Amorphous Silicon Anode Composition for Capacity and Cycle-Life Retention
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Solution Overview
Problem
The demand for rechargeable batteries with high capacity and light weight has increased due to the rapid development of electronic devices and electric vehicles, but existing negative electrode active materials struggle to meet these requirements in terms of energy density and cycle-life.
Innovation Solution
A negative electrode active material comprising amorphous nano-sized Si particles, with a size range of 1 nm to 20 nm, and optionally coated with an amorphous carbon layer, is developed. This material is prepared through a process involving a porous amorphous carbon matrix, silane-coupling reaction, oxidation treatment, metal reduction, and chemical vapor deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional negative electrode active materials are used, then the battery structure is simple and easy to manufacture, but the energy density and cycle-life are insufficient
Solution Approach 1:
The patent uses composite materials by combining amorphous silicon particles with a carbon coating layer. The silicon provides high capacity while the carbon layer provides structural stability and conductivity, resolving the contradiction between high performance and material complexity through a well-defined composite structure.
Solution Approach 2:
The negative electrode is segmented into multiple components: amorphous silicon particles, carbon coating layer, and binder. This segmentation allows each component to perform its specific function optimally, with silicon providing capacity, carbon providing stability, and binder providing structural integrity, thus improving cycle-life while maintaining manufacturability.
2Quantity of substance
If high-capacity negative electrode active materials are used, then the energy density increases, but the structural integrity deteriorates during charge and discharge cycles
Solution Approach 1:
The carbon coating layer is applied beforehand to the amorphous silicon particles to provide a protective cushion that accommodates volume expansion during lithium insertion. This pre-established protective layer prevents structural degradation while maintaining high lithium storage capacity, resolving the contradiction between capacity and structural integrity.
Solution Approach 2:
The carbon coating layer acts as a flexible shell that can accommodate the volume changes of amorphous silicon during charge and discharge cycles. This flexible coating maintains structural integrity while allowing the high-capacity silicon to function, thus resolving the contradiction between capacity and stability.
3Duration of action of stationary object
If amorphous nano-sized Si particles are used, then the cycle-life retention is enhanced, but the manufacturing process becomes more complex
Solution Approach 1:
The carbon coating is applied preliminarily to the amorphous silicon particles before electrode fabrication. This preliminary action ensures that the structural benefits of carbon coating are achieved while allowing subsequent manufacturing steps to proceed with standard electrode processing techniques, thus improving cycle-life retention while minimizing manufacturing complexity.
Solution Approach 2:
The patent controls the particle size parameter of silicon to the nanometer range and maintains amorphous structure, which fundamentally changes the mechanical properties to accommodate volume expansion. This parameter change enables long cycle-life while using a manufacturing process that is otherwise similar to conventional materials, resolving the contradiction between durability and ease of manufacture.
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 amorphous Si-based negative electrode active material exhibits improved high-capacity characteristics and enhanced cycle-life retention, effectively addressing the limitations of existing materials by maintaining structural integrity during charge and discharge cycles.
Implementation Method 1
adding a porous amorphous carbon matrix to a liquid silane compound to prepare a mixture
Implementation Method 2
performing a silane-coupling reaction on the defoamed product to prepare a silica-carbon composite
Implementation Method 3
performing a silane-coupling reaction on the defoamed product to prepare a silica-carbon composite
Implementation Method 4
performing an oxidation treatment on the silica-carbon composite to remove the porous amorphous carbon matrix
Implementation Method 5
subjecting the SiO2 structure to a metal reduction process to prepare a Si structure
Implementation Method 6
forming a carbon layer on the Si structure by performing a chemical vapor deposition process
Implementation Method 7
forming a carbon layer on the Si structure by performing a chemical vapor deposition process
Data Source
AI summary
A negative electrode active material, a method of preparing the negative electrode active material, and a rechargeable lithium battery that includes the negative electrode active material, the negative active material includes amorphous nano-sized Si particles and the rechargeable lithium battery includes a negative electrode including the negative electrode active material, a positive electrode and an electrolyte.