Effect of the soft and hard segment composition on the properties of waterborne polyurethane-based solid polymer electrolyte for lithium ion batteries

A Healable Quasi-Solid Polymer Electrolyte with Balanced Toughness and Ionic Conductivity

Solid polymer electrolytes (SPEs) have garnered extensive attention as potential alternatives to traditional liquid electrolytes, primarily due to their prowess in curbing lithium dendrite formation and preventing electrolyte leaks. The quest for SPEs that are both mechanically robust and exhibit superior ionic conductivity has been vigorous. However, achieving a harmonious balance between these two attributes remains a significant challenge. In this study, we introduce a novel quasi-solid electrolyte, ingeniously crafted from a poly(urethane-urea) network, enriched with lithium salts and plasticizers. This innovative composition not only boasts remarkable toughness but also ensures commendable ionic conductivity. Our post-gelation method yields gel polymer electrolytes that undergo rigorous evaluation, leading to an optimized version that stands out with its exceptional room-temperature ionic conductivity (2.94×10-4 S cm-1) and outstanding toughness (11.9 MJ m-3). Moreover, it demonstrates a broad electrochemical window (4.73 V), remarkable stability across a 600-hour cycle test, a high capacity retention exceeding 80 % after 100 cycles at 0.2 C, and a noteworthy self-healing capability. This quasi-solid polymer electrolyte emerges as a promising contender to replace current liquid electrolyte solutions.

Fabrication of multi-functional biodegradable liquid mulch utilizing xyloglucan derived from tamarind waste for agricultural application

Biodegradable liquid mulch is considered a promising alternative to plastic mulch for sustainable agriculture. This work proposed a xyloglucan-based liquid mulch with multi-function using a combination of chemical modification and blending methods. The esterification product of tamarind xyloglucan (TXG) from forestry wastes was synthesized with benzoic anhydride (BA). The effect of esterification modification was investigated, and BA-TXG was utilized as a film-forming and sand-fixation agent. The rheological properties, thermal stability, and hydrophobicity were improved following esterification. Additionally, waterborne polyurethane and urea were incorporated into the mulch to enhance its mechanical strength (23.28 MPa, 80.71 %), and homogeneity, as well as improve its nutritive properties. The xyloglucan-based liquid mulch has excellent UV protection, a high haze value (approximately 90 %), and retains water at a rate of 80.45 %. SEM and immersion experiment showed the effect of xyloglucan-based liquid mulch on sustainable sand-fixation. Moreover, the liquid mulch treatment demonstrated an impressive germination rate of 83.8 % and degradation rate of 51.59 % (60 days). The modified polysaccharide film increases stability and slows down the degradation rate. Tamarind xyloglucan-based liquid mulch exhibits powerful and diverse optical properties as well as sand fixation functions, indicating their great potential in sustainable agriculture as an alternative to plastic mulch.

Fast Li+ Transport Polyurethane-Based Single-Ion Conducting Polymer Electrolyte with Sulfonamide Side chains in the Hard Segment for Lithium Metal Batteries

Single-ion conducting polymer electrolytes (SICPEs) are considered as one of the most promising candidates for achieving lithium metal batteries (LMBs). However, the application of traditional SICPEs is hindered by their low ionic conductivity and poor mechanical stability. Herein, a self-standing and flexible polyurethane-based single-ion conductor membrane was prepared via covalent tethering of the trifluoromethanesulfonamide anion to polyurethane, which was synthesized using a facile reaction of diisocyanates with poly(ethylene oxide) and 3,5-diaminobenzoic acid (or 3,5-dihydroxybenzoic acid). The polymer electrolyte exhibited excellent ionic conductivity, mechanical properties, lithium-ion transference number, thermal stability, and a broad electrochemical window because of the bulky anions and unique two-phase structures with lithium-ion nanochannels in the hard domains. Consequently, the plasticized electrolyte membrane showed exceptional stability and reliability in a Li||Li symmetric battery. The assembled LiFePO4||Li battery exhibited an outstanding capacity (∼180 mA h g-1), Coulombic efficiency (>96%), and capacity retention. This research provides a promising polymer electrolyte for high-performance LMBs.

Construction of high elastic artificial SEI for air-stable and long-life lithium metal anode

Compared with other anode materials, Li metal anode has higher capacity density and lower electrode potential, which has been considered as one of the most promising anode materials. However, the unstable solid electrolyte interface (SEI) leads to Li dendrite growth and the infinite volumetric expansion of Li metal, which seriously hinders the stability and cycle life of Li metal batteries (LMBs). Here, a polyurethane elastomer (TPU) material with high elasticity and air stability is used as the artificial SEI of Li metal anode. Its designed synergistic effect of soft chain forging and hard chain segments not only gives TPU artificial SEI layer good electronic insulation, Li ion conductivity, Li dendrite growth inhibition, high elastic modulus and flexibility to adapt to Li volume expansion, but also has a significant air protection effect on the Li metal surface, so that the TPU coated Li foil will not occur obvious oxidation phenomenon after being placed in air for 45 min. The Li symmetric battery modified by TPU achieved a stable and long-term cycle performance of 1300 h at 1 mA/cm², it can also cycle stably at a high current density of 10 mA/cm². The Coulomb efficiency of the modified Li/Cu half-cell maintains at above 97% after 400 cycles. In addition, the full cell with LiFePO₄ cathode also delivers a very excellent long cycle stability with 90% capacity retention after 1500 cycles at 5 C. This surface modification strategy of SEI on lithium anode has has great research value and will help to improve the widely application of LMBs.

Bio-Based Solid Electrolytes Bearing Cyclic Carbonates for Solid-State Lithium Metal Batteries

Green resources for lithium-based batteries excite many researchers due to their eco-friendly nature. In this work, a sustainable bio-based solid-state electrolyte was developed based on carbonated soybean oil (CSBO), obtained by organocatalyzed coupling of CO₂ to epoxidized soybean oil. CSBO coupled with lithium bis(trifluoromethanesulfonyl)imide salt on a bio-based cellulose separator resulted in free-standing membranes. Those membranes on electrochemical measurements exhibited ionic conductivity of around 10^-3  S cm^-1 at 100 °C and around 10^-6  S cm^-1 at room temperature with wide electrochemical stability window (up to 4.6 V vs. Li/Li⁺ ) and transference number up to 0.39 at RT. Further investigations on the galvanostatic charge-discharge of LiFePO₄ cathodes with CSBO-based electrolyte membranes and lithium metal anodes delivered the gravimetric capacity of 112 and 157 mAh g^-1 at RT and 60 °C, respectively, providing a promising direction to further develop bio-based solid electrolytes for sustainable solid-state lithium batteries.

Preparation of Polydimethylsiloxane-Modified Waterborne Polyurethane Coatings for Marine Applications

A series of waterborne polyurethane dispersions (WPUs) modified with hydroxyl-terminated polydimethylsiloxane (PDMS) were prepared by incorporating PDMS into the soft segments of polyurethane chains. The structural characteristics of the prepared samples were analyzed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and particle size analysis (PSA). The effect of PDMS content on the thermal and mechanical properties of PDMS-modified waterborne polyurethanes (PS-WPU) was investigated. In addition, the water resistance and dimensional stability of the PS-WPU were investigated by measuring its water absorption ratio and water contact angle along with universal testing machine measurements.

A novel polymer electrolyte with high elasticity and high performance for lithium metal batteries

A polymer electrolyte with high elasticity and high performance is prepared by IN SITU polymerization. The polymer electrolyte is amorphous and has a high ionic conductivity of 7.9 × 10^-4 S cm^-1 and good elasticity. The discharge capacity of Li/LiFePO₄ in the 100th cycle is 133.90 mA h g^-1 (0.5C, 25 °C).

A Novel Polymer Electrolyte Matrix Incorporating Ionic Liquid into Waterborne Polyurethane for Lithium-Ion Battery

Ionic liquid has relatively high conductivity at room temperature and good electrochemical stability. Ionic liquid polymer electrolytes have some advantages of both ionic liquid and polymer. In this work, 1-alkyl-3-(2',3'-dihydroxypropyl)imidazolium chloride (IL-Cl) was incorporated into waterborne polyurethane chain to composite all-solid-state polymer electrolyte matrices. The structure, thermal stability, mechanical property and ionic conductivity of the matrices were investigated by Fourier transform infrared spectroscopy (FTIR), thermogravimetric Analysis (TGA), tensile measurement and electrochemical impedance spectroscopy (EIS). The results demonstrated that when the content of IL-Cl was 14 wt%, the mechanical property of film was optimized, with a maximum tensile strength of 36 MPa and elongation at break of 1030%. In addition, as for the film with IL-Cl content of 16 wt%, its oxygen index value increased to 25.2% and ionic conductivity reached a maximum of 1.2 × 10-5 S·cm-1 at room temperature, showing high flame retardancy and ionic conductivity.

Effects of polysiloxanes with different molecular weights on in vitro cytotoxicity and properties of polyurethane/cotton–cellulose nanofiber nanocomposite films

A series of polyurethane/cotton–cellulose nanofiber nanocomposite films are manufactured using amino-terminated polydimethylsiloxane, polycarbonate diol, isophorone diisocyanate, and dispersed cotton–cellulose nanofibers.