| CPC H01M 10/0468 (2013.01) [H01M 10/0525 (2013.01); H01M 10/0587 (2013.01); H01M 50/121 (2021.01); H01M 50/124 (2021.01); H01M 50/131 (2021.01)] | 3 Claims |
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1. A secondary battery comprising:
a casing having an internal space;
an electrode assembly inserted into the casing with an electrolyte;
a finishing tape covering the electrode assembly and undergoing a volumetric expansion when reacting with the electrolyte; and
a cap plate coupled to an upper portion of the casing and sealing the casing,
wherein the electrode assembly comprises a positive electrode plate, a negative electrode plate, and a separator disposed therebetween,
the positive electrode plate is connected to a positive electrode lead, and
the negative electrode plate is connected to a negative electrode lead,
wherein the finishing tape comprises a microsphere, and the microsphere includes a shell formed of a thermoplastic resin and an encapsulating member completely encapsulated by the shell and including hydrocarbon, and
wherein the microsphere has a diameter in a range of 15 μm to 50 μm before contacting the electrolyte,
wherein the finishing tape comprises:
a first layer formed of a resin and forming a substrate; and
a second layer formed on at least one side of the first layer and including the microsphere,
wherein the second layer is a microsphere structure including microspheres,
wherein the second layer is disposed facing the electrode assembly,
wherein the finishing tape expands in volume in a direction of the electrode assembly,
wherein a thickness of the second layer is increased by the volumetric expansion, and
wherein a difference in thickness of the finishing tape before and after contacting with the electrolyte is larger than a thickness of the first layer and smaller than a thickness of the second layer before expansion.
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