Lithium-Ion Battery Electrode Pore Diameter Control

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Solution Overview

Problem

The endurance capacity retention ratio of energy storage devices is compromised due to uneven lithium ion diffusion rates between the positive and negative composite layers, leading to polarization, precipitation of lithium metal, cracking of the composite layer, and excessive electrolyte decomposition.

Innovation Solution

The energy storage device incorporates a positive composite layer with a peak pore diameter of 0.5 μm or less and a negative composite layer with a peak pore diameter of 0.5 μm or less, maintaining a ratio of 0.60 to 1.70, utilizing amorphous carbon with reduced volume change, and optimizing particle diameters to ensure balanced lithium ion diffusion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the diffusion rate of lithium ions in the positive composite layer is greatly different from the diffusion rate of lithium ions in the negative composite layer, then the energy storage device can operate, but the endurance capacity retention ratio decreases due to polarization and uneven lithium ion distribution

Engineering Contradiction:

Improveendurance capacity retention ratioVSAvoiduniformity of lithium ion distribution

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent controls the pore size parameters of the positive and negative composite layers, specifically setting the peak pore diameter of the positive composite layer to 0.5 μm or less and the peak pore diameter of the negative composite layer to 0.5 μm or less, with their ratio between 0.60 and 1.70. This parameter control ensures balanced lithium ion diffusion rates in both electrodes, preventing polarization and improving endurance capacity retention ratio

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies different pore size characteristics to different electrodes based on their specific requirements. The positive composite layer and negative composite layer are designed with different peak pore diameters within the specified ratio range, optimizing lithium ion diffusion locally in each electrode to achieve overall balance and prevent uneven distribution

Inventive Principle:

Principle #3Local quality

2Productivity

If polarization occurs due to uneven lithium ion distribution, then the electrochemical reactions proceed, but harmful effects such as lithium metal precipitation, composite layer cracking, and electrolyte decomposition occur

Engineering Contradiction:

Improveelectrochemical reaction rateVSAvoidlithium metal precipitation, composite layer cracking, electrolyte decomposition

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent preemptively controls the pore size parameters of the positive and negative composite layers before electrochemical reactions occur. By setting the peak pore diameters to 0.5 μm or less and their ratio to 0.60-1.70, the patent prevents polarization and uneven lithium ion distribution from occurring in the first place, thereby avoiding harmful effects like lithium metal precipitation, composite layer cracking, and electrolyte decomposition

Inventive Principle:

Principle #9Preliminary anti-action

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 configuration enhances the endurance capacity retention ratio by minimizing polarization and maintaining good lithium ion diffusion, thereby preventing issues like lithium metal precipitation, composite layer cracking, and electrolyte decomposition.

Implementation Method 1

the diffusion rate of lithium ions in the positive composite layer is significantly larger than the diffusion rate of lithium ions in the negative composite layer

Methodology Applied

Scientific EffectDiffusion: Diffusion

Implementation Method 2

a negative active material capable of occluding and releasing a lithium ion

Methodology Applied

Scientific EffectIntercalation: Absorption (physical)

Data Source

PatentUS11258065B2Energy storage device

Publication Date: 2022.02.22 GS YUASA INT LTD

AI summary

An energy storage device includes: a positive electrode plate containing a positive composite layer including a positive active material capable of occluding and releasing a lithium ion; and a negative electrode plate containing a negative composite layer including a negative active material capable of occluding and releasing a lithium ion. A peak pore diameter Rp of the positive composite layer in a pore distribution measured by a mercury penetration method is 0.5 μm or less, and a peak pore diameter Rn of the negative composite layer in a pore distribution measured by a mercury penetration method is 0.5 μm or less. A ratio Rp/Rn of the peak pore diameter of the positive composite layer to the peak pore diameter of the negative composite layer is 0.60 or more and 1.70 or less.