Non-aqueous Electrolyte Battery Additive for Uniform Surface Coverage
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Solution Overview
Problem
Nonaqueous electrolyte secondary batteries face reduced cycle characteristics due to insufficient coverage of the composite oxide surface by the cover layer, leading to decomposition when in contact with the electrolyte.
Innovation Solution
A nonaqueous electrolyte secondary battery design that includes a composite oxide with a metal oxide and a phosphate compound having an intramolecular alkenyl group, which covers the composite oxide surface to improve stability and prevent decomposition, using a thin metal oxide layer and triallyl phosphate to enhance coverage without increasing internal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cover layer is formed by a liquid phase method using metal oxide and phosphate compounds, then the surface of composite oxide is covered to prevent decomposition, but the coverage is insufficient and forms islands due to density differences and gas generation during heating
Solution Approach 1:
The invention changes the chemical composition parameters of the phosphate compound by introducing intramolecular alkenyl groups. This modification enables the phosphate compound to form a more uniform cover layer that fills the gaps between metal oxide islands, achieving complete surface coverage and preventing electrolyte contact with composite oxide particles.
Solution Approach 2:
The invention uses a composite cover layer consisting of metal oxide particles and phosphate compounds with intramolecular alkenyl groups. This composite structure combines the protective properties of metal oxide with the film-forming capabilities of the modified phosphate compound, creating a uniform and complete protective layer.
2Reliability
If the thickness of metal oxide layer is increased to improve coverage, then more complete surface coverage is achieved, but internal resistance of the battery increases
Solution Approach 1:
The phosphate compound with intramolecular alkenyl groups acts as an intermediary material that fills the gaps between metal oxide particles. This intermediary substance enables complete surface coverage without requiring increased metal oxide thickness, thus maintaining low internal resistance while achieving reliable protection against decomposition.
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 effectively improves the cycle characteristics and reduces internal resistance of the battery by ensuring complete coverage of the composite oxide surface, maintaining high capacity and output while minimizing the thickness of the metal oxide layer.
Implementation Method 1
an additive covering at least a portion of a surface of the composite oxide; the additive includes a metal oxide and a phosphate compound
Data Source
AI summary
A nonaqueous electrolyte secondary battery includes a positive electrode, a negative electrode, and a nonaqueous electrolyte, wherein the positive electrode includes a composite oxide containing lithium and a transition metal, and an additive covering at least a portion of a surface of the composite oxide. The additive includes a metal oxide and a phosphate compound, and the phosphate compound has at least one intramolecular alkenyl group.