LiCoO2 Cathode Composition for High-Rate Low-Temperature Discharge
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium-ion secondary batteries face challenges in maintaining high discharge capacity, especially at high rates and in low-temperature environments, due to changes in the crystal structure of the positive electrode active material, which inhibit lithium ion insertion and extraction, leading to reduced performance and safety concerns.
Innovation Solution
A positive electrode active material is developed with a layered rock-salt crystal structure containing lithium cobalt oxide, magnesium, aluminum, and nickel, where the concentration of magnesium is between 0.50 and 0.90, and specific conditions are applied during synthesis to promote lithium ion insertion and extraction, including heating steps and the use of additives like magnesium and aluminum to stabilize the crystal structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the surface of the positive electrode active material is covered with an inert oxide to inhibit crystal structure changes, then the crystal structure stability is improved, but the lithium ion insertion and extraction are inhibited, leading to decreased discharge capacity and output performance
Solution Approach 1:
The patent applies parameter changes by controlling the particle size of the positive electrode active material to be 3 μm or less, and optimizing the sintering temperature to 900°C or higher. These parameter changes enable the material to achieve both crystal structure stability and high lithium ion conductivity without requiring an inert oxide coating, thus resolving the contradiction between structural stability and ion insertion/extraction performance
Solution Approach 2:
The patent uses composite materials by combining the positive electrode active material with a conductive agent and binder to form a composite electrode structure. This composite approach allows the active material to maintain its crystal structure while enabling efficient electron and ion transport pathways, thereby achieving both structural stability and high discharge capacity
2Reliability
If the particle size of the positive electrode active material is reduced to enhance lithium ion insertion and extraction, then the discharge capacity is improved, but the crystal structure becomes more susceptible to changes, leading to reduced reliability
Solution Approach 1:
The patent applies parameter changes by optimizing the particle size to 3 μm or less and the sintering temperature to 900°C or higher. This specific combination of parameters creates a unique state where the small particle size facilitates rapid lithium ion diffusion while the high sintering temperature ensures complete crystallization and structural stability, resolving the contradiction between high discharge capacity and crystal structure stability
3Stability of the object's composition
If the sintering temperature is increased to improve crystal structure formation, then the crystal structure stability is improved, but the manufacturing energy consumption increases
Solution Approach 1:
The patent applies parameter changes by setting the sintering temperature to 900°C or higher, which enables the formation of a stable crystal structure with high lithium ion conductivity. This temperature parameter optimization ensures complete reaction and crystallization in a single sintering step, achieving structural stability while minimizing total energy consumption by avoiding the need for additional high-temperature treatment steps
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 enhances lithium ion insertion and extraction, maintaining high discharge capacity, inhibiting capacity loss at high rates, and ensuring stability in low-temperature environments, thereby improving battery safety and reliability.
Implementation Method 1
the concentration of magnesium is between 0.50 and 0.90, and specific conditions are applied during synthesis to promote lithium ion insertion and extraction, including heating steps and the use of additives like magnesium and aluminum to stabilize the crystal structure
Implementation Method 2
specific conditions are applied during synthesis to promote lithium ion insertion and extraction, including heating steps
Data Source
AI summary
A novel positive electrode active material is to be provided. In addition, a battery with favorable charge and discharge characteristics is to be provided. The battery includes a positive electrode, and the positive electrode includes a positive electrode active material including lithium cobalt oxide. The lithium cobalt oxide contains magnesium, aluminum, and nickel, and when the concentration of cobalt in the lithium cobalt oxide measured from XPS analysis is represented as 1, the magnesium concentration (Mg/Co) is higher than or equal to 0.50 and lower than or equal to 0.90; and the half width of a Mg1s peak is higher than or equal to 1.0 eV and lower than or equal to 2.6 eV.