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Supporting Information
Potassium cobalt hexacyanoferrate nanocubic assemblies for high-
performance aqueous aluminum ion batteries
Yue Ru, Shasha Zheng, Huaiguo Xue and Huan Pang*
School of Chemistry and Chemical Engineering, Guangling College, Yangzhou University, Yangzhou, 225009, Jiangsu, P. R. China.
E-mail: [email protected]; [email protected]
S1
Contents
Section A. Supplementary Methods
Section B. Supplementary Data
S2
Section A. Supplementary Methods
Experimental
Materials
All chemicals, Co(NO3)2·6H2O, C6H5Na3O7·2H2O, K3Fe(CN)6, acetylene black, and
polytetrafluoroethylene (PTFE) and isopropanol, were purchased from Shanghai Sinopharm
Chemical Reagent Co. and used without further purification. All aqueous solutions were
freshly prepared with high purity water.
Preparation of CoFe-PBAs
The K2CoFe(CN)6 was synthesized via a one-step hydrothermal method and low-temperature
calcination process. Firstly, the CoFe-PBA precursor was prepared. In a typical preparation, 4
mmol (1.164 g) Co(NO3)2·6H2O and 5.61 mmol (1.65 g) C6H5Na3O7·2H2O were dissolved in
50 mL deionized water to form a homogeneous solution A. At the same time, 2.67 mmol
(0.878 g) K3Fe(CN)6 was dissolved in 50 mL deionized water to form a transparent solution B
as well. The solution B was slowly dropped into the solution A using a pipette and stirred for
5 minutes. Afterwards, the mixed solution was heating in a constant temperature water bath at
25-30 oC for 24 hours to obtain the puce precipitate. The resulting precipitates was collected
by centrifugation and washed with deionized water and ethanol three times respectively and
then dried in vacuum oven at 60 oC for 4 h. At this point, the CoFe-PBA precursor was
synthesized. Then, the as-prepared CoFe-PBA precursor was heated to 100 oC at a rate of 1
oC/min in a tube furnace under nitrogen flow and maintain the temperature at 100 oC for 1h to
form K2CoFe(CN)6. Similar to the calcination method of the K2CoFe(CN)6, other calcined
products (R1, R2 and R3) were heated to 50 oC, 200 oC and 300 oC, respectively.
S3
Characterization
The morphological features were characterized by field emission scanning electron
microscopy (FESEM, Zeiss-Supra55), high resolution transmission electron microscopy
(HRTEM, Tecnai G2 F30 S-TWIN), and energy dispersive X-ray spectrometry (EDS)
mapping. X-ray diffraction (XRD) patterns were examined on a Bruker D8 Advanced X-ray
Diffractometer (Cu-Kα radiation: λ = 0.15406 nm). The chemical states were measured using
an Axis Ultra X-ray photoelectron spectroscope (XPS, Kratos Analytical Ltd., UK) equipped
with a standard monochromatic Al-Kα source (hv=1486.6 eV). Fourier transform infrared
(FTIR) transmission spectra were obtained on a BRUKER-EQUINOX-55 IR
spectrophotometer. Thermogravimetric measurements were determined via a PerkinElmer
Pyris 1 TGA thermogravimetric analysis (TGA) instrument. Nitrogen adsorption-desorption
measurements were performed on a Gemini VII 2390 analyzer at 77 K using the volumetric
method. The specific surface area was obtained from the N2 adsorption-desorption isotherms
and was calculated by the BET method.
Electrochemical Measurements
Fabrication of working electrodes
Activated materials, the CoFe-PBA samples (K2CoFe(CN)6, R0-R3), acetylene black, and
polytetrafluoroethylene (PTFE) were well mixed to form a mixture with a weight ratio of
80:16:8 in isopropanol. After the isopropanol was evaporated, such mixture was pressed onto
a Titanium mesh (The area=1×1 cm2) under a pressure of 30 MPa as the working electrode.
Electrochemical characterization on working electrodes
Electrochemical measurements were carried out on an electrochemical working station (CHI
S4
660D, Shanghai Chenhua) in a three-electrode system, in which the CoFe-PBA electrode was
used as the working electrode, the platinum electrode as a counter electrode and the saturated
calomel (SCE) electrode as the reference electrode. The electrolyte was 1.0 M Al(NO3)3
solution. To compare the cation effects on Al insertion The CoFe-PBA electrodes were tested
with cyclic voltammetry and galvanostatic charge-discharge methods. In the galvanostatic
charge/discharge test, the potential ranged from 0 to 1.2 V (vs. SCE). All the electrochemical
measurements were performed at ambient temperature.
S5
Section B. Supplementary data
Figure S1. SEM images of CoFe-PBA samples for (a, b) R0, (c, d) R1, (e, f) R2 and (g, h) S6
R3.
Figure S2. TGA of the CoFe-PBA precursor (R0) in N2.
S7
Figure S3. XRD pattern of R0-R3 samples.
S8
Figure S4. FTIR patterns of the K2CoFe(CN)6 and R0-R3 samples.
S9
Figure S5. (a) N2 absorption and desorption isotherms. (b) Mesoporous size distributions. (c) Micropore size distributions of the K2CoFe(CN)6.
S10
Figuure S6. Relationship between peak current densities and potential scanning rates of the K2CoFe(CN)6 and R0-R3 samples as working electrode in Al(NO3)3 aqueous solution.
S11
Figure S7. EIS measurements of the K2CoFe(CN)6 and R0-R2 samples.
S12
Figure S8. SEM of the K2CoFe(CN)6 after several electrochemical testments.
S13
Figure S9. Electrochemical performance of K2CoFe(CN)6 electrode in Al2(SO4)3 and AlCl3
electrolytes: a, c) Typical CV curves in Al2(SO4)3 and AlCl3, b, d) Charge/discharge profiles in Al2(SO4)3 and AlCl3.
S14
Figure S10. EIS measurements of the K2CoFe(CN)6 in different types of electrolyte.
S15