Functional-Layer Battery Separator for Dendrite and Heat Shrinkage

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Solution Overview

Problem

High energy density rechargeable lithium batteries face issues with lithium dendrite formation and thermal runaway due to increased current density, leading to separator shrinkage and safety concerns, despite efforts to enhance heat resistance and mechanical strength.

Innovation Solution

A ceramic layer with ceramic particles and a functional layer containing inorganic particles with a working potential greater than or equal to 1 V are integrated into the separator, providing high shape retention and suppressing lithium dendrite formation and side reactions, thereby enhancing battery safety and cycle-life characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the loading amount of active material is increased to achieve high energy density, then energy density is improved, but current density increases causing lithium dendrite formation and short-circuit

Engineering Contradiction:

Improveenergy densityVSAvoidlithium dendrite formation

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The separator is constructed as a composite material comprising inorganic particles (such as Al2O3, SiO2, TiO2, or ZrO2) dispersed in a polyolefin binder resin matrix. This composite structure provides both the mechanical integrity of the polyolefin separator and the thermal stability of inorganic particles, preventing separator shrinkage at high temperatures while maintaining the high energy density design.

Inventive Principle:

Principle #40Composite materials

2Temperature

If inorganic material is coated on polyolefin separator to enhance heat resistance, then thermal stability is improved, but separator shrinkage still occurs leading to thermal runaway

Engineering Contradiction:

Improveheat resistanceVSAvoidseparator shrinkage

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The invention changes the fundamental composition parameters of the separator by incorporating 1-90 wt% inorganic particles (with 10-99 wt% being the preferred range) into the polyolefin matrix. This compositional parameter change fundamentally alters the thermal behavior of the separator, raising the melting point from approximately 160°C (pure polyolefin) to above 200°C, thereby preventing thermal shrinkage and maintaining structural integrity at elevated temperatures.

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If conventional polyolefin separator is used, then manufacturing simplicity is maintained, but shape retention at high temperature deteriorates

Engineering Contradiction:

Improveseparator manufacturingVSAvoidshape retention

Core Design Contradiction:

Ease of manufactureVSShape

Solution Approach 1:

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 effectively prevents separator shrinkage and lithium dendrite formation, ensuring high-capacity, high-density, and long cycle-life characteristics while maintaining battery safety by using a ceramic layer and functional layer in the lithium battery separator.

Implementation Method 1

a functional layer including inorganic particles having a working potential (vs Li/Li+) of 1 V or more

Methodology Applied

Scientific EffectElectrochemical potential difference:

Implementation Method 2

excellent shape retention at high temperatures, preventing rapid shrinkage of the separator due to a short-circuit

Methodology Applied

Scientific EffectThermal stability:

Implementation Method 3

suppressing formation of lithium dendrite and a side reaction on the negative electrode surface

Methodology Applied

Scientific EffectPhysical barrier:

Data Source

PatentEP4372860A1Separator for rechargeable lithium battery, negative electrode-separator assembly and rechargeable lithium battery

Publication Date: 2024.05.22 SAMSUNG SDI CO LTD

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AI summary

Disclosed are a separator for a rechargeable lithium battery, a negative electrode-separator assembly for a rechargeable lithium battery, and a rechargeable lithium battery, the separator including a ceramic layer including ceramic particles and a binder, and a functional layer including inorganic particles having a working potential (vs Li/Li+) of greater than or equal to about 1 V and a binder on the ceramic layer.