Lithium Boron Fluorophosphate Additive for Battery Resistance

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Solution Overview

Problem

Current lithium secondary batteries face challenges in reducing battery resistance, which affects their performance and efficiency, particularly in non-aqueous electrolytic solutions used in lithium batteries.

Innovation Solution

A lithium boron fluorophosphate complex compound is developed, comprising specific lithium boron fluorophosphates and additional compounds like N-methylpyrrolidone, 1,3-dioxolane, and diethyl ether, which are incorporated into the non-aqueous electrolytic solution to reduce battery resistance and enhance discharge capacity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional electrolytes like LiBF3(PO2F2) are used, then the battery can operate, but the battery resistance remains high

Engineering Contradiction:

Improvebattery resistanceVSAvoiddischarge capacity

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent changes the chemical composition parameters of the electrolyte by introducing lithium boron fluorophosphate complex compounds with specific molecular structures (Formulae I-IV) containing B-F-P-O-Li moieties. This chemical parameter change reduces battery resistance while maintaining discharge capacity, resolving the contradiction between reliability and productivity.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite electrolyte system by combining lithium boron fluorophosphate complex compounds with conventional electrolyte components (LiPF6, cyclic carbonates, chain carbonates). This composite approach leverages the beneficial properties of both the novel complex compound (low resistance) and conventional electrolytes (high discharge capacity), simultaneously improving reliability and productivity.

Inventive Principle:

Principle #40Composite materials

2Duration of action of stationary object

If high-temperature storage is performed, then the battery can be stored, but the performance degrades

Engineering Contradiction:

Improvestorage stabilityVSAvoidperformance retention

Core Design Contradiction:

Duration of action of stationary objectVSReliability

Solution Approach 1:

The lithium boron fluorophosphate complex compound acts as a protective agent that preemptively stabilizes the electrolyte system against high-temperature degradation. The compound's unique molecular structure prevents harmful thermal reactions before they occur, cushioning the battery performance against storage-induced degradation and maintaining reliability after high-temperature storage.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If existing boron compounds are used in electrolytes, then the electrolyte can function, but battery resistance is not sufficiently reduced

Engineering Contradiction:

Improvebattery resistanceVSAvoidelectrolyte composition

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The lithium boron fluorophosphate complex compound serves multiple functions simultaneously: it acts as an electrolyte solute, a resistance-reducing agent, and a performance-stabilizing additive. This multi-functionality allows a single compound to address multiple electrolyte performance parameters, reducing battery resistance without requiring complex multi-component formulations, thus resolving the contradiction between reliability improvement and device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 lithium boron fluorophosphate complex compound effectively reduces battery resistance, maintains high discharge capacity, and retains performance even after high-temperature storage, outperforming existing solutions like LiBF3(PO2F2).

Implementation Method 1

a non-aqueous electrolytic solution for a battery, which can reduce battery resistance

Methodology Applied

Scientific EffectIonic conduction: Conduction (electrical)

Implementation Method 2

retains performance even after high-temperature storage

Methodology Applied

Scientific EffectThermal stability:

Data Source

PatentUS11597736B2Lithium boron fluorophosphate complex compound, lithium boron fluorophosphate-containing composition, lithium boron fluorophosphate, additive for lithium secondary battery, non-aqueous electrolytic solution for battery, and lithium secondary battery

Publication Date: 2023.03.07 MITSUI CHEMICALS INC

AI summary

A lithium boron fluorophosphate complex compound including a compound A that is one selected from a group of lithium boron fluorophosphates represented by Formula (I), and a compound B that is one selected from a group of compounds represented by Formulae (II) to (IX). R0 represents a hydrocarbon group, R1 to R7 each independently represent a hydrogen atom or a substituent, R8, R9, R10, R11, and R13 to R21 each independently represent a substituent, and R12, R22, and R23 each independently represent a divalent linking group.