Single-Ion Conducting Polymeric Protective Interlayer for Stable Solid Lithium-Metal Batteries

With many reported attempts on fabricating single-ion conducting polymer electrolytes, they still suffer from low ionic conductivity, narrow voltage window, and high cost. Herein, we report an unprecedented approach on improving the cationic transport number (tLi+) of the polymer electrolyte, i.e., single-ion conducting polymeric protective interlayer (SIPPI), which is designed between the conventional polymer electrolyte (PVEC) and Li-metal electrode. Satisfied ionic conductivity (1 mS cm–1, 30 °C), high tLi+ (0.79), and wide-area voltage stability are realized by coupling the SIPPI with the PVEC electrolyte. Benefiting from this unique design, the Li symmetrical cell with the SIPPI shows stable cycling over 6000 h at 3 mA cm–2, and the full cell with the SIPPI exhibits stable cycling performance with a capacity retention of 86% over 1000 cycles at 1 C and 25 °C. This incorporated SIPPI on the Li anode presents an alternative strategy for enabling high-energy density, long cycling lifetime, and safe and cost-effective solid-state batteries

Single-Ion Conducting Polymeric Protective Interlayer for Stable Solid Lithium-Metal Batteries

With many reported attempts on fabricating single-ion conducting polymer electrolytes, they still suffer from low ionic conductivity, narrow voltage window, and high cost. Herein, we report an unprecedented approach on improving the cationic transport number (tLi+) of the polymer electrolyte, i.e., single-ion conducting polymeric protective interlayer (SIPPI), which is designed between the conventional polymer electrolyte (PVEC) and Li-metal electrode. Satisfied ionic conductivity (1 mS cm–1, 30 °C), high tLi+ (0.79), and wide-area voltage stability are realized by coupling the SIPPI with the PVEC electrolyte. Benefiting from this unique design, the Li symmetrical cell with the SIPPI shows stable cycling over 6000 h at 3 mA cm–2, and the full cell with the SIPPI exhibits stable cycling performance with a capacity retention of 86% over 1000 cycles at 1 C and 25 °C. This incorporated SIPPI on the Li anode presents an alternative strategy for enabling high-energy density, long cycling lifetime, and safe and cost-effective solid-state batteries

Robust and Elastic Polymer Membranes with Tunable Properties for Gas Separation

Polymer membranes with the capability to process a massive volume of gas are especially attractive for practical applications of gas separation. Although much effort has been devoted to develop novel polymer membranes with increased selectivity, the overall gas-separation performance and lifetime of membrane are still negatively affected by the weak mechanical performance, low plasticization resistance and poor physical aging tolerance. Recently, elastic polymer membranes with tunable mechanical properties have been attracting significant attentions due to their tremendous potential applications. Herein, we report a series of urethane-rich PDMS-based polymer networks (U-PDMS-NW) with improved mechanical performance for gas separation. The cross-link density of U-PDMS-NWs is tailored by varying the molecular weight (<i>M</i>_n) of PDMS. The U-PDMS-NWs show up to 400% elongation and tunable Young’s modulus (1.3–122.2 MPa), ultimate tensile strength (1.1–14.3 MPa), and toughness (0.7–24.9 MJ/m³). All of the U-PDMS-NWs exhibit salient gas-separation performance with excellent thermal resistance and aging tolerance, high gas permeability (>100 Barrer), and tunable gas selectivity (up to α­[<i>P</i>_CO₂/<i>P</i>_N₂] ≈ 41 and α­[<i>P</i>_CO₂/<i>P</i>_CH₄] ≈ 16). With well-controlled mechanical properties and gas-separation performance, these U-PDMS-NW can be used as a polymer-membrane platform not only for gas separation but also for other applications such as microfluidic channels and stretchable electronic devices

Effect of Binder Architecture on the Performance of Silicon/Graphite Composite Anodes for Lithium Ion Batteries

Although significant progress has been made in improving cycling performance of silicon-based electrodes, few studies have been performed on the architecture effect on polymer binder performance for lithium-ion batteries. A systematic study on the relationship between polymer architectures and binder performance is especially useful in designing synthetic polymer binders. Herein, a graft block copolymer with readily tunable architecture parameters is synthesized and tested as the polymer binder for the high-mass loading silicon (15 wt %)/graphite (73 wt %) composite electrode (active materials >2.5 mg/cm²). With the same chemical composition and functional group ratio, the graft block copolymer reveals improved cycling performance in both capacity retention (495 mAh/g vs 356 mAh/g at 100th cycle) and Coulombic efficiency (90.3% vs 88.1% at first cycle) than the physical mixing of glycol chitosan (GC) and lithium polyacrylate (LiPAA). Galvanostatic results also demonstrate the significant impacts of different architecture parameters of graft copolymers, including grafting density and side chain length, on their ultimate binder performance. By simply changing the side chain length of GC-<i>g</i>-LiPAA, the retaining delithiation capacity after 100 cycles varies from 347 mAh/g to 495 mAh/g

Influence of Chain Rigidity and Dielectric Constant on the Glass Transition Temperature in Polymerized Ionic Liquids

Polymerized ionic liquids (PolyILs) are promising candidates for a wide range of technological applications due to their single ion conductivity and good mechanical properties. Tuning the glass transition temperature (<i>T</i>_g) in these materials constitutes a major strategy to improve room temperature conductivity while controlling their mechanical properties. In this work, we show experimental and simulation results demonstrating that in these materials <i>T</i>_g does not follow a universal scaling behavior with the volume of the structural units <i>V</i>_m (including monomer and counterion). Instead, <i>T</i>_g is significantly influenced by the chain flexibility and polymer dielectric constant. We propose a simplified empirical model that includes the electrostatic interactions and chain flexibility to describe <i>T</i>_g in PolyILs. Our model enables design of new functional PolyILs with the desired <i>T</i>_g