Concentration-Gradient Positive Electrode Material for Lithium Batteries
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium secondary batteries face challenges with thermal stability and cost due to rapid structural changes in positive electrode active materials like LiCoO2 and LiNiO2, and existing methods for improving stability, such as surface coating and concentration-gradient synthesis, fail to provide consistent and high-capacity solutions.
Innovation Solution
A method using a batch reactor for co-precipitation to create a positive electrode active material with a core-shell structure and concentration-gradient layer, where the relative concentrations of Ni, Co, and Mn are gradually changed, forming a Ni-Co-Mn-based compound with high capacity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If surface coating method is used to improve thermal stability, then thermal stability is improved, but coating uniformity and capacity are reduced
Solution Approach 1:
The invention creates a concentration-gradient layer where the Ni-Co-Mn composition varies continuously from the particle center to the surface, with Ni content decreasing and Mn content increasing toward the outer layer. This gradient structure provides localized thermal stability at the surface while maintaining high-capacity Ni-rich composition in the interior, resolving the contradiction between thermal stability and capacity.
Solution Approach 2:
The invention changes the compositional parameters (Ni, Co, Mn ratios) continuously through the particle radius, creating a concentration-gradient layer with gradual transition. This parameter variation achieves uniform coating effect while maintaining high capacity, overcoming the limitations of conventional thin-film coating methods.
2Ease of manufacture
If conventional batch reactor method is used for production, then manufacturing simplicity is maintained, but production efficiency and consistency are low
Solution Approach 1:
The invention performs preliminary classification of particles by size before the co-precipitation reaction, ensuring all particles have similar surface areas. This preliminary action enables uniform reaction rates and consistent concentration-gradient formation across all particles, significantly improving production efficiency and product consistency while maintaining batch reactor simplicity.
Solution Approach 2:
The invention implements feedback control by monitoring particle formation during co-precipitation and adjusting precursor addition rates accordingly. This feedback mechanism ensures consistent concentration gradients and uniform particle sizes, enhancing production efficiency and quality control in batch processing.
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 achieves high capacity, tapped density, and elongated lifespan with improved thermal stability, allowing for more uniform and economically advantageous production of positive electrode active materials for lithium secondary batteries.
Implementation Method 1
supplying a chelating agent into a batch reactor followed by simultaneously supplying a transition metal while adjusting a concentration thereof continuously, thereby forming a precipitate
Data Source
AI summary
The present invention relates to a method for preparing a positive electrode active material precursor and a positive electrode material for a lithium secondary battery having a concentration-gradient layer using a batch reactor, and to a positive electrode active material precursor and a positive electrode material for a lithium secondary battery prepared by the method. The method for preparing a positive electrode active material precursor and a positive electrode active material for a lithium secondary battery having a concentration-gradient layer using a batch reactor involves supplying a predetermined amount of a chelating agent into the batch reactor, and simultaneously supplying transition metals while continuously adjusting the concentration of the transition metals such that the concentration-gradient layer can be formed from a core to a shell of the positive electrode active material in a more economically advantageous and stable manner, and at the same time a positive electrode active material having an elongated lifespan and improved thermal stability can be provided.