Anode for secondary battery and jelly-roll type electrode assembly including anode
An anode for a secondary battery and a jelly-roll type electrode assembly including the anode. The anode includes an anode current collector that satisfies a creep rate condition represented by Formula 1 within a certain range. When the anode is applied to the jelly-roll type electrode assembly, deformation and/or expansion of electrode assembly can be controlled, even if it contains a silicon-containing anode active material because the stress generated from the exterior is significantly low. It is possible to ensure excellent safety because the stress accumulated in the anode current collector is greatly reduced, which lowers the risk of an internal disconnection of the electrode assembly.
1 . An anode for a secondary battery comprising:
an anode current collector; and
an anode layer mixture present on at least one surface of the anode current collector;
wherein the anode mixture layer comprises an anode active material comprises a silicon material, artificial graphite, and carbon black,
wherein the anode current collector satisfies a creep rate of Formula 1 below by falling in between 27 μm/sec to 40.1 μm/sec, wherein the creep rate is measured under a tensile force condition of 22±2° C. and 300 MPa:
C 60 −C 2/58 [Formula 1]
wherein in Formula 1,
C60 represents a change in length of the anode current collector 60 seconds after the tensile force has been applied, and
C2 represents a change in length of the anode current collector 2 seconds after the tensile force has been applied,
wherein the anode current collector has a tensile strength of 33.6 kg/mm 2 to 34.2 kg/mm 2 ,
wherein the anode current collector comprises copper,
wherein the anode current collector has an elongation rate of 11 to 15%, and
wherein the silicon material is present from 1 to 40 parts by weight with respect to 100 parts by weight of the anode mixture layer.
2 . The anode for the secondary battery of claim 1 , wherein the silicon material of the anode active material comprises one or more silicon-containing materials selected from the group consisting of Si, SiC, and SiOz, wherein 0.5≤z≤2.5.
3 . The anode for the secondary battery of claim 1 , wherein the anode current collector has an average thickness of 1 μm to 500 μm.
4 . The anode for the secondary battery of claim 1 , wherein the elongation rate of the anode current collector is in a range of 11.8 to 12.1.
5 . A jelly-roll type electrode assembly comprising:
a cathode;
the anode according to claim 1 ; and
a separation membrane that is interposed between the cathode and anode,
wherein the cathode, the separation membrane, and the anode are stacked in a winding structure.
6 . A cylindrical secondary battery comprising the jelly-roll type electrode assembly according to claim 5 .