Nickel Cathode Coating for Residual Lithium Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium secondary batteries face challenges in achieving high-capacity, long-life, and thermal stability due to limitations in the positive active materials used, particularly with regards to surface residual lithium and the effectiveness of fluorine coatings in enhancing these characteristics.
Innovation Solution
A method involving the formation of a positive active material precursor with nickel, mixing with lithium salt, and then dry-mixing with a fluorine-containing coating source to reduce surface residual lithium through thermal treatment, resulting in a positive active material with improved fluorine content and reduced lithium residues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fluorine coating is applied to positive active material particles, then thermal stability and battery life are improved, but surface residual lithium increases and charge/discharge capacity decreases
Solution Approach 1:
The patent applies fluorine coating selectively to the surface of positive active material particles, creating a localized fluorinated layer that provides thermal stability and protects against degradation. The coating concentration and depth are controlled to ensure that fluorine is primarily present at the surface rather than throughout the bulk material, thereby maintaining high charge/discharge capacity while improving battery life and thermal stability.
2Temperature
If fluorine coating is applied to positive active material particles, then thermal stability is improved, but surface residual lithium increases
Solution Approach 1:
The patent controls the fluorine coating process parameters including fluorine concentration, coating thickness, and thermal treatment conditions to optimize the balance between thermal stability and surface residual lithium content. By adjusting these parameters, the coating provides adequate thermal protection while minimizing lithium residue that could harmfully accumulate on the particle surface.
3Quantity of substance
If high nickel content is used in positive active material, then charge/discharge capacity is improved, but thermal stability deteriorates
Solution Approach 1:
The patent creates a composite structure by coating fluorine-containing material onto nickel-rich positive active material particles. The core material provides high charge/discharge capacity due to high nickel content, while the fluorine-containing outer layer provides thermal stability and protects the nickel-rich core from degradation at elevated temperatures, thus combining the advantages of both materials.
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 approach enhances the charge/discharge capacity and life characteristics of lithium secondary batteries by minimizing surface residual lithium and optimizing fluorine content, leading to improved thermal stability and performance.
Implementation Method 1
the coating material may react with surface residual lithium of the preliminary positive active material particle by the thermal treating of the preliminary positive active material particle to form a compound of lithium and fluorine
Implementation Method 2
manufacturing a positive active material particle by thermally treating the preliminary positive active material particle on which the coating material is formed
Data Source
AI summary
A method for manufacturing a positive active material is provided. The method includes forming a positive active material precursor including nickel, mixing and firing the positive active material precursor and lithium salt to form a preliminary positive active material particle, forming a coating material including fluorine on the preliminary positive active material particle by dry-mixing the preliminary positive active material particle with a coating source including fluorine, and manufacturing a positive active material particle by thermally treating the preliminary positive active material particle on which the coating material is formed.