Pre-Lithiated Silicon Anode for Stable High-Capacity Li Batteries
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Solution Overview
Problem
Silicon-based negative electrode materials for lithium secondary batteries face issues with mechanical stability due to volume changes during lithium ion intercalation and deintercalation, leading to increased initial irreversible capacity and reduced cycle life.
Innovation Solution
A negative electrode with a silicon-based active material comprising SiO x (0 ≤ x < 2) and Si nanoparticles, uncoated with carbon, is pre-lithiated on at least one surface, maintaining an average particle diameter of 1 nm or less, to minimize volume expansion and improve conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based negative electrode active material is used to increase discharge capacity, then energy density is improved, but mechanical stability deteriorates due to volume changes during lithium ion intercalation and deintercalation
Solution Approach 1:
The silicon-based negative electrode active material is divided into nanoparticles with an average particle diameter of 1 nm or less. This segmentation reduces the overall volume change impact on the electrode structure during lithium ion intercalation and deintercalation, thereby improving mechanical stability while maintaining high discharge capacity.
Solution Approach 2:
The particle size parameter of the silicon-based active material is changed to nanoscale (average particle diameter of 1 nm or less). This parameter change reduces the mechanical stress during volume expansion and contraction, improving structural stability while preserving the high capacity characteristics of silicon.
2Quantity of substance
If silicon-based negative electrode active material is used to increase discharge capacity, then energy density is improved, but initial irreversible capacity increases due to severe volume changes and surface side reactions
Solution Approach 1:
The silicon-based active material is segmented into nanoparticles with an average particle diameter of 1 nm or less. This reduces the surface area per unit volume and minimizes surface side reactions, thereby reducing initial irreversible capacity loss while maintaining high discharge capacity.
Solution Approach 2:
The particle size is changed to nanoscale (average particle diameter of 1 nm or less), which reduces the absolute surface area and the extent of surface side reactions during initial charging, thereby reducing initial irreversible capacity while preserving high discharge capacity.
3Stability of the object's composition
If carbon coating is applied to silicon-based active material to improve stability, then mechanical stability is improved, but particle diameter increases beyond 1 nm
Solution Approach 1:
Instead of applying a carbon coating layer that would increase particle diameter, the invention uses the silicon-based nanoparticles themselves as the functional material. The nanoparticles are designed to withstand volume changes without requiring protective coating, thereby maintaining the small particle diameter of 1 nm or less while achieving the required stability.
4Quantity of substance
If electrode loading is increased to improve energy density, then energy density is improved, but electrode resistance and cell resistance increase
Solution Approach 1:
The electrode is designed with a patterned structure that segments the active material into regions with optimized loading. The silicon-based nanoparticles are distributed in a pattern that increases the reaction surface area while controlling the loading density, thereby reducing resistance while maintaining high energy density.
Solution Approach 2:
The electrode structure transitions from a flat two-dimensional layout to a three-dimensional patterned structure. This dimensional change increases the effective reaction surface area and improves ion transport pathways, thereby reducing resistance while maintaining high energy density through optimized material distribution.
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 enhances the initial capacity and efficiency of the battery while extending its service life by reducing stress on the electrode structure during lithium reactions.
Implementation Method 1
a negative electrode active material layer comprising: a silicon-based negative electrode active material including SiOx (0 ≤ x < 2) and Si nanoparticles, uncoated with carbon
Implementation Method 2
the negative electrode active material layer is pre-lithiated on at least one surface
Data Source
Figure 1~2
AI summary
The present invention relates to an anode for a lithium secondary battery, a lithium secondary battery comprising same, and a manufacturing method for an anode for a lithium secondary battery, the anode comprising an anode active material layer comprising: a silicon-based anode active material containing SiOx (0≤x<2) and Si nanoparticles; an anode conductive material; and an anode binder, wherein the silicon-based anode active material is in a carbon-uncoated state, the Si nanoparticles having an average particle diameter (D50) of 1 nm or smaller, and at least one surface of the anode active material layer is pre-lithiated.