Lithium Nickel Composite Oxide Cover Layer for Battery Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium nickel compound oxides used in non-aqueous electrolyte secondary cells face challenges in achieving both superior high temperature-operation properties and excellent large current-discharge properties due to issues like electrolyte decomposition and increased electrical resistance, which are not adequately addressed by existing methods.
Innovation Solution
A positive electrode active material is developed by mixing a first lithium transition metal composite oxide with a cover layer and a second lithium transition metal composite oxide, where the cover layer is formed from an inorganic compound containing lithium and titanium, and the ratio of these components is optimized to improve conductivity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a lithium nickel compound oxide is used as positive electrode active material, then capacity and cost are improved, but environmental resistance and cycle properties deteriorate due to electrolyte decomposition
Solution Approach 1:
A cover layer comprising an inorganic compound containing lithium and titanium is introduced as an intermediary between the lithium nickel compound oxide and the electrolyte. This cover layer suppresses electrolyte decomposition by the lithium nickel compound oxide, thereby improving environmental resistance while maintaining the high capacity benefits of lithium nickel-based materials.
Solution Approach 2:
The positive electrode active material is formulated as a composite system combining lithium nickel compound oxide grains with a cover layer of inorganic compound containing lithium and titanium. This composite structure leverages the high capacity of lithium nickel oxide while the cover layer provides protective functions, achieving both high capacity and improved environmental resistance.
2Reliability
If surface of grains is covered with conductive agent or layered oxide, then environmental resistance is improved, but capacity and large current discharge properties deteriorate
Solution Approach 1:
The cover layer is designed with specific compositional parameters (inorganic compound containing lithium and titanium) and controlled thickness (1 nm to 100 nm) to optimize the balance between environmental resistance and conductivity. By adjusting these parameters, the cover layer provides protection without excessively impeding lithium ion transport, thereby maintaining large current discharge capabilities.
3Reliability
If metal or metal oxide is dispersed on surfaces to suppress electrolyte decomposition, then environmental resistance is improved, but large current discharge properties deteriorate due to inhibited lithium ion intercalation
Solution Approach 1:
The inorganic compound containing lithium and titanium serves as a mediator that allows lithium ion transport while suppressing electrolyte decomposition. Unlike dispersed metal or metal oxide particles that block ion pathways, this cover layer maintains lithium ion conductivity necessary for large current discharge while providing the protective function against electrolyte 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
This approach effectively suppresses electrolyte decomposition and maintains low internal electrical resistance, enhancing both high temperature-operation and large current-discharge properties, leading to improved cell performance.
Implementation Method 1
a cover layer formed on at least part of the surface of each of the grains for suppressing decomposition of an electrolyte caused by the lithium transition metal composite oxide
Implementation Method 2
maintains low internal electrical resistance, enhancing both high temperature-operation and large current-discharge properties
Data Source
AI summary
A non-aqueous electrolyte secondary cell having superior high temperature-operation properties and excellent large current-discharge properties is provided. The non-aqueous electrolyte secondary cell has a positive electrode composed of a positive electrode collector and positive electrode active material layers formed thereon. A positive electrode active material contained in the above layer is formed of a first composite oxide and a second composite oxide mixed therewith. The first composite oxide is formed of grains of a first lithium transition metal composite oxide containing at least nickel as a transition metal and a cover layer formed on at least part of the surface of each of the grains for suppressing decomposition of an electrolyte caused by the first lithium transition metal composite oxide. The second composite oxide is composed of grains of a second lithium transition metal composite oxide.