Lithium Battery Electrolyte Additive for High-Temperature Cathode Protection

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Solution Overview

Problem

Lithium secondary batteries face issues with reduced power and capacity due to surface damage of nickel-based lithium metal oxide cathodes, especially under high-temperature conditions, leading to increased internal resistance and shortened lifespan.

Innovation Solution

An electrolyte solution containing a specific additive represented by Chemical Formula 1, an organic solvent, and a lithium salt, which forms a robust solid electrolyte interphase (SEI) on the electrodes, enhancing high-temperature storage properties and overall battery performance by reducing gas generation and initial resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If a nickel-based lithium metal oxide is used as cathode active material to achieve high capacity, then the battery capacity increases, but surface damage occurs leading to reduced power and capacity

Engineering Contradiction:

Improvebattery capacityVSAvoidpower stability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

A coating layer comprising a nickel phosphate phase and a lithium phosphate phase is formed on the surface of the nickel-based lithium metal oxide particles. This coating layer acts as an intermediary between the cathode active material and the electrolyte, preventing direct harmful interactions while maintaining electrochemical performance. The dual-phase coating structure specifically addresses surface damage issues by providing both protective and conductive functions.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If the battery operates in high-temperature environment to meet application requirements, then the operational range expands, but gas generation accelerates causing battery expansion

Engineering Contradiction:

Improveoperational environment rangeVSAvoidgas generation

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The patent utilizes the high-temperature operating condition to advantage by forming a stable coating layer that becomes more effective at preventing side reactions as temperature increases. The nickel phosphate and lithium phosphate phases in the coating layer are specifically designed to remain stable and protective under high-temperature conditions, converting the potentially harmful thermal environment into a condition that enhances the protective function of the coating.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Productivity

If repeated charging and discharging is performed to achieve high cycling rate, then the charging speed increases, but side reactions between cathode and electrolyte increase

Engineering Contradiction:

Improvecharging rateVSAvoidside reactions

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The coating layer of nickel phosphate and lithium phosphate phases is pre-formed on the surface of the nickel-based lithium metal oxide particles before battery assembly. This preliminary protective layer prevents direct contact between the reactive cathode material and the electrolyte during subsequent charging and discharging cycles, eliminating side reactions while maintaining high charging rates.

Inventive Principle:

Principle #10Preliminary action

4Device complexity

If the cathode surface is exposed directly to electrolyte to maintain simplicity, then the device structure is simple, but internal resistance increases due to surface damage

Engineering Contradiction:

Improvestructure complexityVSAvoidinternal resistance

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent changes the surface composition parameters of the cathode active material by introducing a coating layer with specific phases (nickel phosphate and lithium phosphate). This parameter change at the surface level provides protective functionality without significantly altering the overall battery structure, maintaining simplicity while reducing internal resistance through prevented surface degradation.

Inventive Principle:

Principle #35Parameter changes

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 improves capacity retention, prevents battery thickness increase, and enhances rapid charge performance, while maintaining lithium ion mobility and cathode active material activity, resulting in improved high-temperature and room-temperature storage properties.

Implementation Method 1

An electrolyte solution including an additive represented by Chemical Formula 1 may form a robust solid electrolyte interphase (SEI) on an electrode surface

Methodology Applied

Scientific EffectSolid electrolyte interphase (SEI) formation:

Implementation Method 2

the lithium secondary battery may include an electrode assembly including a cathode, an anode and a separation layer (separator), and an electrolyte solution immersing the electrode assembly

Methodology Applied

Scientific EffectIon conduction: Conduction (electrical)

Data Source

PatentUS20230395856A1Electrolyte solution for lithium secondary battery and lithium secondary battery including the same

Publication Date: 2023.12.07 SK INNOVATION CO LTD

AI summary

According to the present disclosures, an electrolyte solution for a lithium secondary battery and a lithium secondary battery including the electrolyte solution are provided. The electrolyte solution includes an additive represented by a specific chemical formula, an organic solvent and a lithium salt. The lithium secondary battery including the electrolyte solution provide enhanced high-temperature properties.