Cyclic Sulfone Electrolyte Additive for High-Temperature SEI Stability

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Solution Overview

Problem

Lithium ion batteries face capacity degradation due to electrolyte decomposition and instability of additives, leading to poor high-temperature stability and cycle characteristics, with existing additives being chemically unstable and prone to gas generation during charge/discharge cycles.

Innovation Solution

A cyclic sulfone compound with a specific partial structure is used as an additive in non-aqueous electrolyte solutions, forming a stable solid electrolyte interface (SEI) that enhances cycle characteristics and suppresses gas generation, offering improved high-temperature stability and ion conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional additives (disulfonic acid esters, cyclic carboxylic acid esters) are used to form SEI, then initial charge/discharge performance is improved, but high-temperature stability deteriorates and gas generation occurs during long-term storage

Engineering Contradiction:

ImproveSEI formation capabilityVSAvoidhigh-temperature stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent changes the chemical structure parameters of the additive by introducing a specific cyclic structure with a carbonyl group adjacent to the SEI-forming functional group. This structural modification enables the additive to form a stable SEI film while resisting decomposition at high temperatures, thus resolving the contradiction between SEI formation capability and high-temperature stability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite effect by combining specific structural elements (cyclic structure, carbonyl group, and SEI-forming functional group) into a unified additive molecule. This composite structure synergistically provides both SEI formation capability and high-temperature stability, preventing the gas generation issues associated with conventional additives.

Inventive Principle:

Principle #40Composite materials

2Productivity

If existing additives are used to improve cycle characteristics, then initial charge/discharge capacity is enhanced, but capacity retention over long-term cycles deteriorates due to additive decomposition

Engineering Contradiction:

Improvecharge/discharge capacityVSAvoidcycle life

Core Design Contradiction:

ProductivityVSDuration of action of stationary object

Solution Approach 1:

The patent employs preliminary action by having the additive decompose during initial charge/discharge cycles to form a stable SEI film. This pre-formed SEI protects the electrode from subsequent electrolyte decomposition during long-term cycling, thus improving capacity retention while maintaining initial performance.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The additive acts as a sacrificial material that is consumed during initial cycles to create a protective SEI layer. This disposable approach allows the additive to perform its function of improving cycle life by forming a stable interface, while the bulk electrolyte and electrode remain protected for long-term operation.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Reliability

If additives with low LUMO energy are used to form stable SEI, then electron reception capability is improved, but chemical stability deteriorates due to moisture sensitivity

Engineering Contradiction:

Improveelectron reception capabilityVSAvoidmoisture sensitivity

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by positioning a carbonyl group adjacent to the SEI-forming functional group within the molecule. This localized structural feature enhances electron reception capability at the critical interface region while the overall molecular structure maintains resistance to moisture, thus resolving the contradiction between electron reception and chemical stability.

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 cyclic sulfone compound improves battery characteristics by forming a stable SEI, enhancing cycle performance, charge/discharge capacity, and reducing internal resistance, while maintaining stability over long-term use and storage.

Implementation Method 1

a compound which has a low lowest unoccupied molecular orbital (LUMO) energy level can be easily reduced by electrochemical reduction, and can form a stable SEI film on a surface of an electrode

Methodology Applied

Scientific EffectElectrochemical reduction: Redox Reactions

Data Source

PatentEP3349290B1Additive for nonaqueous electrolyte solutions, nonaqueous electrolyte solution, and electricity storage device

Publication Date: 2023.10.11 SUMITOMO SEIKA CHEM CO LTD

Figure 1

AI summary

Disclosed is an additive for non-aqueous electrolyte solutions, which include a compound represented by Formula (1). In Formula (1), X represents a sulfonyl group or a carbonyl group, R1 represents an alkyl group having 1 to 4 carbon atoms which may be substituted with a halogen atom, or the like, and R2 represents a divalent hydrocarbon group having 1 to 3 carbon atoms which may be substituted with a halogen atom, or represents a divalent group formed of a divalent hydrocarbon group having 1 to 3 carbon atoms which may be substituted with a halogen atom, and an oxygen atom that constitutes a cyclic structure together with the hydrocarbon group.