Sulfur-Controlled Li-Rich Cathode Material for Low Diffusion Resistance
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Solution Overview
Problem
Mn-rich and lithium-rich manganese-based oxides exhibit low rate characteristics due to high resistance, and increasing calcination temperature to improve structural stability leads to excessive growth of primary particles, which worsens diffusion resistance.
Innovation Solution
A positive electrode active material with a sulfur content of 4,000 ppm or more is synthesized by coprecipitating a transition metal solution, washing with water, and calcinating at 800°C to 950°C, preventing primary particle growth while enhancing structural perfection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If calcination temperature is increased to improve structural stability, then structural perfection is enhanced, but primary particle size increases leading to worsened diffusion resistance
Solution Approach 1:
The patent controls the sulfur content parameter in the precursor material to be within 0.01-0.06 wt% before calcination. This parameter control allows the material to maintain structural stability through high-temperature calcination while preventing excessive primary particle growth, thereby resolving the contradiction between structural perfection and particle size control.
2Speed
If primary particle size is reduced to lower diffusion resistance, then rate characteristics improve, but structural stability deteriorates
Solution Approach 1:
By precisely controlling the sulfur content parameter in the precursor to 0.01-0.06 wt%, the patent enables the formation of particles with optimized primary particle size after calcination. This results in shorter lithium migration distances and improved rate characteristics while maintaining structural stability through the controlled sulfur content that prevents excessive particle growth during high-temperature treatment.
3Length of moving object
If sulfur content is increased to prevent primary particle growth, then diffusion resistance is reduced, but excessive sulfur may harm electrochemical performance
Solution Approach 1:
The patent establishes an optimal sulfur content range of 0.01-0.06 wt% in the precursor material. This precise parameter control ensures sufficient sulfur to inhibit primary particle growth during calcination, maintaining small particle sizes for low diffusion resistance, while preventing excessive sulfur content that would degrade electrochemical performance. The narrow optimal range balances these competing requirements.
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 results in a positive electrode active material with improved structural stability and reduced diffusion resistance, maintaining high capacity and energy density without increasing primary particle size.
Implementation Method 1
forming precursor particles for a positive electrode active material by coprecipitating a transition metal-containing solution including sulfate or sulfide of nickel and manganese, an ammonium cation complex-forming agent, and a basic compound
Implementation Method 2
preparing a precursor for a positive electrode active material by washing the precursor particles for the positive electrode active material with water
Implementation Method 3
mixing the precursor for the positive electrode active material and lithium raw material and calcinating the mixture at 800°C to 950°C
Data Source
Figure 1~3
Figure 4
AI summary
A positive electrode active material includes a lithium-rich manganese-based oxide represented by Formula 1, wherein a sulfur content of the positive electrode active material is 4,000 ppm or more based on a total weight of the positive electrode active material. A method for preparing the positive electrode active material, a positive electrode including the positive electrode active material, and a lithium secondary battery including the positive electrode active material are also provided.