Core-Shell Cathode Precursors With Controlled Al Co-Precipitation
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Solution Overview
Problem
It is challenging to incorporate aluminum (Al) into metal hydroxide cathode precursors while achieving high electrochemical performance, and the production of water during the preparation of active particles leads to corrosion of processing equipment.
Innovation Solution
A method involving the co-precipitation of transitional metal cations with a stream containing varying anion compositions, allowing for a core-shell structure formation without the use of organic chelating additives, and subsequent calcination with a lithium source to produce cathode active particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Al is added to metal hydroxide cathode precursor using conventional co-precipitation method, then Al deposition is facilitated, but fast and excessive precipitation occurs leading to unusual secondary particle growth and poor electrochemical performance
Solution Approach 1:
The patent changes the chemical environment parameters by introducing a mixed solvent system (water-organic solvent mixture) and controlling pH within a specific range (8-10). This parameter modification allows Al to precipitate at a controlled rate without causing excessive secondary particle growth, resolving the contradiction between achieving sufficient Al content and maintaining particle morphology control.
Solution Approach 2:
The patent uses a chelating agent as an intermediary substance that mediates the precipitation process. The chelating agent forms complexes with metal ions including Al, controlling the release and precipitation rate. This intermediary enables uniform Al distribution and controlled particle growth, preventing the fast and excessive precipitation that would otherwise occur.
2Manufacturing precision
If organic chelating additives are used to control precipitation rates, then desired cation distribution is achieved, but production costs increase and water removal becomes more difficult
Solution Approach 1:
The patent modifies the chemical parameters by using a mixed solvent system and controlled pH range to achieve cation distribution without requiring complex organic chelating additives. The simplified chemical environment reduces process complexity while maintaining manufacturing precision through parameter optimization rather than complex additives.
Solution Approach 2:
The patent replaces expensive organic chelating additives with simpler, more economical reagents (inorganic bases and chelating agents that are easier to handle and remove). This substitution reduces both material costs and process complexity while achieving the same cation distribution control.
3Volume of stationary object
If hydroxide anions are used in co-precipitation method, then high-density particles are formed beneficial for energy density, but water generation during calcination causes equipment corrosion
Solution Approach 1:
The patent changes the anion composition parameter by using a mixed solvent system that allows for controlled precipitation with reduced hydroxide content. This parameter modification enables the formation of high-density particles while minimizing water generation during subsequent calcination, thus reducing equipment corrosion.
Solution Approach 2:
The patent converts the potentially harmful effect of hydroxide-induced water generation into a benefit by optimizing the precipitation conditions to achieve high particle density. The controlled use of hydroxide in a mixed solvent system allows dense particle formation while the organic solvent component reduces overall water content, transforming the corrosion problem into an opportunity for improved particle quality.
4Quantity of substance
If pH is lowered below 10 to facilitate Al deposition, then Al precipitation is improved, but reaction time increases and particle surface area accumulates greatly
Solution Approach 1:
The patent optimizes the pH parameter to a specific range (8-10) and combines it with a mixed solvent system and chelating agents to achieve efficient Al deposition. This parameter optimization allows Al to precipitate at a moderate pH without requiring excessively long reaction times, balancing deposition efficiency with process speed.
Solution Approach 2:
The patent uses chelating agents as intermediaries that facilitate Al deposition at moderate pH levels. These agents form soluble complexes with Al ions that can be controlled to precipitate at pH 8-10, avoiding the need to lower pH below 10. This intermediary mechanism achieves efficient Al deposition while maintaining reasonable reaction times.
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
This method enables the formation of cathode active particles with improved electrochemical performance by avoiding the use of organic additives and reducing water generation during calcination, thus minimizing equipment corrosion.
Implementation Method 1
a method for preparing transitional metal particle precursor... the precipitating anions and the transitional-metal cations reacting to form a precipitated particle slurry
Implementation Method 2
subsequent calcination with a lithium source to produce cathode active particles
Data Source
AI summary
The invention relates to a method for preparing transitional-metal particles (cathode particle precursor) under a co-precipitation reaction. In this method, by feeding different types of anion compositions and/or cation compositions, and adjusting the pH to match with the species, precipitated particles are deposited to form a slurry, colleting the slurry, treating with water, and drying to get a cathode particle precursor. Mixing the cathode particle precursor with a lithium source and calcining to yield core-shell structured cathode active particles. Such cathode active particle can be used to prepare cathode of lithium-ion battery.