Silicon Anode Oxide Coating for Capacity and Chemical Stability

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Solution Overview

Problem

Silicon compounds used as negative electrode materials in lithium ion secondary batteries are susceptible to erosion during battery operation, leading to a decrease in capacity retention rate.

Innovation Solution

An electrochemical element with a current collector and an active material layer containing lithium silicate composite particles and silicon particles, coated with a first oxide coating that covers at least a portion of the lithium silicate composite particles and electrically conductive carbon material, where the thickness ratio of the coatings is controlled to enhance chemical stability and electrical conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If silicon compounds are used as negative electrode material to increase capacity, then battery capacity is improved, but chemical stability deteriorates due to erosion and side reactions

Engineering Contradiction:

Improvebattery capacityVSAvoidchemical stability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent uses a composite coating structure consisting of an inner coating layer (first coating) and an outer coating layer (second coating) applied over the silicon compound particles. This multi-layer composite structure provides both protection against erosion and maintenance of chemical stability, allowing the silicon compound to function at high capacity while resisting degradation during battery operation.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The coating layers act as intermediary protective barriers between the silicon compound particles and the electrolyte environment. These intermediate layers prevent direct contact between the reactive silicon compound and the electrolyte, thereby reducing side reactions and erosion while maintaining the electrochemical performance of the silicon compound.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If coating is applied to protect lithium silicate composite particles, then chemical stability is improved, but electrical conductivity may deteriorate

Engineering Contradiction:

Improvechemical stabilityVSAvoidelectrical conductivity

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent applies different coating layers with different properties at different locations/levels. The inner coating layer (first coating) provides primary protection and has specific compositional characteristics, while the outer coating layer (second coating) provides additional protection and has different compositional characteristics. This local differentiation allows optimization of both protection and conductivity without compromising either property uniformly across the entire structure.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent controls the thickness and composition parameters of the coating layers to optimize performance. By carefully adjusting the thickness of the inner and outer coating layers and their respective compositions, the patent achieves a balance where sufficient protection is provided while minimizing the impact on electrical conductivity. The thickness ratio and compositional parameters are specifically controlled to maintain energy efficiency.

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 solution improves the chemical stability of the active material layer, resulting in a high-capacity, long-life electrochemical device by suppressing erosion and expansion of the lithium silicate composite particles while maintaining electrical conductivity.

Implementation Method 1

a first coating covers at least a portion of a surface of the lithium silicate composite particles and at least a portion of a surface of the electrically conductive carbon material, the first coating including an oxide of a first element other than a non-metal element

Methodology Applied

Scientific EffectOxidation: Oxidation

Implementation Method 2

a coating formation step, following the supporting step, of allowing the lithium silicate composite particles and the electrically conductive carbon material to expose in a gas phase including a first element other than a non-metal element to form a first coating including an oxide of the first element

Methodology Applied

Scientific EffectChemical Vapour Deposition: Chemical Vapour Deposition

Data Source

PatentUS12620583B2Electrochemical element, method for manufacturing same, and electrochemical device

Publication Date: 2026.05.05 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

An electrochemical element includes a current collector, and an active material layer supported on the current collector, wherein the active material layer contains lithium silicate composite particles each including a lithium silicate phase, and silicon particles dispersed in the lithium silicate phase, and an electrically conductive carbon material, a first coating covers at least a portion of a surface of the lithium silicate composite particles and at least a portion of a surface of the electrically conductive carbon material, the first coating includes an oxide of a first element other than a non-metal element, and T1A>T1C is satisfied, where T1A is an average thickness of the first coating that covers at least a portion of the surface of the lithium silicate composite particles, and T1C is an average thickness of the first coating that covers at least a portion of the surface of the electrically conductive carbon material.