Mono[bidentate]borate Electrolyte for Lithium Battery Moisture Stability

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Solution Overview

Problem

Lithium batteries face issues with the volatility, flammability, and chemical reactivity of organic carbonate solvents, leading to low ionic conductivity and poor cycling performance in secondary batteries, while lithium bis-oxalato borate salts are unstable in the presence of moisture, causing internal resistance increases.

Innovation Solution

The use of a battery electrolyte with a mono[bidentate]borate salt, such as lithium dihalo oxalato borate, dissolved in siloxanes or silanes, which reduces viscosity and enhances ionic conductivity, improving wetting and homogeneity, and includes a poly(alkylene oxide) or cyclic carbonate moiety to increase ion concentration and conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If LiBOB is used to improve cycling performance, then cycling stability is improved, but moisture stability worsens causing internal resistance increase

Engineering Contradiction:

Improvecycling performanceVSAvoidmoisture stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent introduces drying agents (molecular sieves, sodium metal, or calcium hydride) as intermediary substances that remove moisture from the electrolyte system, preventing LiBOB decomposition and maintaining both cycling performance and moisture stability

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent employs inert atmosphere techniques during battery assembly and operation to prevent moisture ingress, creating a protected environment that maintains LiBOB stability and prevents internal resistance increase

Inventive Principle:

Principle #39Inert atmosphere (Inert environment)

2Reliability

If organic carbonate solvents are used, then ionic conductivity is improved, but volatility and flammability increase

Engineering Contradiction:

Improveionic conductivityVSAvoidvolatility and flammability

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent creates a composite electrolyte system combining polysiloxane solvents (for safety) with LiBOB salt and small amounts of organic carbonate additives (for ionic conductivity enhancement), achieving a balance between safety and conductivity

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

This configuration results in improved discharge capacity retention and cycling performance, with discharge capacity retention greater than 80% at 200 cycles, and ionic conductivity suitable for high-energy and long-cycle-life applications like electrical vehicles and biomedical devices.

Implementation Method 1

The electrolyte includes one or more mono[bidentate]borate salts in a solvent. The solvent includes a silane or a siloxane.

Methodology Applied

Scientific EffectDissolution: Solvation

Implementation Method 2

enhances ionic conductivity, improving wetting and homogeneity

Methodology Applied

Scientific EffectIonic conduction: Conduction (electrical)

Implementation Method 3

includes a poly(alkylene oxide) or cyclic carbonate moiety to increase ion concentration and conductivity

Methodology Applied

Scientific EffectSolvation: Solvation

Data Source

PatentUS7718321B2Battery having electrolyte including organoborate salt

Publication Date: 2010.05.18 QUALLION LLC

AI summary

The battery includes an electrolyte activating one or more cathodes and one or more anodes. The electrolyte includes one or more mono[bidentate]borate salts in a solvent. The solvent includes a silane or a siloxane. The mono[bidentate]borate salt can include a lithium dihalo mono[bidentate]borate such as lithium difluoro oxalatoborate (LiDfOB).