High-Nickel Cathode Material Washing for Gas and Lattice Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-nickel positive electrode active materials for lithium secondary batteries face challenges such as gas generation, lattice instability, and increased lithium impurities, which affect battery performance and lifespan.
Innovation Solution
A method for preparing a positive electrode active material with a nickel content of 70 mol % or greater, involving mixing a nickel-rich precursor with a lithium source, firing, and a controlled washing process to remove lithium by-products without damaging the particle structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a high-nickel positive electrode active material is used to increase capacity, then the battery capacity is improved, but gas generation increases and lattice stability decreases
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the inner core region maintains high nickel content (0.6-0.8 mol fraction) for high capacity, while the outer shell region has reduced nickel content (0.3-0.6 mol fraction) for enhanced stability. This spatial differentiation of nickel concentration resolves the contradiction between capacity and stability by assigning different functional requirements to different regions of the same particle.
Solution Approach 2:
The patent creates a composite material structure combining high-nickel and low-nickel regions within a single positive electrode active material particle. The composite consists of an inner high-capacity region and an outer stability-enhancing region, allowing the material to simultaneously achieve high battery capacity and maintain lattice stability during charge-discharge cycles.
2Object-generated harmful factors
If a washing process is applied to remove lithium by-products, then gas generation is reduced, but particle surface damage occurs affecting lifetime
Solution Approach 1:
The patent applies preliminary action by controlling the washing process parameters (washing solution temperature, washing time, and washing solution composition) to remove lithium by-products before they can cause significant harm. The washing is performed under optimized conditions that prevent surface damage while effectively reducing gas generation, thereby eliminating the need for aggressive washing that would compromise particle integrity and battery lifetime.
3Quantity of substance
If nickel content is increased to improve capacity properties, then battery capacity increases, but lithium impurity content on surface increases
Solution Approach 1:
The patent applies local quality by creating a concentration gradient of nickel within the particle structure. The outer shell region has lower nickel content (0.3-0.6 mol fraction) compared to the inner core (0.6-0.8 mol fraction), which reduces lithium impurity formation on the particle surface during synthesis while maintaining high overall nickel content for high battery capacity. This spatial differentiation allows simultaneous optimization of both capacity and purity.
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 removes lithium by-products, enhancing the resistance and lifetime characteristics of the positive electrode active material, while reducing gas generation and maintaining high capacity.
Implementation Method 1
washing the fired body with a washing solution in an amount of 30 parts by weight to 70 parts by weight with respect to 100 parts by weight of the fired body to prepare a lithium transition metal oxide
Implementation Method 2
washing the fired body with a washing solution... to remove lithium by-products remaining on a surface
Data Source
AI summary
A positive electrode active material includes a lithium transition metal oxide having a nickel content of 70 mol % or greater with respect to all metals excluding lithium, wherein EELS analysis results for a particle surface satisfy Equation 1 below:0.85≤I(854 eV)/I(855.5 eV)<1 [Equation 1]wherein I (854 eV) indicates a peak intensity observed around 854 eV, and I (855.5 eV) indicates a peak intensity observed around 855.5 eV.