Secondary Battery Electrode Volume Ratio Coordination

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Solution Overview

Problem

Current secondary batteries face challenges in maintaining stability during charging and discharging while achieving high capacity density due to volume changes in electrodes, which lead to structural deterioration.

Innovation Solution

The electrode structure is designed with a positive electrode and a negative electrode having a volume ratio of 1.1 or more, with one electrode having a volume ratio of 1.9 or more between charged and discharged states, and a total volume ratio of 1.2 or less, using a sponge-like structure of carbon nanotubes and active materials like sulfur and silicon to manage volume changes effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If active materials such as sulfur or silicon are used to increase capacity density, then the amount of lithium ions that can react with the active material increases, but the volume change during charging and discharging becomes large causing deterioration of the battery structure

Engineering Contradiction:

Improvecapacity densityVSAvoidbattery structure stability

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The patent applies the counterweight principle by designing the positive and negative electrodes with complementary volume change characteristics. When one electrode expands during charging/discharging, the other electrode contracts, creating a balancing effect that suppresses overall volume change of the battery while maintaining high capacity density using sulfur and silicon active materials

Inventive Principle:

Principle #8Anti-weight (Counterweight)

Solution Approach 2:

The patent changes the volume ratio parameter between positive and negative electrodes to optimize performance. By controlling the volume ratio to be 0.95-1.05, the patent achieves balanced volume changes that suppress structural deterioration while maintaining high capacity density

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If a composite technology of covering the active material with a shell material is used to suppress volume change, then the volume change is suppressed, but the electrode increases in mass and volume

Engineering Contradiction:

Improvevolume change suppressionVSAvoidelectrode volume

Core Design Contradiction:

Stability of the object's compositionVSVolume of stationary object

Solution Approach 1:

The patent extracts and eliminates the shell material from the electrode structure, relying instead on the intrinsic volume change characteristics of the active materials themselves and the balancing effect between positive and negative electrodes to suppress overall volume change, thereby avoiding the mass and volume increase that would result from adding shell materials

Inventive Principle:

Principle #2Taking out (Extraction)

3Stability of the object's composition

If pores are provided inside the electrode to suppress volume change, then the volume change is suppressed, but the capacity density per electrode volume decreases

Engineering Contradiction:

Improvevolume change suppressionVSAvoidcapacity density per electrode volume

Core Design Contradiction:

Stability of the object's compositionVSQuantity of substance

Solution Approach 1:

The patent converts the harmful volume change of active materials into a beneficial balancing mechanism. The large volume changes of sulfur and silicon electrodes are transformed into a counterbalancing system where expansion of one electrode compensates for contraction of the other, thereby suppressing overall volume change without requiring pores that would reduce capacity density

Inventive Principle:

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

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 suppresses overall volume change, maintaining structural stability and achieving high capacity density by using active materials with large volume changes during charging and discharging.

Implementation Method 1

a positive electrode changing in volume by expansion or contraction during discharging or charging and a negative electrode changing in volume in a reverse way to the positive electrode

Methodology Applied

Scientific EffectVolume expansion and contraction: Thermal Expansion

Data Source

PatentUS11081701B2Secondary battery

Publication Date: 2021.08.03 ZEON CORP

AI summary

A secondary battery includes an electrode structure, the electrode structure includes a positive electrode changing in volume by expansion or contraction during discharging or charging, and a negative electrode changing in volume in a reverse way to the positive. The positive electrode and the negative electrode have a volume ratio of 1.1 or more, the volume ratio being a value obtained by dividing the volume under expansion by the volume under contraction, and the positive electrode or the negative electrode has the volume ratio of 1.9 or more, and has a total volume ratio of 1.2 or less, the total value ratio being a value obtained by dividing a larger value by a smaller value with respect to a total volume of the positive electrode and the negative electrode in a discharged state and a total volume of the positive electrode and the negative electrode in a charged state.