Silicon Composite Anode Coating Gradient for Cycle Durability

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Solution Overview

Problem

The durability of electrochemical devices is reduced due to the significant expansion and contraction of silicon compounds during charge/discharge cycles, particularly affecting the active material layer.

Innovation Solution

An electrochemical element with a current collector and an active material layer that includes lithium silicate composite particles coated with a first oxide coating, where the coating thickness varies to balance expansion suppression and electrical conductivity, with thicker coatings farther from the current collector and thinner coatings closer to it.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If silicon compounds are used as active material, then capacity is improved, but expansion and contraction during charge/discharge reduces durability

Engineering Contradiction:

ImprovecapacityVSAvoiddurability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent embeds silicon particles inside lithium silicate composite particles, creating a nested structure where silicon is protected by the lithium silicate phase. This nested configuration allows silicon to maintain its high capacity functionality while the outer lithium silicate layer suppresses excessive expansion and contraction, thereby improving durability.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The patent creates composite particles consisting of silicon particles dispersed in a lithium silicate phase. This composite structure combines the high capacity advantage of silicon with the structural stability of lithium silicate, resolving the contradiction between capacity and durability by integrating both materials' beneficial properties into a single composite active material.

Inventive Principle:

Principle #40Composite materials

2Reliability

If a coating is applied to suppress expansion, then durability is improved, but electrical conductivity may deteriorate

Engineering Contradiction:

ImprovedurabilityVSAvoidelectrical conductivity

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent carefully controls the thickness parameter of the first coating to optimize the balance between expansion suppression and electrical conductivity. By adjusting this critical parameter, the coating provides sufficient mechanical protection against expansion while maintaining thin enough dimensions to preserve electrical conductivity for effective charge/discharge performance.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies different coating thicknesses at different locations: the first coating is made thinner near the current collector to maintain conductivity, and thicker farther from the current collector to enhance expansion suppression. This spatial variation in coating quality optimizes both electrical performance and structural stability across different regions of the active material layer.

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 design suppresses the expansion of the active material layer, leading to improved durability and a longer life for the electrochemical device.

Implementation Method 1

a first coating that covers at least a portion of a surface of the lithium silicate composite particle... suppression of expansion of the active material layer

Methodology Applied

Scientific EffectMechanical constraint:

Implementation Method 2

the first coating includes an oxide of a first element other than a non-metal element... balance expansion suppression and electrical conductivity

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS12597601B2Electrochemical element, method for producing same, and electrochemical device

Publication Date: 2026.04.07 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 having a lithium silicate composite particle including a lithium silicate phase and silicon particles dispersed therein, and a first coating that covers at least a portion of a surface of the lithium silicate composite particle, the first coating includes an oxide of a first element other than a non-metal element, and 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 particle at a position of 0.25 TA from the current collector surface in the active material layer, and T1t is a thickness of the first coating covering the lithium silicate composite particle at a position of 0.75 TA from the current collector surface in the active material layer.