Amorphous Glass Coated Lithium Composite Cathode for Humidity Stability
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Solution Overview
Problem
Lithium secondary batteries face rapid degradation due to humidity, leading to increased internal resistance and reduced lifespan, particularly affecting positive electrode materials, as existing surface treatment methods like aluminum and boron-based coatings are ineffective in maintaining stability and uniformity.
Innovation Solution
A positive electrode active material is developed with a core comprising lithium composite metal oxide and a surface treatment layer made of amorphous glass containing alkali metal oxide and alkaline earth metal oxide, which is heat-treated at 500°C or less to reduce humidity reactivity and enhance thermal and chemical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aluminum-based surface treatment layer is applied on positive electrode active material, then stability at high voltage is improved, but uniform coating is difficult and defects of increasing resistance occur
Solution Approach 1:
The patent changes the material parameters from crystalline aluminum-based compounds to amorphous glass compositions containing specific metal oxides (Al2O3, SiO2, B2O3, P2O5) in controlled ratios. This parameter change enables uniform coating while maintaining high voltage stability, as the amorphous structure avoids crystalline defects that cause resistance increases.
Solution Approach 2:
The patent uses composite glass materials combining multiple metal oxides (Al2O3, SiO2, B2O3, P2O5) in specific proportions. This composite approach creates a surface treatment layer that achieves both uniform coating and high voltage stability, overcoming the limitations of single-component aluminum-based coatings.
2Manufacturing precision
If boron-based coating material is used, then uniform amorphous coating is attained, but lithium ion transfer is not inhibited and reaction with humidity increases over time
Solution Approach 1:
The patent combines boron-based glass (B2O3) with aluminum oxide (Al2O3), silicon oxide (SiO2), and phosphorus pentoxide (P2O5) in specific ratios. This composite glass material maintains the uniform amorphous coating advantage of boron-based materials while adding components that inhibit humidity reaction, thereby improving long-term stability.
Solution Approach 2:
The patent modifies the glass composition parameters by controlling the ratios of B2O3 (20-80 wt%), Al2O3 (10-60 wt%), SiO2 (5-30 wt%), and P2O5 (1-20 wt%). This parameter optimization achieves both uniform coating and resistance to humidity-induced degradation.
3Use of energy by moving object
If positive electrode active material is used for high voltage operation, then energy density is improved, but degeneration due to humidity increases and battery life is reduced
Solution Approach 1:
The patent introduces a glass-based surface treatment layer as an intermediary between the positive electrode active material and the electrolyte environment. This intermediate layer protects the active material from humidity-induced degradation while allowing high voltage operation, thereby extending battery life without sacrificing energy density.
Solution Approach 2:
The patent modifies the surface properties of the positive electrode active material by applying a glass coating with specific compositional parameters (Al2O3, SiO2, B2O3, P2O5 ratios). This parameter change creates a protective interface that enables high voltage operation while preventing humidity-related 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 amorphous glass surface treatment layer significantly reduces degradation and gas generation, improving the positive electrode's life characteristics and stability at high voltages, extending the battery's lifespan and maintaining excellent performance.
Implementation Method 1
the surface treatment layer comprises an amorphous glass containing an alkali metal oxide and an alkaline earth metal oxide... humidity reactivity may decrease, and the degeneration of the positive electrode active material... due to humidity may be prevented
Implementation Method 2
heat treating at a temperature of 500° C. or less... enhance thermal and chemical stability
Data Source
AI summary
The present invention provides a positive electrode active material for a lithium secondary battery which is capable of preventing the degeneration of a positive electrode active material and the generation of a gas during operating a battery due to humidity, by including a surface treatment layer of an amorphous glass including an alkali metal oxide and an alkaline earth metal oxide on the surface of a core including a lithium composite metal oxide and by decreasing humidity reactivity, and a secondary battery including the same.