Lithium-Nickel-Aluminum Cathode Material With Uniform Al Dispersion
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Solution Overview
Problem
Lithium-nickel-cobalt-aluminum oxide positive electrode active materials produced by conventional methods exhibit uneven aluminum distribution, affecting their performance in lithium ion secondary batteries.
Innovation Solution
A method involving the use of a chelate compound to enhance the solubility of aluminum in the coprecipitation step, allowing for uniform distribution of aluminum in the primary particles by controlling the pH of the metal aqueous solution, resulting in a crystalline oxide with improved charge transfer resistance and cycling performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional coprecipitation method is used to produce lithium-nickel-cobalt-aluminum oxide, then production process is simple, but aluminum distribution becomes uneven
Solution Approach 1:
A chelate compound is introduced as an intermediary substance to control the coprecipitation process. The chelate compound forms complexes with metal ions (particularly aluminum) in the aqueous solution, regulating their precipitation behavior and ensuring uniform aluminum distribution in the final oxide product while maintaining the simplicity of the coprecipitation method
Solution Approach 2:
The pH value of the aqueous solution is precisely controlled and adjusted to an optimal range during coprecipitation. By changing the pH parameter, the precipitation sequence and rate of different metal ions are regulated, preventing premature aluminum precipitation and achieving uniform distribution without complicating the overall process
2Productivity
If aluminum is added to metal aqueous solution without chelate compound, then coprecipitation occurs, but aluminum deposits more easily than other transition metals causing uneven distribution
Solution Approach 1:
The chelate compound acts as a mediator that selectively binds to aluminum ions and other transition metal ions, creating stable complexes that control their relative precipitation rates. This prevents aluminum from depositing too early and ensures simultaneous coprecipitation of all metals, maintaining both efficiency and uniformity
Solution Approach 2:
By adjusting the pH parameter to a specific optimal range in the presence of chelate compound, the solubility products of different metal-chelate complexes are balanced. This parameter control ensures that aluminum and other transition metals precipitate together at similar rates, achieving uniform distribution while maintaining coprecipitation efficiency
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 uniform distribution of aluminum leads to enhanced charge transfer resistance and stable charging/discharging performance at high rates and low temperatures, with improved capacity retention in lithium ion secondary batteries.
Implementation Method 1
adding a chelate compound to a metal aqueous solution in which the aluminum and the other transition metals are dissolved, to improve solubility of the aluminum in water
Implementation Method 2
nickel, cobalt, and aluminum are coprecipitated as hydroxide from an aqueous solution
Implementation Method 3
the hydroxide containing nickel, cobalt, and aluminum is isolated
Data Source
AI summary
Provided is a positive electrode active material in which aluminum is dispersed uniformly.A positive electrode active material is crystalline oxide that contains lithium, nickel, and aluminum, and aluminum is dispersed uniformly in a primary particle in the oxide.