Silicon Anode Composite Shell for Conductivity and Cycle Stability

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Solution Overview

Problem

Lithium-ion batteries face challenges with low conductivity and poor cycle performance due to the use of silicon-based negative electrode materials, which experience significant volume expansion and structural deterioration during charging and discharging.

Innovation Solution

A composite silicon-based negative electrode material is developed, comprising a silicon-based material core layer coated with a metal material shell layer, where the metal material permeates into the core layer, forming a permeation area that enhances conductivity and limits volume expansion, thereby improving the battery's cycle performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If silicon-based material is used as negative electrode material, then specific capacity is improved, but conductivity deteriorates

Engineering Contradiction:
Improvespecific capacityVSAvoidconductivity
Core Design Contradiction:
Quantity of substanceVSReliability

Solution Approach 1:

The patent uses a composite structure consisting of a silicon-based material core layer and a metal material shell layer. The metal material shell layer coats the silicon-based material core layer, forming a composite negative electrode material that combines the high specific capacity of silicon with the high conductivity of metal, thereby resolving the contradiction between specific capacity and conductivity

Inventive Principle:
Principle #40Composite materials

2Quantity of substance

If silicon-based material is used as negative electrode material, then specific capacity is improved, but cycle performance deteriorates

Engineering Contradiction:
Improvespecific capacityVSAvoidcycle performance
Core Design Contradiction:
Quantity of substanceVSDuration of action of stationary object

Solution Approach 1:

The metal material shell layer is formed beforehand to coat and protect the silicon-based material core layer. This protective shell prevents direct contact between the silicon-based material and the electrolyte, cushioning against the harmful effects of volume expansion and structural deterioration during charging and discharging cycles, thereby improving cycle performance while maintaining high specific capacity

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Quantity of substance

If silicon-based material is used as negative electrode material, then specific capacity is improved, but structural stability deteriorates

Engineering Contradiction:
Improvespecific capacityVSAvoidstructural stability
Core Design Contradiction:
Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The metal material shell layer acts as a flexible protective shell that can accommodate the volume expansion of the silicon-based material core layer during lithium insertion while maintaining structural integrity. This shell prevents pulverization and structural collapse, ensuring structural stability throughout charge-discharge cycles

Inventive Principle:
Principle #30Flexible shells and thin films

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 composite material achieves improved conductivity and cycle stability, leading to enhanced first-time coulombic efficiency and cycle retention rate of lithium-ion secondary batteries.

Implementation Method 1

a permeation area formed by the permeation of the metal material shell layer into the silicon-based material core layer

Methodology Applied
Scientific EffectPermeation: Permeation

Implementation Method 2

the metal material shell layer coating the silicon-based material core layer... limits volume expansion

Methodology Applied
Scientific EffectPhysical containment: Physical Containment

Data Source

PatentUS20240250244A1Composite silicon-based negative electrode material, preparation method therefor, negative electrode sheet comprising same, and lithium-ion secondary battery
Publication Date: 2024.07.25 MURATA MFG CO LTD

AI summary

A composite silicon-based negative electrode material, a preparation method therefor, a negative electrode sheet comprising same, and a lithium-ion secondary battery are provided. The composite silicon-based negative electrode material comprises a silicon-based material core layer and a metal material shell layer, wherein the metal material shell layer coats the silicon-based material core layer, and the silicon-based material core layer comprises a permeation area formed by the permeation of the metal material shell layer into the silicon-based material core layer. By means of the composite silicon-based negative electrode material and the preparation method therefor of the present application, the conductivity of the negative electrode material is improved, the expansion rate of the core layer formed by the silicon-based material is limited, and the consumption of lithium ions caused by a reaction between an electrolyte and the surface of the silicon-based material is effectively reduced. Therefore, the first-time coulombic efficiency and cycle performance of the lithium-ion secondary battery formed from the composite silicon-based negative electrode material of the present application are improved.