Aqueous Battery Electrode Slurry for pH and Viscosity Stability
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Solution Overview
Problem
Current aqueous processes for producing electrodes in electrochemical devices, particularly those using high-nickel active materials, face challenges with pH stability and viscosity maintenance over time, leading to reduced capacity and high-temperature durability issues due to the reactivity of materials with water.
Innovation Solution
Incorporating a neutralizing dispersant with a group 13 element, such as boron, and a water-soluble polymer like alginic acid or methylcellulose in the electrode slurry to form a film on complex oxides, which inhibits pH increase and viscosity decrease, ensuring long-term stability and improved high-temperature performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an aqueous process is used to prepare electrode slurry, then safety and environmental impact are improved, but pH stability and viscosity maintenance deteriorate due to hydrolysis of high-nickel active material
Solution Approach 1:
A water-soluble polymer is introduced as an intermediary substance that forms a protective coating on the surface of the high-nickel active material particles. This coating acts as a barrier that reduces direct contact between water and the hydrolysis-prone nickel-containing compounds, thereby maintaining pH stability and viscosity in the aqueous slurry without compromising safety or environmental benefits
Solution Approach 2:
The patent modifies the chemical parameters of the aqueous slurry by adjusting pH control agents, adding specific water-soluble polymers, and optimizing the concentration of binding agents. These parameter changes create a chemical environment that suppresses hydrolysis reactions while maintaining the safety and environmental advantages of the aqueous process
2Stability of the object's composition
If organic solvent is used to prepare electrode slurry, then pH stability and viscosity maintenance are improved, but safety and handling complexity worsen due to fire hazards and explosive limits
Solution Approach 1:
The patent extracts and eliminates the organic solvent from the slurry preparation process, replacing it with water-based components. By removing the flammable organic solvent, the fire hazards and explosive limit monitoring requirements are eliminated, while the desired pH stability and viscosity maintenance are achieved through the use of water-soluble polymers and pH control agents
3Quantity of substance
If high-nickel active material is used to increase electrode capacity, then energy density is improved, but reactivity with water increases causing hydrolysis and gel formation
Solution Approach 1:
A thin film of water-soluble polymer is formed around the high-nickel active material particles, creating a protective shell that prevents direct water contact. This flexible coating allows the high-capacity nickel-containing materials to be used in aqueous slurries without suffering from hydrolysis and gel formation, thereby maintaining both high energy density and aqueous process benefits
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 solution enables the production of electrodes with stable pH and viscosity over extended periods, enhancing the durability and performance of electrochemical devices, especially in high-temperature conditions, while avoiding the need for organic solvents and reducing production complexities.
Implementation Method 1
a film of the water-soluble polymer (C) is formed on a surface of the complex oxide (A)
Implementation Method 2
for the purpose of preventing the deterioration of an electrode active material, using a binder that contains alginic acid in an acid form (Alg-H) as a main component has been considered... for the purpose of obtaining a positive electrode slurry that is stable against moisture, an attempt has been made to use a pH adjuster
Implementation Method 3
since the positive electrode active material is highly reactive with water as described above, hydrolysis of the positive electrode active material proceeds in the presence of water
Data Source
AI summary
An electrode for an electrochemical device includes a neutralizing dispersant; and a complex oxide (A) capable of occluding and releasing lithium ions, wherein the neutralizing dispersant contains: a water-soluble compound (B′) containing a group 13 element (B) of the periodic table; and at least one water-soluble polymer (C) selected from the group consisting of an alkali metal salt, alkaline-earth metal salt, or ammonium salt of alginic acid, methylcellulose, carboxymethyl cellulose, carboxymethyl starch, or carrageenan, pullulan, guar gum, and xanthan gum, a film of the water-soluble polymer (C) is formed on a surface of the complex oxide (A), and the group 13 element (B) of the periodic table is present in the film of the water-soluble polymer (C).