Metal-Doped SiOx Anode Layers for Swelling and Resistance Control
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Solution Overview
Problem
Lithium secondary batteries with silicon-based anodes face issues of increased resistance and potential short circuits due to side reactions with the electrolyte and significant volume contraction and expansion during charging and discharging, which reduce battery life and rapid charging characteristics.
Innovation Solution
An anode structure is developed with a first silicon-based anode mixture layer doped with a metal element and a second carbon-coated silicon-based anode mixture layer, where the second layer has a higher content and smaller particle size to minimize side reactions and expansion, while the first layer has a lower content and larger particle size to prevent detachment, both including graphite and conductive agents for improved conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based anode active material is used to increase capacity, then energy density is improved, but side reactions with electrolyte increase resistance
Solution Approach 1:
A metal element (such as Mg, Li, Ca, Al, Fe, Ti, or V) is introduced as an intermediary substance doped into the silicon-based anode active material. This metal element acts as a mediator that reduces the direct side reactions between the silicon-based material and the electrolyte, thereby suppressing resistance increase while maintaining high capacity.
Solution Approach 2:
The invention uses composite materials by combining silicon-based anode active material with metal elements to create a new composite structure. This composite material (SiOx doped with metal element) exhibits both high capacity characteristics of silicon and reduced reactivity with electrolyte, resolving the contradiction between energy density and resistance.
2Quantity of substance
If silicon-based anode active material is used to increase capacity, then energy density is improved, but volume contraction and expansion cause short circuits and cracks
Solution Approach 1:
The invention changes the physical and chemical parameters of the silicon-based material by doping it with metal elements and controlling particle size distribution. This parameter modification allows the material to accommodate volume changes during charging and discharging without developing cracks or causing short circuits, while maintaining high energy density.
Solution Approach 2:
The invention applies different characteristics to different parts of the anode structure by using a dual-layer configuration where the first layer contains SiOx doped with metal element and the second layer contains carbon-coated SiOx with controlled particle sizes. This local differentiation allows each layer to address specific issues: the first layer provides structural stability while the second layer enhances capacity.
3Stability of the object's composition
If particle size is reduced to suppress expansion, then volume stability is improved, but side reactions with electrolyte increase
Solution Approach 1:
The invention applies different particle size characteristics to different layers: the first layer uses SiOx doped with metal element with larger particle sizes (2.5 μm or more) for volume stability, while the second layer uses carbon-coated SiOx with smaller particle sizes for high capacity. This local differentiation resolves the contradiction between volume stability and resistance.
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 configuration effectively suppresses side reactions and expansion, enhancing room temperature and high-temperature lifespan characteristics and rapid charging capacity retention rates, thereby improving the overall performance of lithium secondary batteries.
Implementation Method 1
the first silicon-based anode active material is SiOx doped with a metal element
Implementation Method 2
The second silicon-based anode active material may be carbon-coated SiOx
Implementation Method 3
capable of suppressing short circuits and cracks in the active material occurring due to an increase in an amount of contraction and expansion of volume during charging and discharging
Data Source
Figure 1
AI summary
The disclosed technology relates to an anode for a lithium secondary battery and a lithium secondary battery including the same, the anode for a secondary battery including: an anode current collector; a first anode mixture layer including a first silicon-based anode active material on at least one surface of the anode current collector; and a second anode mixture layer including a second silicon-based anode active material on the first anode mixture layer, wherein the first silicon-based anode active material is SiOx(0≤x<2) doped with a metal element.