the aforementioned features and advantages of the invention as well as additional features and advantages thereof will be more clearly understood hereafter as a result of a detailed description of the following embodiments when taken conjunction with the drawings . the present invention provided an insulating ring 100 . according to an embodiment of the invention , fig2 shows a insulating ring 100 . the insulating ring 100 has a circular ring body 4 , a positioning member in the center for positioning a core rod 9 of the lithium ion battery . the positioning member comprises at least a positioning protruding part 8 . the positioning member is used to locate the core rod 9 of the cylindrical lithium ion battery ( not shown ). the insulating ring 100 has at least a tab hole 6 . while the insulating ring 100 is applied in the cylindrical lithium ion battery , the tab 11 is lead out at an end of the battery . two tab holes 6 may be set on the insulating ring at two lateral sides of the positioning protruding part 8 . if the tabs 11 are led out from two ends of the battery , one tab hole 6 can be set on the insulating ring 100 . the corresponding portion of insulating ring 100 under the protruding part 8 is equivalent to a supporting part 7 . a plurality of the protruding parts 8 may be formed on the circular ring body 4 . while there is one positioning protruding part , it is equivalent to a positioning hole or sleeve ( not shown ) to locate the battery core rod . while there are two positioning protruding parts 8 , it is equivalent to a positioning groove to locate the battery core rod 9 . while there are four ( or more ) positioning protruding parts , it is equivalent to a clamping component to locate the battery core rod 9 . in an embodiment of the invention , there are two positioning protruding parts 8 and the two protruding parts 8 form a positioning groove , thus it is easy for design and manufacture . the positioning protruding part 8 has a height of 1 - 3 mm , the thickness of which is about 0 . 2 - 0 . 5 times of the thickness of the insulating ring 100 . according to an embodiment of the invention , the positioning protruding part 8 may be integrally formed with the insulating ring 100 . in this case the whole insulating ring 100 can be formed by injection molding and it is very convenient for manufacture . further , a plurality of via holes 5 may be configured along a circumferential direction of the insulating ring for injecting electrolyte . according to some embodiments , the plurality of the via holes 5 are located along the circumferential direction of the insulating ring 100 at even intervals . the shape of the via holes 5 can be one selected from circle , sector , quadrangle , triangle , and circular - arc . while the insulating ring 100 is applied in the lithium ion batteries , the via holes 5 may be used for injecting electrolyte , which may improve the injecting efficiency of the electrolyte . as shown in fig6 a , according to an embodiment of the invention , the protruding part 8 may be substantially interference fitted with an outer wall of the core rod 9 . as shown in fig6 b , according to an embodiment of the invention , the protruding parts 8 are flexible formed to tightly press an outer wall of the core rod 9 when the core rod 9 is inserted therebetween . the present invention further provides a lithium ion battery comprising : a cylindrical shell , a battery core 10 , a core rod 9 , a insulating ring 100 and electrolyte . the battery core 10 is disposed in the shell . the battery core 10 is formed by coiling a positive plate , a separator and a negative plate . the core rod 9 is inserted in the center of the battery core 10 . the battery core 10 has a leading out tab 11 . as shown in fig3 and fig4 , the insulating ring 100 is the insulating ring 100 in the present invention . the core rod 9 matches the protruding part 8 of the insulating ring 100 . the positioning protruding part 8 fixes the core rod 9 to avoid movements of the core rod 9 and the tabs in the battery while the battery is impacted or vibrating . as shown in fig5 , the tab 11 is led out through the tab hole 6 of the insulating ring 100 , the hole 6 holds and locates the tab 11 so that the tab 11 will not move easily . as shown in fig2 , an insulating ring 100 is provided and the ring 4 has six via holes 5 ; the centers of the via holes 5 are located at the concentric circle of the insulating ring . the via holes 5 are located on the surface of insulating ring 100 at the same intervals . there may be a positioning member in the center of the insulating ring 100 . the positioning member comprises two sector - shaped positioning protruding parts 8 . the two sector - shaped protruding parts 8 are faced with each other , forming a positioning groove . the height of the sector - shaped positioning protruding part 8 is about 3 mm . the thickness of part 8 is about 0 . 2 times of the thickness of the insulating ring 100 . besides there are two tab holes 6 at two sides of the sector - shaped positioning protruding part 8 . while the insulating ring 100 is applied in a cylindrical lithium ion battery , it matches the battery core 10 . as shown in fig3 , the two sector - shaped protruding parts 8 forms a groove and the core rod 9 of the battery core 10 is fixed in the groove so that movement of the core rod 9 in the battery core 10 may be avoided . meanwhile , while the sector - shaped positioning protruding part 8 fixes the core rod 9 , the leading out tabs 11 of the battery core 10 penetrate through the tab hole 6 . as shown in fig4 , the tab hole 6 holds the tab 11 effectively to avoid movement of the tab 11 . therefore , while the battery is impacted by an outer force or vibrating , the protruding parts 8 forming a positioning groove holds the core rod 9 , the tab hole 6 holds and fixes the tab 11 . both core rod 9 and tab 11 will not easily move and will not easily contact with each other , so that short circuit caused by contact of the core rod 9 and tab 11 may be avoided . in this case , the safety performance of the cylindrical lithium ion batteries may be improved . it will be apparent to those skilled in the art that variations and modifications of the present invention may be made without departing from the scope or spirit of the present invention . therefore , it is to be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims . although specific terms are employed herein , they are used in a generic and descriptive sense only and not for purposes of limitation .