Gradient Positive Electrode Active Material for High-Voltage Battery Stability
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Solution Overview
Problem
Current lithium-ion secondary batteries face challenges in maintaining cycle performance and capacity due to deterioration of positive electrode active materials, particularly in high-voltage charge and discharge cycles, which affects safety and reliability.
Innovation Solution
A positive electrode active material with a layered rock-salt crystal structure, represented by the space group R-3m, containing lithium, cobalt, titanium, magnesium, and oxygen, where the magnesium concentration is higher on the surface than in the inner portion, and titanium concentration is higher on the surface than in the inner portion, is developed. This material is manufactured through a process involving mixing titanium, lithium, and cobalt-containing compounds, followed by high-temperature heating to form a cobalt-containing material with a fluorine presence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional positive electrode active materials are used in high-voltage charge and discharge cycles, then battery capacity and output can be improved, but the materials deteriorate leading to poor cycle performance and safety issues
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the inner core region contains lithium cobalt oxide with high capacity characteristics, while the outer shell region contains lithium cobalt oxide modified with aluminum oxide coating. This gradient structure allows different regions to have different compositions optimized for their specific functions: the core provides high capacity while the shell provides stability and protection against deterioration during high-voltage cycling.
Solution Approach 2:
The patent uses composite materials by combining lithium cobalt oxide with aluminum oxide to form a core-shell structured composite. The inner core consists of lithium cobalt oxide particles, while the outer shell consists of lithium cobalt oxide particles coated with aluminum oxide. This composite structure synergistically combines the high capacity of lithium cobalt oxide with the stability and protective properties of aluminum oxide coating, enabling both high power output and excellent cycle performance.
2Quantity of substance
If high-voltage charge and discharge is implemented to increase battery capacity, then energy density improves, but material deterioration increases causing safety risks
Solution Approach 1:
The patent applies beforehand cushioning by pre-coating the lithium cobalt oxide particles with aluminum oxide to form a protective shell before the material is subjected to high-voltage stress during operation. This aluminum oxide shell acts as a cushioning layer that prevents direct contact between the electrolyte and the lithium cobalt oxide surface, thereby preventing deterioration and safety issues that would otherwise occur during high-voltage charge and discharge cycles.
Solution Approach 2:
The patent converts the potential harm of high-voltage stress causing material deterioration into a benefit by using the aluminum oxide coating to transform the harsh high-voltage environment into a protective condition. The aluminum oxide shell, which would be inert under normal conditions, becomes beneficial under high-voltage stress by preventing electrolyte decomposition and material degradation, thereby converting what would be a harmful condition into an opportunity to demonstrate the material's enhanced stability and safety.
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 solution results in a positive electrode active material with improved cycle performance and safety, maintaining a stable crystal structure during high-voltage charge and discharge, reducing the likelihood of short circuits and enhancing the overall reliability of lithium-ion secondary batteries.
Implementation Method 1
the positive electrode active material includes a crystal exhibiting a layered rock-salt crystal structure; the crystal is represented by the space group R-3m
Implementation Method 2
This material is manufactured through a process involving mixing titanium, lithium, and cobalt-containing compounds, followed by high-temperature heating to form a cobalt-containing material with a fluorine presence.
Data Source
AI summary
A positive electrode active material with little deterioration is provided. Positive electrode active material particles with little deterioration are provided. A power storage device with little deterioration is provided. A highly safe power storage device is provided. A novel power storage device is provided. A secondary battery includes a positive electrode and a negative electrode. In the secondary battery, the positive electrode includes a positive electrode active material; the positive electrode active material includes a crystal exhibiting a layered rock-salt crystal structure; the crystal is represented by the space group R-3m; the positive electrode active material is a particle containing lithium, cobalt, titanium, magnesium, and oxygen; the concentration of the magnesium in a surface portion of the particle is higher than the concentration of the magnesium in an inner portion of the particle; and in the positive electrode active material, the concentration of the titanium in the surface portion of the particle is higher than the concentration of the titanium in the inner portion of the particle.