Composite Cathode Coating for High-Voltage Li-Ion Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium-ion secondary batteries face challenges in achieving stable charge and discharge cycles, high capacity, reliability, safety, and cost effectiveness due to instability of positive electrode active materials at high potentials and temperatures.
Innovation Solution
A method involving a composite structure where a particulate first material, such as lithium cobalt oxide, is coated with a second material like aluminum oxide or LiM2PO4, inhibiting the release of transition metals and oxygen, thereby enhancing stability and cycle performance, and using a graphene compound to cover at least 80% of the particle surface for improved durability and heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a high potential is applied to the positive electrode active material to achieve high capacity, then the charge and discharge capacity is improved, but the crystal structure stability deteriorates causing significant deterioration in charge and discharge cycles
Solution Approach 1:
The patent applies composite materials by combining the positive electrode active material with a specific compound having a spinel structure or distorted spinel structure. This composite structure allows the material to maintain high charge and discharge capacity while the spinel component provides structural stability, preventing crystal structure deterioration during cycling. The composite effectively integrates the high capacity characteristics with the structural stability needed for reliable operation.
Solution Approach 2:
The patent uses a compound with spinel or distorted spinel structure as an intermediary material that mediates between the high potential requirements and crystal structure stability. This intermediary compound acts as a structural buffer that maintains stability during high potential charging while still allowing the necessary electrochemical reactions to occur, thus protecting the overall crystal structure from deterioration.
2Use of energy by moving object
If the positive electrode active material is exposed to high potential during charging to achieve high capacity, then the energy storage is improved, but the stability of the crystal structure reduces causing deterioration in cycle performance
Solution Approach 1:
The patent creates a composite material system where the positive electrode active material is combined with a spinel or distorted spinel structure compound. This composite enables high energy storage by allowing charging at high potentials while the spinel component maintains crystal structure stability, preventing the composition from deteriorating during repeated charge and discharge cycles.
Solution Approach 2:
The patent utilizes parameter changes by employing a compound with spinel or distorted spinel structure that has specific structural characteristics. The spinel structure's inherent stability parameters allow the material to withstand high potential conditions during charging, maintaining compositional stability while enabling high energy storage capacity through controlled parameter changes during electrochemical cycling.
3Reliability
If a coating material is applied to cover the particle surface to improve stability and reduce metal release, then the cycle performance is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent employs composite materials where the positive electrode active material is combined with a spinel or distorted spinel structure compound that forms a coating or integrated structure on the particle surface. This composite approach improves cycle performance by reducing transition metal release while maintaining relatively simple manufacturing processes, as the composite can be synthesized in a single step rather than requiring separate coating operations.
Solution Approach 2:
The patent merges the positive electrode active material with the spinel or distorted spinel structure compound into a single integrated composite material. This merging eliminates the need for separate coating steps, reducing manufacturing complexity while still achieving the protective effect of surface coverage that improves cycle performance and reduces metal release into the electrolyte.
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 method results in a positive electrode active material that maintains stability at high potentials, improves cycle performance, and enhances the safety and reliability of secondary batteries by reducing capacity loss and increasing heat resistance.
Implementation Method 1
a structure where at least part of a particle surface of a particulate first material functioning as a positive electrode active material is covered with a second material
Implementation Method 2
using a graphene compound to cover at least 80% of the particle surface for improved durability and heat resistance
Data Source
AI summary
A positive electrode active material that is stable in a high potential state or a high temperature state and a highly safe secondary battery are provided. The positive electrode includes a first material and a second material and includes a region where at least part of a surface of the first material is covered with the second material. The first material includes a lithium cobalt oxide containing magnesium, fluorine, aluminum, and nickel. The second material includes a composite oxide (containing one or more selected from Fe, Ni, Co, and Mn) having an olivine crystal structure.