Lithium Battery Negative Electrode Density and Inner Pressure Control

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Rechargeable lithium batteries face challenges in maintaining optimal inner pressure after charging and discharging, leading to deteriorated cycle-life characteristics due to volume changes in electrodes, which affect lithium ion movement and capacity retention.

Innovation Solution

A rechargeable lithium battery design with a negative electrode active mass density of 1.6 g/cc or more and an inner pressure of 0.95 kgf/cm2 to 1.65 kgf/cm2, achieved by adjusting the active mass standing time before sealing, ensures sufficient electrolyte impregnation and maintains suitable pressure for efficient lithium ion movement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the inner pressure of the battery is increased to maintain electrode contact and facilitate lithium ion movement, then the lithium ion conductivity and capacity retention improve, but the risk of electrode deformation and side reactions increases

Engineering Contradiction:

Improvecapacity retentionVSAvoidelectrode deformation

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies parameter changes by precisely controlling the inner pressure within the range of 0.95 to 1.65 kgf/cm² after formation charging and discharging. This optimized pressure parameter ensures sufficient lithium ion movement and electrode contact while preventing excessive pressure that would cause electrode deformation and side reactions, thereby resolving the contradiction between capacity retention and electrode integrity

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs beforehand cushioning by adjusting the active mass density to 1.6 g/cc or more before battery assembly. This pre-optimization of electrode density ensures that the electrodes maintain appropriate volume and structural integrity during subsequent charging and discharging cycles, cushioning against excessive pressure fluctuations that would otherwise lead to deformation

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Quantity of substance

If the active mass density of the negative electrode is increased to improve capacity, then the energy density and capacity retention improve, but the inner pressure increases leading to electrode deformation

Engineering Contradiction:

ImprovecapacityVSAvoidinner pressure

Core Design Contradiction:

Quantity of substanceVSStress or pressure

Solution Approach 1:

The patent applies parameter changes by optimizing both the active mass density (1.6 g/cc or more) and the inner pressure (0.95 to 1.65 kgf/cm²) simultaneously. This coordinated parameter optimization allows the battery to achieve high capacity through increased active material density while maintaining pressure within safe limits through controlled standing time and electrolyte impregnation, preventing the pressure-capacity trade-off

Inventive Principle:

Principle #35Parameter changes

3Reliability

If the standing time of the active mass is extended to improve electrolyte impregnation, then the electrolyte distribution and lithium ion movement improve, but the production time increases

Engineering Contradiction:

Improvelithium ion movementVSAvoidproduction time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies parameter changes by optimizing the standing time parameter to achieve the optimal balance between electrolyte impregnation and production efficiency. By controlling the standing time within a specific range that achieves sufficient electrolyte distribution throughout the active mass, the patent ensures good lithium ion movement without requiring excessively long processing times, thus resolving the contradiction between reliability and production time

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

This design enhances capacity retention and cycle-life characteristics by maintaining optimal inner pressure, preventing excessive pressure fluctuations that can lead to electrode deformation and side reactions.

Implementation Method 1

a non-aqueous electrolyte, wherein the negative electrode has an active mass density of about 1.6 g/cc or more, and the rechargeable lithium battery has an inner pressure of about 0.95 kgf/cm2 to about 1.65 kgf/cm2

Methodology Applied

Scientific EffectIonic conduction: Conduction (electrical)

Implementation Method 2

a separator positioned between the positive electrode and the negative electrode

Methodology Applied

Scientific EffectPhysical separation: Semipermeable Membrane

Data Source

PatentUS20230170457A1Rechargeable lithium battery

Publication Date: 2023.06.01 SAMSUNG SDI CO LTD

AI summary

A rechargeable lithium battery includes a positive electrode including a positive active material; a negative electrode including a negative active material; a separator positioned between the positive electrode and the negative electrode; and a non-aqueous electrolyte, wherein the negative electrode has an active mass density of about 1.6 g/cc or more, and the rechargeable lithium battery has an inner pressure of about 0.95 kgf/cm2 to about 1.65 kgf/cm2.