Lithium Borate Electrolyte Films for Lower Battery Internal Resistance

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Solution Overview

Problem

Lithium secondary batteries face challenges in reducing internal resistance, which affects their performance and storage stability over time.

Innovation Solution

A non-aqueous electrolyte solution containing a lithium salt with fluorine and a specific lithium borate compound, represented by Formula (I), is used, along with a lithium-containing composite oxide as the positive electrode active material, to form films on the electrodes, reducing internal resistance through chemical reactions during the aging process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional electrolytes are used in lithium secondary batteries, then the batteries can operate with basic performance, but the internal resistance increases over time and storage stability deteriorates

Engineering Contradiction:
Improvestorage stabilityVSAvoidinternal resistance
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the chemical composition parameters of the electrolyte by introducing a lithium borate compound with specific molecular structure (Formula I) where R represents a single bond or alkylene group with 1-4 carbon atoms. This compositional parameter change results in reduced internal resistance and improved storage stability without sacrificing basic battery operation

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite electrolyte system by combining the lithium borate compound (Formula I) with conventional electrolyte components including lithium salts and non-aqueous solvents. This composite approach leverages the beneficial properties of the lithium borate compound while maintaining the functional characteristics of conventional electrolytes, achieving both reduced internal resistance and improved storage stability

Inventive Principle:
Principle #40Composite materials

2Reliability

If the internal resistance is reduced through electrolyte modification, then storage stability improves, but the complexity of electrolyte composition increases

Engineering Contradiction:
Improvestorage stabilityVSAvoidelectrolyte composition
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies local quality by introducing the lithium borate compound specifically at the electrode-electrolyte interface where it forms protective films. The compound's molecular structure (Formula I) is designed to interact locally with electrode surfaces, providing targeted improvement in storage stability and internal resistance without requiring complete redesign of the entire electrolyte system

Inventive Principle:
Principle #3Local quality

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 solution effectively reduces the internal resistance of lithium secondary batteries, particularly the positive electrode resistance, and stabilizes the electrodes, leading to improved storage stability and performance over extended periods.

Implementation Method 1

a negative electrode film containing an organic component and an inorganic component, derived from a lithium borate compound represented by Formula (I) and the electrolyte, is formed on at least a portion of a surface of the negative electrode, and a positive electrode film containing an inorganic component, derived from a lithium borate compound represented by Formula (I) and the electrolyte, is formed on at least a portion of a surface of the positive electrode

Methodology Applied
Scientific EffectChemical reaction: Chemical Bonding

Data Source

PatentEP3828188B1Lithium borate compound, additive for lithium secondary cell, nonaqueous liquid electrolyte for lithium secondary cell, lithium secondary cell precursor, and lithium secondary cell and method for manufacturing same
Publication Date: 2024.11.13 MITSUI CHEMICALS INC
  • EP3828188B1 patent drawingFigure 1
  • EP3828188B1 patent drawingFigure 2
  • EP3828188B1 patent drawingFigure 3

AI summary

The present disclosure provides a lithium borate compound represented by the following Formula (I), an additive for a lithium secondary battery, which contains the lithium borate compound, a non-aqueous electrolyte solution for a lithium secondary battery, a lithium secondary battery precursor, and a lithium secondary battery and method of producing the same. In Formula (I), R represents a single bond or an alkylene group having from 1 to 4 carbon atoms.