Portsmouth, UK, 2-4 September 2021 Processing and characterisation of water hyacinth cellulose nanofibres-based aluminium-ion battery separators

Abstract

Water hyacinth is an invasive plant that can be converted to high value cellulose nanofibers. This study presents battery separators prepared from water hyacinth cellulose nanofibres (WHCNF) via a freeze-thawing crosslinking method, using polyethylene glycol as a binder. The separators consist of 95 wt.%, 90 wt.%, 85 wt.% and 80 wt.% WHCNF. The thickness, wettability, electrolyte uptake, porosity and thermal stability of the separators are studied and compared with Celgard 2325, a commercial tri-layer separator. Also, tensile tests are carried out and an aluminium-ion cell is made to compare the performance of the different WHCNF separators using Nyquist plots and battery discharge curves. The results show that WHCNF separators have high thermal stability and wettability, making it a promising sustainable alternative material to petroleum-based polymeric commercial separators.

Paper Supercapacitor Developed Using a Manganese Dioxide/Carbon Black Composite and a Water Hyacinth Cellulose Nanofiber-Based Bilayer Separator

“…EIS analysis is carried out to assess the ionic conductivity of the separators. This involves soaking both separators in a 3 M KOH electrolyte between two stainless steel (SS) electrodes Figure shows the Nyquist plot for both Celgard and bilayer separators.…”

“…This involves soaking both separators in a 3 M KOH electrolyte between two stainless steel (SS) electrodes. 20 Figure 4 shows the Nyquist plot for both Celgard and bilayer separators. The intercept of the Nyquist plot on the Z real axis represents the bulk resistance ( R b ), which is used with eq 4 to get the ionic conductivity of the separators.…”

“…The bilayer WHCNF separator was prepared by fabricating the base layer by a freeze–thawing process, comprising of WHCNF and poly­(ethylene glycol) 4000 (PEG). PEG is a nontoxic, inexpensive, stable, easy-to-use, and biodegradable plasticizer that imparts cross-linking, flexibility, increased wettability, and electrolyte uptake to the separator . Layer two via doctor blade and NIPS is made of nontoxic, low environmental impact, and low-cost poly­(vinyl alcohol) (PVA), which includes its high chemical resistance, aqueous solubility, and biodegradability. , At high temperatures, the pure PVA layer melts and the pores close, stopping further ion transportation and the flow of current, also known as the separator shutdown effect for the safety of the device.…”

“…In a previous study on the processing and characterization of a water hyacinth cellulose nanofibers (WHCNF) separator via freeze–thawing, it was demonstrated that a high ratio of WHCNF (95 wt %) increased the porosity, electrolyte uptake, and wettability of the separator. This makes it a promising and sustainable option for a separator material . Furthermore, freeze-drying, − nonsolvent-induced phase separation (NIPS), ,− thermally induced phase separation, , and electrospinning − are commonly used processes to fabricate CNF separators.…”

“…This makes it a promising and sustainable option for a separator material. 20 Furthermore, freeze-drying, 21 − 25 nonsolvent-induced phase separation (NIPS), 24 , 26 − 28 thermally induced phase separation, 29 , 30 and electrospinning 31 − 33 are commonly used processes to fabricate CNF separators. An ultrathin (19 μm) cellulose nanofiber (CNF) separator is fabricated to suppress the polysulfide shuttle effect and dendrite growth for the lithium–sulfur battery (LSB) using isopropanol/water suspension through a vacuum filtration process.…”