Discussed is a welding quality inspection apparatus that can include a measurement unit including a first resistance measurement member to measure a first resistance value by directly contacting a first measurement point and a second resistance measurement member to measure a second resistance value by directly contacting a second measurement point; and a control unit to judge that a welding defect occurs and sorts a defective item when the first resistance value or the second resistance value obtained from the measurement unit exceeds a threshold resistance value. The first measurement point may be positioned on a first electrode terminal exposed to an outside of the secondary battery, and the second measurement point may be positioned on the welding portion of the first electrode current collector provided inside the secondary battery.

A method for forming graphene-oxide (GO) embedded with gallium-iron alloy (galfenol) nanoparticles. The method includes submerging galfenol bulk material in a solution comprising deionized water and polyvinylpyrrolidone (PVP). The method includes ablating, a first time, the galfenol bulk material submerged in the solution with a laser. The method includes removing the galfenol bulk material from the solution after ablating with the laser. The method includes drying the galfenol bulk material after removing the galfenol bulk material from the solution. The method includes submerging galfenol bulk material in deionized water after drying the galfenol bulk material. The method includes ablating, a second time, the galfenol bulk material submerged in the deionized water and ablating a second time the galfenol bulk material submerged in the deionized water.