Positive Electrode Active Material With Ion-Conductive Surface Phase
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Solution Overview
Problem
Lithium secondary batteries face challenges in maintaining high initial discharge capacity and cycle characteristics due to the presence of carbon atoms in the positive electrode active material, which can lead to gas generation and battery deterioration.
Innovation Solution
A positive electrode active material for lithium secondary batteries is developed, comprising Li, Ni, and an element X (such as Al, Ti, Nb, B, W, Zr, Mg, Sn, or P, with specific abundance ratios of carbon and other elements, forming a lithium metal composite oxide and a composite phase, optimized through thermal treatment and coating processes to enhance ion conductivity and reduce resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a carbon atom remains in the positive electrode active material, then the initial discharge capacity can be maintained, but gas is generated during discharge reaction causing battery deterioration
Solution Approach 1:
The patent converts the harmful effect of carbon atoms by coating them with metal or metal oxide to form a composite structure. The carbon atoms that would normally decompose to generate gas are now enclosed within the coating layer, transforming them from a harmful component into a contained element that no longer causes battery deterioration while preserving the initial discharge capacity.
Solution Approach 2:
The patent creates a composite material structure where a metal or metal oxide coating layer is formed on the surface of particles containing carbon atoms. This composite structure combines the benefits of carbon-containing materials for high initial discharge capacity with the protective properties of metal/metal oxide coatings that prevent gas generation and electrolyte decomposition, thereby improving both energy utilization and battery reliability.
2Device complexity
If a compound having a carbon atom remains on the surface of particles, then the material composition is simplified, but the electrolyte solution decomposes to generate gas
Solution Approach 1:
The patent converts the harmful surface carbon compounds into a beneficial configuration by coating them with metal or metal oxide. The carbon-containing compounds that would otherwise react with electrolyte to generate gas are now enclosed within the coating layer, transforming them from a source of harm into a contained component that no longer causes electrolyte decomposition.
Solution Approach 2:
The metal or metal oxide coating acts as an intermediary barrier between the carbon-containing compounds and the electrolyte solution. This intermediate layer prevents direct contact and chemical reaction between the carbon compounds and electrolyte, thereby eliminating gas generation while maintaining the simplified material composition benefit.
3Reliability
If a metal or metal oxide coating is applied to suppress gas generation, then battery characteristics improve, but the manufacturing process becomes more complex
Solution Approach 1:
The patent optimizes the coating parameters including the thickness (1 nm to 100 nm), composition (metal or metal oxide), and formation method to achieve effective gas suppression. By carefully controlling these parameters, the coating process becomes more manageable and manufacturable while still providing sufficient protection against gas generation and electrolyte decomposition.
Solution Approach 2:
The patent applies the coating selectively on the surface of particles containing carbon atoms rather than uniformly throughout the entire material. This localized approach ensures that the coating is applied only where needed to prevent gas generation, reducing unnecessary manufacturing complexity while maintaining effective protection at the critical particle surfaces.
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 achieves a high initial discharge capacity and excellent cycle characteristics, even when carbon atoms are present, by forming an ion conductive phase on the surface of the particles, thereby reducing gas generation and improving battery performance.
Implementation Method 1
forming an ion conductive phase on the surface of the particles, thereby reducing gas generation and improving battery performance
Data Source
AI summary
A positive electrode active material for a lithium secondary battery, containing at least Li, Ni, an element X, and a carbon atom, in which the element X is one or more elements selected from the group consisting of Al, Ti, Nb, B, W, Zr, Mg, Sn, and P, and (1) and (2) are satisfied.Cx/Cy≤10 (1)0<(Cy/Cz)≤100 (2)(In (1) or (2), Cx is an abundance (mass %) of the element X obtained by measurement using X-ray photoelectron spectroscopy. Cy is an abundance (mass %) of the carbon atom obtained from a C1s spectrum obtained by measurement using the X-ray photoelectron spectroscopy. Cz is an abundance (mass %) of the carbon atom obtained by measurement using a combustion-infrared absorption method.)