Dry Anode Film Core-Shell Structure for Low-Resistance Li Batteries
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Solution Overview
Problem
Existing lithium batteries face challenges in achieving high energy density and reduced weight due to the use of solvents in electrode manufacturing, leading to high internal resistance and poor mechanical strength.
Innovation Solution
A dry anode film with a core/shell structure is developed, comprising a carbon-based material and a silicon-based active material core, coated with a composite of metal oxide and carbon-based materials, which are uniformly mixed to reduce internal resistance and improve mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a slurry including a solvent is used to manufacture the electrode, then the electrode can be manufactured with conventional methods, but an excessive amount of solvent is used during manufacturing leading to high internal resistance
Solution Approach 1:
The patent changes the manufacturing method from wet slurry coating to dry powder coating, fundamentally altering the process parameters to eliminate solvent usage. This parameter change resolves the contradiction by maintaining ease of manufacture through conventional coating equipment while eliminating the harmful solvent that causes high internal resistance
Solution Approach 2:
The patent extracts and removes the solvent component from the electrode manufacturing process entirely. By using a dry method that excludes organic solvents, the invention eliminates the source of high internal resistance while still achieving proper electrode formation through direct powder coating on the current collector
2Ease of manufacture
If a slurry including a solvent is used to manufacture the electrode, then the electrode can be manufactured with conventional methods, but the mechanical strength is poor
Solution Approach 1:
The patent changes the binding mechanism from solvent-based adhesion to dry mechanical interlocking and van der Waals forces. The dry powder coating method creates stronger mechanical bonds between particles and the current collector, improving mechanical strength while eliminating solvent-related weaknesses
Solution Approach 2:
The patent uses a composite structure with core/shell anode active material particles where the shell provides structural integrity. This composite material approach enhances mechanical strength at the particle level, which translates to improved overall electrode mechanical properties
3Quantity of substance
If silicon-based active material is used to increase capacity, then high energy density is achieved, but volume changes during charging and discharging occur
Solution Approach 1:
The patent encapsulates silicon-based active material particles within a shell structure, creating a core/shell configuration where the core contains the high-capacity silicon and the shell provides structural stability. This nesting approach allows the silicon to expand and contract during charging/discharging while the shell maintains overall particle integrity and prevents volume changes at the macro level
Solution Approach 2:
The patent applies different material properties to different parts of the anode active material particle. The core region contains silicon for high capacity while the shell region provides structural stability and controlled porosity. This local differentiation of material quality allows simultaneous achievement of high capacity and volume stability
4Device complexity
If the anode active material is directly coated on the current collector, then the manufacturing process is simplified, but side reactions occur reducing efficiency
Solution Approach 1:
The patent applies a shell coating with specific local properties to the anode active material particles before coating them on the current collector. This shell provides a controlled interface that prevents direct contact between the active material and electrolyte, eliminating side reactions while maintaining the simplicity of direct coating methodology
Solution Approach 2:
The shell structure acts as an intermediary layer between the anode active material and the electrolyte. This intermediate shell prevents direct interaction that causes side reactions, while still allowing ionic transport for electrochemical function, thereby improving initial efficiency without adding complex manufacturing steps
Data Source
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Figure 3A~3B
AI summary
Provided are dry negative electrode film, and a dry negative electrode and a lithium battery comprising same, the dry negative electrode film comprising dry negative electrode active material, and a dry binder. The dry negative electrode active material contains composite negative electrode active material comprising cores, and shells on the surface of the cores. Each core comprises carbon-based material, a mixture of carbon- and silicon-based material, a composite of carbon- and silicon-based material, or a combination thereof. Each shell contains a composite of one or more types of first metal oxide and first carbon-based material. The first metal oxide is in a carbon-based material matrix and is expressed by the chemical formula MaOb (0<a≤3, 0<b< 4, and when a is 1, 2, or 3, b is not an integer) where M is at least one metal selected from Groups 2 to 16 in the periodic table.