Non-aqueous Electrolyte Solution for Silicon Battery Cycle Stability

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Lithium secondary batteries face reduced capacity and inadequate cycle characteristics due to high reactivity between LiPF6 electrolyte salt and silicon, leading to irreversible SEI coating film formation and capacity loss.

Innovation Solution

A non-aqueous electrolyte solution containing an imide salt, such as lithium bis(trifluoromethanesulfonyl) imide, and lithium oxalate borate, combined with halogenated carbonic acid esters like 4-fluoro-1,3-dioxolan-2-one, which improves cycle characteristics and battery performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If LiPF6 is used as electrolyte salt with silicon-containing negative electrode material, then initial capacity can be achieved, but cycle characteristics deteriorate due to thick SEI coating film formation and irreversible Li absorption

Engineering Contradiction:

Improvebattery capacityVSAvoidcycle characteristics

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent changes the chemical composition parameters of the electrolyte salt from conventional LiPF6 to imide salts (LiFSO3, LiTFSO3, LiBF3SO3) combined with specific lithium salts (LiClO4, LiPF6, LiBF4). This parameter change in electrolyte composition prevents the formation of thick SEI coating films on silicon-containing negative electrodes, thereby improving cycle characteristics while maintaining battery capacity

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs a composite electrolyte salt system combining imide salts with specific lithium salts in defined ratios (imide salt 5-50 wt%, LiClO4 10-40 wt%, LiPF6 10-40 wt%, LiBF4 10-40 wt%). This composite material approach creates a synergistic effect that stabilizes the SEI coating film on silicon-containing electrodes, resolving the contradiction between initial capacity and cycle characteristics

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If conventional electrolyte salts are used with silicon-containing negative electrode material, then battery assembly is straightforward, but capacity retention deteriorates due to irreversible Li absorption in SEI coating film

Engineering Contradiction:

Improvebattery assemblyVSAvoidcapacity retention

Core Design Contradiction:

Ease of manufactureVSQuantity of substance

Solution Approach 1:

The patent modifies the electrolyte salt composition parameters by introducing imide salts (lithium fluorosulfonate, lithium trifluoromethanesulfonate, lithium pentafluoroethanesulfonate) in combination with specific ratios of LiClO4, LiPF6, and LiBF4. This parameter change prevents excessive SEI coating film formation on silicon-containing electrodes, thereby improving capacity retention while maintaining ease of battery assembly through standard manufacturing processes

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 enhances battery capacity retention and cycle stability by forming a stable protective film on the electrode surfaces, reducing decomposition reactions and maintaining capacity over repeated charging and discharging.

Implementation Method 1

the reactivity between LiPF6 used as an electrolyte salt and silicon is high, they are easily reacted to form a thick SEI coating film on the surface

Methodology Applied

Scientific EffectSEI coating film formation: Chemical Bonding

Implementation Method 2

the electrolyte salt contains an imide salt as a main electrolyte salt... and at least one lithium oxalate borate selected from the group consisting of lithium bis(oxalate) borate (LiBOB), lithium fluoro(oxalate) borate (LiFOB), and lithium difluoro(oxalate) borate (LiDFOB)

Methodology Applied

Scientific EffectElectrochemical reaction: Redox Reactions

Implementation Method 3

since the reactivity between LiPF6 used as an electrolyte salt and silicon is high, they are easily reacted to form a thick SEI coating film on the surface

Methodology Applied

Scientific EffectReactivity reduction: Chemical Bonding

Implementation Method 4

A non-aqueous electrolyte solution according to an embodiment of the present technology includes an electrolyte salt; and a non-aqueous solvent

Methodology Applied

Scientific EffectIonic conduction: Conduction (electrical)

Data Source

PatentUS11050089B2Non-aqueous electrolyte solution, non-aqueous electrolyte secondary battery using non-aqueous electrolyte solution, battery pack using non-aqueous electrolyte secondary battery, and electronic apparatus

Publication Date: 2021.06.29 MURATA MFG CO LTD

AI summary

To provide a non-aqueous electrolyte solution capable of improving cycle characteristics of a secondary battery, and a non-aqueous electrolyte secondary battery using the non-aqueous electrolyte solution.A non-aqueous electrolyte solution according to an embodiment of the present technology includes an electrolyte salt and a non-aqueous solvent. The electrolyte salt contains an imide salt as a main electrolyte salt and at least one lithium oxalate borate selected from the group consisting of lithium bis(oxalate) borate (LiBOB), lithium fluoro(oxalate) borate (LiFOB), and lithium difluoro(oxalate) borate (LiDFOB). The non-aqueous solvent contains at least one halogenated carbonic acid ester selected from the group consisting of a halogenated chain carbonic acid ester and a halogenated cyclic carbonic acid ester.