Facile processing of graphite recycled from spent AA/Lithium-ion batteries for the fabrication of highly efficient supercapacitors

In the current state of waste generation and environmental degradation, it is important to provide approaches to efficiently decrease the presence of spent alkaline or lithium ion batteries (LIBs) in the environment due to their toxic composition. Therefore, this study proposed the recycling of graphite (Grap) from alkaline batteries and from LIBs and its use for the fabrication of supercapacitors (SCs). For this purpose, Alkaline Duracell batteries with AA size (DAA), Lenovo (LCL) and Huawei (LCH) LIBs were collected and disassembled in order to obtain the respective Grap from each type of battery. The recycled DAA Grap was utilized into graphene (Gr) supercapacitors (GDAA-SC devices), producing a high capacitance (Cs) of 862.48 F g −1 and energy density (E) of 119.78 Wh kg −1 . Also, graphite extracted from LCL and LCH batteries were used to assemble two additional devices labeled as GLCL-SC and GLCH-SC, respectively. The GLCL-SC and GLCH-SC devices exhibited Cs/E of 686.02 F g −1 /95.28 Wh kg −1 and 605.13 F g −1 /84.04 Wh kg −1 , respectively. In general, SCs made with DAA graphite produced 25–42 % higher Cs and E in comparison with SCs made with graphite extracted from LIBs. Also, DDA Graphite showed on its surface oxygen-vacancy defects and Mn 3+ /Mn 4+ -K + /K 2+ /K 3+ species (according to Raman and UV–vis measurements), which allowed the charge storage by redox reactions. In contrast, LCL or LCH graphite did not show such redox species, thus, devices made with these graphite stored charge by Electric-Double-Layer mechanism. Furthermore, the GDAA-SC device hold 91.4 % of its initial capacitance after 1000 charge-discharge cycles and showed a capacitance retention of 88 % over 1000 bending cycles. Moreover, the GDAA-SC device operated at temperatures in the range of 40–80 °C exhibiting capacitances of 144–502 F g −1 and energy densities of 20–70 Wh kg −1 , making them attractive for portable/wearable applications. Thus, using recycled Graphite from spent batteries not only decreases the cost for SCs but also reduces the contamination in the environment. • Supercapacitors (SCs) were made with recycled graphites from AA and LIB batteries. • Maximum energy density of 119.78 Wh kg −1 was obtained using graphite from AA batteries. • SCs made with graphite from AA and LIBs had capacitances of 862.48 F g −1 and 605–687 F g −1 , respectively. • Graphite from AA batteries had Mn 3+ /Mn 4+ and K + /K 2+ /K 3+ species, which stored charge by redox reactions. • Graphite from LIB did not contain redox species, thus, it stored charge by EDL mechanism.