Silicon Composite Anode with Dual-Reference Electrodes

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Solution Overview

Problem

Lithium ion batteries face challenges with anode material stability due to volume changes, leading to mechanical stress and potential drift in sensing, which affects battery operation and cycle life, especially in dry room manufacturing conditions.

Innovation Solution

The use of a silicon composite anode with carbon nanowires or thin films, combined with a dual-reference electrode system and optimized electrolyte solutions, along with surface modification to control moisture and potential distribution, enhances stability and cycle life by maintaining a natural potential difference and preventing lithium plating.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If silicon-based anode materials are used to increase capacity, then battery capacity is improved, but volume change during cycling causes mechanical stress and electrode deterioration

Engineering Contradiction:

Improvebattery capacityVSAvoidelectrode integrity

Core Design Contradiction:

Quantity of substanceVSStrength

Solution Approach 1:

Silicon particles are embedded within graphite matrix, creating a nested structure where silicon is contained inside graphite. This allows silicon to expand and contract during lithium insertion/extraction while being constrained by the graphite shell, preventing electrode deterioration while maintaining high capacity.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The anode uses a composite structure combining silicon and graphite materials. Silicon provides high capacity while graphite provides structural stability and accommodates volume changes. The composite nature allows both materials to contribute their advantageous properties simultaneously.

Inventive Principle:

Principle #40Composite materials

2Stability of the object's composition

If particle size is decreased to reduce mechanical stress, then electrode stability is improved, but surface area to volume ratio increases leading to higher reactivity and side reactions

Engineering Contradiction:

Improveelectrode stabilityVSAvoidside reactions

Core Design Contradiction:

Stability of the object's compositionVSObject-generated harmful factors

Solution Approach 1:

A thin graphite shell is formed around silicon particles, creating a flexible protective layer that accommodates volume changes while protecting the silicon core. This thin film structure maintains electrode stability without significantly increasing harmful surface reactions.

Inventive Principle:

Principle #30Flexible shells and thin films

3Reliability

If reference electrode potential is monitored to control battery operation, then safety is improved, but potential drift occurs over time affecting sensing accuracy

Engineering Contradiction:

Improvebattery safetyVSAvoidpotential sensing accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The reference electrode material is changed from traditional lithium metal to lithium titanium oxide (LTO), which exhibits superior potential stability. LTO maintains a constant potential during cycling, eliminating the drift problem and ensuring accurate long-term sensing for battery safety control.

Inventive Principle:

Principle #35Parameter changes

4Ease of operation

If metallic lithium reference electrode is used for potential control, then battery operation control is improved, but it cannot be applied in dry room manufacturing conditions

Engineering Contradiction:

Improvebattery operation controlVSAvoidmanufacturing condition compatibility

Core Design Contradiction:

Ease of operationVSEase of manufacture

Solution Approach 1:

The reference electrode material is changed from metallic lithium to lithium titanium oxide, altering the material properties to be less sensitive to moisture and oxygen. This enables the reference electrode to function properly in dry room manufacturing conditions while maintaining its potential control capability.

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

This approach achieves stable performance with 80% capacity retention after 1000 cycles, improved cycle life, and safer battery operation by controlling anode and cathode potentials independently, minimizing mechanical stress and moisture impact.

Implementation Method 1

huge volume change of active silicon

Methodology Applied

Scientific EffectVolume change:

Implementation Method 2

silicon deposited on the carbon in the form of nanowires

Methodology Applied

Scientific EffectAdsorption: Adsorption

Implementation Method 3

lithium ion electrochemical cell

Methodology Applied

Scientific EffectDiffusion: Diffusion

Implementation Method 4

maintain its sensing potential

Methodology Applied

Scientific EffectElectrochemical potential:

Implementation Method 5

electrolyte between each of the anode, cathode, first reference electrode, and second reference electrode

Methodology Applied

Scientific EffectIonic conduction: Conduction (electrical)

Data Source

PatentUS10367236B2Anode, cell, and method of stabilizing an anode for use in a lithium ion electrochemical cell

Publication Date: 2019.07.30 ONED MATERIAL INC

AI summary

A battery comprises an anode, a cathode, a first reference electrode, and a second reference electrode. The battery also include an electrolyte between each of the anode, cathode, first reference electrode, and second reference electrode.