Porous Silicon Anode Material for Volume-Stable Lithium Batteries
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Solution Overview
Problem
Silicon-based negative electrode active materials experience significant volume expansion during charging and discharging, leading to disconnection of the conductive path and deterioration of battery performance, limiting their commercialization in high-capacity lithium secondary batteries.
Innovation Solution
A porous silicon-based active material is prepared by etching crushed silicon with an alkaline solution, adjusting the specific surface area and tap density to 5-80 m²/g and 0.2-0.8 g/cm³, respectively, to enhance lithium intercalation and deintercalation reactions and mitigate volume change.
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 rapidly expands during charging causing conductive path disconnection and battery characteristic deterioration
Solution Approach 1:
The patent applies porous silicon-based compound as the negative electrode active material. The porous structure provides internal void space that can accommodate volume expansion during lithiation, preventing particle cracking and conductive path disconnection. This allows the use of high-capacity silicon-based materials while maintaining electrode integrity and battery reliability throughout charge-discharge cycles.
Solution Approach 2:
The patent employs composite silicon-based compounds combining silicon with other materials (such as carbon matrices or metal oxides). This composite structure provides mechanical support and conductive pathways that accommodate silicon's volume expansion while maintaining electrical conductivity and structural integrity, thereby preserving battery performance and reliability.
2Quantity of substance
If silicon-based compound with high capacity is used, then energy density is improved, but volume expansion causes particle stress and service life reduction
Solution Approach 1:
The porous structure of the silicon-based compound provides internal buffer space that absorbs volume expansion stress during charging. This prevents particle cracking and structural degradation, thereby extending the service life of the battery while maintaining high energy density from the silicon-based active material.
3Stability of the object's composition
If thin film coating is applied to suppress volume expansion, then volume change is reduced, but battery performance deteriorates
Solution Approach 1:
Instead of applying thin film coatings that may impede lithium ion transport and deteriorate performance, the patent utilizes the intrinsic porous structure of the silicon-based compound itself. This porous architecture provides volume stability through internal void space while maintaining open pathways for lithium ion diffusion, thereby preserving battery performance.
4Reliability
If particle diameter is adjusted to prevent conductive path disconnection, then conductive path integrity is improved, but manufacturing complexity increases
Solution Approach 1:
The patent utilizes porous silicon-based compounds with optimized particle morphology that inherently maintain conductive path integrity. The porous structure and controlled particle size distribution are achieved through a single-step synthesis process, avoiding the need for multiple post-processing steps such as coating or assembly operations, thereby simplifying manufacturing while ensuring conductive path stability.
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 porous structure improves the uniformity of lithium reactions, reduces stress on the particles, and extends the service life of the battery by buffering volume changes, maintaining the integrity of the conductive path.
Implementation Method 1
etching the surface of a crushed silicon-based active material itself through an alkaline solution treatment
Implementation Method 2
a negative electrode active material for intercalating and de-intercalating lithium ions from the positive electrode
Data Source
Figure 1~3
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.