Li-Ion Battery Separator and Electrolyte for Heat-Treated Assembly

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Solution Overview

Problem

Lithium-ion secondary batteries used in electronic devices face degradation of charging and discharging characteristics and safety issues due to heat treatment during manufacturing, particularly when the battery and housing are integrally formed.

Innovation Solution

The power storage device incorporates a positive electrode with LiCoO2, a negative electrode with spherical natural graphite of varying crystallinity, a separator made of polyphenylene sulfide or solvent-spun regenerated cellulosic fiber, and an electrolytic solution containing LiBETA and a mixture of propylene carbonate and ethylene carbonate, along with a flexible exterior body, to enhance heat resistance and flexibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If heat treatment is applied during manufacturing, then the housing and battery are integrally formed, but the charging and discharging characteristics are degraded

Engineering Contradiction:

Improveintegral formation of housing and batteryVSAvoidcharging and discharging characteristics

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The separator is pre-treated with a silane coupling agent before battery assembly, creating a heat-resistant protective layer in advance. This preliminary action ensures that when heat treatment is later applied during manufacturing to integrally form the housing and battery, the separator already has enhanced thermal stability and prevents degradation of charging and discharging characteristics

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes the chemical composition parameters of the separator by introducing silane coupling agents and specific additives. This parameter change transforms the separator's thermal properties, enabling it to withstand manufacturing heat treatment temperatures while maintaining its functional characteristics for reliable charging and discharging

Inventive Principle:

Principle #35Parameter changes

2Temperature

If heat treatment temperature is increased, then heat resistance is improved, but safety against heat treatment is compromised

Engineering Contradiction:

Improveheat resistanceVSAvoidsafety against heat treatment

Core Design Contradiction:

TemperatureVSObject-affected harmful factors

Solution Approach 1:

A silane coupling agent is introduced as an intermediary substance between the separator and the heat treatment process. This intermediary forms a protective interface layer that allows the separator to withstand high temperatures for heat resistance while the coupling agent itself decomposes safely, preventing direct thermal damage to the battery components and maintaining safety

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent converts the potentially harmful high-temperature heat treatment into a beneficial process by using heat-resistant separator materials and silane coupling agents that stabilize the battery structure at elevated temperatures. The heat treatment that could cause safety issues instead becomes a method to enhance structural integrity and thermal stability when proper materials are used

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Ease of manufacture

If conventional separator materials are used, then manufacturing is simple, but heat resistance is insufficient

Engineering Contradiction:

Improveseparator manufacturingVSAvoidheat resistance

Core Design Contradiction:

Ease of manufactureVSTemperature

Solution Approach 1:

The separator is constructed as a composite material system combining base separator material with silane coupling agents and heat-resistant additives. This composite structure maintains the manufacturing simplicity of conventional separators while introducing new thermal properties through the composite formulation, achieving high heat resistance without complicating the manufacturing process

Inventive Principle:

Principle #40Composite materials

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 solution provides a power storage device with improved heat resistance, safety, and flexibility, maintaining charging and discharging characteristics even under high-temperature conditions.

Implementation Method 1

the silane coupling agent is condensed to form a silane crosslinked structure

Methodology Applied

Scientific EffectSilane crosslinking: Chemical Bonding

Implementation Method 2

the silane coupling agent is condensed to form a silane crosslinked structure

Methodology Applied

Scientific EffectCondensation: Condensation

Implementation Method 3

heat treatment performed when the electronic devices are processed

Methodology Applied

Scientific EffectHeat treatment: Heat Treatment

Data Source

PatentUS20260045556A1Power storage device, method for manufacturing power storage device and electronic device

Publication Date: 2026.02.12 SEMICON ENERGY LAB CO LTD

AI summary

To provide a power storage device whose charge and discharge characteristics are unlikely to be degraded by heat treatment. To provide a power storage device that is highly safe against heat treatment. The power storage device includes a positive electrode, a negative electrode, a separator, an electrolytic solution, and an exterior body. The separator is located between the positive electrode and the negative electrode. The separator contains polyphenylene sulfide or solvent-spun regenerated cellulosic fiber. The electrolytic solution contains a solute and two or more kinds of solvents. The solute contains LiBETA. One of the solvents is propylene carbonate.