A dual-layer micro/nanostructured fibrous membrane with enhanced ionic conductivity for lithium-ion battery

Quasi-Solid-State Polymer Electrolyte Based on Electrospun Polyacrylonitrile/Polysilsesquioxane Composite Nanofiber Membrane for High-Performance Lithium Batteries

Considering the safety problem that is caused by liquid electrolytes and Li dendrites for lithium batteries, a new quasi-solid-state polymer electrolyte technology is presented in this work. A layer of 1,4-phenylene bridged polysilsesquioxane (PSiO) is synthesized by a sol-gel way and coated on the electrospun polyacrylonitrile (PAN) nanofiber to prepare a PAN@PSiO nanofiber composite membrane, which is then used as a quasi-solid-state electrolyte scaffold as well as separator for lithium batteries (LBs). This composite membrane, consisting of the three-dimensional network architecture of the PAN nanofiber matrix and a mesoporous PSiO coating layer, exhibited a high electrolyte intake level (297 wt%) and excellent mechanical properties. The electrochemical analysis results indicate that the ionic conductivity of the PAN@PSiO-based quasi-solid-state electrolyte membrane is 1.58 × 10^-3 S cm^-1 at room temperature and the electrochemical stability window reaches 4.8 V. The optimization of the electrode and the composite membrane interface leads the LiFePO₄|PAN@PSiO|Li full cell to show superior cycling (capacity of 137.6 mAh g^-1 at 0.2 C after 160 cycles) and excellent rate performances.

Design of A High Performance Zeolite/Polyimide Composite Separator for Lithium-Ion Batteries

A zeolite/polyimide composite separator with a spongy-like structure was prepared by phase inversion methods based on heat-resistant polyimide (PI) polymer matrix and ZSM-5 zeolite filler, with the aim to improve the thermal stability and electrochemical properties of corresponding batteries. The separator exhibits enhanced thermal stability and no shrinkage up to 180 °C. The introduction of a certain number of ZSM-5 zeolites endows the composite separator with enhanced wettability and electrolyte uptake, better facilitating the free transport of lithium-ion. Furthermore, the composite separator shows a high ionic conductivity of 1.04 mS cm⁻¹ at 25 °C, and a high decomposition potential of 4.7 V. Compared with the PP separator and pristine PI separator, the ZSM-5/PI composite separator based LiFePO₄/Li cells have better rate capability (133 mAh g⁻¹ at 2 C) and cycle performance (145 mAh g^-1 at 0.5 C after 50 cycles). These results demonstrate that the ZSM-5/PI composite separator is promising for high-performance and high-safety lithium-ion batteries.

A facile non-solvent induced phase separation process for preparation of highly porous polybenzimidazole separator for lithium metal battery application

The drawbacks of low porosity, inferior electrolyte wettability, low thermal dimensional stability and permissive lithium dendrite growth of the conventional microporous polyolefin-based separators hinder their widely application in the high power density and safe Lithium ion batteries. Herein, highly porous polybenzimidazole-based separator is prepared by a facile non-solvent induced phase separation process (NIPS) using water, ethanol, chloroform and ethyl acetate as the coagulation bath solvent, respectively. It was found that the ethanol is suitable to fabricate uniform morphology macroporous separator with the porosity of 92%, electrolyte uptake of 594 wt.%, and strong mechanical strength of 15.9 MPa. In addition, the experimental tests (electrochemical analysis and XPS test) and density functional theory calculation suggest that the electron-rich imidazole ring of polybenzimidazle can enhance Li⁺ mobility electrostatic attraction interaction while the block the PF₆⁻ mobility via electrostatic repulsion interaction. Therefore, high Li⁺ transference number of 0.76 was obtained for the neat polybenzimidazole-based polymer electrolyte. As a proof of concept, the Li/LiFePO₄ cell with the polybenzimidazole-based polymer electrolyte/1.0 M LiPF₆⁻ ethylene carbonate/dimethyl carbonate (v:v = 1:1) electrolyte exhibits excellent rate capability of >100 mAh g⁻¹ at 6 C (1 C = 170 mA g⁻¹) and superior cycle stability of 1000 cycles.