Lithium Battery Positive Electrode Additive for High-Temperature Stability
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Solution Overview
Problem
Lithium rechargeable batteries face challenges in maintaining high-temperature storage characteristics due to electrolyte decomposition and metal ion separation at the positive electrode surface, leading to decreased open-circuit voltage and cycle performance.
Innovation Solution
Incorporating a bifunctional positive electrode additive with —CN and C═O groups, such as acetyl cyanide or 3-(1,2,3,4-tetrahydronaphthalen-6-yl)-3-oxopropanenitrile, which helps prevent electrolyte decomposition and reduces metal ion separation, thereby enhancing high-temperature storage characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional positive electrode materials are used, then the battery can operate at high voltage, but electrolyte decomposition and metal ion separation occur at the positive electrode surface during high-temperature storage, leading to decreased open-circuit voltage and cycle performance
Solution Approach 1:
The patent introduces a positive electrode additive containing carbonyl and cyano groups as an intermediary substance between the positive electrode active material and the electrolyte. This additive preferentially reacts with the positive electrode surface to form a protective interface layer, preventing direct contact and harmful reactions between the electrolyte and metal ions (particularly Mn2+) at high temperatures, thus maintaining open-circuit voltage stability during high-temperature storage
Solution Approach 2:
The additive performs preliminary protective action by reacting with the positive electrode surface before harmful electrolyte decomposition and metal ion separation can occur. The carbonyl and cyano groups in the additive bind to metal ion sites on the positive electrode surface, creating a protective barrier that prevents subsequent high-temperature degradation reactions, thereby preserving voltage stability
2Temperature
If the positive electrode additive with carbonyl and cyano groups is added, then high-temperature storage characteristics are improved, but the device complexity increases due to additional components
Solution Approach 1:
The patent optimizes the concentration parameter of the positive electrode additive, specifying it should be present at 0.01 to 5.0 wt% based on the total weight of positive electrode materials. This parameter optimization ensures sufficient protective effect at the positive electrode surface while minimizing the amount of additional substance required, thus improving high-temperature storage performance without excessively increasing device complexity
Solution Approach 2:
The positive electrode additive serves multiple functions simultaneously: it acts as a surface modifier, electrolyte decomposition inhibitor, and metal ion separation preventant. The carbonyl and cyano groups provide dual functionality by both binding to metal ions and forming protective interface layers, reducing the need for multiple separate additives and thereby limiting the increase in device complexity
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 additive effectively suppresses electrolyte decomposition and metal ion separation, maintaining a stable open-circuit voltage and improving high-temperature storage performance by bonding strongly to the positive electrode surface.
Implementation Method 1
the positive electrode additive... bonding strongly to the positive electrode surface
Implementation Method 2
the positive electrode additive... bonding strongly to the positive electrode surface
Data Source
AI summary
A positive electrode for a lithium rechargeable battery, the positive electrode including a positive electrode active material; a binder; and a positive electrode additive represented by the following Formula 1:wherein R is a substituted or unsubstituted C1 to C10 alkyl group or a substituted or unsubstituted C5 to C30 aryl group and n is 0 or 1.