Anode for secondary batteries using pencil graphite, manufacturing method thereof, and lithium secondary battery using the same

Binder-free graphite anode formed by rubbing pencil lead onto textured foil

This technology is an electrode manufacturing process that creates a textured surface by mechanically grinding a metal current collector, then directly rubbing it with a pencil lead containing a mixture of graphite and silica-based clay to bond a graphene layer without the use of a binder.

Conventional processes using binders increase internal electrode resistance and reduce active surface area. Furthermore, they face limitations where the binder dissolves during charge/discharge cycles due to swelling, causing the active material to detach and leading to a decline in battery capacity and stability.

This technology involves grinding metal foil using equipment such as a ball mill to create a surface with an average roughness of 2–14㎛. By rubbing a pencil lead over this surface, a physically bonded multi-layer graphene structure is formed, achieving high electrical conductivity and a uniform SEI layer without the need for a binder. It can be applied to educational battery kits, low-cost small secondary batteries, and flexible electrode prototyping, allowing for the rapid production of anodes using simple tools without the need for slurry mixing or drying equipment.

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Key Features:

• A step of grinding metal foil to form a textured surface with an average roughness of 2 to 14㎛
• A step of forming a pencil graphite layer by rubbing a pencil containing silica-based clay and graphite onto the textured metal foil surface
• Grinding devices that create surface roughness on foil with a predetermined particle size, such as ball mills, vibration mills, planetary ball mills, tube mills, or jet mills
• A step of further rubbing the foil surface, on which the pencil graphite layer is formed, with graphene or carbon nanotube carbon structures

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