A novel imide-based hybrid gel polymer electrolyte: Synthesis and its application in electrochromic device

Accepted Manuscript A novel imide-based hybrid gel polymer electrolyte: Synthesis and its application in electrochromic device Jianping Zhou, Jianfeng Wang, Hua Li, Fenglei Shen PII:

S1566-1199(18)30314-8

DOI:

10.1016/j.orgel.2018.06.023

Reference:

ORGELE 4746

To appear in:

Organic Electronics

Received Date: 17 May 2018 Accepted Date: 17 June 2018

Please cite this article as: J. Zhou, J. Wang, H. Li, F. Shen, A novel imide-based hybrid gel polymer electrolyte: Synthesis and its application in electrochromic device, Organic Electronics (2018), doi: 10.1016/j.orgel.2018.06.023. 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

A novel imide-based hybrid gel polymer electrolyte: synthesis and its application in electrochromic device Jianping Zhou, Jianfeng Wang, Hua Li*, Fenglei Shen* Department of Inorganic Materials, College of Chemistry Chemical Engineering and Materials Science,

E-mail: [email protected]; [email protected]

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Soochow University, 199 Renai Road, Suzhou, Jiangsu Province, 215123, PR China.

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Abstract A novel imide-based organic-inorganic gel polymer electrolyte based on the reaction of

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poly(propylene glycol) bis(2-aminopropyl ether) (2-APPG) with pyromellitic dianhydride (PMDA) and followed by the reaction with 3-isocyanatepropyltriethoxysilane (ICS) is successfully fabricated. The results reveal that the electrolyte has hardly any weight loss up to 100 °C, exhibiting a high ionic conductivity of 1.01×10-3 S cm-1 at room temperature and the Li ion transference numbers (t+) is as

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high as 0.65, as well as good electrochemical stability with electrochemical stability window up to 10 V. An archetype electrochromic device is assembled by using the organic-inorganic gel polymer electrolyte as conductive medium. The results confirm that the device has a high voltage (5 V) stability

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performance, high coloration efficiency (193.3 cm2 C-1) and good cycle performance (450 cycles over a

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voltage range of −3.5-2.5 V). So the presented organic-inorganic gel electrolyte is a very promising material for electrochemical application. Keywords: Gel polymer electrolyte; Thermal stability; Electrochemical performance; Electrochromic performance

1. Introduction The rapid economic development and energy shortages lead to the urgent demand for efficient

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ACCEPTED MANUSCRIPT energy storage devices, so numerous researchers are increasingly concerned on the manufacture of efficient energy storage devices, such as lithium ion batteries, supercapacitors, dye-sensitized solar cells (DSSCs), electrochromic (EC) devices [1-4], etc. Electrolytes, which are an important component

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for electrochemical devices, play an indispensable role between two electrodes as conductive medium in practical application. Therefore, the electrolytes should meet some basic requirements including high ionic conductivity (>10-4 S cm-1, at room temperature), good thermal stability and wide electrochemical

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stability windows (ESW) (~5 V) [5-7]. The solvent of liquid electrolytes easy leak and volatilize,

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resulting in safe problems [8, 9], the all-solid electrolytes is a promising alternative to liquid electrolytes which can preclude the disadvantage of liquid electrolytes, but they inherently have low conductivities due to the crystallization of the polymer and thus make them inadequate for practical application [10]. In order to integrate the advantages of all-solid electrolytes and liquid electrolytes, gel

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polymer electrolytes (GPEs) have been introduced. GPEs have received increasing attention due to excellent forming ability and flexibility, relatively high ionic conductivities, wide ESW, good affinity with the electrodes and the ability to design flexible, thin and small electrochemical devices [5, 11, 12].

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GPEs are usually prepared using a polymer as the host and a liquid electrolyte to provide

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transmission ions. Poly(vinylidene fluoride) (PVDF) and its copolymer with poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP), poly(ethylene oxide) (PEO), poly(methyl methacrylate) (PMMA), poly(acrylonitrile) (PAN)], etc. which are some main polymer matrices that have succeeded in preparing GPEs [13-17], but each polymer has its own disadvantages: poor compatibility, poor thermal stability, etc. Furthermore, the comprehensive properties of GPEs need to be further improved when considering these factors of cycle performance, ionic conductivities and the interface stability between electrolytes and electrodes for commercial applications. Therefore, fruitful researchers try

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ACCEPTED MANUSCRIPT various methods to improve the performance of GPEs including doping inorganic particles [18, 19], designing interpenetrating polymer network (IPN) [20, 21], synthesizing copolymers or blending polymer [22], etc. Although these alternatives enhance the room temperature ionic conductivities, some lack

of

stable

structure

and

electrochemical

stability

for

commercial

applications.

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are

Organic-inorganic hybrid, which combine organic and inorganic groups, is a prospect way to enhance the performance of GPEs [23, 24], endowing electrolytes the special properties of each component.

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Moreover, among the different synthesis method for GPEs, the sol-gel method is a simple and efficient

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way for synthesizing electrolytes under different conditions, as it allows a wide composition, organic-inorganic ratios and an excellent control of porosity and functional groups. These special characteristic endow the possibility of organic-inorganic materials serve as electrolytes in electrochemical devices. In previous study, an organic-inorganic GPE was successfully synthesized by

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sol-gel process [25]. It exhibits a high ionic conductivities value of 1.43×10-3 S cm-1 at 30 °C and wide ESW (10 V), but unfortunately presents a poor cycle performance and poor ductility. For the purpose of enhancing the performance of GPEs, we developed a novel organic-inorganic

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material via the reaction of 2-APPG with pyromellitic dianhydride (PMDA) and followed by the

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reaction with ICS. PMDA was used to react with the terminal amino groups of 2-APPG and attain an imide-based polymer which is contribute to reduce cross-linking density than previous study [25], at the same time, increasing the ability of segmental movement which can enhance the ionic conductivities and ductility property of GPEs. Moreover, the ethylene (EO) chains of 2-APPG could form instant ion interaction with Li+ and promoting the transportation of Li+ by the hopping mechanism [26]. Apart from it, the ICS provides chemical cross-linking points and forms silicate network by hydrolysis which benefits ion transport, which may endow GPEs an enhanced thermal stability and

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ACCEPTED MANUSCRIPT dimensional stability. In this work, we investigated the thermal, mechanical and electrochemical properties of GPEs. Finally, the archetype EC devices were assembled using the GPEs as conductive

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medium to confirm its potential applications.

2. Experiment methods

2.1. Materials

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3-isocyanatepropyltriethoxysilane (ICS, 99%), lithium bis(trifluoromethylsulfonyl) imide (LiTFSI, aladdin, 99%), pyromellitic dianhydride (PMDA), poly(propylene glycol) bis(2-aminopropyl ether)

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(2-APPG) (designated as A-400 (Mw=400) and A-2000 (Mw=2000)), anhydrous ethanol and acetic acid were acquired from Alddin. Tungsten powder (99.9%), N, N-dimethylformamide (DMF) and hydrogen peroxide (30%) were acquired from Shanghai Reagent Co., Ltd. Indium tin oxide (ITO) conductive

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glass with 10 Ω was purchased from Zhuhai Kaivo Optoelectronic Technology Co. Ltd. The ITO glass was ultrasonic treatment for 1 h and then was dried under air conditions.

2.2. The synthesis of organic-inorganic GPE

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The organic-inorganic GPEs are synthesized by sol-gel process [27] which is changed slightly.

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Briefly, GPEs are prepared via the reaction between the terminal amino groups of 2-APPG and the anhydride groups of PMDA and followed by the reaction with the isocyanate groups of ICS (Supporting Information, Fig. S1). A homogeneous solution consists of 2-APPG (0.0025 mol) and PMDA (0.002 mol) dissolved into DMF (10 ml) and mechanical stirred at 60 °C for 6 h, attaining a viscous solution (AP). Then, ICS (0.001 mol) was added to AP and mechanical stirred at 100 °C for 6 h, resulting in a viscous precursor (API). LiTFSI (0.001 mol) and anhydrous ethanol (3.3 ml) were added to the API and mechanical stirred at 20 °C for 3 h, attaining a uniform solution. Finally, 0.58 ml glacial

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ACCEPTED MANUSCRIPT CH3COOH was added to the above solution and mechanical stirred for 4 h to catalyze hydrolysis and formed silicate network framework. The GPEs were attained when solvent is evaporated about 85%, The GPEs samples are abbreviated as API-x, where A, P and I denote 2-APPG, PMDA and ICS,

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respectively; x represents the mole percentage of A-2000 in A-400 and A-2000. The composition ratio of raw materials for GPEs is showed Table 1. Moreover, the gel polymer electrolyte (API-100)

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membrane is prepared and its tensile property is tested, as shown in Fig. S2 (Supporting Information).

2.3. Preparation of the EC layer

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WO3 layers are prepared by the means reported by Wang [28] which was changed slightly. 0.93 g tungsten powder was dissolved in 15 ml hydrogen peroxide and mechanical stirred for a half hour at 0 °C and then mechanical stirred at 20 °C for 19 h to attain a resultant homogeneous solution. The homogeneous solution was refluxed at 100 °C for 1.5 h, resulting in a clear orange solution. Afterward,

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the solution was mingled with a total volume ratio of anhydrous CH3CH2OH and H2O =7: 3. Finally, the WO3 sol solution was plated on clean ITO glasses by dip-coating and dried at 20°C. The

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WO3-coated-ITO glasses were preserved under air conditions before assembling the EC devices.

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2.4. Preparation of EC devices

The EC devices are assembled according to the following framework structure [29]: ITO-1/WO3

layer/GPE/ITO-2 (Supporting Information, Fig. S3), where ITO-1 and ITO-2 are the two transparent electrodes (TEs) which are applied the voltage, WO3 film is the EC layer and GPE is used as the conductive medium for ion. The GPE solution is applied on the surface of WO3-coated-ITO and then the ITO-2 is softly pushed against this GPE to guarantee a uniform distribution. Finally, copper foil is plated at both ends of ITO to ensure a good conductive contact for test. The EC devices have an area

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ACCEPTED MANUSCRIPT about 1×1 cm2.

2.5. Characterizations The structures of GPEs were characterized by Fourier transform infrared spectra (Bruker

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VERTEX 70, Germany) over a range of 600-4000 cm-1 with a resolution of 4 cm-1.

The thermal stability of GPEs were determined using thermogravimetric analysis (TGA-Q5000,

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TA) over a temperature range of 25-690 °C with a heating/cooling rate of 10 °C min-1 under N2 conditions. Differential scanning calorimeter (DSC-Q200, TA) was performed over a temperature range

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of −70-150 °C with a heating/cooling rate 10 °C min-1under N2 conditions.

The AC impedance measurements of GPEs were carried out and the data was recorded with the amplitude of 5 mV at an open circuit potential over a frequency range of 1-105 Hz using electrochemical workstation (CHI600E, Shanghai Chenhua). The ionic conductivities of GPEs can be

σ=

d RbA

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calculated according to the following Eq. (1):

(1)

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Where σ is the ionic conductivities of GPEs, d (0.1 cm) is the thickness of the GPEs, Rb is the bulk resistance of GPEs and A (1 cm2) is the contact area of electrode and GPEs.

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The Li ion transference numbers (t+) was got according to the means described by Evants [30]. The GPEs were sandwiched between two ITO electrodes over a frequency range of 1-105 Hz with the applied voltage amplitude of 5 mV. The t+ values were calculated according to the Eq. (2):

t+ =

Is (△V − I 0 × R 0) × I 0 (△V − Is × Rs )

(2)

Where I0 and Rs are the initial-state current and resistance, respectively; △V is the applied voltage; Is and Rs are the stable-state current and resistance, respectively.

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ACCEPTED MANUSCRIPT Linear sweep voltammetry (LSV) was used to measure the ESW of GPEs with a scan rate of 10 mV s-1 over a voltage of 5-10 V vs. ITO/Li+ and the test limitation of electrochemical workstation is 10 V. The ITO glass was used as working electrode and another one is used as counter and reference

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electrodes. The chronoamperometry (CA) measurement of the EC device with API-100 electrolyte was carried out and the data was recorded with the applied step voltage between −5.0 V and +5.0 V at a step

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interval of 40 s. The UV-Vis double beam spectrophotometer (TC, PU1810 Instruments, Beijing) was

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determined the optical transmittance of EC device over a wavelength range of 380-900 nm. The cycling performance of EC device with API-100 electrolyte was characterized by cyclic voltammetry over the voltage of −3.5-+2.5 V with a scan rate of 30 mV s-1.

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3. Results and Discussion

3.1. The structure of raw materials and organic-inorganic GPEs FTIR spectra of raw materials and GPEs are displayed in Fig. 1. As seen in Fig. 1(a), the peak at

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1273 cm-1, which is belong to the feature absorption peaks of C–O stretching vibrations, disappears and

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a new peak at 1373 cm-1 (Fig. 1(e-h)) which is assigned to the stretching of C–N vibrations [31], appears in the spectrum of GPEs samples. The absorbance peaks at 1720 and 1770 cm-1 are attributed to the feature absorption peaks of imide units in polyimide (PI) [32]. Moreover, the FTIR peak observed at 1804 cm-1 is attributed to C=O stretching of PMDA, whereas the peak observed at 1770 cm-1 is assigned as C=O stretching of the API-x electrolytes. The above results certify the reaction between PMDA and 2-APPG, resulting in forming polyimide (PI) structure. Apart from it, the absorption peak at 2270 cm-1 (Fig. 1 (b)), which is belong to the stretching

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ACCEPTED MANUSCRIPT peaks of isocyanate groups for ICS [33], disappears and a new peak at 1578 cm-1 (Fig. 1(e-h)) appears in the spectrum of GPEs samples which might be ascribed to the bending vibrations of grafted N–H groups [34]. The above results certify the reaction between ICS and 2-APPG and the formation of urea

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linkages. These peaks at 1013, 1099 and 1190 cm−1 (Fig. 1(e-h)) could be designated to the vibrations of the C–O–Si, C–O–C and Si–O–Si, respectively, indicating the three-dimensional network is formed

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in GPEs.

3.2. Thermal properties

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The thermal stability is vital for safe and a decisive factor for electrolytes in electrochemical devices [35]. The TGA thermograms for API-x electrolyte samples are presented in Figure 2a. As shown, the electrolyte samples have hardly any weight loss up to 100 °C, indicating that electrolyte samples have adequate thermal stability for practical application. The decomposition of electrolyte

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samples can be divided into three steps: the first step is a weight loss of 10% below 300 °C, corresponding to the evaporation of organic solvents and dehydration of entrapped moisture [36]. The

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secondly weight loss between 300 °C to 500 °C, which is much greater than the first step and corresponded to the degradation of polymer. The final weight loss process occurred between 400 °C to

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690 °C, which might be attributed to breakdown of silicate network framework. So the thermal stability performance of GPEs is enough for electrochemical devices as confirmed by this TGA test. The glass transition temperature (Tg) is another important thermal performance. As depicted in Fig.

2b and Table 1, the Tg values decrease as the concentration of A-2000 increases: the Tg values of API-0, API-20, API-50, API-80, API-100 are −48.9 °C, −52.6 °C, −56.2 °C, −60.5 °C and −64.1 °C, respectively. This is because of the reason that the cross-linking density of precursor (API) can be decrease with the concentration of A-2000 increases, i.e., the ethylene oxide (EO) chain segments are

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ACCEPTED MANUSCRIPT more flexible in the matrix, resulting in a decreased Tg value.

3.3. Electrochemical properties Impedance analysis method is used to determine the ionic conductivities of the GPEs. The AC

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impedance spectra of API-x GPEs, x= 0, 20, 50, 80, 100 at 20 °C, are displayed in Fig. 3a and the intercept of curves at Z' axis denotes the Rb of API-x GPEs [37]. The conductivities (σ) are calculated

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from the impedance spectra plots according to the Eq. (1) and shown in Fig. 3b and Table 1, the calculated σ values for API-0, API-20, API-50, API-80 and API-100 gel polymer electrolytes are

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1.47×10-4, 2.64×10-4, 7.09×10-4, 9.17×10-4 and 1.01×10-3 S cm-1 at room temperature, respectively. Among all electrolyte samples, the ionic conductivities of GPEs are increase as the percent of A-2000 enhance which can be assigned to various reasons: on the one hand, the electrolytes have lower cross-linking density as the percent of A-2000 enhance, so polymer segments have better flexible and

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EO chains are easier to form instant ion interaction with Li+ and promoting the transportation of Li+ by the hopping mechanism, which ultimately raises ionic conductivities [26, 38]. On the other hand, Tg

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values of the GPEs decrease with increasing the percent of A-2000 (Fig. 2b). The API-100 GPE has lower Tg value and higher free volume than that of other API-x GPEs, so that Li+ ions, solvated

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molecules and polymer chains are easier to shift in free volume, which is help to attain an increased ionic conductivity. Moreover, the increased ionic conductivities are usually observed when electrolytes have a low Tg value [39], according to free volume theory [40]. So theAPI-100 electrolyte exhibits a maximum ionic conductivity. The contribution of lithium ions is a crucial factor for the electrolytes, due to the polarization of electrolytes is often discovered at low lithium ion transference numbers (t+) state, so increasing the t+ of GPEs is a practical and effective method to enhance the performance of electrochemical application

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ACCEPTED MANUSCRIPT [41]. The stable-state current means [30, 42] has been widely applied to gauge the t+ value, which play a vital role in restraining the ions polarization. The data for all the measurements are showed in Fig. 4 and the calculated values by Eq. (2) are displayed in Table 2. The API-100 exhibits a maximum t+

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value (0.65), which is larger than other polymer electrolytes (t+≤0.5) and liquid electrolytes (0.2-0.4) [43]. Such a large t+ value minimize ions polarization effect and the formation of concentration gradient, ultimately enhancing Li+ ion diffusion and cycle performance [44, 45].

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Compatibility between electrodes and electrolytes has an important effect on electrochemical

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application, which can be assessed by the interfacial resistance (Ri) between electrolytes and electrodes. The Ri is related to the passive layer and the resistances of charge transfer on the electrodes surface[46], so Ri can be assessed according to storage time using electrochemical impedance spectrum (EIS) at open circuit state [47, 48]. Fig. 5 exhibits the AC-impedance spectra of ITO/API-0/ITO and

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ITO/API-100/ITO cells over storage time. The depressed semicircle is associated with the conduction process and the distribution of Li+, which may be corresponded to the Rb, while the low frequency section is attributed to the effect of the charge transfer in the interface, corresponding to the Ri [37].

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The Ri in the API-0 GPE increases more quickly and still is not stable state until 30 days (Fig. 5a). In

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contrast, the Ri in the API-100 GPE is 96 Ω at initial state and then increases over time and becomes relatively stable from 25 days (Fig. 5b). This result indicates that the API-100 GPE has a better affinity with ITO electrode than that of API-0 GPE, which is ascribed to the API-100 GPE has larger t+ value that suppressed the polarization effectively and a stable solid electrolyte film is formed on the ITO surface [49], in other words, A-2000 is contributed to inhibit the polarization of electrolyte in practical application.

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ACCEPTED MANUSCRIPT The electrochemical stability of electrolytes is very significant parameter for practical applications. We further evaluated the electrochemical stability of ITO/API-x GPEs/ITO cell by linear sweep voltammetry. As depicted in Fig. 6, API-x GPEs is stable in entire test voltage range, indicating the

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presented GPEs have good electrochemical stability and the potential to be applied in high voltage application. Such a wide ESW of API-x electrolytes can be assigned to the formation of urea bridges and PI structure, such a unique polymer structure may be assure the electrochemical stability of

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electrolytes. Furthermore, the excellent affinity between the polymer matrix and solvent molecules [51,

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52] can have a significant effect on it, too.

3.4. Performance of GPEs in the EC device

The API-100 electrolyte display a better electrochemical performance than that of API-x electrolytes, so the EC device is assembled using API-100 as conductive medium, at the same time, the

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WO3 layer is applied as EC layer. The CA curve of EC device with API-100 GPE from 1 to 100 cycles is illustrated in Fig. 7a and the API-100 GPE is stable and has no polarization breakdown with

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reduction/oxidation process. So the presented electrolyte has the potential to be applied under high voltage conditions. The coloration efficiency (CE) is associated with EC property of the EC device and

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defined as the change in optical density per unit of inserted charge: CE= △OD/△Q, △OD= log(Tb/Tc)

(3)

Here △Q is average charge density (C cm-2) and Tc, Tb are the optical transmittance (T) at coloration and bleaching states, respectively. The EC device has a CE value as high as 193.3 cm2·C-1 during first coloration/bleaching process, which is bigger than other literatures (Table 3) [5, 53-55], indicating the presented EC device with API-100 GPE as conductive medium is promising to be applied under a conditions where demand a large optical modulation with small inserted charge.

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ACCEPTED MANUSCRIPT The WO3 layer, changing itself color reversibly when apply low direct current voltage via the reaction of reduction/oxidation with the inserting/extracting of Li+ (Eq. (4)), which could be evaluated using the contrast of optical transmittance during coloration/bleaching process [56].

Clear

L ixWO3

（4）

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WO3 + xLi+ + xe-

Dark blue

As described in Fig. 7b, the EC device has almost same average transmittances at as-deposited and

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bleached states (Fig. S4, Supporting Information) and the values of transmittance for EC device are

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75.2%, 72.2% and 38.2% at the as-deposited, bleached and colored states, respectively. Moreover, the change value of optical density is 0.28 by calculating at the wavelength of 550 nm, which indicates the presented electrolyte is a promising material for EC device.

The cyclic voltammograms of the EC device with the API-100 electrolyte are recorded and

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illustrated in Fig. 8 from1 to 450 cycles. A reduction current peak gradually emerges around applied voltage of −1 V which is ascribed the reduction of WO3, indicating the Li+ insert into the WO3 layer to form lithium tungsten bronze (LixWO3) [57]. The oxidation current peak gradually appears around

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applied voltage of +1 V, which may be corresponded to the extraction of Li+ from LixWO3 [54]. There

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is no any other peaks is observed, indicating has no other undesired reactions take place. As seen in Fig. 8, the EC device with API-100 GPE has a almost same cycle process over a range of 1-200 cycles, which indicates the process with the insertion/extraction of Li+ between WO3 layer and API-100 GPE have a good reversibility. The maximum current of EC device during reduction and oxidation process is gradually decreased after 200 cycles, which might be ascribed to the weakened interfacial contact between the electrolyte and the WO3 layer, resulting from the volume change of active materials with the insertion/extraction of Li+ [55]. Furthermore, the EC device with the API-100 GPE has a better

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ACCEPTED MANUSCRIPT cycle performance than previous study [25], this is because that the API-100 electrolyte exhibits a high t+ and a stable polymer structure.

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4. Conclusions A novel imide-based organic-inorganic GPE is successfully synthesized by sol-gel method. The API-100 GPE has hardly any weight loss up to 100 °C which indicate it has good thermal stability,

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exhibiting a ionic conductivity as high as 1.01×10-3 S cm-1 at room temperature, high Li ion transference numbers (0.65) and wide ESW (up to 10 V). An archetype EC device using API-100

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electrolyte as conductive medium displays a high voltage stability (5 V), high coloration efficiency of 193.3 cm2 C-1 and good cycle performance as long as 450 cycles, confirming the presented imide-based organic-inorganic GPE is a promising material for electrochemical application.

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Acknowledgements

This research thanks for the support from National Natural Science Foundation of China (grant No.21301123) and the Priority Academic Program Development of Jiang Su Higher Education

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Institutions (PAPD).

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[26] T. Uma, T. Mahalingam, U. Stimming, Mater. Chem. Phys 82 (2003) 478-483. [27] H.Y. Wu, D. Saikia, C.P. Lin, F.S. Wu, G.T.K Fey, H.M. Kao, Polymer 51 (2010) 4351-4361. [28] W. Wang, Y. Pang, S.N.B. Hodgson, J. Mater. Chem 20 (2010) 8591-8599. [29] H. Li, H. Wu, J. Xiao, Y. Su, J. Robichaud, Y. Djaoued, Chem. Commun 52 (2016) 892-895. [30] J. Evans, C.A. Vincent, P.G. Bruce, Polymer 28 (1987) 2324-2328. [31] J. Lee, C.L. Lee, K. Park, I.D. Kim, J. Power. Sources 248 (2014) 1211-1217. [32] E. Han, Y. Wang, X. Chen, G. Shang, W. Yu, H. Niu, S. Qi, D. Wu, R. Jin, ACS Appl. Mater.

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Energy. Mater. Sol. Cells 169 (2017) 98-106.

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1929, pp. 551-555.

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ACCEPTED MANUSCRIPT Table 1 The composition ratio of raw materials and some properties for the prepared GPEs. -3

2-APPG (×10 mol)

Samples

PMDA

-3

(×10

ICS

-3

Tg (°C)

(×10

σ (×10-4 S cm−1)

A-400

mol)

mol)

0

2.5

2

1

−48.9

1.47

API-20

0. 5

2

2

1

−52.6

2.64

API-50

1.25

1.25

2

1

−56.2

7.09

API-80

2

0.5

2

1

−60.5

9.17

API-100

2.5

0

2

1

−64.1

API-0

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A-2000

10.1

Table 2 Corresponding calculated values and lithium-ion transference number (t Li+) for GPEs at room temperature. Ro (Ω)

Rs（Ω）

Io （10-5 A）

Is （10-5 A）

t+

API-0

681

2718

11.6

1.96

0.27

API-20

379

1187

44.1

API-50

141

262

87.8

API-80

109

210

105

API-100

95.5

162

122

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Samples

0.32

16.1

0.54

21.3

0.56

22.4

0.65

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Table 3 The performance of recent GPEs and EC devices. sr. no.

GPE

composition

Ionic conductivity −1

(polymer/electrolyte)

OPS/LiClO4-PC-EC-D EC 2

1.6×10-4 at 30 °C

ED2003/GLYMO/MPE

2.9×10-3 at room

PMMA/[Emim]BF4

coloration

stability window

efficiency

(V)

(cm2 C-1)

＜5

183

5

4.5

33.5

53

~5

42.4

54

~5

23.19

55

10

193.3

this

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(S cm )

Electrochemical

ref.

temperature

4

PPC/LiClO4/BMIMBF4 PCL/ICPTES-[C2mim] [C(CN) 3]

-3

°

2.4×10 at 25 C

2-APPG/PMDA/ICS/Li

1.01×10-3 at room

TFSI -DMF

temperature

work

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1.5×10-3 at 20 °C

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poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol) bis(2-aminopropyl ether) (ED2003),2,4,6-trichloro-1,3,5-triazine (CC),3-(glycidyloxypropyl)tri-Methoxysilane (GLYMO ） , ethylene carbonate (EC), propylene carbonate(PC), diethyl carbonate (DEC), poly(methyl methacrylate) (PMMA),1-Ethyl-3-methylimidazoliumtetrafluoroborate ([Emim]BF4), poly(propylene carbonate) (PPC), LiClO4,

1-butyl-3-methylimidazolium

poly(ɛ-caprolactone) (PCL(530)),

1-ethyl-3-methylimidazolium bis(2-aminopropyl

ether)

3-isocyanatepropyltriethoxysilane (ICS), N,N-dimethylformamide (DMF)

3-isocyanatepropyltriethoxysilane (ICPTES),

tricyanomethanide [C2mim][C(CN)3], (2-APPG),

tetrafluoroborate (BMIMBF4),

Pyromellitic

poly(propylene dianhydride

glycol) (PMDA)

lithium bis(trifluoromethylsulfonyl) imide (LiTFSI),

ACCEPTED MANUSCRIPT

A novel imide-based hybrid gel polymer electrolyte: synthesis and its application in electrochromic device Jianping Zhou, Jianfeng Wang, Hua Li*, Fenglei Shen* Department of Inorganic Materials, College of Chemistry Chemical Engineering and Materials Science,

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Soochow University, 199 Renai Road, Suzhou, Jiangsu Province, 215123, PR China.

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E-mail: [email protected]; [email protected]

Fig. 1 FTIR spectra of raw materials and GPEs from 600 to 4000 cm−1: PMDA (a), ICS (b), 2-APPG

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(c), API-0 (d), API-20 (e), API-50 (f), API-80 (g), API-100 (h).

Fig. 2(a) TGA curves of GPEs: API-0 (a), API-20 (b), API-50 (c), API-80 (d), API-100 (e); (b) DSC curves

of

GPEs:

API-0

(a),

API-20

(b),

API-50

(c),

API-80

(d),

API-100

(e).

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Fig. 3(a) The impedance spectra of the ITO/API-x/ITO cell, x= 0, 20, 50, 80, 100, inset shows the high frequency region; (b) the ionic conductivities of API-x electrolytes, x= 0, 20, 50, 80, 100, at room

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temperature.

Fig. 4(a) Room temperature current-time curves of the ITO/API-x/ITO cell, x= 0, 20, 50, 80, 100; (b) and (c) corresponding AC impedance plots of the cell before and after the steady-state current, respectively. Inset shows the high frequency region.

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Fig. 5(a) The AC-impedance spectra of the ITO/API-0/ITO cell and (b) the ITO/API-100/ITO cell at

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different storage time at room temperature. Inset shows the high frequency region.

Fig. 6 Linear sweep voltammograms curves of the cell prepared with API-x electrolytes, x= 0, 20, 50,

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80, 100, at room temperature.

Fig.

7(a)

Chronoamperometry

current

measurement

of

ITO-coated-glass-1/WO3

coated

ITO/API-100/ITO-coated-glass-2 EC device with potential steps of −5 and +5 V at every 40 s (100 cycles) and (b) UV-Vis spectra of the EC device at the as-deposited, bleached and colored states in the 1st cycle, at room temperature.

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various cycles, at room temperature.

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Fig. 8 Cyclic voltammograms of the EC device fabricated with API-100 gel polymer electrolyte at

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Highlights 1.

A novel imide-based organic/inorganic gel polymer electrolyte is successfully synthesized according to sol-gel process.

2.

The electrolyte possesses excellent electrochemical properties.

3.

An archetype electrochromic device with the electrolyte exhibits a high voltage stability, high

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coloration efficiency and good cycle performance.