Toward Sustainable Polymer Materials for Rechargeable Batteries: Utilizing Natural Feedstocks and Recycling/Upcycling of Polymer Waste.

The ever-increasing demand for rechargeable battery systems in the era of electric vehicles has spurred extensive research into developing polymeric components for batteries, such as separators, polymer electrolytes, and binders. However, current battery systems rely on expensive and nonrenewable resources, which potentially have a negative environmental impact. Therefore, polymer materials derived from natural resources have gained significant attention, primarily due to their cost-effective and environmentally sustainable features. Moreover, natural feedstocks often possess highly polar functional groups and high molecular weights, offering desirable electro-chemo-mechanical features when applied as battery materials. More recently, various recycling and upcycling strategies for polymeric battery components have also been proposed given the substantial waste generation from end-of-life batteries. Recycling polymeric materials includes an overall process of recovering the components from spent batteries followed by regeneration into new materials. Polymer upcycling into battery materials involves transforming daily-used plastic waste into high-value-added battery components. This review aims to give a state-of-the-art overview of contemporary methods to develop sustainable polymeric materials and recycling/upcycling strategies for various battery applications.

Interweaving Elastic and Hydrogen Bond-Forming Polymers into Highly Tough and Stress-Relaxable Binders for High-Performance Silicon Anode in Lithium-Ion Batteries.

A central challenge in practically using high-capacity silicon (Si) as anode materials for lithium-ion batteries is alleviating significant volume change of Si during cycling. One key to resolving the failure issues of Si is exploiting carefully designed polymer binders exhibiting mechanical robustness to retain the structural integrity of Si electrodes, while concurrently displaying elasticity and toughness to effectively dissipate external stresses exerted by the volume changes of Si. Herein, a highly elastic and tough polymer binder is proposed by interweaving polyacrylic acid (PAA) with poly(urea-urethane) (PUU) elastomer for Si anodes. By systematically tuning molecular parameters, including molecular weights of hard/soft segments and structures of hard segment components, it is demonstrated that the mechanical properties of polymer binders, such as elasticity, toughness, and stress relaxation ability, strongly affect the cycling performance of Si electrodes. This study provides new insight into the rational design of polymer binders capable of accommodating the volume changes of Si, primarily by judicious modulation of the mechanical properties of polymer binders.

Effect of Travel Expenditure on Life Satisfaction for Middle-Aged and Older Adults in Korea: Moderating Effect of COVID-19 Pandemic.

The aim of this research was to examine the effects of travel expenditures on life satisfaction in the context of the COVID-19 pandemic. For the research, a curvilinear relationship was established between life satisfaction and travel expenditures that was then compared between 2018 and 2020. The study subjects were middle-aged and older adults who completed the 2018 and 2020 waves of the Korean Longitudinal Study of Aging. Demographic, travel expenditure, and life satisfaction data were collected, and quadratic regression analysis was conducted to examine the effects of travel expenditures on life satisfaction before and during the COVID-19 pandemic. The first-order condition was computed to determine the optimal level of travel expenditures to maximize life satisfaction, and the results exhibit that the utility of travel expenditure decreased during the COVID-19 pandemic.

Regulating Na Electrodeposition by Sodiophilic Grafting onto Porosity-Gradient Gel Polymer Electrolytes for Dendrite-Free Sodium Metal Batteries.

Sodium metal batteries have been emerging as promising candidates for post-Li battery systems owing to the natural abundance, low costs, and high energy density of Na metal. However, exploiting an Na metal anode is accompanied by uncontrolled Na electrodeposition, particularly concerning dendrite growth, hampering practical Na metal battery applications. Herein, we propose sodiophilic gel polymer electrolytes with a porosity-gradient Janus structure to alleviate Na dendrite growth. Tethering only 1.1 mol % sodiophilic poly(ethylene glycol) to poly(vinylidene fluoride-co-hexafluoropropylene) suppresses Na dendrites by regulating homogeneous Na+ distribution, which relies on molecular-level coordination between Na+ and the sodiophilic functional groups. By exploiting the porosity-gradient Janus structure, we have demonstrated that regular porosity and well-defined morphology of polymer electrolytes, particularly at the Na/electrolyte interface, significantly impact dendrite growth. This study provides new insights into the rational design of Na dendrite-suppressing polymer electrolytes, primarily focusing on the ion-regulating ability achieved by surface engineering.

Antecedents of Subjective Health among Korean Senior Citizens Using Archival Data.

This study aimed to investigate the determinants of subjective health among South Korean senior citizens. Secondary data for the year 2018 was used from the Senior Citizen Research Panel data collected by the Korea Employment Information Service. A total of 3822 valid observations were analyzed. The dependent variable was subjective health, and the independent variables were religion participation, social gathering participation, economic activity, food expenditure, leisure expenditure, travel frequency, and art watching frequency. Descriptive analysis, correlation matrix, and independent t-test were carried out for data analysis. Multiple linear regression analysis was employed using assets, age, and gender as control variables to test the research hypotheses. The results indicate that all the proposed attributes have a significant positive impact on the subjective health of Korean senior citizens, with implications for policy making.

Exploring Korean Middle- and Old-Aged Citizens' Subjective Health and Quality of Life.

The goal of this research is to investigate the determinants of subjective health and quality of life with a particular focus on middle- and old-aged citizens. Subjective health is an antecedent of quality of life. For both attributes, travel frequency, economic activity, and cultural activity frequency are the main explanatory variables. Korean middle- and old-aged citizen research panel data was used to derive the data; the study periods are 2008, 2010, 2012, 2014, and 2016. The present work used an econometric method to analyze this panel data. The results show that subjective health positively affects quality of life; meanwhile, economic activity positively affects both subjective health and quality of life. It is also found that cultural activity and travel exert inverted U-shape impacts on subjective health and quality of life. The control variables in this research were gender, body mass index, birth year, and personal assets. These results could help guide policy makers in designing more efficient welfare policies for middle- and old-aged citizens.

Dendrite-Suppressing Polymer Materials for Safe Rechargeable Metal Battery Applications: From the Electro-Chemo-Mechanical Viewpoint of Macromolecular Design.

Metal batteries have been emerging as next-generation battery systems by virtue of ultrahigh theoretical specific capacities and low reduction potentials of metallic anodes. However, significant concerns regarding the uncontrolled metallic dendrite growth accompanied by safety hazards and short lifespan have impeded practical applications of metal batteries. Although a great deal of effort has been pursued to highlight the thermodynamic origin of dendrite growth and a variety of experimental methodologies for dendrite suppression, the roles of polymer materials in suppressing the dendrite growth have been underestimated. This review aims to give a state-of-the-art overview of contemporary dendrite-suppressing polymer materials from the electro-chemo-mechanical viewpoint of macromolecular design, including i) homogeneous distribution of metal ion flux, ii) mechanical blocking of metal dendrites, iii) tailoring polymer structures, and iv) modulating the physical configuration of polymer membranes. Judiciously tailoring electro-chemo-mechanical properties of polymer materials provides virtually unlimited opportunities to afford safe and high-performance metal battery systems by resolving problematic dendrite issues. Transforming these rational design strategies into building dendrite-suppressing polymer materials and exploiting them towards polymer electrolytes, separators, and coating materials hold the key to realizing safe, dendrite-free, and long-lasting metal battery systems.

Sustainable Lignin-Derived Cross-Linked Graft Polymers as Electrolyte and Binder Materials for Lithium Metal Batteries.

This study concerns the development of a well-defined synthetic route to obtain lignin-derived multifunctional graft polymers by simple chemical modification and atom-transfer radical polymerization. By grafting ion-conducting and cross-linkable moieties onto the lignin, star-shaped functional polymers are prepared. Upon cross-linking under ultraviolet light irradiation, the resulting polymer network exhibits mechanical stability even at high temperature, whereas the chain mobility is maintained despite the cross-linked structure. Their use as solid polymer electrolytes (SPEs) and binders for all-solid-state lithium metal batteries (LMBs) is also evaluated. The lignin-derived graft polymers provide a facile ion conduction pathway and also efficiently suppress lithium dendrite growth during cycling, thereby attaining excellent cycling performance for the LMB cell compared to that with a conventional liquid electrolyte-Celgard system.

Superlattice by charged block copolymer self-assembly.

Charged block copolymers are of great interest due to their unique self-assembly and physicochemical properties. Understanding of the phase behavior of charged block copolymers, however, is still at a primitive stage. Here we report the discovery of an intriguing superlattice morphology from compositionally symmetric charged block copolymers, poly[(oligo(ethylene glycol) methyl ether methacrylate-co-oligo(ethylene glycol) propyl sodium sulfonate methacrylate)]-b-polystyrene (POEGMA-PS), achieved by systematic variation of the molecular structure in general, and the charge content in particular. POEGMA-PS self-assembles into a superlattice lamellar morphology, a previously unknown class of diblock nanostructures, but strikingly similar to oxygen-deficient perovskite derivatives, when the fraction of charged groups in the POEGMA block is about 5-25%. The charge fraction and the tethering of the ionic groups both play critical roles in driving the superlattice formation. This study highlights the accessibility of superlattice morphologies by introducing charges in a controlled manner.

Bicontinuous Microemulsions in Partially Charged Ternary Polymer Blends.

We describe the phase behavior of a partially charged ternary polymer blend model system, comprising a compositionally symmetric poly[(oligo(ethylene glycol) methyl ether methacrylate-co-oligo(ethylene glycol) propyl sodium sulfonate methacrylate)]-b-polystyrene (POEGMA23-PS) diblock polymer and the constituent POEGMA23 and PS homopolymers, along the volumetrically symmetric isopleth, where 23 denotes the percentage of charged monomers in the POEGMA chain. Small-angle neutron and X-ray scattering and dynamic mechanical spectroscopy measurements reveal morphological transitions from a layered superlattice to swollen lamellae to a bicontinuous microemulsion (BµE), followed by macroscopic phase separation, with increasing homopolymer content. The BµE channel occurs between 85 and 90% homopolymer addition, positioned approximately at the isotropic Lifshitz composition predicted by mean-field theory for neutral systems. The resulting BµE morphology exhibits a periodicity of 26 nm, yielding a mesoscopically structured but macroscopically disordered bicontinuous structure. That this structure can be achieved in a charged polymer system is surprising, given the huge asymmetries typically induced by adding charge to either diblock copolymers or binary polymer blends.

Quasi-Solid-State Rechargeable Li-O2 Batteries with High Safety and Long Cycle Life at Room Temperature.

As interest in electric vehicles and mass energy storage systems continues to grow, Li-O2 batteries are attracting much attention as a candidate for next-generation energy storage systems owing to their high energy density. However, safety problems related to the use of lithium metal anodes have hampered the commercialization of Li-O2 batteries. Herein, we introduced a quasi-solid polymer electrolyte with excellent electrochemical, chemical, and thermal stabilities into Li-O2 batteries. The ion-conducting QSPE was prepared by gelling a polymer network matrix consisting of poly(ethylene glycol) methyl ether methacrylate, methacrylated tannic acid, lithium trifluoromethanesulfonate, and nanofumed silica with a small amount of liquid electrolyte. The quasi-solid-state Li-O2 cell consisted of a lithium powder anode, a quasi-solid polymer electrolyte, and a Pd3Co/multiwalled carbon nanotube cathode, which enhanced the electrochemical performance of the cell. This cell, which exhibited improved safety owing to the suppression of lithium dendrite growth, achieved a lifetime of 125 cycles at room temperature. These results show that the introduction of a quasi-solid electrolyte is a potentially new alternative for the commercialization of solid-state Li-O2 batteries.

Environmentally Sustainable Aluminum-Coordinated Poly(tetrahydroxybenzoquinone) as a Promising Cathode for Sodium Ion Batteries.

Na-ion batteries are attractive as an alternative to Li-ion batteries because of their lower cost. Organic compounds have been considered as promising electrode materials due to their environmental friendliness and molecular diversity. Herein, aluminum-coordinated poly(tetrahydroxybenzoquinone) (P(THBQ-Al)), one of the coordination polymers, is introduced for the first time as a promising cathode for Na-ion batteries. P(THBQ-Al) is synthesized through a facile coordination reaction between benzoquinonedihydroxydiolate (C6O6H22-) and Al3+ as ligands and complex metal ions, respectively. Tetrahydroxybenzoquinone is environmentally sustainable, because it can be obtained from natural resources such as orange peels. Benzoquinonedihydroxydiolate also contributes to delivering high reversible capacity, because each benzoquinonedihydroxydiolate unit is capable of two electron reactions through the sodiation of its conjugated carbonyl groups. Electrochemically inactive Al3+ improves the structural stability of P(THBQ-Al) during cycling because of a lack of a change in its oxidation state. Moreover, P(THBQ-Al) is thermally stable and insoluble in nonaqueous electrolytes. These result in excellent electrochemical performance including a high reversible capacity of 113 mA h g-1 and stable cycle performance with negligible capacity fading over 100 cycles. Moreover, the reaction mechanism of P(THBQ-Al) is clarified through ex situ XPS and IR analyses, in which the reversible sodiation of C═O into C-O-Na is observed.

Dendrite Suppression by Synergistic Combination of Solid Polymer Electrolyte Crosslinked with Natural Terpenes and Lithium-Powder Anode for Lithium-Metal Batteries.

Lithium-metal anode has fundamental problems concerning formation and growth of lithium dendrites, which prevents practical applications of next generation of high-capacity lithium-metal batteries. The synergistic combination of solid polymer electrolyte (SPE) crosslinked with naturally occurring terpenes and lithium-powder anode is promising solution to resolve the dendrite issues by substituting conventional liquid electrolyte/separator and lithium-foil anode system. A series of SPEs based on polysiloxane crosslinked with natural terpenes are prepared by facile thiol-ene click reaction under mild condition and the structural effect of terpene crosslinkers on electrochemical properties is studied. Lithium powder with large surface area is prepared by droplet emulsion technique (DET) and used as anode material. The effect of the physical state of electrolyte (solid/liquid) and morphology of lithium-metal anode (powder/foil) on dendrite growth behavior is systematically studied. The synergistic combination of SPE and lithium-powder anode suggests an effective solution to suppress the dendrite growth owing to the formation of a stable solid-electrolyte interface (SEI) layer and delocalized current density.

Enhanced Osteogenic Commitment of Human Mesenchymal Stem Cells on Polyethylene Glycol-Based Cryogel with Graphene Oxide Substrate.

Graphene oxide (GO) is considered a comparatively recent biomaterial with enormous potential because of its nontoxicity, high dispersity, and enhanced interaction with biomolecules. These characteristics of GO can promote the interactions between the substrates and cell surfaces. In this study, we incorporated GO in a cryogel-based scaffold system to observe their influence on the osteogenic responses of human tonsil-derived mesenchymal stem cells (hTMSCs). Compared to polyethylene glycol (PEG)-based cryogel scaffold, GO-embedded PEG-based (PEGDA-GO) cryogels not only showed improved cell attachment and focal adhesion kinase (FAK) signaling activation but also enhanced cell viability. Taken together, we demonstrated that PEGDA-GO cryogels can stimulate osteogenic differentiation under an osteoinductive condition and enhance osteogenic phenotypes compared to the control group. In summary, we demonstrate that GO embedded in cryogels system is an effective biofunctionalizing scaffold to control osteogenic commitment of stem cells.

Gel Polymer Electrolytes Containing Anion-Trapping Boron Moieties for Lithium-Ion Battery Applications.

Gel polymer electrolytes (GPEs) based on semi-interpenetrating polymer network (IPN) structure for lithium-ion batteries were prepared by mixing boron-containing cross-linker (BC) composed of ethylene oxide (EO) chains, cross-linkable methacrylate group, and anion-trapping boron moiety with poly(vinylidene fluoride) (PVDF) followed by ultraviolet light-induced curing process. Various physical and electrochemical properties of the GPEs were systematically investigated by varying the EO chain length and boron content. Dimensional stability at high temperature without thermal shrinkage, if any, was observed due to the presence of thermally stable PVDF in the GPEs. GPE having 80 wt % of BC and 20 wt % of PVDF exhibited an ionic conductivity of 4.2 mS cm-1 at 30 °C which is 1 order of magnitude larger than that of the liquid electrolyte system containing the commercial Celgard separator (0.4 mS cm-1) owing to the facile electrolyte uptake ability of EO chain and anion-trapping ability of the boron moiety. As a result, the lithium-ion battery cell prepared using the GPE with BC showed an excellent cycle performance at 1.0 C maintaining 87% of capacity during 100 cycles.

Solid Polymer Electrolytes Based on Functionalized Tannic Acids from Natural Resources for All-Solid-State Lithium-Ion Batteries.

Solid polymer electrolytes (SPEs) for all-solid-state lithium-ion batteries are prepared by simple one-pot polymerization induced by ultraviolet (UV) light using poly(ethylene glycol) methyl ether methacrylate (PEGMA) as an ion-conducting monomeric unit and tannic acid (TA)-based crosslinking agent and plasticizer. The crosslinking agent and plasticizer based on natural resources are obtained from the reaction of TA with glycidyl methacrylate and glycidyl poly(ethylene glycol), respectively. Dimensionally stable free-standing SPE having a large ionic conductivity of 5.6×10(-4)  Scm(-1) at room temperature can be obtained by the polymerization of PEGMA into P(PEGMA) with a very small amount (0.1 wt %) of the crosslinking agent and 2.0 wt % of the plasticizer. The ionic conductivity value of SPE with a crosslinked structure is one order of magnitude larger than that of linear P(PEGMA) in the waxy state.

Polymer composite electrolytes having core-shell silica fillers with anion-trapping boron moiety in the shell layer for all-solid-state lithium-ion batteries.

Core-shell silica particles with ion-conducting poly(ethylene glycol) and anion-trapping boron moiety in the shell layer were prepared to be used as fillers for polymer composite electrolytes based on organic/inorganic hybrid branched copolymer as polymer matrix for all-solid-state lithium-ion battery applications. The core-shell silica particles were found to improve mechanical strength and thermal stability of the polymer matrix and poly(ethylene glycol) and boron moiety in the shell layer increase compatibility between filler and polymer matrix. Furthermore, boron moiety in the shell layer increases both ionic conductivity and lithium transference number of the polymer matrix because lithium salt can be more easily dissociated by the anion-trapping boron. Interfacial compatibility with lithium metal anode is also improved because well-dispersed silica particles serve as protective layer against interfacial side reactions. As a result, all-solid-state battery performance was found to be enhanced when the copolymer having core-shell silica particles with the boron moiety was used as solid polymer electrolyte.

High-performance reverse osmosis CNT/polyamide nanocomposite membrane by controlled interfacial interactions.

Polyamide reverse osmosis (RO) membranes with carbon nanotubes (CNTs) are prepared by interfacial polymerization using trimesoyl chloride (TMC) solutions in n-hexane and aqueous solutions of m-phenylenediamine (MPD) containing functionalized CNTs. The functionalized CNTs are prepared by the reactions of pristine CNTs with acid mixture (sulfuric acid and nitric acid of 3:1 volume ratio) by varying amounts of acid, reaction temperature, and reaction time. CNTs prepared by an optimized reaction condition are found to be well-dispersed in the polyamide layer, which is confirmed from atomic force microscopy, scanning electron microscopy, and Raman spectroscopy studies. The polyamide RO membranes containing well-dispersed CNTs exhibit larger water flux values than polyamide membrane prepared without any CNTs, although the salt rejection values of these membranes are close. Furthermore, the durability and chemical resistance against NaCl solutions of the membranes containing CNTs are found to be improved compared with those of the membrane without CNTs. The high membrane performance (high water flux and salt rejection) and the improved stability of the polyamide membranes containing CNTs are ascribed to the hydrophobic nanochannels of CNTs and well-dispersed states in the polyamide layers formed through the interactions between CNTs and polyamide in the active layers.