Aliphatic Nitrile Cathode Protection Layer for High-Temperature Stability
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries face capacity reduction and safety issues due to structural breakdown, increased interfacial resistance, and exothermic reactions, particularly at high temperatures, leading to potential fires or explosions.
Innovation Solution
A cathode with a protection layer formed by complexation between the cathode active material and an aliphatic nitrile compound, combined with an anode passivation layer from vinylene carbonate or its derivatives, effectively stabilizes electrodes and controls exothermic reactions, enhancing cycle life and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a non-aqueous electrolyte secondary battery uses a cathode active material capable of absorbing and releasing lithium ions, then high capacity and high energy density are achieved, but the cathode structural breakdown and interfacial resistance increase occur particularly at high temperatures
Solution Approach 1:
The patent applies preliminary action by forming a protective coating layer on the cathode active material surface before battery operation. This coating, formed through pre-treatment with specific compounds, prevents cathode structural breakdown and transition metal dissolution during subsequent high-temperature charging cycles, thereby maintaining both high energy density and structural reliability
Solution Approach 2:
The patent uses an intermediary substance (protective coating formed from specific organic compounds) that mediates between the cathode active material and the electrolyte. This intermediary layer prevents direct harmful interactions while allowing lithium ion transport, thus maintaining high capacity while preventing structural degradation and metal dissolution at elevated temperatures
2Speed
If the battery operates at high temperature, then charging speed and reaction efficiency are improved, but exothermic reactions and thermal runaway risk increase
Solution Approach 1:
The patent converts the harmful exothermic reactions into a beneficial protective mechanism. The protective coating on the cathode prevents direct contact between the electrolyte and cathode materials, thereby preventing uncontrolled exothermic reactions while allowing controlled electrochemical reactions to proceed at high temperatures for fast charging
3Reliability
If the SEI layer on the anode becomes thicker to protect against degradation, then anode stability improves, but lithium ion migration is prevented
Solution Approach 1:
The patent applies parameter changes by modifying the composition and structure of the protective layers on both electrodes. The anode protective layer is designed with specific properties (porosity, thickness, composition) that allow lithium ion transport while providing stability, thus achieving both anode reliability and ion transport efficiency through optimized material parameters
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 significantly improves high-temperature cycle life and safety by preventing structural breakdown and exothermic heat generation, reducing the risk of battery fires and explosions, while maintaining performance and efficiency.
Implementation Method 1
a cathode having a protection layer formed by a complex between a surface of a cathode active material and an aliphatic nitrile compound
Implementation Method 2
control exothermic heat generated from a reaction between the electrolyte solution and the cathode and exothermic heat generated from structural breakdown of the cathode
Implementation Method 3
an anode having a passivation layer formed by a compound selected from the group consisting of vinylene carbonate, its derivative and an ether compound
Data Source
AI summary
The present invention provides a cathode having a protection layer formed by a complex between the surface of a cathode active material and an aliphatic nitrile compound, as well as an electrochemical device comprising the cathode. Also, the present invention provides an electrochemical device comprising: (1) a cathode having a protection layer formed by a complex between the surface of a cathode active material and an aliphatic nitrile compound; (2) an anode having a passivation layer formed by a compound selected from the group consisting of vinylene carbonate, its derivative and an ether compound; and (3) an electrolyte solution containing a lithium salt and a solvent.