Three-Dimensional Coating Layer Modified Polyolefin Ceramic-Coated Separators to Enhance the Safety Performance of Lithium-Ion Batteries

Abstract

Although the ceramic-coated separators have been industrialized and widely used in power lithium-ion batteries to replace the polyolefin separators, the safety of batteries still cannot fully meet the demand of practical application with the rapid growth of energy density. In this work, a ceramic-coated separator further modified by phenol-formaldehyde resin has been developed, in which a three-dimension coating layer is formed both on the surface and in the pores of the pristine separator by introducing phenolformaldehyde resin through a simple soakage process. Such membranes show extremely high thermal stability up to 300°C, maintain a high mechanical strength even after a heat-treatment at 220°C for 30 min, and show a shut-down function above 138°C. With the advantages of abundant sources, low cost, environment-friendly property and simple preparation process, the phenol-formaldehyde resin modified separators are expected to replace the commercial ceramic-coated separators, greatly improve the safety performance of batteries, and realize the reassuring application of lithium-ion batteries in power batteries and large-scale energy storage devices.

Ceramic-Coated Separator to Enhance Cycling Performance of Lithium-ion Batteries at High Current Density

“…polymer separators with the inert ceramic oxides leads to an increase in ionic conductivity [5], and that's why the C-PP separator's had the lowest impedance value. Overall, despite the extremely fast 5C rate condition, our experiments achieved remarkable capacity stability compared to previous papers using ceramic-coated separators [8,[24][25][26].…”

A Rational Design for a High‐Safety Lithium‐Ion Battery Assembled with a Heatproof–Fireproof Bifunctional Separator

“…This result was consistent with our previous report. [ 10 ] This is because PFR formed a 3D coating layer throughout the entire substrate separator and connected the ceramic‐coated layer and PE separator as a whole. Therefore, it enhanced the adhesion, strength, and toughness of the ceramic‐coated layer, preventing the ceramic‐coated layer from shrinking with the PE separator.…”

“…Preparation of APP-CCS@PFR: CCS@PFR was prepared as described in a previous study. [10] A single-sided ceramic-coated separator, with a 3 µm Al 2 O 3 coating layer on a 20 µm PE separator (Jinhuigaoke, Guangdong, China), was immersed in a 50 g L −1 PFR (Mw ≈ 2000, Shanghai Macklin Biochemical Co., Ltd., China) solution with ethanol as the solvent. After removing the redundant solution, the separator was placed in a vacuum oven at 70 °C for 24 h, and CCS@PFR was obtained.…”

“…However, limited by the poor thermal stability of the polyolefin separator, the separator modified with only APP particles will suffer from severe shrinkage at elevated temperatures, and this will not only expose the combustibles to the oxidants but also cause an internal short‐circuit at elevated temperatures. Inspired by our previous studies, [ 3a,10 ] herein a phenol‐formaldehyde‐resin (PFR)‐modified ceramic‐coated separator (CCS@PFR), which exhibits an excellent thermal dimension stability (exhibiting no visible shrinkage up to 300 °C), was employed as a substrate separator. A layer of APP particles was coated onto the uncoated side of the CCS@PFR separator to yield a heatproof–fireproof bifunctional separator APP‐CCS@PFR, as shown in Figure a.…”

PEI-SiO2 composite membranes with high thermal stability: Synthesis by self-assembled in situ growth and application in lithium-ion batteries

“…Among them, application of a ceramic coating on a polyolefin membrane has been widely investiagted. 19,20 Jeon et al performed alumina (Al 2 O 3 ) coating on a microporous PE membrane. The coated membrane showed excellent electrolyte uptake capacity and thermal stability.…”