Mussel Inspired Modification of Polypropylene Separators by Catechol/Polyamine for Li-Ion Batteries

Abstract

Inspired by the remarkable adhesion of mussel, dopamine, a mimicking adhesive molecule, has been widely used for surface modification of various materials ranging from organic to inorganic. However, dopamine and its derivatives are expensive which impede their application in large scale. Herein, we replaced dopamine with low-cost catechol and polyamine (only 8% of the cost of dopamine), which could be polymerized in an alkaline solution and deposited on the surfaces of various materials. By using this cheap and simple modification method, polypropylene (PP) separator could be transformed from hydrophobic to hydrophilic, while the pore structure and mechanical property of the separator remained intact. The uptake of electrolyte increased from 80% to 270% after the hydrophilic modification. Electrochemical studies demonstrated that battery with the modified PP separator had a better Coulombic efficiency (80.9% to 85.3%) during the first cycle at a current density of 0.1 C, while the discharging current density increased to 15 C and the discharge capacity increased by 1.4 times compared to the battery using the bare PP separator. Additionally, the modification allowed excellent stability during manifold cycles. This study provides new insights into utilizing low-cost chemicals to mimic the mussel adhesion and has potential practical application in many fields.

Bifunctional separator as a polysulfide mediator for highly stable Li–S batteries

“…The value of R ct for the cell featuring the bifunctional separator (151 Ω) was less than that (176 Ω) detected for the cell containing the pristine separator; similarly, the value of R s of the cell featuring the bifunctional separator (4.50 Ω) was lower than that (4.76 Ω) for the cell incorporating the pristine separator. We ascribe the decreases in the values of R ct and R s to increased electrolyte retention within the separator, due to hydrophilic PEDOT:PSS surface; similar results, based on polymer coatings on the separator, have been reported previously [50,69]. A simple wetting test was performed to verify the hydrophilic character of bifunctional separator as shown in the ( Figure S7).…”

Surface engineering of polymer membranes via mussel-inspired chemistry

“…The deep color of PDA-coated surfaces may be also a problem in some cases [176,177]. To overcome these shortcomings, researchers are looking for the alternative choices [178]. Recently, natural polyphenols with similar structure as catecholamine have also drawn an increasing attention.…”

Positively charged nanofiltration membranes via economically mussel-substance-simulated co-deposition for textile wastewater treatment

“…What is more, the high cost of dopamine is undesirable in practical application. Recently, plant-derived phenols or polyphenols, containing a remarkable high content of catechol and gallic acid groups, have been reported capable of forming multifunctional coatings [14][15][16]. Intriguingly, such coatings have the excellent properties like dopamine-derived coatings by simulating a similar complex mechanism of reactions, but bear with much lower cost (less than 1/10 cost of DA).…”

“…Some works have reported the applications of these coating in Li-ion batteries and dyes adsorptions. In particular, Wang et al have fabricated hydrophilic modified polypropylene separators by the co-deposition of catechol and polyamine for Li-ion batteries [15]. Qiu et al have reported the co-deposition of catechol and PEI onto microfiltration (MF) membranes for decolorization of dye water [16].…”