Epoxy-based interlocking membranes for all solid-state lithium ion batteries: The effects of amine curing agents on electrochemical properties
Journal
Polymers
Journal Volume
13
Journal Issue
19
Date Issued
2021
Author(s)
Abstract
In this study, a series of crosslinked membranes were prepared as solid polymer electrolytes (SPEs) for all-solid-state lithium ion batteries (ASSLIBs). An epoxy-containing copolymer (glycidyl methacrylate-co-poly(ethylene glycol) methyl ether methacrylate, PGA) and two amine curing agents, linear Jeffamine ED2003 and hyperbranched polyethyleneimine (PEI), were utilized to prepare SPEs with various crosslinking degrees. The PGA/polyethylene oxide (PEO) blends were cured by ED2003 and PEI to obtain slightly and heavily crosslinked structures, respectively. For further optimizing the interfacial and the electrochemical properties, an interlocking bilayer membrane based on overlapping and subsequent curing of PGA/PEO/ED2003 and PEO/PEI layers was developed. The presence of this amino/epoxy network can inhibit PEO crystallinity and maintain the dimensional stability of membranes. For the slightly crosslinked PGA/PEO/ED2003 membrane, an ionic conductivity of 5.61 × 10?4 S cm?1 and a lithium ion transference number (tLi+) of 0.43 were obtained, along with a specific capacity of 156 mAh g?1 (0.05 C) acquired from an assembled halfcell battery. However, the capacity retention retained only 54% after 100 cycles (0.2 C, 80 °C), possibly because the PEO-based electrolyte was inclined to recrystallize after long term thermal treatment. On the other hand, the highly crosslinked PGA/PEO/PEI membrane exhibited a similar ionic conductivity of 3.44 × 10?4 S cm?1 and a tLi+ of 0.52. Yet, poor interfacial adhesion between the membrane and the cathode brought about a low specific capacity of 48 mAh g?1. For the reinforced interlocking bilayer membrane, an ionic conductivity of 3.24 × 10?4 S cm?1 and a tLi+ of 0.42 could be achieved. Moreover, the capacity retention reached as high as 80% after 100 cycles (0.2 C, 80 °C). This is because the presence of the epoxy-based interlocking bilayer structure can block the pathway of lithium dendrite puncture effectively. We demonstrate that the unique interlocking bilayer structure is capable of offering a new approach to fabricate a robust SPE for ASSLIBs. ? 2021 by the authors. Licensee MDPI, Basel, Switzerland.
Subjects
All-solid-state lithium ion battery (ASSLIBs)
Amino/epoxy
Interlocking bilayer
Solid state electrolyte (SPE)
Acrylic monomers
Cathodes
Crosslinking
Crystallinity
Curing
Electrochemical properties
Ionic conduction in solids
Ionic conductivity
Ions
Lithium-ion batteries
Membranes
Polyelectrolytes
Polyethylene glycols
Polyethylenes
Solid-State Batteries
All-solid-state lithium ion batteries
All-solid-state lithium ion battery
Bi-layer
Epoxy
Interlockings
Solid polymer electrolytes
Solid state electrolyte (solid polymer electrolyte)
Solid-state electrolyte
Solid electrolytes
SDGs
Type
journal article