Silicon Alloy Anode Coating for SEI Prevention

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Solution Overview

Problem

Silicon alloy anodes in lithium-ion batteries face challenges such as significant volume expansion and contraction during lithium insertion/extraction, leading to pulverization and the continuous formation of thick solid-electrolyte interphase (SEI) films, which reduces cycling life and efficiency.

Innovation Solution

The use of nano-structured metal oxides as coatings on silicon anode materials to prevent SEI film formation and mitigate volume expansion, improving cycling life stability by providing a protective layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If silicon alloy anodes are used to increase capacity, then energy density is improved, but volume expansion and contraction occur leading to pulverization and reduced cycling life

Engineering Contradiction:

Improveenergy densityVSAvoidcycling life

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

A coating layer comprising metal oxides and metal hydroxides is applied to the silicon alloy particles before electrode fabrication. This preliminary protective layer prevents direct contact between the silicon alloy and electrolyte, mitigating volume expansion stress and preventing pulverization during cycling, thereby extending cycling life while maintaining high energy density

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The coating layer of metal oxides and hydroxides acts as a cushioning layer that absorbs and distributes the mechanical stress from silicon alloy volume expansion during lithiation. This beforehand cushioning prevents particle fracture and maintains structural integrity over multiple cycles, resolving the contradiction between high capacity and cycling stability

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Use of energy by moving object

If silicon alloy anodes are used to increase capacity, then energy density is improved, but thick SEI films form continuously reducing efficiency

Engineering Contradiction:

Improveenergy densityVSAvoidcoulombic efficiency

Core Design Contradiction:

Use of energy by moving objectVSLoss of energy

Solution Approach 1:

The coating layer of metal oxides and hydroxides serves as an intermediary layer between the silicon alloy anode and the electrolyte. This intermediary prevents direct reaction between silicon and electrolyte, blocking continuous SEI film formation and the associated energy loss, while still allowing lithium ion transport to maintain high coulombic efficiency and energy density

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If coating layers are applied to prevent SEI formation, then cycling life is improved, but manufacturing complexity increases

Engineering Contradiction:

Improvecycling lifeVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The coating is applied by controlling pH parameters during particle synthesis, where metal oxide and hydroxide coatings form in situ through pH adjustment. This parameter-based approach simplifies manufacturing compared to separate coating steps, as the coating forms during the existing synthesis process without requiring additional complex equipment or procedures

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The coating layer forms self-assembled on the silicon alloy particles during the synthesis process through controlled precipitation of metal oxides and hydroxides. This self-service approach eliminates the need for separate coating operations, reducing manufacturing complexity while ensuring uniform coverage that improves cycling life

Inventive Principle:

Principle #25Self-service

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 application of nano-structured metal oxides significantly enhances the cycling life and performance of silicon alloy anodes by preventing SEI growth and maintaining electrical conductivity.

Implementation Method 1

The use of nano-structured metal oxides as coatings on silicon anode materials to prevent SEI film formation

Methodology Applied

Scientific EffectSEI film formation prevention:

Implementation Method 2

The use of nano-structured metal oxides as coatings on silicon anode materials to prevent SEI film formation and mitigate volume expansion

Methodology Applied

Scientific EffectVolume expansion mitigation:

Implementation Method 3

The application of nano-structured metal oxides significantly enhances the cycling life and performance of silicon alloy anodes by preventing SEI growth and maintaining electrical conductivity

Methodology Applied

Scientific EffectElectrical conductivity maintenance:

Data Source

PatentUS11177471B2Anode materials for lithium ion batteries and methods of making and using same

Publication Date: 2021.11.16 SICONA BATTERY TECH PTY LTD

AI summary

An electrochemically active material includes a silicon alloy material having the formula:SiwM1xCyOz,where w, x, y, and z represent atomic % values and w+x+y+z=1; M1 comprises a transition metal; w>0; x>0; y≥0; and z≥0. The electrochemically active material also includes a metal-based material having the formula:M2aObAc, where a, b, and c represent atomic % values and a+b+c=1; M2 comprises a metal; A is an anion; a>0; b≥0; and c≥0.