Application of PVDF Organic Particles Coating on Polyethylene Separator for Lithium Ion Batteries

Abstract

Surface coating modification on a polyethylene separator serves as a promising way to meet the high requirements of thermal dimensional stability and excellent electrolyte wettability for lithium ion batteries (LIBs). In this paper, we report a new type of surface modified separator by coating polyvinylidene fluoride (PVDF) organic particles on traditional microporous polyethylene (PE) separators. The PE separator coated by PVDF particles (PE-PVDF separator) has higher porosity (61.4%), better electrolyte wettability (the contact angle to water was 3.28° ± 0.21°) and superior ionic conductivity (1.53 mS/cm) compared with the bare PE separator (51.2%, 111.3° ± 0.12°, 0.55 mS/cm). On one hand, the PVDF organic polymer has excellent organic electrolyte compatibility. On the other hand, the PVDF particles contain sub-micro spheres, of which the separator can possess a large specific surface area to absorb additional electrolyte. As a result, LIBs assembled using the PE-PVDF separator showed better electrochemical performances. For example, the button cell using a PE-PVDF as the separator had a higher capacity retention rate (70.01% capacity retention after 200 cycles at 0.5 C) than the bare PE separator (62.5% capacity retention after 200 cycles at 0.5 C). Moreover, the rate capability of LIBs was greatly improved as well—especially at larger current densities such as 2 C and 5 C.

Functionalized Separator Strategies toward Advanced Aqueous Zinc‐Ion Batteries

“…At present, domestic and foreign researchers have adopted various methods to realize the functionalization of separators. [52][53][54][55][56] As for the preparation methods for functionalized separators, we gave detailed examples for some of them in the following sections.…”

Fluorine-Initiated Carboxyl Group Enhanced Combination Properties of the Polyethylene Separator for Lithium-Ion Batteries

“…Under environmental pressures like global warming and other trends, policies regarding “carbon neutrality” lead us facing a new round of pressure from energy substitution and industrial adjustment. , Among various alternative energy sources, lithium-ion batteries have high energy density, long cycle life, low self-discharge rate, and excellent leading position in environmental protection. − Lithium-ion batteries have been widely used in 3C products, − electric vehicles, energy storage, and other fields in the past 20 years. − Actually, with the continuous improvement in battery capacity and charge–discharge flow of lithium-ion in recent years, higher requirements are put forward for the performance of lithium-ion batteries. − A lithium-ion battery is mainly composed of positive electrode, negative electrode, separator, and electrolyte. Separator is an important part of a lithium-ion battery, and the main role of the separator is to prevent a battery short circuit.…”

“…However, considering the nonpolar chain structure of the polymer used in this field, the surface energy of polyolefin separator is low, and the infiltration performance of electrolyte is poor, which makes it difficult for the polyolefin separator to be fully infiltrated by the electrolyte. In addition, polyolefin separator has poor heat resistance and dimensional stability, these factors limit the further optimization of lithium-ion battery performance. ,,, …”

Upgrading the Properties of Ceramic-Coated Separators for Lithium Secondary Batteries by Changing the Mixing Order of the Water-Based Ceramic Slurry Components

“…However, the role of separators, one of the main components of batteries, has been underestimated because they are regarded as merely preventing direct short circuits between cathodes and anodes [4,5]. However, in recent years, the role of separators has become more important than ever because the standards for battery safety are gradually increasing for the successful implementation of high-energy-density Li secondary batteries [6,7].…”