Tuning the Mn2+/Mn3+ ratio of ZnMn2O4 from spent zinc-carbon battery powder to enhance the electrochemical performance

Recycling metal resources from spent battery powder to prepare electrode materials is an eco-friendly and sustainable strategy. However, direct utilization of spent battery powder is mostly ignored, and the prepared electrode materials by this approach exhibit limited electrochemical performance. Herein, we employ unpurified spent zinc-carbon battery powder (SP) and carbon nanotubes (CNTs) as raw materials to fabricate SP/CNTs via the ball milling method, and then use a novel electrochemical activation strategy to obtain oxygen vacancy-rich SP@CNTs (Ov-SP@CNTs) materials. Under the combined action of CNTs doping and oxygen vacancies caused by the tuning of Mn 2+ /Mn 3+ ratio via the electrochemical activation strategy, the optimum electrode (Ov-SP@CNTs-10) for supercapacitor shows the specific capacitance of 443.9 F g −1 at 1 A g −1 , which is nearly six and three times higher than that of SP and SP/CNTs electrodes, respectively. Additionally, the packaged asymmetric supercapacitor (ASC) device with Ov-SP@CNTs-10 as the cathode and commercial active carbon (AC) as the anode manifests a large energy density of 25.51 Wh·kg −1 at the power density of 399.98 W kg −1 , and the capacity retention of 88.58% after 10,000 cycles at 4 A g −1 . This work opens up a new way for the direct utilization of SP to prepare high-performance supercapacitor electrode materials.