High electrochemical stability of polyvinylidene fluoride (PVDF) porous membranes using phase inversion methods for lithium-ion batteries

A binder plays an important role in lithium-ion batteries (LIBs), especially for the electrode materials which have large volume expansion during charge and discharge. In this work, we designed a cross-linked polymeric binder with an esterification reaction of Sodium Carboxymethyl Cellulose (CMC) and Fumaric Acid (FA), and successfully used it in an Sb2O3 anode for LIBs. Compared with conventional binder polyvinylidene fluoride (PVDF) and CMC, the new cross-linked binder improves the electrochemical stability of the Sb2O3 anode. Specifically, with CMC-FA binder, the battery could deliver ~611.4 mAh g−1 after 200 cycles under the current density of 0.2 A g−1, while with PVDF or CMC binder, the battery degraded to 265.1 and 322.3 mAh g−1, respectively. The improved cycling performance is mainly due to that the cross-linked CMC-FA network could not only efficiently improve the contact between Sb2O3 and conductive agent, but can also buffer the large volume charge of the electrode during repeated charge/discharge cycles.

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The Synthesis and Electrochemical Performance of Si Composite with Hollow Carbon Microtubes by the Carbonization of Milkweed from Nature as Anode Template for Lithium Ion Batteries

Energies ◽

10.3390/en13195124 ◽

2020 ◽

Vol 13 (19) ◽

pp. 5124

Author(s):

Eun Hyuk Chung ◽

Jong Pil Kim ◽

Hyun Gyu Kim ◽

Jae-Min Chung ◽

Sei-Jin Lee ◽

...

Keyword(s):

Electron Microscopy ◽

Electrical Conductivity ◽

Electrochemical Performance ◽

Pore Size ◽

Lithium Ion Batteries ◽

Polyvinylidene Fluoride ◽

Lithium Ion ◽

Size Analysis ◽

Pore Size Analysis ◽

Hollow Carbon

It has been reported that improving electrical conductivity and maintaining stable structure during discharge/charge process are challenge for Si to be used as an anode for lithium ion batteries (LIB). To address this problem, milkweed (MW) was carbonized to prepare hollow carbon microtubes (HCMT) derived from biomass as an anode template for LIB. In order to improve electrical conductivity, various materials such as chitosan (CTS), agarose, and polyvinylidene fluoride (PVDF) are used as carbon source (C1, C2, and C3) by carbonization. Carbon coated HCMT@Si composits, HCMT@Si@C1, HCMT@Si@C1@C2, and HCMT@Si@C1@C3, have been successfully synthesized. Changes in structure and crystallinity of HCMT@Si composites were characterized by using X-ray diffraction (XRD). Specific surface area for samples was calculated by using BET (Brunauer–Emmett–Teller). Also, pore size and particle size were obtained by particle and pore size analysis system. The surface morphology was evaluated using high resolution scanning electron microscopy (HR-SEM), Field Emission transmission electron microscopy (TEM). The thermal properties of HCMT@Si composites were analyzed by thermogravimetric analysis (TGA). Our research was performed to study the synthesis and electrochemical performance of Si composite with HCMT by the carbonization of natural micro hollow milkweed to form an inner space. After carbonization at 900 °C for 2 h in N2 flow, inner diameter of HCMT obtained was about 10 μm. The electrochemical tests indicate that HCMT@Si@C1@C3 exhibits discharge capacity of 932.18 mAh/g at 0.5 A/g after 100 cycles.

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