Fluoride-Coated Cathode Material for High-Voltage Cycle Stability
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries, such as lithium-ion batteries, experience performance deterioration due to side reactions between the cathode active material and the non-aqueous electrolyte, leading to reduced battery capacity and cycle retention.
Innovation Solution
A coated cathode active material is developed with a coating layer containing LiAlF4, LiF, and Li3AlF6, which is applied to the surface of the cathode active material particles to enhance stability and reduce side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a high operating voltage of 4.5V is used in a lithium-ion secondary battery, then the power and energy density are improved, but side reactions occur between the cathode active material and non-aqueous electrolyte, causing deterioration in battery performance such as reduced capacity and cycle retention
Solution Approach 1:
A coating layer comprising LiAlF4, LiF, and Li3AlF6 is applied to the surface of the cathode active material particles. This coating layer acts as an intermediary between the cathode active material and the non-aqueous electrolyte, preventing direct contact and side reactions while allowing lithium ion transport, thereby maintaining high voltage performance without capacity deterioration
Solution Approach 2:
The coating layer is formed as a composite structure containing multiple compounds (LiAlF4, LiF, and Li3AlF6) with complementary properties. This composite coating provides enhanced chemical stability and electrochemical performance compared to single-compound coatings, effectively suppressing side reactions at the high operating voltage of 4.5V
2Duration of action of stationary object
If the cathode active material is coated with a protective layer to prevent side reactions, then the capacity retention and cycle life are improved, but the manufacturing process complexity increases
Solution Approach 1:
The coating layer is formed on the cathode active material particles before electrode assembly, preparing the surface in advance to prevent side reactions during battery operation. This preliminary coating action ensures long cycle life from the first charge-discharge cycle without requiring complex post-processing
Solution Approach 2:
The coating process utilizes controlled temperature parameters (heat treatment at 300-500°C) to form the protective layer. By optimizing the temperature parameter, the coating is formed effectively without requiring additional complex equipment or multi-step processes, balancing protection performance with manufacturing simplicity
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 coated cathode active material improves battery capacity and capacity retention, with improved cycle characteristics and high-voltage performance.
Implementation Method 1
a coating layer on a surface of the cathode active material particle, wherein the coating layer includes LiAlF4, LiF, and Li3AlF6
Implementation Method 2
heat-treating the precursor, to prepare the coated cathode active material described herein. The heat treatment may include heat-treating at about 300° C. to about 500° C.
Data Source
AI summary
A coated cathode active material, a method of preparing the same, and a cathode and a non-aqueous electrolyte secondary battery, each including the same, the coated cathode active material including: a cathode active material particle and a coating layer on a surface of the cathode active material particle, the coating layer including LiAlF4, LiF, and Li3AlF6.