Silicon Anode Coating for Electrolyte Corrosion Resistance

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Solution Overview

Problem

The silicate phase in composite particles for negative electrodes in secondary batteries undergoes corrosion due to side reactions with non-aqueous electrolytes, leading to deteriorated cycle properties.

Innovation Solution

A coating layer comprising a lithium sulfonate compound and a linear saturated fatty acid compound with 10 or more carbon atoms is applied to the surface of silicon-containing particles, which includes an ion-conducting phase, to protect the particles from electrolyte interaction and suppress side reactions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If a silicate phase is used as a negative electrode active material, then capacity density is improved, but cycle properties deteriorate due to corrosion from side reactions with non-aqueous electrolyte

Engineering Contradiction:

Improvecapacity densityVSAvoidcycle properties

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

A coating layer comprising a lithium sulfonate compound and a linear saturated fatty acid compound is applied as an intermediary between the silicate phase and the non-aqueous electrolyte. This coating layer suppresses side reactions and corrosion while maintaining ion conductivity, thereby improving cycle properties without sacrificing capacity density.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The negative electrode active material is designed as a composite structure combining a silicate phase with dispersed silicon particles, surrounded by a dual-component coating layer. This composite structure leverages the high capacity of silicon while using the silicate phase as a buffer, and the coating layer as a protective barrier, achieving both high capacity and good cycle stability.

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If silicon particles are dispersed in silicate phase, then capacity density is improved, but particle breakage occurs due to expansion and contraction during charge and discharge

Engineering Contradiction:

Improvecapacity densityVSAvoidparticle integrity

Core Design Contradiction:

Quantity of substanceVSStrength

Solution Approach 1:

The silicate phase is designed with specific compositional characteristics (containing Li, Si, and M elements in controlled ratios) to provide localized mechanical buffering around silicon particles. This local structural optimization allows the silicate phase to accommodate silicon expansion and contraction without causing particle breakage, while maintaining overall particle integrity.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The composite structure of silicon particles dispersed in silicate phase creates a synergistic system where the silicate phase acts as a mechanical buffer that absorbs expansion stress, preventing silicon particle breakage during charge-discharge cycles while maintaining high capacity density.

Inventive Principle:

Principle #40Composite materials

3Reliability

If a coating layer is applied to suppress side reactions, then cycle properties are improved, but device complexity increases

Engineering Contradiction:

Improvecycle propertiesVSAvoidstructure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The coating layer uses specific chemical compounds (lithium sulfonate and linear saturated fatty acid) with defined molecular characteristics to achieve effective protection. By optimizing the chemical parameters of the coating materials and their thickness, the patent achieves superior corrosion resistance with a relatively simple single-layer structure, avoiding the need for complex multi-layer coatings.

Inventive Principle:

Principle #35Parameter changes

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 coating effectively suppresses corrosion and improves the cycle properties of secondary batteries by maintaining the integrity of the silicon-containing particles.

Implementation Method 1

The silicate phase in the composite particle tends to undergo gradual corrosion due to a side reaction that occurs inside a battery containing a non-aqueous electrolyte

Methodology Applied

Scientific EffectSide reaction suppression:

Implementation Method 2

the silicon-containing particle includes: an ion-conducting phase

Methodology Applied

Scientific EffectIon conduction:

Data Source

PatentUS20250219094A1Negative electrode material for secondary batteries, and secondary battery

Publication Date: 2025.07.03 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

A negative electrode for a secondary battery includes a silicon-containing particle, and a coating layer that covers at least a portion of the surface of the silicon-containing particle. The silicon-containing particle includes an ion-conducting phase, and silicon phases dispersed in the ion-conducting phase. The coating layer includes a lithium sulfonate compound and a linear saturated fatty acid compound having 10 or more carbon atoms.