Improving Fast and Safe Transfer of Lithium Ions in Solid-State Lithium Batteries by Porosity and Channel Structure of Polymer Electrolyte

Abstract

Solid-state lithium batteries using solid polymer electrolytes can improve the safety and energy density of batteries. Smoother lithium-ion channels are necessary for solid polymer electrolytes with high ionic conductivity. The porosity and channel structure of the polymer film affect the transfer of lithium ions. However, their controllable synthesis remains a big challenge. Here, we developed a simple synthesis approach toward wrinkled microporous polymer electrolytes by combining the amphoteric (water solubility and organic solubility) polymer in three polymer blends. The homogeneous blend solution spontaneously wrinkled to vertical fold channels as the solvent evaporated. Two minor polymers, poly(vinyl pyrrolidone) (PVP) and polyetherimide (PEI), formed close stacks, and Janus PVP was dispersed in the poly(vinylidene fluoride) (PVDF) matrix. The interfacial tensions between the three polymers were different, so stress was produced when they solidified. The solvent was evaporated to the top layer of the polymers when the temperature increased. The bottom layer wrinkled owing to the stress during solidification. The evaporation of the solvent generated micropores to form the lithium-ion channel. They helped Li + transference and created a wrinkled microporous PVDF-based polymer electrolyte, which achieved an ionic conductivity of 5.1 × 10 −4 S cm −1 and a lithium-ion transference number of 0.51 at room temperature. Meanwhile, the good flame retardancy and tensile strength of the polymer electrolyte film can improve the safety of the battery. At 0.5C and room temperature, the batteries with a LiFePO 4 cathode and the wrinkled microporous LiTFSI/PEI/PVP/PVDF electrolyte reached a high discharge specific capacity of 122.1 mAh g −1 at the 100th cycle with a Coulombic efficiency of above 99%. The results of tensile and self-extinguishing tests show that the polymer electrolyte film has good safety application prospects.

Lithium‐Metal Batteries via Suppressing Li Dendrite Growth and Improving Coulombic Efficiency

“…[ 76 ] Due to their good mechanical properties, solid electrolytes provide physical obstacles to stop Li dendrite propagation in LMBs. Most of the current solid electrolytes belong to either inorganic ceramic electrolytes, [ 77 ] or solid polymer electrolytes, [ 78 ] or organic–inorganic composite electrolytes. [ 79 ] A few criteria need to be met for developing solid electrolytes in LMBs, which are sufficiently high modulus, high Li + ion conductivity at ambient temperature, wide electrochemical stable window, low interfacial resistance, and good contact with both electrodes.…”

A Review of High-Energy Density Lithium-Air Battery Technology: Investigating the Effect of Oxides and Nanocatalysts

“…Increased defects increase the storage capacity of lithium ions. For example, milling operations on carbon nanotubes increase the density of defects, reduce the length of carbon nanotubes, and can affect the performance of the electrode [14,[220][221][222][223][224], and high irreversible capacity due to SEI layer formation and other side effects suffers severely [15,225,226]. erefore, chemical etching and milling methods are suggested to eliminate these defects.…”

Effect of cathode-side gas flow channels section geometry on the removal process of liquid slug in a proton exchange membrane fuel cell

“…Fuel cells in recent years have been receiving greater attention for clean power generation. 1,2 A proton exchange membrane fuel cell (PEMFC) as a device for producing electricity through the electrochemical reaction between hydrogen (fuel) and oxygen (oxidant) [3][4][5][6][7][8] can be a quick, clean and efficient solution to generate power for different energy demand levels, such as automotive transportation, 9 residential power sources, and portable electronic devices. 10,11 However, this technology, despite all its advantages, can be restricted on a large scale due to several technical and operational issues.…”