LiF-Coated Lithium Manganese Cathode for Low-Temperature Calcination
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Solution Overview
Problem
Existing lithium manganese-based oxides used as positive electrode active materials in lithium secondary batteries face challenges such as insufficient phase development and lithium ion conductivity at low temperatures, leading to degraded rate performance and capacity retention.
Innovation Solution
A positive electrode active material is developed, which includes a lithium manganese-based oxide with phases belonging to the C2/m and R3-m space groups, and a coating containing fluorine, such as LiF, to enhance phase development and reduce side reactions at lower calcination temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If overlithiated lithium manganese-based oxide is synthesized at low temperature, then energy consumption is reduced, but phase development is insufficient and lithium ion conductivity is poor
Solution Approach 1:
LiF is introduced as an intermediary substance during the calcination process. It acts as a mediator that facilitates phase development at lower temperatures by modifying the reaction environment and promoting the formation of the desired layered structure without requiring excessive thermal energy.
Solution Approach 2:
The invention changes the chemical composition parameters by incorporating LiF into the calcination process. This parameter change allows the system to achieve proper phase development at reduced temperatures by altering the reaction chemistry rather than relying solely on thermal energy.
2Use of energy by stationary object
If overlithiated lithium manganese-based oxide is synthesized at low temperature, then energy consumption is reduced, but lithium ion conductivity is poor
Solution Approach 1:
LiF serves as a intermediary that enhances lithium ion conductivity at lower synthesis temperatures. It modifies the local environment around lithium ions, facilitating their movement through the crystal structure without requiring high temperature processing.
Solution Approach 2:
By changing the compositional parameters to include LiF, the invention achieves improved lithium ion conductivity at reduced temperatures. The presence of LiF alters the electrochemical properties and ion transport pathways in the material.
3Reliability
If LiF is added to promote phase development, then phase development is improved, but specific surface area increases leading to more side reactions
Solution Approach 1:
The invention optimizes the LiF content parameter to achieve the right balance. By controlling the amount of LiF added, it promotes sufficient phase development while limiting the increase in specific surface area that would lead to excessive side reactions with electrolytes.
Solution Approach 2:
LiF is distributed locally during the calcination process to promote phase development in critical regions without uniformly increasing the overall surface area. This localized action allows phase improvement while minimizing the creation of additional reactive surfaces.
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 improves the electrochemical properties and stability of lithium secondary batteries by promoting phase development and reducing specific surface area, thereby enhancing capacity and rate performance compared to conventional overlithiated lithium manganese-based oxides.
Implementation Method 1
a positive electrode active material including an overlithiated lithium manganese-based oxide, which can be synthesized at a lower temperature than that in a conventional synthesis process
Implementation Method 2
a coating containing fluorine, such as LiF, to enhance phase development and reduce side reactions at lower calcination temperatures
Data Source
Figure 1
AI summary
The present invention relates to a positive electrode active material and a lithium secondary battery including the same, and more particularly, to a positive electrode active material including an overlithiated lithium manganese-based oxide, which can be synthesized at a lower temperature than that in a conventional synthesis process, and compensate for phase development and lithium ion conductivity, which are insufficient when synthesized at low temperatures, and a lithium secondary battery including the same.