Boehmite Nanosheets-coated Separator with Enhanced Performance for Lithium-ion Batteries

doi:10.15541/jim20220050

Abstract

Abstract:

It has received extensive attention to modify polyolefin separator by boehmite coating for the improvement of thermal stability and electrolyte wettability, but how to affect the electrochemical performance of the boehmite- coated separators is unclear. In this work, boehmite nanosheets with a mean particle size of 150 nm were synthesized by a simple hydrothermal method, and these nanosheets were coated on the surface of polyethylene (PE) separator by a scraper. The boehmite nanosheet-coated separator has porosity of 46.6%, electrolyte uptake of 138.9%, ionic conductivity of 0.47 mS/cm, and lithium-ion transference number of 0.42. The battery assembled with this separator exhibits good cycling stability, retaining 93.7% discharge specific capacity after 100 cycles at 1C (1C= 150 mA/g). Meanwhile, the boehmite nanosheet-modified separator has a uniformly distributed pore structure, which optimizes the lithium-ion transport flux and suppresses the formation of lithium dendrites.

Key words: boehmite, lithium-ion battery, separator, porous coating, particle size distribution

CLC Number:

TQ174

FENG Kun, ZHU Yong, ZHANG Kaiqiang, CHEN Zhang, LIU Yu, GAO Yanfeng. Boehmite Nanosheets-coated Separator with Enhanced Performance for Lithium-ion Batteries[J]. Journal of Inorganic Materials, 2022, 37(9): 1009-1015.

Figures/Tables 9

Fig. 1 (a) XRD pattern, (b)SEM image, (c)AFM image, and (d) cross-sectional height profile of boehmite nanosheets

Fig. 2 Physical properties of PE, PE-AlOOHNP and PE-AlOOHNS Surface SEM images of (a) PE, (b) PE-AlOOHNP and (c) PE-AlOOHNS; Electrolyte contact angles of (d) PE, (e) PE-AlOOHNP and (f) PE-AlOOHNS with insets showing pictures of the electrolyte-wetted separators; (g) Initial photo of the separators at 25 ℃; Photos of the separators after heat treatment at (h) 130 ℃ and (i) 150 ℃ for 30 min (1: PE, 2: PE-AlOOHNP, 3: PE-AlOOHNS)

Fig. 3 (a)Nyquist plots of SS/SS cells assembled with different separators; (b) Chronoamperometry profile of Li/PE-AlOOHNS/Li cell with inset showing EIS plots before and after polarization; (c) LSV curves of SS/Li cells assembled with different separators; (d) Rate capabilities, (e) EIS spectra and (f) cycle performances of LFP/Li cells with different separators Colorful figures are available on website

Fig. 4 Voltage profiles of Li/Li symmetric cells assembled with (a) PE, (b) PE-AlOOHNP and (c) PE-AlOOHNS, and (d) schematic illustration of suppressing lithium dendrite formation

Table S1 Physical parameters of different separators

	Thickness/μm	Porosity/%	Electrolyte uptake /%	Bulk resistance /Ω	Ionic conductivity /(mS·cm^-1)	Lithium-ion transference number
PE	9	39.6	84.6	1.06	0.43	0.15
PE-AlOOH_NP	12	42.4	112.5	1.37	0.45	0.39
PE-AlOOH_NS	12	46.6	138.9	1.31	0.47	0.42

Fig. S1 Particle size distribution of boehmite nanosheets

Fig. S2 DSC curves of different separators

Fig. S3 Chronoamperometry profile of Li/PE/Li cell with inset showing the EIS plots before and after polarization

Fig. S4 Chronoamperometry profile of Li/PE-AlOOHNP/Li cell with inset showing the EIS plots before and after polarization

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