Silicon-Oxide Negative Electrode Slurry pH Stabilization
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Solution Overview
Problem
Silicon-based negative electrode active materials in lithium secondary batteries face challenges due to high volume expansion/contraction, irreversible capacity, and pH changes in the slurry, leading to reduced charge/discharge efficiency and stability.
Innovation Solution
Incorporating specific amounts of aluminum, boron, zinc, or zirconium elements into the negative electrode slurry, where these elements are bound to oxygen, to stabilize the slurry and prevent base reactions with silicon, thereby improving rheological properties and reducing gas generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If metal-doped silicon-based oxide is used as negative electrode active material, then capacity and high-speed charge characteristics are improved, but metal oxide reacts with moisture to increase pH and change viscosity of slurry
Solution Approach 1:
The patent applies preliminary anti-action by adding a base substance (such as carboxymethyl cellulose or starch) to the slurry before the metal-doped silicon-based oxide can react with moisture. This pre-established base component neutralizes the pH increase that would otherwise occur when metal oxide reacts with water, thereby preventing viscosity changes and maintaining slurry stability while preserving the high capacity and charge characteristics of the doped material.
2Productivity
If metal-doped silicon-based oxide is used as negative electrode active material, then capacity and high-speed charge characteristics are improved, but state of manufactured negative electrode becomes poor
Solution Approach 1:
The patent applies preliminary anti-action by pre-adding base substances to the slurry formulation before electrode manufacturing. This prevents the harmful reactions between metal oxide and moisture that would otherwise degrade electrode quality, while maintaining the beneficial charge/discharge efficiency improvements from metal doping.
Solution Approach 2:
The patent uses base substances (carboxymethyl cellulose, starch, or hydroxides) as intermediary components that mediate between the metal-doped silicon-based oxide and the slurry environment. These intermediaries neutralize harmful reactions and maintain proper slurry rheology, enabling the production of high-quality electrodes with improved charge characteristics.
3Quantity of substance
If silicon-based active material is used, then higher capacity than carbon-based material is achieved, but volume expansion/contraction and irreversible capacity increase
Solution Approach 1:
The patent employs composite materials by combining silicon-based active material with metal dopants (such as Al, Mg, or Ca) and base substances. This composite structure allows the silicon-based material to deliver high capacity while the metal dopants and base components constrain volume expansion/contraction and reduce irreversible capacity loss during charging and discharging cycles.
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 approach enhances the discharge capacity, initial efficiency, and lifespan of the battery by maintaining stable slurry viscosity and preventing damage to binders, resulting in improved performance and longevity.
Implementation Method 1
when the negative electrode slurry has a pH of 10 or more, Si of the active material reacts with a base (OH—) in the slurry to generate gas and to change rheological properties of the slurry
Implementation Method 2
In order to solve the above problems, a method of adding an acid including Al, B, Zn or Zr in a process of manufacturing the negative electrode slurry has been proposed
Data Source
AI summary
A negative electrode, a method of manufacturing a negative electrode, a negative electrode slurry, and a secondary battery including the negative electrode are disclosed. The negative electrode includes a negative electrode current collector and a negative electrode active material layer on a surface of the negative electrode current collector. The negative electrode active material layer includes a silicon-containing active material. The silicon-containing active material comprises silicon-containing particles including SiOx, wherein 0<x<2, and Li. The negative electrode includes 0.05 part by weight or more and 1.5 parts by weight or less of one or more element selected from the group consisting of aluminum, boron, zinc and zirconium, based on 100 parts by weight of a total weight of the negative electrode active material layer. The negative electrode includes a structure where one or more element selected from the group consisting of aluminum, boron, zinc and zirconium are bound to oxygen.