Lithium Battery Electrode with Meltdown Polymer for Thermal Safety

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Solution Overview

Problem

Rechargeable lithium batteries face safety concerns due to excessive heat generation during charging and recharging, which can lead to hazards.

Innovation Solution

An electrode for rechargeable lithium batteries is designed with a current collector, a first active material layer, and a second active material layer that includes a meltdown polymer disposed on the surface of the active material, which helps in managing heat and ensuring safety by creating a short circuit if overheating occurs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a rechargeable lithium battery uses conventional active material layers, then the battery structure is simple and manufacturing is easy, but excessive heat generation occurs during charging and recharging leading to safety hazards

Engineering Contradiction:

Improvebattery safetyVSAvoidelectrode structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The active material layer is segmented into two distinct layers: a first active material layer in direct contact with the current collector, and a second active material layer containing meltdown polymer particles on its surface. This segmentation allows the first layer to handle electrochemical reactions while the second layer provides thermal safety, resolving the contradiction between safety and structural simplicity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The second active material layer is formed as a composite material combining active material particles with meltdown polymer particles disposed on their surfaces. This composite structure integrates the electrochemical functionality of the active material with the thermal safety properties of the meltdown polymer, achieving both performance and safety requirements.

Inventive Principle:

Principle #40Composite materials

2Reliability

If the meltdown polymer is disposed extensively on the active material surface, then safety is improved through better heat management, but lithium ion movement efficiency decreases due to reduced active material surface exposure

Engineering Contradiction:

Improvethermal safetyVSAvoidlithium ion efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The meltdown polymer particles are distributed locally on the surface of active material particles rather than forming a continuous coating. This local quality approach ensures that safety functionality is provided at critical points while leaving sufficient active material surface area exposed for efficient lithium ion transport, balancing safety and performance.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The second active material layer has a porous structure where meltdown polymer particles are disposed among active material particles, creating a three-dimensional network. This porous architecture allows lithium ions to move through the layer while maintaining thermal safety, as the polymer particles are distributed throughout the volume rather than forming a dense barrier.

Inventive Principle:

Principle #31Porous materials

3Reliability

If the second active material layer is made thicker to enhance safety functionality, then heat management is improved, but the overall battery energy density decreases

Engineering Contradiction:

Improveheat management capabilityVSAvoidenergy density

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

Rather than making the entire active material layer thick for safety, the invention applies partial action by incorporating meltdown polymer particles only in the second layer at controlled concentrations (0.1-10 wt%). This provides sufficient thermal safety functionality without unnecessarily increasing layer thickness, thereby maintaining energy density.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The invention changes the compositional parameters of the second active material layer by incorporating meltdown polymer at optimized concentrations (0.1-10 wt% based on active material weight). This parameter optimization ensures adequate thermal safety while minimizing the impact on energy density, as the polymer content is kept within ranges that balance safety and performance.

Inventive Principle:

Principle #35Parameter changes

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 electrode improves lithium ion efficiency and safety by allowing efficient lithium ion movement while providing a mechanism to prevent overheating and ensure battery shutdown, thus enhancing overall battery performance and safety.

Implementation Method 1

a second active material layer which is formed on the first active material layer and includes a second active material having a meltdown polymer disposed on a surface of the active material

Methodology Applied

Scientific EffectMelting: Melting

Data Source

PatentUS11430987B2Electrode and a rechargeable lithium battery including the electrode

Publication Date: 2022.08.30 SAMSUNG SDI CO LTD

AI summary

Disclosed are an electrode for a rechargeable lithium battery and a rechargeable lithium battery. The electrode includes a current collector, a first active material layer, and a second active material layer. The first active material layer is formed on the current collector and includes a first active material. The second active material layer is formed on the first active material layer. The second active material layer includes a second active material having an active material and a meltdown polymer disposed on the surface of the active material.