LiPO2F2 Electrolyte for Silicon Anode SEI Stability

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Solution Overview

Problem

Conventional lithium-ion battery electrolytes are costly, inefficient, and limit battery lifetime due to instability and poor compatibility with silicon-based anodes and high-voltage cathodes, leading to rapid capacity fade and safety concerns.

Innovation Solution

The use of LiPO2F2-containing electrolyte formulations and additives forms stable solid-electrolyte and cathode-electrolyte interphase layers, reducing electrolyte reactions, preventing silicon anode expansion, and enhancing thermal stability, while also improving ionic conductivity and safety.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional lithium-ion battery electrolytes are used, then the battery can operate, but the battery lifetime is limited due to instability and poor compatibility with silicon-based anodes

Engineering Contradiction:

Improvebattery lifetimeVSAvoidelectrolyte stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent changes the chemical composition parameters of the electrolyte by introducing LiPO2F2 salt and specific additive combinations (e.g., VC + DAPC, or FEC + DAPC) to achieve stable interphase layer formation on silicon anodes, resolving the incompatibility between conventional electrolytes and silicon-based electrodes

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses electrolyte additives as intermediary substances that mediate between the silicon anode and the main electrolyte, forming protective interphase layers (SEI and CEI) that prevent direct harmful interactions while maintaining ionic conductivity

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If conventional electrolytes are used with silicon-based anodes, then the battery can function, but rapid capacity fade occurs

Engineering Contradiction:

Improvebattery capacity retentionVSAvoidbattery cycle life

Core Design Contradiction:

ProductivityVSDuration of action of stationary object

Solution Approach 1:

The patent employs preliminary action by using electrolyte additives that pre-form stable protective interphase layers on the silicon anode surface before the battery enters normal cycling operation, preventing subsequent capacity-fading reactions

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent converts the naturally formed unstable SEI layer (which causes capacity fade) into a beneficial stable protective layer by controlling its composition through additive selection, transforming a harmful phenomenon into a protective mechanism

Inventive Principle:

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

3Reliability

If conventional electrolytes are used, then the battery can operate, but safety concerns arise due to poor thermal stability

Engineering Contradiction:

Improvebattery safetyVSAvoidthermal stability

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent introduces electrolyte additives as intermediary substances that form thermal-stable interphase layers on the electrode surfaces, acting as a protective barrier that prevents thermal runaway and improves battery safety

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

This approach improves the cycle life and safety of silicon anode-based lithium-ion batteries by forming stable interphase layers, reducing capacity fade, and increasing thermal stability, thus addressing the limitations of conventional electrolytes.

Implementation Method 1

The use of LiPO2F2-containing electrolyte formulations and additives forms stable solid-electrolyte and cathode-electrolyte interphase layers

Methodology Applied

Scientific EffectSolid-electrolyte interphase (SEI) formation:

Implementation Method 2

The use of LiPO2F2-containing electrolyte formulations and additives forms stable solid-electrolyte and cathode-electrolyte interphase layers

Methodology Applied

Scientific EffectCathode-electrolyte interphase (CEI) formation:

Implementation Method 3

reducing electrolyte reactions

Methodology Applied

Scientific EffectElectrolyte decomposition resistance:

Implementation Method 4

preventing silicon anode expansion

Methodology Applied

Scientific EffectSilicon anode expansion prevention:

Implementation Method 5

enhancing thermal stability

Methodology Applied

Scientific EffectThermal stability enhancement:

Implementation Method 6

improving ionic conductivity

Methodology Applied

Scientific EffectIonic conduction: Conduction (electrical)

Data Source

PatentUS20200388885A1Silicon-based energy storage devices with lipo2f2 salt-containing electrolyte formulations

Publication Date: 2020.12.10 ENEVATE CORP

AI summary

Electrolytes and electrolyte additives for energy storage devices comprising lithium difluorophosphate (LiPO2F2) and an electrolyte additive are disclosed. The energy storage device comprises a first electrode and a second electrode, wherein 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, an electrolyte, a lithium-containing salt comprising LiPO2F2, and at least one electrolyte additive compound.