Lithium-Ion Battery Electrolyte Additives for Safety and Low-Temperature Performance

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Solution Overview

Problem

Lithium-ion batteries face issues with overcharge safety, gas generation during charging and discharging, and poor low-temperature performance due to the decomposition of electrolytes, leading to potential explosions and reduced efficiency.

Innovation Solution

The use of additives such as 1,3-propane sultone, succinic anhydride, ethenyl sulfonyl benzene, halobenzene, biphenyl, cyclohexylbenzene, and vinylene carbonate in the electrolyte to suppress solvent decomposition, reduce gas generation, and enhance electrochemical properties, improving overcharge safety and low-temperature performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional aqueous electrolyte solutions are used, then chemical stability and ease of manufacture are improved, but maximum voltage is limited to about 2V due to water decomposition

Engineering Contradiction:
Improvechemical stabilityVSAvoidmaximum voltage
Core Design Contradiction:
ReliabilityVSPower

Solution Approach 1:

The patent changes the fundamental parameter of the electrolyte from aqueous to non-aqueous organic solvents. This parameter change allows the battery to operate at voltages above 2V (up to 3-4V) by eliminating water decomposition limitations, while maintaining chemical stability through careful selection of electrochemically stable organic solvents with wide electrical potential windows.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses composite electrolyte systems combining multiple organic solvents (high dielectric constant solvents, low-viscosity solvents, and electrochemically stable solvents) with lithium salts and additives. This composite approach achieves both high voltage operation and chemical stability that cannot be obtained with single components.

Inventive Principle:
Principle #40Composite materials

2Quantity of substance

If electrolyte decomposition occurs during charging and discharging, then gas is generated increasing battery thickness, but electrical conductivity rate remains low

Engineering Contradiction:
Improvegas generationVSAvoidelectrical conductivity rate
Core Design Contradiction:
Quantity of substanceVSReliability

Solution Approach 1:

The patent applies preliminary action by using additives that form protective films on electrode surfaces before significant electrolyte decomposition occurs. This preliminary film formation prevents subsequent gas-generating decomposition reactions while maintaining electrical conductivity through the stable interface.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent introduces additives as intermediary substances that mediate between the electrolyte and electrode surfaces. These intermediaries form stable interface layers that prevent direct electrolyte decomposition and gas generation, while still allowing efficient charge transfer to maintain electrical conductivity.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Object-affected harmful factors

If over-charging or short-circuiting occurs, then dangerous conditions such as explosion can occur due to solvent flammability and evaporation, but heat stability remains poor

Engineering Contradiction:
Improvesafety against overchargeVSAvoidheat stability
Core Design Contradiction:
Object-affected harmful factorsVSTemperature

Solution Approach 1:

The patent applies preliminary anti-action by using additives that preemptively form protective films on electrodes before dangerous conditions occur. These films prevent overcharge by blocking further lithium ion insertion, and prevent thermal runaway by creating thermal barriers, thus countering harmful effects before they manifest.

Inventive Principle:
Principle #9Preliminary anti-action

Solution Approach 2:

The patent converts the potential harm of electrolyte decomposition into a beneficial protective film formation process. The controlled decomposition of additives creates stable interface layers that prevent uncontrolled decomposition and dangerous conditions, transforming a harmful process into a protective mechanism.

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

4Reliability

If small amounts of additives are added to improve electrical conductivity and cycling efficiency, then production costs do not significantly increase, but performance is substantially improved

Engineering Contradiction:
Improveelectrical conductivity rateVSAvoidadditive concentration
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent applies local quality by concentrating additives at specific locations (electrode interfaces) where they are most needed. The additives form localized protective films and improve local electrical conductivity at the electrode-electrolyte interfaces, while requiring minimal overall quantities in the bulk electrolyte, thus not significantly increasing production costs.

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 additives effectively prevent overcharge-related issues, reduce battery thickness, and maintain high performance at both low and high temperatures, ensuring safety and efficiency by minimizing gas generation and enhancing electrochemical stability.

Implementation Method 1

The additives suppress the decomposition of solvents such as dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, ethyl methyl carbonate, butylene carbonate, and methyl ethylene carbonate

Methodology Applied
Scientific EffectDecomposition suppression:

Implementation Method 2

Most newer lithium-ion batteries use carbon material for their negative electrodes. They use materials that can embed and detach lithium

Methodology Applied
Scientific EffectIon embedding and detachment:

Implementation Method 3

The electrolyte is an important component of a battery, greatly affecting its properties

Methodology Applied
Scientific EffectElectrochemical reaction:

Data Source

PatentUS7833661B2Electrolytes for lithium ion secondary batteries
Publication Date: 2010.11.16 BYD CO LTD

AI summary

The present invention relates to additives for electrolytes of lithium ion secondary batteries that include one or more of the following: 1,3-propane sultone, succinic anhydride; ethenyl sulfonyl benzene, and halobenzene. It can also include biphenyl, cyclohexylbenzene; and vinylene carbonate. The weight of said 1,3-propane sultone is between 0.5 wt. % and 96.4 wt. %, said succinic anhydride is between 0.5 wt. % and 96.4 wt. %; said ethenyl sulfonyl benzene is between 0.5 wt. % and 95.2 wt. %; and said halobenzene is between 0.5 wt. % and 95.2 wt. % of the weight of the additive. Batteries with electrolytes containing said additives have improved over-charge characteristics and low temperature properties, and reduced gas generation during charging and discharging.