Fluorinated Phosphite Electrolyte Additive for High-Temperature Li-Ion Cycling

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Solution Overview

Problem

Lithium-ion batteries face poor high-temperature cycle and storage performance due to the limitations of existing electrolytes, particularly with ternary positive electrode materials that are prone to phase changes and side reactions at high voltages.

Innovation Solution

An electrolyte additive with a fluorine-substituted phosphite structure is introduced, enhancing the electrochemical performance by improving oxidation resistance, chemical stability, and reducing gas production, which stabilizes the electrode interface and suppresses oxygen evolution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If traditional electrolytes are used with ternary positive electrode materials, then high specific capacity is achieved, but high-temperature cycle performance deteriorates

Engineering Contradiction:

Improvespecific capacityVSAvoidhigh-temperature cycle performance

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent introduces a fluorinated phosphite compound as an intermediary substance that mediates between the electrolyte and the ternary positive electrode material. This compound forms a protective interface layer that prevents direct harmful interactions while allowing ionic transport, thereby improving high-temperature cycle performance without sacrificing the high specific capacity of ternary materials.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies the chemical composition parameters of the electrolyte by incorporating fluorinated phosphite compounds with specific molecular structures (formula I). This parameter change in the electrolyte composition enables the formation of stable protective films on the electrode surface, resolving the contradiction between maintaining high capacity and improving thermal stability.

Inventive Principle:

Principle #35Parameter changes

2Power

If high voltage is applied to ternary material, then energy density is improved, but phase change occurs causing oxygen precipitation and side reactions

Engineering Contradiction:

Improveenergy densityVSAvoidelectrode material stability

Core Design Contradiction:

PowerVSStability of the object's composition

Solution Approach 1:

The fluorinated phosphite compound performs preliminary protective action by forming a stable surface film on the ternary positive electrode material before high-voltage operation begins. This pre-formed protective layer prevents oxygen precipitation and phase changes that would otherwise occur during high-voltage charging, enabling safe operation at higher voltages for improved energy density.

Inventive Principle:

Principle #9Preliminary anti-action

3Ease of operation

If existing electrolyte composition is used, then basic battery function is achieved, but high-temperature storage performance deteriorates

Engineering Contradiction:

Improvebasic battery functionVSAvoidhigh-temperature storage performance

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent creates a composite electrolyte system by combining traditional electrolyte components (lithium salts and carbonate solvents) with fluorinated phosphite compounds. This composite formulation maintains the basic battery functions provided by conventional electrolytes while adding the thermal stability and protective film-forming capabilities of the fluorinated phosphite, thereby improving high-temperature storage performance.

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 additive significantly improves the high-temperature cycle and storage performance of lithium-ion batteries by forming a stable passivation film, reducing impedance, and inhibiting metal ion dissolution, thereby maintaining battery capacity and preventing overcharging.

Implementation Method 1

forming a stable passivation film

Methodology Applied

Scientific EffectPassivation film formation: Deposition (physical)

Implementation Method 2

stabilizes the electrode interface

Methodology Applied

Scientific EffectAdsorption: Adsorption

Implementation Method 3

enhancing the electrochemical performance by improving oxidation resistance

Methodology Applied

Scientific EffectOxidation resistance: Oxidation

Implementation Method 4

improving oxidation resistance, chemical stability

Methodology Applied

Scientific EffectChemical stability:

Implementation Method 5

inhibiting metal ion dissolution

Methodology Applied

Scientific EffectInhibition of dissolution:

Data Source

PatentUS20240186575A1Additive for electrolyte of lithium-ion battery and electrolyte and lithium-ion secondary battery including same

Publication Date: 2024.06.06 MURATA MFG CO LTD

AI summary

An additive for an electrolyte of a lithium-ion battery and an electrolyte and a lithium-ion secondary battery including same are provided. The additive for an electrolyte of a lithium-ion battery has a structure of formula (1), wherein R1, R2, and R3 are each independently a saturated or unsaturated hydrocarbon group, a cyano group, an amide group, a pyridyl group, a thienyl group, or an aryl group having a carbon atom number of 5-15 and being substituted by at least one fluorine atom