A method for producing clean black mass, anode or cathode for subsequent recycling is provided, the method comprising subjecting an intact battery to a shredding process to produce an aggregate, wherein the smallest particle generated is between 2.5 percent and 40 percent of original battery size. Also provided is a shredder for minimizing aggregation of whole batteries, the shredder comprising a shaft defining a longitudinal axis and a latitudinal axis; and a plurality of teeth disposed on said knives which fit on said shaft at an angle to the latitudinal axis selected from 15 degrees and 45 degrees, wherein the teeth have a first proximal end integrally molded to the shaft and a second free distal end.