Silicon Thin Film Anode with Carbon Coating for Lithium Battery
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Solution Overview
Problem
Conventional silicon thin film anodes for lithium secondary batteries face challenges in maintaining cycle characteristics and capacity due to structure variations caused by volume changes during charging and discharging, leading to separation from the collector and decreased performance.
Innovation Solution
A silicon thin film anode structure comprising a metal collector, an anode active material layer with a carbon coating, and an interface stabilizing layer formed by reacting metallic and silicon components, along with an optional metallic buffer layer, to enhance stability and prevent volume changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a conventional silicon thin film anode structure is used, then the battery can achieve high energy density, but the silicon layer separates from the collector due to volume changes during charging and discharging, leading to decreased capacity and cycle performance
Solution Approach 1:
The patent applies a carbon coating layer (thin film) over the silicon anode active material layer. This carbon shell accommodates the volume expansion and contraction of silicon during lithium insertion and extraction, preventing structural degradation and maintaining electrical contact with the collector, thus preserving both energy density and cycle performance
Solution Approach 2:
The patent creates a composite structure combining silicon (high capacity) with carbon (structural stability and conductivity). The silicon-carbon composite maintains the high energy density benefit of silicon while the carbon component provides mechanical integrity and electrical conductivity throughout charge-discharge cycles, resolving the contradiction between energy density and cycle performance
2Use of energy by moving object
If a conventional silicon thin film anode structure is used, then the battery can achieve high energy density, but structure variation occurs due to volume change, causing separation from the collector
Solution Approach 1:
The carbon coating layer acts as a flexible shell that conforms to the changing volume of the silicon core during lithiation and delithiation. This flexible enclosure maintains structural integrity while accommodating volume changes, preventing the silicon from detaching from the collector and maintaining both energy density and structural stability
Solution Approach 2:
The carbon coating layer serves as an intermediary between the silicon active material and the electrolyte/collector. It mediates the mechanical stress and volume changes, protecting the silicon structure while maintaining electrical conductivity and preventing direct contact issues that would cause separation and loss of energy density
3Use of energy by moving object
If a conventional silicon thin film anode structure is used, then the battery can achieve high energy density, but capacity decreases gradually due to silicon layer separation
Solution Approach 1:
The carbon coating layer prevents silicon layer separation by providing continuous mechanical support and electrical conductivity throughout charge-discharge cycles. This maintains intimate contact between the high-capacity silicon and the current collector, ensuring that the theoretical capacity of silicon is fully realized and maintained over time, preserving both energy density and usable capacity
Solution Approach 2:
The silicon-carbon composite structure combines the high capacity of silicon with the structural stability and conductivity of carbon. This composite ensures that the high energy density potential of silicon is fully utilized without the capacity fade caused by separation, maintaining both high energy density and stable capacity delivery
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 solution effectively maintains the anode's capacity and cycle performance by minimizing volume changes, preventing separation from the collector, and ensuring stable conductivity, resulting in improved cycle efficiency and extended lifespan.
Implementation Method 1
by reacting the metallic component with the silicon component in an annealing manner
Implementation Method 2
reacting the metallic component with the silicon component in an annealing manner to form an interface stabilizing layer
Implementation Method 3
a carbon coating layer covering the anode active material layer
Data Source
AI summary
Disclosed are a silicon thin film anode for a lithium secondary battery having enhanced cycle characteristics and capacity and a preparation method thereof. A preparation method for a silicon thin film anode for a lithium secondary battery, comprises: preparing a collector including a metal; forming an anode active material layer including a silicon on the collector; forming one or more interface stabilizing layer, by annealing the collector and the anode active material layer under one of an inert atmosphere, a reduced atmosphere, and a vacuum atmosphere to react a metallic component of at least one of the collector and the anode active material layer with a silicon component of the anode active material layer at an interface therebetween; and forming a carbon coating layer on the anode active material layer by performing an annealing process in a hydrocarbon atmosphere.