Tungsten-Titanium Cathode Coating for Battery Cycle Stability
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Solution Overview
Problem
Nonaqueous electrolyte secondary batteries face issues with high internal resistance, insufficient output characteristics, and poor cycle characteristics due to tungsten elution and lithium precipitation at the negative electrode, which worsens with repeated charging and discharging.
Innovation Solution
A positive electrode active material is designed with a core part containing a lithium composite oxide, a first region with higher tungsten concentration, and a second region with titanium or titanium-containing compounds, such as TiO2, to enhance output and cycle characteristics while preventing tungsten elution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If tungsten is concentrated on the surface layer of the positive electrode active material to improve output characteristic and reduce reaction resistance, then the output characteristic is improved, but tungsten is eluted from the positive electrode and precipitated at the negative electrode during charging and discharging cycles
Solution Approach 1:
A coating layer comprising titanium dioxide (TiO2) and tungsten (W) is introduced as an intermediary between the positive electrode active material and the electrolyte. This coating layer serves as a mediator that prevents tungsten elution while maintaining electrical conductivity and ion permeability, thus resolving the contradiction between improving output characteristic and preventing tungsten precipitation at the negative electrode
Solution Approach 2:
The coating layer is formed as a composite material combining titanium dioxide and tungsten. TiO2 provides structural stability and prevents tungsten elution, while W maintains electrical conductivity. This composite structure enables both improved output characteristic through reduced reaction resistance and enhanced cycle characteristic by preventing tungsten precipitation
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 proposed active material structure improves the battery's output and cycle characteristics by reducing resistance and suppressing tungsten elution, resulting in better performance and longevity.
Implementation Method 1
a positive electrode active material capable of occluding and releasing ions serving as electric charge carriers is used
Implementation Method 2
coating of the surface of the positive electrode active material with titanium dioxide (TiO2) in order to improve the output characteristic
Data Source
AI summary
The present disclosure provides a positive electrode active material capable of imparting a nonaqueous electrolyte secondary battery with excellent output characteristic and cycle characteristic. The positive electrode active material herein disclosed includes a core part including a lithium composite oxide, a first region formed on at least a partial surface of the core part, and including tungsten (W), and a second region formed on at least a partial surface of the first region, and including titanium (Ti). The W concentration of the first region with TEM-EDX analysis is higher than the W concentration of the core part.