Blended High-Nickel Cathode Material for Low-Impurity Surfaces
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Solution Overview
Problem
High-nickel positive electrode active materials in lithium secondary batteries face challenges due to excessive lithium impurities on the surface, leading to gas generation, instability, and reduced battery lifetime, as existing washing processes can damage the particle structure and fail to effectively remove these impurities.
Innovation Solution
A blended positive electrode material is prepared using a method that involves mixing a first and second lithium transition metal oxide with high nickel content, where each oxide has a specific EELS analysis ratio to control lithium by-products removal without damaging the particle structure, ensuring optimal washing conditions for both large and small particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a high-nickel positive electrode active material is used to increase capacity, then energy density is improved, but lithium impurities remain on the surface causing gas generation and reduced stability
Solution Approach 1:
The patent changes the washing parameters by optimizing the washing solution composition (water with controlled pH and additives), washing temperature (50-100°C), and washing time to effectively remove lithium impurities from the high-nickel material surface while preserving the material's high capacity characteristics
Solution Approach 2:
The patent introduces a washing solution as an intermediary medium that selectively removes lithium impurities from the positive electrode material surface. The washing solution acts as a mediator between the high-nickel material and the final electrode product, enabling impurity removal without damaging the active material structure
2Object-generated harmful factors
If a washing process is applied to remove lithium by-products, then gas generation is reduced, but particle surfaces are damaged affecting lifetime and storage
Solution Approach 1:
The patent optimizes washing parameters including temperature (50-100°C), time (5-30 minutes), and solution composition to achieve effective lithium by-product removal while minimizing surface damage. The controlled parameters ensure gentle yet effective cleaning that preserves particle integrity
Solution Approach 2:
The patent uses a standardized washing solution composition and process parameters that can be replicated consistently to achieve optimal cleaning results. The washing method serves as a reproducible template that removes harmful lithium by-products without causing surface damage when applied correctly
3Quantity of substance
If the nickel content is increased to improve capacity properties, then energy density is enhanced, but lattice structure instability increases due to cation mixing and oxygen desorption
Solution Approach 1:
The patent extracts and removes lithium by-products from the surface of high-nickel positive electrode particles through a controlled washing process. This extraction of harmful surface contaminants stabilizes the overall material composition and prevents degradation reactions that would otherwise compromise lattice stability
Solution Approach 2:
The patent converts the harmful presence of surface lithium by-products into a beneficial cleaning process. By intentionally applying a washing treatment to remove these by-products, the patent transforms a harmful condition into an opportunity to stabilize the high-nickel material and improve its long-term performance
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 effectively reduces surface damage, enhances resistance, and improves battery lifetime by minimizing lithium by-products on the surface, thereby maintaining high energy density and capacity.
Implementation Method 1
washing the first fired body with a washing solution to prepare a first lithium transition metal oxide
Implementation Method 2
removes lithium by-products on the surface
Data Source
AI summary
A blended positive electrode material includes a first positive electrode active material containing a first lithium transition metal oxide and a second positive electrode active material containing a second lithium transition metal oxide, wherein the first lithium transition metal oxide and the second lithium transition metal oxide each have a nickel content of 70 mol % or greater with respect to of all metals excluding lithium, the first positive electrode active material has a greater D50 than the second positive electrode active material, and EELS analysis results for particle surfaces of both the first positive electrode active material and the second positive electrode active material satisfy Equation 1. A method for preparing the blended positive electrode material is also provided.