The crusher is positioned after the shredding step in the spent battery recycling process, serving as secondary or tertiary crushing equipment. Its function is to further reduce the coarse fragments obtained from shredding into finer particles, thereby achieving complete liberation of the positive and negative electrode active materials from the copper and aluminum foils. The most commonly used type is the hammer crusher, which relies on high-speed rotating hammers to impact the material. The product particle size can be controlled to below six millimetres or even finer to meet the requirements of subsequent sorting or leaching operations. The crusher must be operated in conjunction with an enclosed conveying system, a dust collection system, and an inert gas protection system to ensure safe operation. During production, the equipment current and material temperature should be monitored, and the hammer wear should be inspected regularly to maintain stable crushing performance. At present, most industrial lines adopt PLC-based automatic control to achieve continuous production.