Cathode Active Material Coating for High-Voltage Battery Stability
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Solution Overview
Problem
Current lithium ion secondary batteries face issues with capacity deterioration, gas generation, and thermal stability, particularly when used at high charge voltages and temperatures, limiting their cycle life and energy density.
Innovation Solution
A cathode active material is developed with a particle structure that includes a film containing a metal salt represented by a specific formula, which enhances chemical stability and prevents gas generation, allowing for higher charge voltage and energy density while maintaining excellent charge-discharge cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If charge voltage is raised to increase energy density, then battery capacity is improved, but capacity deterioration accelerates and cycle life is shortened
Solution Approach 1:
A coating layer comprising metal oxide and amorphous carbon is applied to the cathode active material surface. The metal oxide provides structural stability and chemical inertness, while the amorphous carbon layer serves as an intermediary that prevents direct contact between the electrolyte and cathode surface, thereby reducing side reactions and capacity deterioration during high-voltage charging cycles
Solution Approach 2:
The coating layer is formed as a composite structure combining metal oxide and amorphous carbon. This composite material leverages the structural stability and chemical resistance of metal oxide along with the electrochemical stability and conductivity of amorphous carbon, achieving both high energy density and improved cycle life at elevated charge voltages
2Use of energy by moving object
If charge voltage is increased to enhance capacity, then energy density is improved, but gas generation increases causing leakage and deformation
Solution Approach 1:
The amorphous carbon layer in the coating acts as a protective intermediary barrier between the electrolyte and the cathode active material. This barrier prevents direct electrochemical reactions that would otherwise generate gas at high charge voltages, thereby suppressing gas generation, leakage, and battery deformation while maintaining high energy density
Solution Approach 2:
The coating layer transforms the potentially harmful high-voltage environment into a beneficial condition by using the metal oxide and carbon materials to stabilize the cathode surface. This stabilization converts the high-voltage stress that would normally cause gas generation into an opportunity to demonstrate the coating's protective function, eliminating gas generation issues while preserving high energy density benefits
3Use of energy by moving object
If charge voltage is raised to improve energy density, then battery capacity is increased, but thermal stability deteriorates
Solution Approach 1:
The coating layer comprising metal oxide and amorphous carbon serves as a thermal barrier and chemical buffer between the cathode active material and the electrolyte. This intermediary structure suppresses thermal runaway reactions and maintains compositional stability even when the battery operates at high charge voltages that would normally compromise thermal stability
Solution Approach 2:
The composite coating structure combines the high melting point and chemical stability of metal oxide with the thermal resistance and structural integrity of amorphous carbon. This composite material configuration maintains thermal stability while enabling the cathode to operate at higher charge voltages for improved energy density
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 results in a battery with improved capacity retention, reduced gas generation, and enhanced thermal stability, enabling higher energy density and longer cycle life even at high charge voltages, making it suitable for advanced portable electronic devices.
Implementation Method 1
a film that is disposed at least partially to the particle and contains a metal salt represented by a formula (1)
Data Source
AI summary
The invention provides a cathode active material that includes: a particle containing a cathode material capable of absorbing and releasing an electrode reactive material; and a film that is disposed at least partially to the particle and contains a metal salt represented by a formula (1).(R1 represents a (a1+b1+c1) valent group and M1 represents a metallic element. a1, d1, e1 and n each represent an integer of 1 or more and b1 and c1 each represent an integer of 0 or more. However, b1 and c1 satisfy (b1+c1)≧1.), a cathode therewith and a non-aqueous electrolyte secondary battery.