High-Nickel Cathode Material Cooling Profile for Low LiOH Impurities
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Solution Overview
Problem
Existing positive electrode active materials face issues with high levels of impurities, particularly LiOH, and poor lithium distribution, leading to reduced battery performance, and existing cooling profiles in manufacturing processes do not adequately address these issues.
Innovation Solution
A manufacturing method involving controlled heating and cooling profiles, including a high-temperature heating phase followed by a gradual cooling phase to specific temperatures, reduces impurities and improves lithium distribution, resulting in a positive electrode active material with enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional heating and cooling profiles are used in manufacturing positive electrode active material, then the production process is simple and fast, but the material contains high levels of LiOH impurities and has poor lithium distribution
Solution Approach 1:
The cooling process is divided into three distinct stages with different cooling rates: first stage at 1-5°C/min, second stage at 5-10°C/min, and third stage at 10-20°C/min. This segmentation allows optimization of lithium distribution in different temperature ranges while maintaining manageable process complexity through systematic progression.
Solution Approach 2:
The cooling rate parameter is dynamically adjusted across three stages, transitioning from slow (1-5°C/min) to moderate (5-10°C/min) to faster (10-20°C/min) rates. This parameter change strategy optimizes lithium distribution by controlling crystallization kinetics at different cooling phases, achieving high manufacturing precision through parameter optimization.
2Reliability
If excess lithium source material is used to ensure complete reaction, then the positive electrode active material achieves good performance, but the amount of LiOH impurity increases
Solution Approach 1:
The heating temperature is optimized to a specific range of 750-850°C, which provides sufficient thermal energy for complete reaction of stoichiometric amounts of lithium source material, ensuring good battery performance while minimizing excess lithium that would form LiOH impurities. This parameter optimization resolves the contradiction between reliability and harmful factors.
Solution Approach 2:
An oxygen atmosphere is introduced during the heating process to promote complete oxidation and reaction of lithium source material. This ensures that stoichiometric amounts react fully, achieving good battery performance without requiring excess lithium that would generate LiOH impurities, thus resolving the contradiction through atmospheric control.
3Quantity of substance
If high nickel content (x≥70.0 mol %) is used in the positive electrode active material, then the battery energy density is improved, but the material becomes more sensitive to cation mixing and surface degradation
Solution Approach 1:
The heating temperature is optimized to 750-850°C, which provides sufficient energy to reduce cation mixing in high nickel content materials while avoiding excessive temperature that would cause surface degradation. This parameter optimization allows achieving high energy density through high nickel content while maintaining surface stability.
Solution Approach 2:
Minor amounts of other metal elements (y≤30.0 mol % Mn, z≤30.0 mol % Co, a≤5.0 mol % A) are incorporated with the high nickel content (x≥70.0 mol %) to create a composite material system. These additional elements stabilize the crystal structure and surface, reducing sensitivity to cation mixing and surface degradation while maintaining high energy density.
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 produces a positive electrode active material with reduced LiOH content and improved electrochemical performance, requiring less lithium source material and minimizing the need for additional processing steps.
Implementation Method 1
heating a precursor material at a heating temperature T1 between 750° C. and 1000° C.
Implementation Method 2
cooling the heated product to a second temperature T2 between 600° C. and 800° C.
Data Source
AI summary
Positive electrode active material, wherein the metal has a composition M, which consists of Ni in a content x, Mn in a content y, Co in a content z, and A in a content a. A is at least one chemical element other than Li, Ni, Mn, Co, and O. x, y, z, and a are expressed as molar contents and x+y+z+a=100%. Further, x≥70.0%, 0≤y≤30.0%, 0≤z≤30.0%, 0≤a≤5.0%, and an X-Ray diffractogram from Cu K-α X-ray radiation source of the positive electrode active material has a (003) peak at 2θ=17.0° to 20.0° and (104) peak at 2θ=43.0° to 46.0°. The ratio (maximum intensity of the (003) peak)/(maximum intensity of the (104) peak) is at least 1.880.