Low-density amorphous silicon anode for lithium-ion batteries
Solution Overview
Problem
Conventional lithium-ion battery anodes using carbon materials suffer from low energy density and electric mileage due to low specific capacity, while silicon-based anodes exhibit rapid capacity fade and poor durability due to volume expansion upon lithium insertion.
Innovation Solution
An anode active material made from low-density amorphous silicon is developed, with a method involving a solution of low-density silicon, a conductive material, and a binder, coated onto an electrode substrate without pressing to preserve inter-particle porosity, allowing controlled expansion and maintaining dimensional stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If graphite is used as anode material, then stability and cycle-life are improved, but specific capacity and energy density deteriorate
Solution Approach 1:
The invention changes the density parameter of silicon from conventional high-density to low-density form. This parameter change allows the silicon to accommodate volume expansion during lithium insertion without particle cracking, while maintaining high specific capacity (3500-4400 mAh/g) and improving cycle-life through preserved structural integrity.
Solution Approach 2:
The invention creates a composite structure by combining low-density silicon particles with a binder material. This composite approach allows the silicon to provide high capacity while the binder maintains structural coherence during expansion, resolving the contradiction between capacity and stability.
2Quantity of substance
If silicon is used as anode material, then specific capacity and energy density are improved, but dimensional stability and cycle-life deteriorate due to volume expansion
Solution Approach 1:
The invention changes the density parameter of silicon from conventional high-density to low-density form. This parameter change allows the silicon to accommodate volume expansion during lithium insertion without particle cracking, while maintaining high specific capacity (3500-4400 mAh/g) and improving cycle-life through preserved structural integrity.
Solution Approach 2:
The invention utilizes the porous structure inherent in low-density silicon to accommodate volume expansion. The porous architecture provides internal space for expansion without external pressure, preventing particle cracking and maintaining dimensional stability during charge-discharge cycles.
3Quantity of substance
If high-density silicon is used, then active material loading is improved, but inter-particle porosity and expansion accommodation deteriorate
Solution Approach 1:
The invention changes the density parameter of silicon from conventional high-density to low-density form. This parameter change allows the silicon to accommodate volume expansion during lithium insertion without particle cracking, while maintaining high specific capacity (3500-4400 mAh/g) and improving cycle-life through preserved structural integrity.
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 low-density silicon anode achieves a higher specific capacity than conventional graphite and maintains cycle life and durability by accommodating volume expansion within the electrode structure, enhancing energy density and electric mileage.
Implementation Method 1
silicon's high theoretical lithium storage capacity of 3500 to 4400 mAh/g. However, silicon active materials suffer from rapid capacity fade, poor cycle life and poor durability. One primary cause of this rapid capacity fade is the massive volume expansion of silicon (typically up to 300%) upon lithium insertion.
Implementation Method 2
The low bulk density of the amorphous silicon provides inter-particle porosity that allows the silicon to expand upon lithiation without increasing the thickness of the anode active material layer by a large amount.
Data Source
AI summary
An anode active material for a lithium-ion battery cell comprises low density silicon. The anode active material is provided in an anode for a lithium-ion battery. Also disclosed are methods of making the anode active material.