Silicon Negative Electrode with Buffer Layer for Solid-State Battery

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Solution Overview

Problem

Conventional solid-state batteries face challenges in achieving high energy density and excellent cycle characteristics due to issues with silicon as a negative electrode active material, poor ionic conductivity, and reaction with current collectors, leading to decreased discharge capacity and cycle life.

Innovation Solution

A battery design featuring a solid electrolyte layer between positive and negative electrodes, with a negative electrode active material layer composed of columnar silicon particles that are substantially free of electrolyte, enhancing energy density and cycle characteristics by reducing sulfide formation and increasing ion conduction paths.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If silicon is used as negative electrode active material to increase energy density, then discharge capacity is improved, but cycle characteristics deteriorate due to poor ionic conductivity and reaction with current collectors

Engineering Contradiction:

Improvedischarge capacityVSAvoidcycle characteristics

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

A buffer layer comprising Cr, Ti, W, C, Ta, Au, Pt, Mn, or Mo is introduced between the silicon-based negative electrode active material and the current collector. This intermediary layer prevents direct contact and reaction between silicon and the current collector, suppressing harmful chemical reactions while maintaining electrical conductivity and mechanical adhesion, thereby improving cycle characteristics without sacrificing discharge capacity

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the physical and chemical parameters of the negative electrode structure by introducing a specific buffer layer composition and controlling its thickness (1-10 μm). This parameter modification optimizes the balance between ionic conductivity, electrical conductivity, and chemical stability, enabling silicon to maintain high discharge capacity while achieving excellent cycle life through suppressed degradation reactions

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If conventional electrode structures are used to simplify manufacturing, then ease of manufacture is improved, but energy density and cycle characteristics deteriorate

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidenergy density

Core Design Contradiction:

Ease of manufactureVSQuantity of substance

Solution Approach 1:

The negative electrode is segmented into distinct functional layers: a silicon-based active material layer and a separate buffer layer positioned between the active material and current collector. This segmentation allows each layer to be optimized independently - the silicon layer for maximum energy density and the buffer layer for interface stability - while maintaining a relatively simple manufacturing process through sequential deposition or lamination techniques

Inventive Principle:

Principle #1Segmentation

3Quantity of substance

If silicon particles are used as negative electrode active material to increase capacity, then discharge capacity is improved, but resistance increases due to sulfide formation

Engineering Contradiction:

Improvedischarge capacityVSAvoidresistance

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The invention converts the potentially harmful interaction between silicon and sulfide-containing solid electrolytes into a beneficial configuration by positioning the buffer layer as a controlled interface. The buffer layer, comprising elements like Cr, Ti, W, C, Ta, Au, Pt, Mn, or Mo, acts as a protective barrier that prevents uncontrolled sulfide formation while maintaining optimal ionic conductivity pathways, thereby eliminating resistance issues without reducing the high capacity benefits of silicon

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

The battery achieves high energy density and extended cycle life with improved discharge capacity and reduced resistance, maintaining performance over multiple charge-discharge cycles.

Implementation Method 1

the solid electrolyte layer includes a solid electrolyte having lithium-ion conductivity

Methodology Applied

Scientific EffectLithium-ion conductivity: Conduction (electrical)

Implementation Method 2

the columnar particles include silicon as a main component... increasing ion conduction paths

Methodology Applied

Scientific EffectIon conduction: Conduction (electrical)

Data Source

PatentUS20230088683A1Battery and method of manufacturing battery

Publication Date: 2023.03.23 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

A battery of the present disclosure includes a positive electrode, a negative electrode, and a solid electrolyte layer. The solid electrolyte layer is positioned between the positive electrode and the negative electrode. The solid electrolyte layer includes a solid electrolyte having lithium-ion conductivity. The negative electrode includes: a negative electrode current collector; and a negative electrode active material layer positioned between the negative electrode current collector and the solid electrolyte layer. The negative electrode active material layer has a plurality of columnar particles and is substantially free of an electrolyte. The columnar particles include silicon as a main component.