Battery Separator Additives for Lower Pin Removal Force
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current battery separators face challenges in pin removal during the battery jelly roll making process due to increased thinness and pore size, with existing additives like calcium stearate tending to 'bloom' or 'snow' at high temperatures, and electrolyte additives having short shelf life and reproducibility issues.
Innovation Solution
Incorporation of additives such as polysiloxane and lithium stearate into microporous polymeric films and coatings for battery separators, which reduce pin removal force, improve puncture strength, and enhance electrolyte wettability, while maintaining stability and shelf life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If separator thickness is reduced to improve battery energy density, then battery energy density is improved, but pin removal force increases making the jelly roll making process difficult
Solution Approach 1:
The patent changes the chemical composition parameters of the separator by incorporating specific additives (polysiloxane, lithium stearate, calcium stearate) at controlled concentrations (0.1-5 wt%) to modify the surface properties and reduce pin removal force while maintaining thin separator structure
Solution Approach 2:
The patent creates a composite separator structure by combining base polyolefin materials with functional additives (polysiloxane, lithium stearate, calcium stearate) to achieve both thinness for high energy density and reduced pin removal force through the synergistic effects of the composite composition
2Force
If calcium stearate is used as an additive to reduce pin removal force, then pin removal force is reduced, but the additive blooms or snows at high temperatures during extrusion
Solution Approach 1:
The patent uses polysiloxane as an intermediary substance that mediates between the base polymer and other additives, providing thermal stability during extrusion while maintaining the pin removal force reduction effect through its lubricating properties
Solution Approach 2:
The patent creates a composite additive system where polysiloxane and lithium stearate work synergistically to provide both pin removal force reduction and thermal stability during the extrusion process, preventing the blooming issue associated with calcium stearate alone
3Reliability
If electrolyte additives are used to improve battery performance, then battery performance is improved, but shelf life is reduced due to short stability duration
Solution Approach 1:
The patent incorporates electrolyte additives directly into the separator matrix during manufacturing, creating a self-contained system where the separator serves as both a physical barrier and an electrolyte additive reservoir, eliminating the need for separate electrolyte additive solutions with limited shelf life
Solution Approach 2:
The patent pre-incorporates electrolyte additives into the separator structure during the extrusion process, so that the additives are already in position and ready to function when the battery is assembled, avoiding subsequent handling and storage issues that reduce shelf life
4Productivity
If separator pore size is increased to improve ion transport, then ion transport is improved, but pin removal force increases making handling difficult
Solution Approach 1:
The patent changes the surface chemical composition parameters by adding lubricating additives (polysiloxane, lithium stearate, calcium stearate) that reduce surface friction and pin removal force, allowing larger pore sizes to be maintained without increasing handling difficulty
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The use of polysiloxane and lithium stearate additives in battery separators reduces pin removal force, increases puncture strength, and improves electrolyte wettability, addressing the challenges of separator thinness and electrolyte stability, and extends the shelf life of battery separators.
Implementation Method 1
The use of polysiloxane and lithium stearate additives in battery separators reduces pin removal force
Implementation Method 2
improves electrolyte wettability
Data Source
AI summary
Described herein, are battery separators, comprising the following: a microporous polymeric film; and an optional coating layer on at least one side of the microporous polymeric film, wherein at least one of the microporous polymeric film and the optional coating comprises an additive. The additive is selected from the group consisting of a lubricating agent, a plasticizing agent, a nucleating agent, a shrinkage reducing agent, a surfactant, an SEI improving agent, a cathode protection agent, a flame retardant additive, LiPF6 salt stabilizer, an overcharge protector, an aluminum corrosion inhibitor, a lithium deposition agent or improver, or a solvation enhancer, an aluminum corrosion inhibitor, a wetting agent, and a viscosity improver. Also, described herein are batteries, including lithium-ion batteries, comprising one or more of the described separators. Methods for making the battery separators are also described.