Lithium Silicate Interface Layer for Battery Adhesion

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Solution Overview

Problem

Current lithium ion battery negative electrodes face challenges in achieving strong adhesion between the current collector and active material layers, leading to stress and separation issues during charge-discharge cycles, which affect cycle characteristics.

Innovation Solution

A lithium silicate layer is introduced at the interface between the negative electrode current collector and active material layer, formed by maintaining a silicon oxide layer in a specific atmosphere, allowing lithium to bond with oxygen and enhance adhesion without contributing to charge-discharge reactions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If alloy-type active materials are used to increase energy density, then capacity is improved, but stress and adhesion strength deteriorate due to expansion during lithium absorption

Engineering Contradiction:

Improvelithium absorption capacityVSAvoidadhesion strength between current collector and active material layer

Core Design Contradiction:

Quantity of substanceVSStrength

Solution Approach 1:

A lithium silicate layer is introduced as an intermediary between the current collector and the alloy-type active material layer. This intermediate layer has low expansion characteristics and forms strong chemical bonds (Li-O-Si) with both the current collector and the active material, thereby maintaining adhesion strength even when the active material expands during lithium absorption.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The negative electrode is constructed as a composite structure consisting of the current collector, the lithium silicate layer, and the alloy-type active material layer. This composite design combines the high capacity of alloy materials with the structural stability and bonding capability of lithium silicate, resolving the contradiction between capacity and adhesion.

Inventive Principle:

Principle #40Composite materials

2Use of energy by moving object

If alloy-type active materials absorb lithium, then energy density is improved, but stress causes separation and deformation

Engineering Contradiction:

Improveenergy densityVSAvoidcycle characteristics

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The lithium silicate layer serves as a stress-absorbing intermediary that prevents the transmission of expansion stress from the alloy-type active material to the current collector. This mediation maintains the structural integrity of the electrode during charge-discharge cycles, thereby improving reliability and cycle characteristics.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The lithium silicate layer is formed in advance before the active material layer is applied. This pre-formed layer acts as a cushioning buffer that accommodates the volume changes of the active material during lithium absorption, preventing cracks and separation before they occur.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Weight of moving object

If thin film of active material is formed to reduce weight, then weight is reduced, but adhesion strength is insufficient

Engineering Contradiction:

Improvenegative electrode weightVSAvoidadhesion strength between current collector and active material layer

Core Design Contradiction:

Weight of moving objectVSStrength

Solution Approach 1:

The lithium silicate layer acts as a bonding intermediary that enhances adhesion between the thin active material film and the current collector. Even when the active material layer is thin and lightweight, the lithium silicate layer provides sufficient mechanical strength and chemical bonding to prevent separation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The lithium silicate layer is specifically positioned at the critical interface between the current collector and the active material layer, where adhesion is most needed. This localized placement provides enhanced bonding strength exactly where required, without adding unnecessary weight throughout the entire electrode structure.

Inventive Principle:

Principle #3Local quality

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 solution significantly increases the adhesion strength between the current collector and active material layer, preventing separation and enhancing the cycle characteristics of lithium ion batteries by managing stress and maintaining high energy density.

Implementation Method 1

Lithium silicate having a Li-O-Si bond does not contribute to charge-discharge reactions

Methodology Applied

Scientific EffectChemical bonding: Chemical Bonding

Implementation Method 2

it is possible to prevent excessive stress from occurring at the interface by providing a lithium silicate layer

Methodology Applied

Scientific EffectStress relaxation: Stress Relaxation

Data Source

PatentEP2472648B1Negative electrode for lithium ion battery and method for producing the same, and lithium ion battery

Publication Date: 2017.11.15 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

Figure 1A~1B
Figure 1C
Figure 2

AI summary

A negative electrode for a lithium ion battery 10 includes a negative electrode current collector 11, a negative electrode active material layer 14, and a lithium silicate layer 15. The negative electrode active material layer 14 contains silicon. The lithium silicate layer 15 contains lithium, oxygen, and silicon forming a Li-O-Si bond, and is formed at the interface between the negative electrode current collector 11 and the negative electrode active material layer 14. The negative electrode active material layer 14 and the lithium silicate layer 15 may be composed of columnar bodies.