Si-Anode Electrolyte Composition for Low-Gassing Li-Ion Batteries

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Solution Overview

Problem

Conventional lithium-ion battery technologies face challenges with silicon-based anodes due to large volume changes, unstable solid electrolyte interphase (SEI) formation, and electrolyte decomposition, leading to reduced cycle life and energy density, especially when paired with high-voltage cathodes like Ni-rich NCM or LCO.

Innovation Solution

Development of new electrolyte compositions that replace fluoroethylene carbonate (FEC) with combinations of solvents such as propylene carbonate (PC) and ethyl methyl carbonate (EMC), which form stable and flexible SEI layers on silicon anodes and high-voltage cathodes, reducing gassing and maintaining cycle life performance at elevated temperatures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If fluoroethylene carbonate (FEC) is used as electrolyte additive, then SEI layer formation is improved, but gassing increases significantly

Engineering Contradiction:

ImproveSEI layer stabilityVSAvoidgassing

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent changes the chemical composition parameters of the electrolyte by replacing FEC with a combination of VC (vinylene carbonate) at 0.5-5% and F3EC (trifluoroethylene carbonate) at 5-30%, along with adjusting the carbonate solvent ratios. This parameter change resolves the contradiction by achieving stable SEI formation without the excessive gassing problem caused by FEC

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite electrolyte system combining multiple additives (VC and F3EC) with specific carbonate solvent mixtures (EC/DMC/DEC). This composite approach allows the electrolyte to simultaneously achieve stable SEI layer formation and suppress gassing, as VC provides robust SEI while F3EC reduces decomposition reactions that cause gas generation

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If silicon-based anodes are used, then energy density is improved, but volume expansion and SEI instability occur

Engineering Contradiction:

Improveenergy densityVSAvoidSEI layer stability

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The patent modifies the electrolyte composition parameters by using VC (0.5-5%) and F3EC (5-30%) instead of conventional FEC, along with specific carbonate ratios. This allows silicon anodes to form stable SEI layers despite volume expansion during lithiation/delithiation cycles, maintaining both high energy density and SEI stability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The electrolyte additives VC and F3EC act as intermediaries that mediate between the silicon anode and the electrolyte. They form a stable protective SEI layer that accommodates silicon's volume changes, preventing direct contact between the electrolyte and silicon surface, thus maintaining SEI stability while preserving high energy density

Inventive Principle:

Principle #24Intermediary (Mediator)

3Quantity of substance

If high-voltage cathodes (Ni-rich NCM or LCO) are used, then energy density is improved, but electrolyte decomposition increases

Engineering Contradiction:

Improveenergy densityVSAvoidelectrolyte decomposition

Core Design Contradiction:

Quantity of substanceVSLoss of energy

Solution Approach 1:

The patent changes the electrolyte composition by using F3EC (5-30%) which has higher oxidation stability suitable for high-voltage cathodes, combined with VC and specific carbonate solvents. This parameter change enables operation with Ni-rich NCM or LCO cathodes at high voltage while minimizing electrolyte decomposition

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The electrolyte additives VC and F3EC serve as intermediaries that form protective films on the high-voltage cathode surface. This intermediary layer prevents direct contact between the electrolyte and the high-voltage cathode material, reducing decomposition reactions and enabling stable high-voltage operation with high energy density

Inventive Principle:

Principle #24Intermediary (Mediator)

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 new electrolyte compositions enhance cycle life, energy density, and safety by minimizing electrolyte decomposition and gassing, while allowing for high-voltage operation without significant loss in cycle life, even at elevated temperatures.

Implementation Method 1

unstable solid electrolyte interphase (SEI) formation

Methodology Applied

Scientific EffectSolid electrolyte interphase (SEI) formation:

Implementation Method 2

form stable and flexible SEI layers on silicon anodes

Methodology Applied

Scientific EffectElectrochemical reaction:

Implementation Method 3

electrolyte decomposition, leading to reduced cycle life and energy density

Methodology Applied

Scientific EffectElectrolyte decomposition: Decomposition (biological)

Data Source

PatentUS20230268555A1Prevention of gassing in si dominant lithium-ion batteries

Publication Date: 2023.08.24 ENEVATE CORP

AI summary

A system and/or method for replacing solvents/additives such as fluoroethylene carbonate (FEC) to create new electrolyte compositions for lithium-ion energy storage devices with silicon-based electrode materials and reduce undesirable gassing. The electrolyte compositions may be used in an energy storage device comprising a first electrode and a second electrode, where at least one of the first electrode and the second electrode is a Si-based electrode, a separator between the first electrode and the second electrode, and the electrolyte composition.