Silylborate Electrolyte for Rechargeable Lithium Battery

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Solution Overview

Problem

Rechargeable lithium batteries face challenges in achieving high power and storage characteristics with long cycle life due to limitations in electrolyte stability and ion conductivity, particularly at low temperatures and during high-temperature storage.

Innovation Solution

An electrolyte composition including a lithium salt, a silylborate-based compound, and an anhydride component in specific weight ratios, along with a non-aqueous organic solvent, which improves interface characteristics and reduces battery resistance while maintaining storage capabilities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If conventional electrolytes are used to achieve basic battery operation, then the battery can function, but the power characteristics and storage stability are insufficient

Engineering Contradiction:

Improvepower characteristicsVSAvoidstorage stability

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The electrolyte uses a composite system combining silylborate-based compounds with specific anhydride components (succinic anhydride, methyl succinic anhydride, or dimethyl succinic anhydride) in a non-aqueous organic solvent. This composite approach creates synergistic effects where the silylborate compound provides base electrolyte functionality while the anhydride component forms stable SEI films, achieving both high power characteristics through improved ion conductivity and excellent storage stability through enhanced interface protection.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The invention optimizes the weight ratio of silylborate-based compound to anhydride component within 0.1 to 15, with preferred ranges of 0.3 to 3 or 0.5 to 2. This parameter optimization balances the competing requirements: sufficient anhydride content to form protective SEI films for storage stability, while maintaining adequate silylborate compound for ion conductivity and power characteristics.

Inventive Principle:

Principle #35Parameter changes

2Power

If electrolyte composition is optimized for high power output, then power characteristics improve, but storage stability deteriorates

Engineering Contradiction:

Improvepower outputVSAvoidstorage stability

Core Design Contradiction:

PowerVSStability of the object's composition

Solution Approach 1:

The anhydride component acts as an intermediary substance that mediates between the electrolyte and electrode interfaces. It forms stable SEI films that protect the electrodes from degradation, enabling the electrolyte to maintain high ion conductivity for power output while the SEI layer provides the stability needed for long-term storage. The silylborate-based compound and anhydride component work together in specific ratios to achieve this balance.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Speed

If battery operates at low temperatures, then mobility is reduced, but using conventional electrolytes causes capacity fading

Engineering Contradiction:

Improvelithium ion mobilityVSAvoidcapacity retention

Core Design Contradiction:

SpeedVSStability of the object's composition

Solution Approach 1:

The electrolyte composition is specifically designed with silylborate-based compounds and anhydride components in optimized ratios that maintain low viscosity and high ion conductivity across a wide temperature range. The anhydride-formed SEI films remain stable at low temperatures, preventing capacity fading while allowing sufficient lithium ion mobility for battery operation in cold conditions.

Inventive Principle:

Principle #35Parameter changes

4Reliability

If battery undergoes prolonged high-temperature storage, then storage characteristics should be maintained, but conventional electrolytes cause resistance increase and capacity loss

Engineering Contradiction:

Improvestorage characteristicsVSAvoidresistance increase

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The anhydride component provides beforehand cushioning by forming stable protective SEI films on the electrodes before degradation can occur during high-temperature storage. These pre-formed protective layers prevent harmful reactions between the electrolyte and electrodes, cushioning against resistance increase and capacity loss that would otherwise occur during prolonged high-temperature storage.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 electrolyte composition enhances lithium ion mobility, reduces battery resistance, and maintains power output and storage characteristics, even at low temperatures and during prolonged high-temperature storage, without undesirable side reactions or capacity fading.

Implementation Method 1

improves interface characteristics and reduces battery resistance

Methodology Applied

Scientific EffectInterface formation:

Implementation Method 2

enhances lithium ion mobility

Methodology Applied

Scientific EffectIon mobility: Conduction (electrical)

Data Source

PatentUS8945776B2Electrolyte for rechargeable lithium battery and rechargeable lithium battery including the same

Publication Date: 2015.02.03 SAMSUNG SDI CO LTD

AI summary

An electrolyte for a rechargeable lithium battery and a rechargeable lithium battery including the same, the electrolyte including a lithium salt, a silylborate-based compound, an anhydride component, and a non-aqueous organic solvent.