High-Voltage Li-Ion Electrolyte Additive for Thermal Runaway Suppression
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Solution Overview
Problem
Lithium ion secondary batteries face safety concerns due to increased risk of thermal runaway when charged to high voltages, particularly in abnormal conditions like internal short circuits, which compromises their reliability and safety for applications in electric vehicles and energy storage systems.
Innovation Solution
Incorporating a nonaqueous electrolyte solution with a specific additive having an aromatic ring structure, which enhances safety against short circuits by improving the battery's performance and reducing the risk of thermal runaway when charged to voltages between 4.35 to 5 V.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the charging voltage is increased to improve energy density and battery performance, then the battery capacity and output are improved, but the safety of the battery deteriorates due to increased risk of thermal runaway
Solution Approach 1:
A diamine compound (1,2-phenylenediamine or 1,4-phenylenediamine) is introduced as an intermediary substance in the electrolyte solution. This additive acts as a mediator that suppresses the harmful reaction between the lithium ion secondary battery components and the electrolyte, thereby preventing thermal runaway while allowing high-voltage charging (4.35-5V) to proceed safely.
Solution Approach 2:
The invention changes the chemical composition parameters of the electrolyte solution by adding specific diamine compounds at concentrations of 0.01-10% by weight. This parameter change modifies the chemical behavior of the electrolyte, enabling it to resist thermal runaway reactions even at elevated charging voltages up to 5V.
2Reliability
If phosphorus-based materials or ionic liquids are added to the electrolyte solution to improve safety and flame resistance, then the safety is improved, but the battery performance deteriorates due to low ionic conductivity
Solution Approach 1:
Instead of using phosphorus-based materials or ionic liquids that compromise ionic conductivity, the invention changes the chemical parameter by introducing diamine compounds (1,2-phenylenediamine or 1,4-phenylenediamine). These compounds provide flame resistance and thermal runaway suppression without significantly affecting the ionic conductivity of the electrolyte solution, thus maintaining battery performance.
3Reliability
If large amounts of phosphorus-based material or ionic liquid are added to make the electrolyte flame-retardant, then the safety is improved, but the cost increases and battery performance worsens
Solution Approach 1:
The invention optimizes the concentration parameter of the diamine compound additive to 0.01-10% by weight in the electrolyte solution. This optimized parameter range achieves effective flame resistance and thermal runaway suppression at much lower concentrations compared to phosphorus-based materials or ionic liquids, thereby reducing material costs and avoiding performance degradation.
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 use of this additive in the nonaqueous electrolyte solution significantly improves the safety of lithium ion secondary batteries, preventing excessive temperature increases and smoke emission during short-circuit tests, ensuring safer operation for high-voltage charging.
Implementation Method 1
the nonaqueous electrolyte solution containing a diamine compound as an additive... improves the safety against short circuits... preventing excessive temperature increases and smoke emission during short-circuit tests
Data Source
AI summary
The present invention provides a lithium ion secondary battery which is provided with: a nonaqueous electrolyte solution; and a positive electrode and a negative electrode, each of which is capable of absorbing and desorbing lithium. This lithium ion secondary battery is configured such that the nonaqueous electrolyte solution contains (A) an electrolyte, (B) a nonaqueous organic solvent and (C) a compound that is obtained by substituting at least one hydrogen atom, which is bonded to a carbon atom in an aromatic ring of a compound that has at least one aromatic ring and no amino group, by a group that is represented by formula (1); and this lithium ion secondary battery is charged at a voltage within the range of 4.35-5 V for use.(In the formula, R represents a hydrogen atom, an optionally substituted monovalent aliphatic hydrocarbon group having 1-60 carbon atoms, an optionally substituted monovalent aromatic hydrocarbon group having 6-60 carbon atoms, or an optionally substituted monovalent heterocyclic ring-containing group having 2-60 carbon atoms; and the broken line represents a bonding hand).