Nitrile Additive for Lithium Battery Electrolyte
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Solution Overview
Problem
Lithium batteries experience irreversible side reactions with carbonate-based polar nonaqueous solvents during charging, leading to the formation of passivation layers with high resistance, which affects the battery's lifetime characteristics.
Innovation Solution
An organic electrolyte solution for lithium batteries is developed, incorporating a nitrile-based additive that forms more stable protection and solid electrolyte interface layers, reducing resistance and improving battery longevity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carbonate-based polar nonaqueous solvents are used in lithium batteries, then high ionic conductivity and high dielectric constant are achieved, but irreversible side reactions occur during charging causing high resistance passivation layers
Solution Approach 1:
A cyclic carboxylate compound is introduced as an intermediary additive in the electrolyte solution. This compound acts as a mediator that preferentially reacts with electrode surfaces to form stable protective layers (SEI on negative electrode and protection layer on positive electrode), preventing direct harmful reactions between the carbonate-based solvent and electrode materials. The cyclic carboxylate compound sacrifices itself to create a stable interface, reducing irreversible side reactions and lowering passivation layer resistance.
Solution Approach 2:
The invention changes the chemical composition parameters of the electrolyte solution by incorporating specific cyclic carboxylate compounds (such as cyclic carboxylic acid salts or esters) at controlled concentrations (0.1-10 wt%). This parameter change modifies the electrochemical behavior at electrode interfaces, leading to formation of more stable and conductive passivation layers compared to conventional electrolyte compositions.
2Reliability
If stable passivation layers are formed to prevent electrolyte decomposition, then battery reliability improves, but charge reversibility may be affected by layer resistance
Solution Approach 1:
The invention optimizes the chemical structure and concentration parameters of the cyclic carboxylate additive to achieve optimal passivation layer properties. By selecting specific cyclic carboxylate compounds and controlling their content (0.1-10 wt%), the passivation layers formed have both high stability (for reliability) and low resistance (for good charge reversibility), resolving the trade-off between protection and energy loss.
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 nitrile-based additive enhances the stability and durability of the protection and solid electrolyte interface layers, leading to improved charge reversibility and extended battery lifespan.
Implementation Method 1
an irreversible side reaction between the electrolyte solution and a positive or negative electrode may occur during an initial charging process
Implementation Method 2
a passivation layer such as a solid electrolyte interface (SEI) may be formed on a surface of the negative electrolyte
Data Source
Figure 1A~1B
Figure 1C~2A
Figure 2B~2C
AI summary
An additive for an electrolyte of a lithium battery, the additive being a nitrile-based compound represented by Formula 1 below, an organic electrolyte solution including the additive, and a lithium battery including the organic electrolyte solution are provided: In Formula 1, R is either an unsaturated functional group selected from an unsubstituted or substituted C2-20 alkenyl group, an unsubstituted or substituted C2-20 alkynyl group, an unsubstituted or substituted C6-C40 aryl group, and an unsubstituted or substituted C2-C40 heteroaryl group, or a polar functional group including a heteroatom; and X is a C2-20 alkylene group optionally substituted by one or more groups selected from an unsubstituted or substituted C2-20 alkyl group, an unsubstituted or substituted C3-12 cycloalkyl group, an unsubstituted or substituted C2-20 alkenyl group, an unsubstituted or substituted C2-20 alkynyl group, an unsubstituted or substituted C6-C40 aryl group, an unsubstituted or substituted C2-C40 heteroaryl group, and a polar functional group including a heteroatom.