REF: https://data2.manualslib.com/pdf2/49/4888/488709-lenovo/ideapad_n585.pdf?c117d49e930adbf96844766ee5d0fc67
The above link is to the hardware maintenance manual for your laptop. The parts list does not list a CMOS battery part number, nor can I find a reference to the CMOS clearing/battery. However, you can use the above manual to remove the motherboard and look for the battery.