Surface Texturing Method for Polymer Sheets in All-Solid-State Batteries

Solid Electrolyte Interface Expansion Process Combining Sub-Zero Freezing and Intermittent Fiber Laser Irradiation

This technology maximizes the effective contact area between active materials and solid electrolytes and enhances ionic conductivity by using laser irradiation to form micro-patterns, such as dimples, on the surface of polymer sheets that include solid electrolytes and anodes for all-solid-state batteries.

Unlike liquid electrolytes, the solid electrolytes in all-solid-state batteries are difficult to bond perfectly with active material particles, resulting in a small interfacial contact area. Consequently, this has led to limitations such as low ionic conductivity and difficulty in securing sufficient pathways for lithium-ion movement.

This technology involves freezing the polymer sheet to approximately -15°C and performing a process of irradiating a fiber laser at low power and high speed three times, followed by a cooling period of at least 10 minutes. By repeating this cycle five times for a total of 15 irradiations, precise surface patterns are etched without thermal damage to the polymer. It can be applied to polymer-based solid electrolyte sheets, polymer binder-based anode sheets, and pilot-scale all-solid-state cell manufacturing lines, allowing for non-contact control of pattern depth and the implementation of various textures without the need for mold changes.

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Key Features:

• A step of freezing the polymer sheet at a predetermined temperature of approximately -15°C prior to texturing
• A focus alignment step of setting the distance between the polymer sheet and the laser focus to 350–360mm
• A step of forming patterns of a specific depth by repeating a cycle of three laser irradiations followed by a pause of at least 10 minutes, five times
• Fiber laser operated at a scanning speed of 40–50mm/s, a frequency of 100KHz, and a pulse width of 50ns

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