Unsaturated Organoboron Electrolyte for High Voltage Lithium-Ion Batteries

Solution Overview

Problem

High voltage lithium-ion batteries face challenges in maintaining stable solid electrolyte interface (SEI) passivation layers, leading to electrolyte oxidation and transition metal oxide dissolution, which affects their energy density and cycling performance.

Innovation Solution

An electrolyte composition comprising LiPF6 in a liquid carrier with unsaturated organoboron compounds, such as trivinylboroxine, is used, which polymerizes to form a stable, cross-linked polymer at the electrode surface, enhancing SEI formation and reducing impedance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If high voltage cycling is used to achieve high energy density, then cell energy increases, but electrolyte oxidation and transition metal oxide dissolution increase

Engineering Contradiction:

Improvecell energyVSAvoidelectrolyte stability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The unsaturated organoboron compound performs preliminary action by polymerizing in advance to form a stable SEI passivation layer on the cathode surface before electrolyte oxidation and metal dissolution can occur. This pre-formed protective layer prevents subsequent degradation reactions during high voltage cycling.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The unsaturated organoboron compound acts as an intermediary substance that mediates between the high voltage cathode and the electrolyte. It forms a cross-linked polymer interface layer that allows ionic transport while blocking harmful reactions between the electrolyte and cathode materials.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Use of energy by moving object

If high voltage cycling is used to achieve high energy density, then cell energy increases, but transition metal oxide dissolution increases

Engineering Contradiction:

Improvecell energyVSAvoidcathode material dissolution

Core Design Contradiction:

Use of energy by moving objectVSLoss of substance

Solution Approach 1:

The unsaturated organoboron compound performs preliminary action by polymerizing in advance to form a stable SEI passivation layer on the cathode surface before electrolyte oxidation and metal dissolution can occur. This pre-formed protective layer prevents subsequent degradation reactions during high voltage cycling.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The unsaturated organoboron compound acts as an intermediary substance that mediates between the high voltage cathode and the electrolyte. It forms a cross-linked polymer interface layer that allows ionic transport while blocking harmful reactions between the electrolyte and cathode materials.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of manufacture

If conventional electrolyte compositions are used in high voltage batteries, then manufacturing simplicity is maintained, but cycling performance deteriorates

Engineering Contradiction:

Improveelectrolyte formulation simplicityVSAvoidcycling performance

Core Design Contradiction:

Ease of manufactureVSDuration of action of moving object

Solution Approach 1:

The invention changes the chemical parameter of the electrolyte by introducing unsaturated organoboron compounds with specific functional groups (vinyl, allyl, propargyl) that can polymerize. This parameter change enables the formation of stable cross-linked SEI layers while maintaining conventional electrolyte formulation simplicity.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The electrolyte composition creates a composite system by combining conventional carbonate esters and LiPF6 with unsaturated organoboron compounds. This composite approach allows the organic component to polymerize and form a stable protective layer, improving cycling performance while maintaining ease of manufacture.

Inventive Principle:

Principle #40Composite materials

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 composition significantly improves long-term cell cycling performance by reducing capacity fade and full cell impedance, with up to 4 times less capacity fade and 4-fold reduction in impedance after long-term cycling.

Implementation Method 1

which polymerizes to form a stable, cross-linked polymer at the electrode surface

Methodology Applied

Scientific EffectPolymerization:

Implementation Method 2

Stable solid electrolyte interface (SEI) passivation layers at the positive and negative electrodes can ameliorate some of these undesirable effects

Methodology Applied

Scientific EffectSEI passivation:

Data Source

PatentUS10122046B2Electrolyte compositions for high voltage lithium-ion batteries

Publication Date: 2018.11.06 UCHICAGO ARGONNE LLC

AI summary

The present invention provides an electrolyte composition for a lithium-ion battery comprising LiPF6 in a liquid carrier comprising a carbonate ester and an unsaturated organoboron compound comprising two or three unsaturated hydrocarbon groups, each unsaturated hydrocarbon group being covalently bonded to a boron atom. The unsaturated hydrocarbon groups are independently selected from vinyl, allyl, propargyl, substituted vinyl, substituted allyl, and substituted propargyl. The substituents of the substituted vinyl, allyl and propargyl groups independently comprise one or more of alkyl and phenyl. The alkyl and phenyl groups optionally can bear one or more substituent selected from halogen (e.g., F), hydroxy, amino, alkoxy, and perfluoroalkoxy.