Li-Ion Battery Electrolyte Additives for PF5 and HF Suppression

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Solution Overview

Problem

Lithium-ion batteries face issues with thermal instability due to the formation of phosphorus pentafluoride (PF5) and hydrofluoric acid (HF), which degrade the positive electrode material and cause rapid capacity loss, and existing additives exacerbate gas generation and storage performance under high-temperature conditions.

Innovation Solution

An electrolyte composition including vinylene carbonate and a boron-containing compound, such as lithium tetrafluoroborate, is used to inhibit PF5 and HF formation, forming a stable solid electrolyte interface (SEI) film that enhances thermal and electrochemical performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If lithium salts with poor thermal stability are used, then the electrolyte can provide adequate ionic conductivity, but the lithium salts decompose under high-temperature conditions to form PF5 which reacts with impurities to form HF that corrodes the positive electrode material

Engineering Contradiction:

Improveionic conductivityVSAvoidelectrode corrosion and capacity loss

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a boron-containing compound as an intermediary substance that acts as a HF scavenger. This intermediary captures HF through chemical reaction, preventing it from corroding the positive electrode material, while the lithium salt continues to provide ionic conductivity.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent converts the harmful HF byproduct of lithium salt decomposition into a beneficial effect by using the boron-containing compound to capture HF and form stable complexes, thereby preventing electrode corrosion and capacity loss while maintaining the original lithium salt's ionic conductivity benefits.

Inventive Principle:

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

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 electrolyte reduces PF5 and HF content, preventing gas generation and electrode corrosion, thereby improving the lithium-ion battery's high- and low-temperature cycle performance and overall electrochemical stability.

Implementation Method 1

The nitrogen-including five-membered heterocycle in the compound exhibits Lewis basicity, enabling it to form a complex with PF5. As a result, the Lewis acidity and reactivity of PF5 are reduced

Methodology Applied

Scientific EffectLewis acid-base complexation: Lewis

Implementation Method 2

forming a stable solid electrolyte interface (SEI) film that enhances thermal and electrochemical performance

Methodology Applied

Scientific EffectSEI film formation:

Implementation Method 3

some lithium salts have poor thermal stability and are prone to decompose under high-temperature conditions to form phosphorus pentafluoride (PF5), which can further react with trace impurities in the electrolyte to form hydrofluoric acid (HF)

Methodology Applied

Scientific EffectThermal decomposition: Thermolysis

Data Source

PatentEP4712193A1Electrolyte and use thereof

Publication Date: 2026.03.18 GUANGZHOU TINCI MATERIALS TECH

AI summary

Provided in the present application are an electrolyte and the use thereof. The electrolyte comprises a first additive as shown in formula 1, vinylene carbonate and a boron-containing compound. Applying the electrolyte to a battery can not only reduce the content of PF5 and HF in the electrolyte, but can also improve the electrochemical performance of the lithium-ion battery.