Amorphous Boron Silicon Oxide Coating for High-Voltage Battery Stability
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Solution Overview
Problem
Lithium secondary batteries face limitations in lifetime and high-voltage stability due to moisture reactivity and electrolyte decomposition, particularly in positive electrode materials, leading to reduced performance and capacity over repeated charge/discharge cycles.
Innovation Solution
A positive electrode active material comprising a lithium nickel manganese cobalt oxide core with a boron and silicon-containing amorphous oxide surface treatment layer, which enhances thermal and chemical stability, reduces moisture reactivity, and improves lithium ion conductivity, thereby extending battery life and maintaining high-voltage performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aluminum-based surface treatment layers are coated on the surface of positive electrode active material, then high voltage stability is improved, but manufacturing complexity increases and resistance increases due to crystallinity
Solution Approach 1:
The patent changes the physical state parameter of the aluminum-based coating from crystalline to amorphous by controlling the coating process and heat treatment conditions. This parameter change resolves the contradiction by maintaining the protective function against moisture and electrolyte decomposition while eliminating the high resistance associated with crystalline structures, and simplifying the manufacturing process.
Solution Approach 2:
The patent creates a composite surface treatment layer combining aluminum-based compounds with other elements to form an amorphous structure. This composite approach maintains the high voltage stability provided by aluminum-based materials while the amorphous composite structure prevents crystallinity-induced resistance increases and simplifies manufacturing compared to pure crystalline coatings.
2Productivity
If boron-based coatings are applied to positive electrode active material, then lithium ion conductivity is improved, but moisture reactivity increases leading to coating degradation over time
Solution Approach 1:
The patent develops a composite coating system where boron-based compounds are combined with aluminum-based compounds or other stabilizing elements. This composite structure maintains the high lithium ion conductivity provided by boron while the additional components form a protective barrier against moisture reactivity, preventing coating degradation over time and improving long-term reliability.
Solution Approach 2:
The patent introduces an intermediary layer or composite structure where boron-based coating is combined with moisture-resistant materials. This intermediary approach allows the boron coating to provide lithium ion conductivity while the accompanying materials act as mediators that reduce moisture reactivity and prevent coating degradation during extended operation.
3Use of energy by moving object
If positive electrode material is operated at high voltages, then energy density is improved, but lifetime decreases due to material deterioration and electrolyte decomposition
Solution Approach 1:
The patent applies an amorphous surface treatment layer as an intermediary between the positive electrode active material and the electrolyte. This intermediary layer protects the electrode material from direct contact with moisture and electrolyte components, preventing degradation reactions that would otherwise occur at high voltages. This allows the battery to operate at high voltages for improved energy density while the protective intermediary layer maintains material integrity and extends battery lifetime.
Solution Approach 2:
The patent changes the surface morphology parameter from crystalline to amorphous in the coating layer. This parameter change creates a more uniform and stable interface that reduces electrochemical reactions between the electrode material and electrolyte at high voltages. The amorphous structure provides better protection against material deterioration while maintaining ionic conductivity, enabling sustained high-voltage operation and extended battery lifetime.
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 boron and silicon-containing amorphous oxide surface treatment layer significantly improves the cycle characteristics, thermal stability, and high-temperature resistance of lithium secondary batteries, maintaining discharge capacity and efficiency even at high voltages, such as 4.3 V or higher.
Implementation Method 1
the surface treatment layer includes a boron (B) and silicon (Si)-containing amorphous oxide
Implementation Method 2
improved thermal and chemical stability
Implementation Method 3
improved thermal and chemical stability
Data Source
AI summary
A positive electrode active material for a secondary battery and a secondary battery including the same are provided. The positive electrode active material for a secondary battery includes on the surface of a core, a surface treatment layer composed of a B and Si-containing amorphous oxide, and thus may exhibit reduced moisture reactivity, improved thermal and chemical stability, and high-voltage stability.