Over-current protection device

An over-current protection device, comprising:

• a first electrode layer;
• a second electrode layer;
• and
• a positive temperature coefficient (PTC) material layer laminated between the first electrode layer and the second electrode layer, the PTC material layer comprising:
• a polymer matrix comprising a fluorine-free polyolefin-based polymer and a fluoropolymer, wherein the total volume of the PTC material layer is calculated as 100%, and the fluorine-free polyolefin-based polymer accounts for 41-55% and the fluoropolymer accounts for 5-7% by volume of the PTC material layer;
• a conductive filler dispersed in the polymer matrix, thereby forming an electrically conductive path in the PTC material layer;
• and
• a titanium-containing inner filler dispersed in the polymer matrix, wherein the titanium-containing inner filler has a compound represented by a general formula (I):
• MTiO3 (I)
• wherein the M represents transition metal or alkaline earth metal, and the total volume of the PTC material layer is calculated as 100%, and the titanium-containing inner filler accounts for 1-9% by volume of the PTC material layer.