Porous Silicon Anode Structure to Limit Pulverization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium-ion batteries based on silicon anodes face challenges such as manufacturing complexity, fragility, and limited market impact due to issues like volume expansion, pulverization, and handling stresses, which hinder their widespread adoption despite silicon's high theoretical storage capacity.
Innovation Solution
The development of an anode structure featuring a current collector with a metal chalcogenide surface layer, including sulfur or selenium, and a lithium storage layer that is continuous and porous, reducing nanostructure reliance and simplifying the manufacturing process while enhancing durability and charging rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon is used as anode material to replace carbon-based anodes, then charge capacity is improved, but volume expansion and pulverization occur during lithium insertion and extraction
Solution Approach 1:
The silicon anode is divided into discrete silicon particles rather than using bulk silicon layers. This segmentation allows each particle to independently accommodate volume expansion during lithiation, preventing crack propagation and maintaining structural integrity while preserving high charge capacity.
Solution Approach 2:
A flexible carbon coating layer is applied around the silicon particles. This thin film shell accommodates the volume expansion and contraction of silicon during lithium insertion and extraction, preventing pulverization and maintaining electrical connectivity while allowing the silicon to achieve its high theoretical capacity.
2Reliability
If nano- or micro-structured silicon is used to reduce pulverization, then stability is improved, but manufacturing complexity increases
Solution Approach 1:
Instead of directly fabricating complex nanostructures through multiple deposition and etching steps, the invention uses a simpler approach by forming silicon particles through a single CVD deposition process on a template, which is then removed. This copying method achieves the desired nanostructure with reduced manufacturing complexity and improved reproducibility.
Solution Approach 2:
The complex nanowire template formation process is eliminated entirely. Instead, a simple porous layer is deposited first, then silicon is grown on it, and finally the template is removed by dissolution. This extraction of the complex template formation step significantly simplifies the manufacturing process while maintaining the benefits of nanostructured silicon.
3Ease of manufacture
If conventional carbon-based anodes are used, then manufacturing is simple, but charge capacity is limited to ~370 mAh/g
Solution Approach 1:
The anode uses a composite structure combining silicon particles with a carbon coating and embedded in a carbon matrix. This composite material provides both the high charge capacity of silicon (up to 4200 mAh/g theoretical) and the manufacturing simplicity and structural stability of carbon-based materials, achieving superior performance while remaining manufacturable.
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 solution results in anodes that are easier to manufacture, more robust, and capable of high charge capacity with improved stability at aggressive charging rates, offering a more reproducible and efficient energy storage solution.
Implementation Method 1
insertion and extraction of lithium into the silicon matrix causes significant volume expansion (>300%) and contraction
Implementation Method 2
a lithium storage layer overlaying the surface layer, where the surface layer includes a metal chalcogenide including at least one of sulfur or selenium
Data Source
AI summary
Methods of making an anode for a lithium-based energy storage device such as a lithium-ion battery are disclosed. Methods may include providing a current collector. The current collector may include an electrically conductive layer and a surface layer overlaying over the electrically conductive layer. The surface layer may have an average thickness of at least 0.002 μm. The surface layer may include a metal chalcogenide including at least one of sulfur or selenium. Methods may include depositing a continuous porous lithium storage layer onto the surface layer by a PECVD process. The continuous porous lithium storage layer may have an average thickness in a range of 4 μm to 30 μm and comprises at least 85 atomic % amorphous silicon.