Lenovo often lists several part numbers, one is called "FRU p/n", on is called "ASM p/n", and occasionally the model number is just listed on the battery with no preface. Also on many Lenovo cartridges there is a red or orange circle with a number inside it (also may contain a + sign).
Examples of Lenovo Battery part numbers:
01AV458
45N1001
57++
70+
L17C4PH1
0A36302
OA36302