Silicon Anode Crystal Plane Etching for Longer Cycle Life
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Solution Overview
Problem
Silicon-based negative electrode active materials face issues with volume expansion during charging, leading to disconnection of conductive paths and poor battery performance, and existing solutions to mitigate this problem often result in further deterioration of battery characteristics.
Innovation Solution
A silicon-based active material is prepared by etching the crystal planes using an alkali solution to adjust the specific surface area of the (220) and (111) crystal planes, resulting in improved lithium ion mobility and reduced stress, with the (220) plane having a specific surface area of 1-30 m²/g and the (111) plane having a specific surface area of 0.1-5 m²/g.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based compound is used as negative electrode active material to increase capacity, then discharge capacity is improved, but volume expansion occurs during charging leading to disconnection of conductive path
Solution Approach 1:
The silicon-based compound particles are divided into smaller granules through pulverization, creating multiple smaller units instead of large particles. This segmentation reduces the overall volume expansion impact on conductive paths and maintains better electrical connectivity during charging cycles.
Solution Approach 2:
The invention creates a non-uniform particle size distribution with a specific Dv10 value range (0.1-3 μm) to optimize local properties. The fine particles provide high capacity while the controlled size distribution ensures adequate conductive path maintenance, creating different functional zones within the electrode structure.
2Stability of the object's composition
If measures are taken to suppress volume expansion such as coating with thin film or adjusting particle diameter, then volume expansion is reduced, but battery performance deteriorates
Solution Approach 1:
The invention optimizes the particle size distribution parameters, specifically controlling the Dv10 value within 0.1-3 μm range, to achieve the right balance between volume stability and performance. By adjusting this critical parameter, the electrode maintains structural integrity while preserving high discharge capacity without requiring additional coating layers.
3Ease of manufacture
If pulverized silicon-based active material with plate-like surface composed of 111 crystal plane is used, then preparation is simple, but lithium ion mobility is low causing poor battery service life
Solution Approach 1:
The invention changes the crystal plane orientation parameter by controlling the pulverization process to reduce the proportion of 111 crystal planes on the particle surface. This parameter change in surface crystallography directly improves lithium ion mobility while maintaining the simplicity of the pulverization preparation method.
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 adjusted crystal plane distribution enhances lithium intercalation and deintercalation reactions, reducing particle cracking and improving the service life maintenance rate of the electrode.
Implementation Method 1
A silicon-based active material is prepared by etching the crystal planes using an alkali solution to adjust the specific surface area of the (220) and (111) crystal planes
Implementation Method 2
The adjusted crystal plane distribution enhances lithium intercalation and deintercalation reactions, reducing particle cracking and improving the service life maintenance rate of the electrode
Data Source
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AI summary
The present application relates to a negative electrode active material, a method for preparing the negative electrode active material, a negative electrode composition, a negative electrode for a lithium secondary battery including the same, and a lithium secondary battery including the negative electrode.