METHOD FOR THE PRODUCING THERMALLY STABLE COMPOSITE SEPARATORS FOR LITHIUM BATTERIES

A method forming a thermally stable composite separator for lithium batteries by applying a non-porous polymer layer and using a coagulation medium to create a uniform porous structure addresses the inefficiencies and instability of conventional separators, enhancing production speed and safety.

DE102018132553B4Undetermined Publication Date: 2026-06-25GM GLOBAL TECHNOLOGY OPERATIONS LLC
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Patent Information

Authority / Receiving Office
DE · DE
Patent Type
Patents
Current Assignee / Owner
GM GLOBAL TECHNOLOGY OPERATIONS LLC
Filing Date
2018-12-17
Publication Date
2026-06-25

AI Technical Summary

Technical Problem

Conventional methods for producing lithium-ion and lithium-sulfur battery separators are time-consuming and expensive, and the resulting separators are prone to heat shrinkage, increasing the risk of battery short circuits due to inadequate pore uniformity and thermal stability.

Method used

A method involving the application of a non-porous polymer layer on a porous insulating substrate, followed by contact with a coagulation medium to precipitate a substantially uniform porous polymer layer, using specific polymers, nanoparticles, and submicron particles, with controlled solvent and viscosity conditions to enhance thermal stability and pore uniformity.

Benefits of technology

The resulting thermally stable composite separator exhibits improved pore uniformity and thermal stability, reducing the risk of battery short circuits and enabling faster, more efficient production.

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Abstract

A method for forming a thermally stable composite separator for an electrochemical cell that cycles lithium ions, wherein the method comprises: contacting one or more coated surface areas of a porous insulating substrate with a coagulation medium, wherein the one or more coated surface areas have at least one non-porous polymer layer comprising a polymer, one or more particulate additives, and a solvent, wherein contact with the coagulation medium removes the solvent, causing the polymer to form at least one substantially uniform porous polymer layer on the one or more coated surface areas to form the thermally stable composite separator, wherein the coagulation medium has a first viscosity (Pa-s) that is greater than a second viscosity of the solvent.and wherein a solubility parameter difference between the polymer and the coagulation medium is smaller than that between the polymer and water, wherein the one or more particulate additives are selected from one or more nanoparticles with an average diameter of less than 100 nm; one or more submicron particles with an average diameter of more than or equal to 100 nm and less than or equal to 2 µm; and combinations thereof, wherein the polymer comprises at least 200 repeating units and is selected from the group consisting of: aramid fibers, polyamide, polyvinylidene fluoride (PVdF), polysulfide, polyimide (PI), polyacrylic, polycarbonate and combinations thereof, wherein the one or more nanoparticles and the one or more submicron particles comprise materials that are independently selected from the group consisting of: aluminum oxide (Al2O3), silicon dioxide (SiO2), titanium dioxide (TiO2),Calcium chloride (CaCl2), metal oxides, carbooxides, nitrides, titanates, clays, phosphates and combinations thereof; and wherein the solvent comprises more than or equal to 2 wt.% to less than or equal to 20 wt.% of one or more calcium chlorides (CaCl2) and lithium chlorides (LiCl), dissolved in N-methyl-2-pyrrolidone (NMP).
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