Lithium-Ion Capacitor Electrode Layout to Suppress Lithium Plating

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Solution Overview

Problem

In electrochemical devices like lithium-ion capacitors, metal lithium deposition on the negative electrode leads to internal short-circuiting, which is not effectively addressed by existing technologies.

Innovation Solution

The electrochemical device design includes a positive electrode with reversibly doped anions and a negative electrode with reversibly doped lithium ions, where the negative electrode mixture layer's state of charge is meticulously controlled to suppress metal lithium deposition, with specific dimensions and materials optimized for high reliability and reduced resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the negative electrode is pre-doped with lithium ions to achieve high energy density, then the energy density is improved, but metal lithium deposition occurs causing internal short-circuiting

Engineering Contradiction:

Improveenergy densityVSAvoidinternal short-circuiting risk

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent applies local quality by creating different state of charge conditions in different regions of the negative electrode. The end regions are maintained at a lower state of charge (X%) compared to the center region (Y%), where X < Y. This spatial differentiation prevents metal lithium deposition at the ends where it is most likely to occur, while still maintaining high overall energy density through the charged center region.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent implements preliminary action by pre-doping lithium ions into the negative electrode in a controlled manner before operation. The negative electrode is pre-charged to specific state of charge levels in different regions (X% at ends, Y% at center) before the electrochemical device begins normal operation. This preliminary charging state prevents subsequent metal lithium deposition during cycling.

Inventive Principle:

Principle #10Preliminary action

2Loss of energy

If the negative electrode mixture layer is made thinner to reduce resistance, then the internal resistance is reduced, but the capacity and energy density decrease

Engineering Contradiction:

Improveinternal resistanceVSAvoidenergy density

Core Design Contradiction:

Loss of energyVSUse of energy by moving object

Solution Approach 1:

The patent applies parameter changes by optimizing the thickness and dimensions of the negative electrode mixture layer. Specifically, the ratio of the length in the first direction (L1) to the length in the second direction (L2) is controlled to be 1.5 or more. This dimensional parameter optimization allows the electrode to maintain low resistance while preserving sufficient capacity and energy density.

Inventive Principle:

Principle #35Parameter changes

3Use of energy by moving object

If the negative electrode mixture layer dimensions are increased to boost capacity, then the energy density is improved, but the state of charge uniformity decreases leading to lithium deposition

Engineering Contradiction:

Improveenergy densityVSAvoidstate of charge uniformity

Core Design Contradiction:

Use of energy by moving objectVSStability of the object's composition

Solution Approach 1:

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent implements asymmetry by intentionally creating an asymmetric state of charge distribution across the negative electrode. Rather than maintaining uniform charging, the electrode is designed with higher charge density in the center region and lower charge density at the end regions. This asymmetric charge distribution optimizes both capacity utilization and prevention of lithium deposition.

Inventive Principle:

Principle #4Asymmetry

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 effectively suppresses metal lithium deposition on the negative electrode, ensuring high reliability and reduced internal resistance while maintaining high energy density and output characteristics.

Implementation Method 1

a positive electrode mixture layer which is supported on the positive electrode current collector and into which anions are reversibly doped

Methodology Applied

Scientific EffectReversible doping: Adsorption

Implementation Method 2

a negative electrode mixture layer which is supported on the negative electrode current collector and into which lithium ions are reversibly doped

Methodology Applied

Scientific EffectReversible doping: Adsorption

Data Source

PatentUS20260031334A1Electrochemical device

Publication Date: 2026.01.29 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

An electrochemical device includes a positive electrode, a negative electrode, a separator, and a lithium-ion conductive electrolyte. The positive electrode includes a current collector, and a mixture layer which is supported on the current collector and into which anions are reversibly doped. The negative electrode includes a negative electrode current collector, and a mixture layer which is supported on the current collector and into which lithium ions are reversibly doped. A length L1 of the negative electrode mixture layer in a first direction is longer than a length L2 in a second direction orthogonal to the first direction. A state of charge of two end regions adjacent to both ends of the negative electrode mixture layer in the second direction is X %, a state of charge of a center region of the negative electrode mixture layer in the second direction is Y %, and X<Y is satisfied.