Resin‐silica composite nanoparticle grafted polyethylene membranes for lithium ion batteries

Abstract

To avoid the peeling‐off of ceramic nanoparticles (NPs) from polyolefin membranes usually occurred in commercially available ceramic NPs coated polyolefin separators for lithium batteries, we propose a simple one‐pot in‐situ reaction method to modify commercial polyethylene (PE) separators by surface grafting 3‐Aminophenol/formaldehyde (AF)/silica (SiO2) composite NPs. The AF/SiO2 composite NPs form self‐supporting connected pores on the modified layer of the separator surface, which ensures the transportation of Li+. Moreover, the PE@AF/SiO2 separators has higher electrolyte wettability and compatibility than neat PE separators attributed to the plentiful polar functional groups in the AF/SiO2 layer and AF/SiO2 composite NPs, resulting in higher lithium ion transference number (tLi+= 0.62) and ionic conductivity (σ = 0.722 mS cm−1). More importantly, the discharge capacity, capacity retention rate and coulombic efficiency (136.2 mA h g−1, 87.9% and 99%, respectively) after 200 cycles of Li|NMC half batteries with PE@AF/SiO2 separators, are all more excellent than that with the pure PE separator (125 mA h g−1, 83.1% and 85%, respectively). Our results show that the PE@AF/SiO2 separators obtained by this modification method have higher electrochemical stability in the lithium battery system.

A Light-Thin Chitosan Nanofiber Separator for High-Performance Lithium-Ion Batteries

“…It can be observed that the electrolyte was able to diffuse rapidly in the CME15 and CME25 separators, with contact angles of 18 • and 21 • , respectively; whereas, the Celgard separator presented poor wettability with contact angles of 82 • due to its intrinsically hydrophobic nature and low surface energy [47]. The better wettability of the CME separators can be ascribed to the improved porosity and the good affinity of the polar functional groups (-NH 2 and -OH) on the chitosan chain with the polar electrolyte [52,53]. In addition, the electrolyte formed obvious oval droplets on the surface of CM25 with a surface contact angle of 78 • .…”

Enhancing the β Phase of Poly(vinylidene fluoride) Nanofibrous Membranes for Thermostable Separators in Lithium-Ion Batteries

“…22 Furthermore, the coating layer stripping from separators will not only dramatically lower the practical performance but also possibly cause serious LIB safety problems. 23 Particularly for LIBs with high energy density assembled in electric vehicles (for example, Tesla 4680), in order to achieve satisfactory cycle stability (i.e., preventing powder falling down during cycling), it is highly necessary to coat a big quantity of PVDF binders onto the separators. 24 Magnetron sputtering, an eco-friendly membrane functionalization approach, could generate an interembedded structure even in the absence of binders between the separator and ceramic layers, enhancing the adhesion to overcome stripping defects.…”

“…The ceramic nanoparticle coating has been proven to be an effective technique for improving the thermal stability of membranes. − However, traditional coating-modified strategies have not taken the membrane thickness and weight into consideration, which could lead to reduced LIB energy density . Furthermore, the coating layer stripping from separators will not only dramatically lower the practical performance but also possibly cause serious LIB safety problems .…”