Silicon-Anode Li-Ion Electrolyte Additive for High-Temperature Cycling

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Solution Overview

Problem

Lithium-ion batteries face challenges with high-temperature storage characteristics and cycle stability due to the dissolution of transition metals, which leads to increased resistance and self-discharge, especially when using silicon-based negative electrode active materials.

Innovation Solution

Incorporating a non-aqueous electrolyte solution with an additive containing a phosphonate functional group, such as a compound represented by Formula 1, to form a robust inorganic film on the surface of the electrodes, thereby preventing degradation and enhancing cycle characteristics and high-temperature storage stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a silicon-based negative electrode active material is used to increase capacity, then energy density is improved, but the SEI film is lost due to electrode expansion causing increased resistance and electrolyte solution side reactions

Engineering Contradiction:

Improveenergy densityVSAvoidcycle stability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent applies preliminary action by forming a robust SEI film containing inorganic components (LiF, Li2SiO3, Li3PO4) before the silicon electrode undergoes expansion during cycling. This pre-formed protective film prevents subsequent degradation, maintains electrode integrity during expansion, and suppresses electrolyte side reactions throughout the battery's operational life.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent employs composite materials by creating a multi-component SEI film comprising LiF, Li2SiO3, and Li3PO4 inorganic compounds. This composite structure combines the advantages of each component: LiF provides low electron conductivity and stability, Li2SiO3 offers mechanical strength and flexibility to accommodate expansion, and Li3PO4 contributes to overall film robustness, collectively preventing SEI loss during silicon electrode expansion.

Inventive Principle:

Principle #40Composite materials

2Duration of action of moving object

If transition metal is dissolved due to positive electrode structure collapse or acid attack, then positive electrode resistance increases and self-discharge occurs, but the battery continues to operate

Engineering Contradiction:

Improveoperational durationVSAvoidelectrode stability

Core Design Contradiction:

Duration of action of moving objectVSReliability

Solution Approach 1:

The patent converts the harmful effect of acid attack and transition metal dissolution into a beneficial outcome by using the acid (HF) to transform unstable transition metals into stable, insoluble compounds (e.g., MnF2, CoF2, NiF2). This process eliminates the harmful dissolution and redeposition of transition metals that cause resistance increase and self-discharge, while maintaining battery operational duration.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Productivity

If the SEI film is lost due to electrode expansion during cycling, then resistance increases and electrolyte solution side reactions increase, but the battery continues to function

Engineering Contradiction:

Improvecycle rateVSAvoidside reactions

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent applies parameter changes by modifying the chemical composition of the SEI film to include specific inorganic compounds with distinct properties: LiF provides low electron conductivity and stability, Li2SiO3 offers mechanical strength and flexibility to accommodate expansion, and Li3PO4 contributes to overall film robustness. These compositional changes enable the SEI film to maintain integrity during electrode expansion while suppressing side reactions.

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

The use of the phosphonate-containing additive in the electrolyte solution effectively forms a stable film on the electrodes, reducing capacity loss, suppressing side reactions, and improving the overall performance of lithium-ion batteries under high-temperature conditions.

Implementation Method 1

the additive includes a compound represented by Formula 1... a robust inorganic component film may be formed on a surface of the negative electrode including the silicon-based negative electrode active material

Methodology Applied

Scientific EffectFilm formation through chemical reaction: Chemical Bonding

Data Source

PatentUS20250192230A1Lithium Secondary Battery

Publication Date: 2025.06.12 LG ENERGY SOLUTION LTD

AI summary

A lithium secondary battery with improved high-temperature storage characteristics and high-temperature cycle characteristics is described. Such lithium secondary battery includes a positive electrode, a negative electrode including a silicon-based negative electrode active material, a separator disposed between the positive electrode and the negative electrode, and a non-aqueous electrolyte solution containing a lithium salt, an organic solvent, and an additive, wherein the additive may include a compound represented by Formula 1,wherein, in Formula 1, R1 to R3 are described herein.