Lithium Silicate Anode Coating Gradient for Erosion and Conductivity

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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 that includes lithium silicate composite particles coated with an oxide of a first element, where the coating thickness varies to balance erosion suppression and electrical conductivity, with thicker coatings near the current collector and thinner coatings further away.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a coating is applied to suppress erosion of silicon compound particles, then capacity retention rate improves, but electrical conductivity deteriorates

Engineering Contradiction:

Improvecapacity retention rateVSAvoidelectrical conductivity

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies a non-uniform coating thickness distribution where the coating is thicker near the current collector (suppressing erosion locally) and thinner toward the electrode surface (maintaining conductivity). This local quality variation resolves the contradiction by optimizing protection and conductivity in different spatial zones of the same particle coating.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses a composite coating structure comprising multiple materials (e.g., oxide coating layer and carbon-containing coating layer) with different properties. The oxide layer provides erosion resistance while the carbon-containing layer maintains electrical conductivity, thus resolving the contradiction through material composition rather than single-material thickness adjustment.

Inventive Principle:

Principle #40Composite materials

2Duration of action of stationary object

If a thick coating is applied to suppress erosion, then durability improves, but electrical conductivity deteriorates

Engineering Contradiction:

ImprovedurabilityVSAvoidelectrical conductivity

Core Design Contradiction:

Duration of action of stationary objectVSObject-generated harmful factors

Solution Approach 1:

The patent implements position-dependent coating thickness where durability-critical regions (near current collector) receive thicker coating while conductivity-critical regions (near electrode surface) receive thinner coating. This spatially differentiated approach allows the system to achieve both durability and conductivity without the trade-off that would result from uniform thick coating.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The coating is segmented into multiple layers with different functions: an inner oxide layer for erosion resistance and durability, and an outer carbon-containing layer for electrical conductivity. This segmentation allows each layer to optimize its specific function without compromising the other, resolving the durability-conductivity contradiction.

Inventive Principle:

Principle #1Segmentation

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 enhances the capacity retention rate and durability of the electrochemical device by suppressing erosion and maintaining electrical conductivity, resulting in a high-capacity and long-life electrochemical device.

Implementation Method 1

silicon compounds are more susceptible to erosion by side reactions during battery operation than when using a carbon material as the negative electrode material

Methodology Applied

Scientific EffectErosion suppression: Erosion

Implementation Method 2

a coating formation step, after the supporting step, of forming a first coating including an oxide of a first element other than a non-metal element by allowing the lithium silicate composite particles to expose in a gas phase including a first element on at least a portion of a surface thereof

Methodology Applied

Scientific EffectPhysical vapor deposition: Physical Vapour Deposition

Data Source

PatentUS12586781B2Electrochemical element, method for manufacturing same, and electrochemical device

Publication Date: 2026.03.24 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

An electrochemical element includes a current collector, and an active material layer on the current collector, wherein the active material layer includes active material particles each including lithium silicate composite particles with a lithium silicate phase and silicon particles dispersed therein, and a first coating covering at least a portion of a surface of the lithium silicate composite particles, the first coating includes an oxide of a first element other than a non-metal element, the active material layer has a thickness TA, and T1b>T1t, where T1b is a thickness of the first coating covering the lithium silicate composite particles at a position of 0.25TA from the surface of the current collector in the active material layer, and T1t is a thickness of the first coating covering the lithium silicate composite particles at a position of 0.75TA from the surface of the current collector in the active material layer.