-electron and 12-electron reduction (two-unit) processes.18 CR2032-type coin cells with HATNPFs as cathode materials were fabricated. Cathodes were prepared by mixing HATNPFs with graphene oxide (GO) and poly (vinylidene fluoride (PVDF) in N-methyl-2-pyrrolidone (NMP). The obtained paste was coated on aluminum foil and NMP was then removed under vacuum. It was found that GO is a particularly suitable conductive material for HATNPFs (Figure S11), which may be due to the strong interaction between HATN molecule and functionalities of GO.63 The interaction between HATNPF1 and GO was characterized by FT-IR, and a blue shift in the wavenumber of the C=C stretch in GO from 1645 to 1652 cm-1 was observed (Figure S8b), indicating strong π-π interaction between HATNPF1 and GO.


11

(b)

1 st Cycle 2 nd Cycle 10 th Cycle

3.5 3.0 2.5 2.0 1.5

(d)

1 st Cycle 2 nd Cycle 10 th Cycle

3.5 3.0 2.5 2.0 1.5 0

50 100 150 200 -1 Specific capacity (mAh g )

250

Coulombic efficiency

400

50

200

Discharge capacity

0

0 150

50 100 Cycle number

600 Specific capacity (mA h g-1)

4.0

100 600

0

0 100 200 300 Specific capacity (mAh g-1)

(c)

800 Coulombic efficiency (%)

4.0

Page 12 of 26

100 Coulombic efficiency

400

50 200

0

Discharge capacity

0 0

50 100 150 Cycle number

Coulombic efficiency (%)

Voltage (V) vs Li/Li+

(a)

Voltage (V) vs Li/Li+

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Specific capacity (mA h g-1)


200

Figure 5. Voltage profiles and cycle performances of synthesized HATNPF1 (a) and (b), HATNPF2 (c) and (d). Cyclic voltammetry (CV) measurements of HATNPF1 and HATNPF2 were performed in the range of 1.5-4.0 V at a scan rate of 0.2 mV S-1 (Figure S12), and these materials displayed two broad peaks, demonstrating their multi-electron redox capability during the lithiation and delithiation processes and the highly reversible nature of these polymer electrodes. The broad peaks at 2.2 V originate from the first three redox couples of HATN unit, and the broad peaks at 2.6 V come from the next three redox couples HATN unit; similar results were observed for the HATN monomer prepared as cathode material.64 Voltage profiles of synthesized polymers were measured as shown in Figure 5. Interestingly, the porous polymer HATNPF1 exhibited a high initial charge capacity of 315 mAh g-1 and a first discharge capacity of 309 mA h g-1, with the discharge capacity being ~74% of theoretical capacity. HATNPF2 also exhibited a good initial charge capacity of 224 mA h g-1 and a discharge capacity of 205 mAh g-1, and the fully


12

Page 13 of 26

reversible discharge capacity is around 51% of theoretical capacity. Under the same testing conditions, the HATN monomer showed a low initial capacity and very low stability (Figure S13). HATNPF1 exhibited a gradually decreasing trend to reach 94% retention of the original capacity upon 130 cycles at 50 mA g-1 (Figure 5b). However, HATNPF2 exhibited lower stability with 56 % retention of the original capacity upon 130 cycles at 50 mA g-1 (50 %

300 200

0.1 A/g

0.2

0.3 0.4 0.5

0.1 1 2

100 4

0 HATNPF1 0

20


100

-1

-1

Discharge capacity

400

Specific capacity (mA h g )

retention upon 200 cycles) (Figure 5d).


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Discharge capacity

300 200 100

0.1 A/g

0.2

0.1

0.3 0.4 0.5 1 2 4

0

HATNPF2 0

20


100

Figure 6. Cycling performance of HATNPF1 and HATNPF2 at different rates. The rate capabilities of these two polymer cathodes were investigated by discharge-charge cycling for 10 cycles at each current density increasing from 0.1, 0.2, 0.3, 0.4, 0.5, 1, 2 to 4 A g-1 (Figure 6). In general, whilst both polymers exhibited good rate capabilities, their capacities showed a slow decline as the current density increased. When batteries were charged and discharged at the high current density of 2 A g-1, the capacities of HATNPF1 and HATNPF2 cathodes were 174 and 112 mA h g-1, which correspond to 65% and 56% of capacity at current density of 0.1 A g-1. However, both polymer cathodes delivered similar capacities at 4A/g (HATNPF1: 88 mA h g-1, HATNPF2: 83 mA h g-1). Additionally, the high capacities rebounded as the current density was reduced from 4 A g-1 to 0.1 A g-1, and the rate capability curves are


13


highly reversible even when the cycles are carried out at different rates for both the organic electrodes. These results indicate that these polymer cathodes are capable of rapid charging and discharging, and batteries incorporating said cathodes could be charged within minutes to high capacities. 800 HATNPF1 HATNPF2

600 -Z''(Ohm)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 14 of 26

400 200 0 0

400

800 Z' (Ohm)

1200

1600

Figure 7. Nyquist plots of the HATNPF1 and HATNPF2. It is known that factors determining rate capability are primarily electronic conductivity and solid-state ion transport for materials showing similar redox behaviour. The electrochemical impedance spectroscopy (EIS) results for HATNPF1 and HATNPF2 are shown in the form of Nyquist plots in Figure 7. It is apparent that the resistance to ion transport and charge transfer in HATNPF1 is smaller than that of HATNPF2, leading to improved long-term cycling stability (Figure 5 and Figure 8). Figure 8 shows the long-term cycling stability and Coulombic efficiency of two polymer cathodes at a current density of 500 mA g-1. HATNPF1 demonstrates excellent long-term cycling stability. The specific capacity of HATNPF1 is 180 mA h g-1 at begin and stabilizes at 165 mA h g-1 from 800th cycle to 1200th cycle, which shows capacity retention of approximately 92% of the initial capacity after 1200 cycles. This initial capacity is lower than the capacity at 500 mA g-1 in rate capability experiment (Figure 6a), which may due to different testing conditions. The specific capacity of HATNPF2 slowly decays to 102 mA h g-1 from 153 mA h g-1 after 1200


14

Page 15 of 26

cycles, which shows capacity retention of approximately 66% of the initial capacity. The Columbic efficiencies for both materials were stable at ~100% throughout 1200 cycles. Both the stability and the capacity of HATNPF1 and HATNPF2 cathodes are much higher than HATNCMP33 and other previously reported porous polymers.39-53 The HATNPF1 cathode demonstrated better performance in the aspects of specific capacity and long term cycling stability as compared to HATNPF2 cathode, which may be due to their different structures. From the HOMO plots, HATNPF1 with limited conjugation structure shows that both the HATNPF13and HATNPF16- anions are stable. The rigid framework makes the polymer structure strong and stable during charge-discharge processes. The higher surface area means higher porosity and better network structure which indicates higher electronic and ionic conductivity. HATNPF2 polymer shows well delocalized electron cloud after reduction. Its relatively poor performance as cathode may be due to its flexible and imperfect framework structure which could be seen from

400

Coulombic efficiency HATNPF1 50 Discharge capacity

200

0

0 0

200 400 600 800 1000 1200 Cycle number

-1

800 100 600 400

Coulombic efficiency HATNPF2 50 Discharge capacity

200

0

0 0


100 600


-1

800


its relatively low surface area.


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


200 400 600 800 1000 1200 1400 Cycle number

Figure 8. HATNPF1 demonstrated a better cycling stability than HATNPF2 (500 mA g-1). CONCLUSION


15


Page 16 of 26

We have designed and synthesized two new HATN-based porous polymers for use as cathode materials for lithium ion batteries. The new polymers were synthesized by wet chemical process under mild and facile conditions. They exhibit high specific capacity, excellent rate capability, long-term cycling stability, and near-unity Coulombic efficiency as cathode materials. Frameworks of these two polymers have different levels of π-conjugation, flexibility and porosity, as reflected in their DFT-calculated HOMO-LUMO gaps and electrochemical performance. In general, these new HATN-based polymers have great potential as more environmentally friendly cathode materials than existing ones for high-capacity and fastcharging energy storage devices. Notes The authors declare no competing financial interest. ACKNOWLEDGMENTS This work was supported by the Institute of Bioengineering and Nanotechnology (Biomedical Research Council, Agency for Science, Technology and Research (A*STAR), Singapore). The authors thank the A*STAR Computational Resource Centre for the use of its high-performance computing facilities. Supporting Information Computational details and additional experimental data are available in supporting information.

REFERENCES (1)

Larcher, D.; Tarascon, J. M. Towards Greener and More Sustainable Batteries for Electrical Energy Storage. Nat. Chem. 2015, 7, 19-29.


16

Page 17 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(2)

Song, H.-K.; Lee, K. T.; Kim, M. G.; Nazar, L. F.; Cho, J. Recent Progress in Nanostructured Cathode Materials for Lithium Secondary Batteries. Adv. Funct. Mater. 2010, 20, 3818-3834.

(3)

Schon, T. B.; McAllister, B. T.; Li, P.-F.; Seferos, D. S. The Rise of Organic Electrode Materials for Energy Storage. Chem. Soc. Rev. 2016, 45, 6345-6404.

(4)

Xie, J.; Zhang, Q. Recent Progress in Rechargeable Lithium Batteries with Organic Materials as Promising Electrodes. J. Mater. Chem. A 2016, 4, 7091-7106.

(5)

Zhu, Z.; Chen, J. Advanced Carbon-Supported Organic Electrode Materials for Lithium (Sodium)-Ion Batteries. J. Electrochem. Soc. 2015, 162, A2393-A2405.

(6)

Muench, S.; Wild, A.; Friebe, C.; Häupler, B.; Janoschka, T.; Schubert, U. S. PolymerBased Organic Batteries. Chem. Rev. 2016, 116, 9438-9484.

(7)

Song, Z.; Zhou, H. Towards Sustainable and Versatile Energy Storage Devices: an Overview of Organic Electrode Materials. Energy Environ. Sci. 2013, 6, 2280-2301.

(8)

Liang, Y.; Zhang, P.; Yang, S.; Tao, Z.; Chen, J. Fused Heteroaromatic Organic Compounds for High-Power Electrodes of Rechargeable Lithium Batteries. Adv. Energy Mater. 2013, 3, 600-605.

(9)

Zhao, Q.; Guo, C.; Lu, Y.; Liu, L.; Liang, J.; Chen, J. Rechargeable Lithium Batteries with Electrodes of Small Organic Carbonyl Salts and Advanced Electrolytes. Ind. Eng. Chem. Res. 2016, 55, 5795-5804.

(10) Zhang, Y. G.; Wang, J. Q.; Riduan, S. N. Strategies toward Improving the Performance of Organic Electrodes in Rechargeable Lithium (Sodium) Batteries. J. Mater. Chem. A 2016, 4, 14902-14914.


17


Page 18 of 26

(11) Lee, S. H.; Kim, J.-K.; Cheruvally, G.; Choi, J.-W.; Ahn, J.-H.; Chauhan, G. S.; Song, C. E. Electrochemical Properties of New Organic Radical Materials for Lithium Secondary Batteries. J. Power Sources, 2008, 184, 503-507. (12) Janoschka, T.; Hager, M. D.; Schubert, U. S. Powering up the Future: Radical Polymers for Battery Applications. Adv. Mater. 2012, 24, 6397-6409. (13) Oyaizu, K.; Nishide, H. Radical Polymers for Organic Electronic Devices: A Radical Departure from Conjugated Polymers? Adv. Mater. 2009, 21, 2339-2344. (14) Talapaneni, S. N.; Hwang, T. H.; Je, S. H.; Buyukcakir, O.; Choi, J. W.; Coskun, A. Elemental-Sulfur-Mediated Facile Synthesis of a Covalent Triazine Framework for HighPerformance Lithium-Sulfur Batteries. Angew. Chem. Int. Ed. 2016, 55, 3106-3111. (15) Häupler, B.; Wild, A.; Schubert, U. S. Carbonyls: Powerful Organic Materials for Secondary Batteries. Adv. Energy Mater. 2015, 5, 1402034-1402068. (16) Hong, J.; Lee, M.; Lee, B.; Seo, D.-H.; Park, C. B.; Kang, K. Biologically Inspired Pteridine Redox Centres for Rechargeable Batteries. Nat. Commun. 2014, 5. 5335-5344. (17) Schon, T. B.; Tilley, A. J.; Bridges, C. R.; Miltenburg, M. B.; Seferos, D. S. Bio-Derived Polymers for Sustainable Lithium-Ion Batteries. Adv. Funct. Mater. 2016, 26, 6896-6903. (18) Liang, Y.; Zhang, P.; Chen, J. Function-oriented Design of Conjugated Carbonyl Compound Electrodes for High Energy Lithium Batteries. Chem. Sci. 2013, 4, 1330-1337. (19) Nokami, T.; Matsuo, T.; Inatomi, Y.; Hojo, N.; Tsukagoshi, T.; Yoshizawa, H.; Shimizu, A.; Kuramoto, H.; Komae, K.; Tsuyama, H.; Yoshida, J.-I. Polymer-Bound Pyrene4,5,9,10-tetraone for Fast-Charge and -Discharge Lithium-Ion Batteries with High Capacity. J. Am. Chem. Soc. 2012, 134, 19694-19700.


18

Page 19 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(20) Wu, H.; Shevlin, S. A.; Meng, Q.; Guo, W.; Meng, Y.; Lu, K.; Wei, Z.; Guo, Z. Flexible and Binder-Free Organic Cathode for High-Performance Lithium-Ion Batteries. Adv. Mater. 2014, 26, 3338-3343. (21) Song, Z.; Qian, Y.; Zhang, T.; Otani, M.; Zhou, H. Poly(benzoquinonyl sulfide) as a HighEnergy Organic Cathode for Rechargeable Li and Na Batteries. Adv. Sci. 2015, 2, 1500124. (22) Zhang, K.; Guo, C.; Zhao, Q.; Niu, Z.; Chen, J. High-Performance Organic Lithium Batteries with an Ether-Based Electrolyte and 9,10-Anthraquinone (AQ)/CMK-3 Cathode. Adv. Sci. 2015, 2, 1500018. (23) Chen, D.; Avestro, A.-J.; Chen, Z.; Sun, J.; Wang, S.; Xiao, M.; Erno, Z.; Algaradah, M. M.; Nassar, M. S.; Amine, K.; Meng, Y.; Stoddart, J. F. A Rigid Naphthalenediimide Triangle for Organic Rechargeable Lithium-Ion Batteries. Adv. Mater. 2015, 27, 29072912. (24) Wu, H.; Shevlin, S. A.; Meng, Q.; Guo, W.; Meng, Y.; Lu, K.; Wei, Z.; Guo, Z. Flexible and Binder-Free Organic Cathode for High-Performance Lithium-Ion Batteries. Adv. Mater. 2014, 26, 3338-3343. (25) DeBlase, C. R.; Hernández-Burgos, K.; Rotter, J. M.; Fortman, D. J.; dos S. Abreu, D.; Timm, R. A.; Diógenes, I. C. N.; Kubota, L. T.; Abruña, H. D.; Dichtel, W. R. CationDependent Stabilization of Electrogenerated Naphthalene Diimide Dianions in Porous Polymer Thin Films and Their Application to Electrical Energy Storage. Angew. Chem. Int. Ed. 2015, 54, 13225-13229. (26) Ma, T.; Zhao, Q.; Wang, J.; Pan, Z.; Chen, J. A Sulfur Heterocyclic Quinone Cathode and a Multifunctional Binder for a High-Performance Rechargeable Lithium-Ion Battery. Angew. Chem. Int. Ed. 2016, 55, 6428-6432.


19


Page 20 of 26

(27) Sakaushi, K.; Nickerl, G.; Wisser, F. M.; Nishio-Hamane, D.; Hosono, E.; Zhou, H.; Kaskel, S.; Eckert, J. An Energy Storage Principle using Bipolar Porous Polymeric Frameworks. Angew. Chem. Int. Ed. 2012, 51, 7850-7854. (28) Su, Y.; Liu, Y.; Liu, P.; Wu, D.; Zhuang, X.; Zhang, F.; Feng, X. Compact Coupled Graphene and Porous Polyaryltriazine-Derived Frameworks as High Performance Cathodes for Lithium-Ion Batteries. Angew. Chem. Int. Ed. 2015, 54, 1812-1816. (29) Sun, T.; Li, Z.-J.; Wang, H.-G.; Bao, D.; Meng, F.-L.; Zhang, X.-B. A Biodegradable Polydopamine-Derived Electrode Material for High-Capacity and Long-Life Lithium-Ion and Sodium-Ion Batteries. Angew. Chem. Int. Ed. 2016, 55, 10662-10666. (30) Song, Z.; Qian, Y.; Gordin, M. L.; Tang, D.; Xu, T.; Otani, M.; Zhan, H.; Zhou, H.; Wang, D. Polyanthraquinone as a Reliable Organic Electrode for Stable and Fast Lithium Storage. Angew. Chem. Int. Ed. 2015, 54, 13947-13951. (31) Iordache, A.; Delhorbe, V.; Bardet, M.; Dubois, L.; Gutel, T.; Picard, L. Perylene-Based All-Organic Redox Battery with Excellent Cycling Stability. ACS Appl. Mater. Interfaces, 2016, 8, 22762-22767. (32) Häupler, B.; Hagemann, T.; Friebe, C.; Wild, A., Schubert, U. S. DithiophenedioneContaining Polymers for Battery Application, ACS Appl. Mater. Interfaces, 2015, 7, 34733479 (33) D.-H. Yang, Z.-Q. Yao, D. Wu, Y.-H. Zhang, Z. Zhou, X.-H. Bu, Structure-modulated crystalline covalent organic frameworks as high-rate cathodes for Li-ion batteries, J. Mater. Chem. A, 2016, 4, 18621-18627. (34) Wang, Y.; Song, Y.; Xia, Y. Electrochemical Capacitors: Mechanism, Materials, Systems, Characterization and Applications. Chem. Soc. Rev. 2016, 45, 5925-5950.


20

Page 21 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(35) Mulzer, C. R.; Shen, L.; Bisbey, R. P.; McKone, J. R.; Zhang, N.; Abruña, H. D.; Dichtel, W. R. Ultrahigh Surface Area Three-Dimensional Porous Graphitic Carbon from Conjugated Polymeric Molecular Framework. ACS Cent. Sci. 2016, 2, 667-673. (36) Xu, F.; Chen, X.; Tang, Z.; Wu, D.; Fu, R.; Jiang, D. Redox-active Conjugated Microporous Polymers: a New Organic Platform for Highly Efficient Energy Storage. Chem. Commun. 2014, 50, 4788-4790. (37) Sakaushi, K.; Hosono, E.; Nickerl, G.; Gemming, T.; Zhou, H.; Kaskel, S.; Eckert, J. Aromatic porous-honeycomb electrodes for a sodium-organic energy storage device. Nat. Comm. 2013, 4, 1485-1497. (38) Xu, Y.; Jin, S.; Xu, H.; Nagai, A.; Jiang, D. Conjugated Microporous Polymers: Design, Synthesis and Application. Chem. Soc. Rev. 2013, 42, 8012-8031. (39) Xu, F.; Jin, S.; Zhong, H.; Wu, D.; Yang, X.; Chen, X.; Wei, H.; Fu, R.; Jiang, D. Electrochemically Active, Crystalline, Mesoporous Covalent Organic Frameworks on Carbon Nanotubes for Synergistic Lithium-ion Battery Energy Storage. Sci. Rep. 2015, 5, 8225. (40) Liang, Y.; Chen, Z.; Jiang, Y.; Rong, Y.; Facchetti, A.; Yao, Y. Heavily n-Dopable πConjugated Redox Polymers with Ultrafast Energy Storage Capability. J. Am. Chem. Soc. 2015, 137, 4956-4959. (41) Zhang, S.; Huang, W.; Hu, P.; Huang, C.; Shang, C.; Zhang, C.; Yang, R.; Cui, G. Conjugated Microporous Polymers with Excellent Electrochemical Performance for Lithium and Sodium Storage. J. Mater. Chem. A 2015, 3, 1896-1901.


21


Page 22 of 26

(42) Sakaushi, K.; Hosono, E.; Nickerl, G.; Zhou, H.; Kaskel, S.; Eckert, J. Bipolar Porous Polymeric Frameworks for Low-cost, High-power, Long-life All-organic Energy Storage Devices J. Power Sources, 2014, 245, 553-556. (43) Tian, D.; Zhang, H.-Z.; Zhang, D.-S.; Chang, Z.; Han, J.; Gao, X.-P.; Bu, X.-H. Li-ion Storage and Gas Adsorption Properties of Porous Polyimides (PIs). RSC Adv. 2014, 4, 7506-7510. (44) Zhang, C.; Yang, X.; Ren, W.; Wang, Y.; Su, F.; Jiang, J.-X. Microporous Organic Polymer-based Lithium Ion Batteries with Improved Rate Performance and Energy Density. J. Power Sources, 2016, 317, 49-56. (45) Segura, J. L.; Jua´rez, R.; Ramosb, M.; Seoane, C. Hexaazatriphenylene (HAT) Derivatives: from Synthesis to Molecular Design, Self-organization and Device Applications. Chem. Soc. Rev. 2015, 44, 6850-6885. (46) J. Winsberg, T. Hagemann, T. Janoschka, M. D. Hager, U. S. Schubert, Redox-Flow Batteries: From Metals to Organic Redox-Active Materials, Angew. Chem. Int. Ed. 2017, 56, 686-711. (47) Y. Zhang, Y. Huang, G. Yang, F. Bu, K. Li, I. Shakir, Y. Xu, Dispersion–Assembly Approach to Synthesize Three-Dimensional Graphene/Polymer Composite Aerogel as a Powerful Organic Cathode for Rechargeable Li and Na Batteries, ACS Appl. Mater. Interfaces, 2017, 9, 15549–15556. (48) S. Wang, Q. Wang, P. Shao, Y. Han, X. Gao, L. Ma, S. Yuan, X. Ma, J. Zhou, X. Feng, B. Wang, Exfoliation of Covalent Organic Frameworks into Few-Layer Redox-Active Nanosheets as Cathode Materials for Lithium-Ion Batteries, J. Am. Chem. Soc. 2017, 139, 4258-4261.


22

Page 23 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(49) M. Kolek, F. Otteny, P. Schmidt, C. Muck-Lichtenfeld, C. Einholz, J. Becking, E. Schleicher, M. Winter, P. Bieker, B. Esser, Energy Environ. Sci. 2017, DOI: 10.1039/C7EE01473B. (50) Y. G. Zhang, S. N. Riduan, J. Q. Wang, Redox Active Metal/Covalent Organic Frameworks for Energy Storage: Balancing Porosity and Electrical Conductivity, Chem. Eur. J. 2017, 23, 16419-16431. (51) J. Xie, C. E. Zhao, Z. Q. Lin, P. Y. Gu, Q. C. Zhang, Nanostructured Conjugated Polymers for Energy-Related Applications beyond Solar Cells, Chem. Asia J. 2016, 11, 1489-1511. (52) L. Ma, S. Wang, X. Feng, B. Wang, Recent advances of covalent organic frameworks in electronic and optical applications, Chin. Chem. Lett. 2016, 27, 1383-1394. (53) Z. Xiang, Q. Dai, J.-F. Chen, L. Dai, Edge Functionalization of Graphene and TwoDimensional Covalent Organic Polymers for Energy Conversion and Storage, Adv. Mater. 2016, 28, 6253-6261. (54) Kou, Y.; Xu, Y.; Guo, Z.; Jiang, D. Supercapacitive Energy Storage and Electric Power Supply Using an Aza-Fused π-Conjugated Microporous Framework. Angew. Chem. Int. Ed. 2011, 50, 8753-8757. (55) Matsunaga, T.; Kubota, T.; Sugimoto, T.; Satoh, M. Organic Radical Battery Approaching Practical Use. Chem. Lett. 2011, 40, 750-752. (56) Hanyu, Y.; Sugimoto, T.; Ganbe, Y.; Masuda, A.; Honma, I. Multielectron Redox Compounds for Organic Cathode Quasi-Solid State Lithium Battery. J. Electrochem. Soc. 2014, 161, A6-A9.


23


Page 24 of 26

(57) Mahmood, J.; Lee, E. K.; Jung, M.; Shin, D.; Jeon, I.-Y.; Jung, S.-M.; Choi, H.-J.; Seo, J.M.; Bae, S.-Y.; Sohn, S.-D.; Park, N.; Oh, J. H.; Shin, H.-J.; Baek, J.-B. Nitrogenated Holey Two-dimensional Structures. Nat. Commun. 2015, 6, 6486. (58) Makhseed, S.; Ibrahim, F.; Samuel, J. Phthalimide Based Polymers of Intrinsic Microporosity. Polymer, 2012, 53, 2964-2972. (59) Vadehra, G. S.; Maloney, R. P.; Garcia-Garibay, M. A.; Dunn, B. Naphthalene Diimide Based Materials with Adjustable Redox Potentials: Evaluation for Organic Lithium-Ion Batteries. Chem. Mater. 2014, 26, 7151-7157. (60) Hernández-Burgos, K.; Burkhardt, S. E.; Rodríguez-Calero, G. G.; Hennig, R. G.; Abruña, H. D. Theoretical Studies of Carbonyl-Based Organic Molecules for Energy Storage Applications: The Heteroatom and Substituent Effect. J. Phys. Chem. C 2014, 118, 60466051. (61) Park, M.; Shin, D. S.; Ryu, J.; Choi, M.; Park, N.; Hong, S. Y.; Cho, J. Organic-CatholyteContaining Flexible Rechargeable Lithium Batteries. Adv. Mater. 2015, 27, 5141-5146. (62) Kawai, K.; Kodera, H.; Osakada, Y.; Majima, T. Sequence-independent and rapid longrange charge transfer through DNA. Nat. Chem. 2009, 1, 156-159. (63) Georgakilas, V.; Tiwari, J. N.; Kemp, K. C.; Perman, J. A.; Bourlinos, A. B.; Kim K. S.; Zboril, R. Noncovalent Functionalization of Graphene and Graphene Oxide for Energy Materials, Biosensing, Catalytic, and Biomedical Applications. Chem. Rev. 2016, 116, 5464-5519. (64) Peng, C.; Ning, G.-H.; Su, J.; Zhong, G.; Tang, W.; Tian, B.; Su, C.; Yu, D.; Zu, L.; Yang, J.; Ng, M.-F.; Hu, Y.-S.; Yang, Y.; Armand M.; Loh, K. P. Reversible Multi-Electron


24

Page 25 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Redox Chemistry of π-Conjugated N-containing Heteroaromatic Molecule-based Organic Cathodes. Nat. Energy, 2017, 2, 17074-17082.


25


Page 26 of 26

Table of Contents Electrochemical performance is improved by balancing the porosity and conductivity of organic network cathodes.


26

Hexaazatrinaphthylene-Based Porous Organic Polymers as Organic

Recommend Documents