Utilization of spent graphite from lithium-ion batteries waste as sustainable reinforcing filler for thermal, vibration-damping, and noise control applications

This study explores the practical application of using spent graphite (SG) derived from lithium-ion battery waste as a sustainable reinforcing filler for fabricating rubber composites. Two types of rubber, natural rubber (NR) and butyl rubber (BR), were employed as matrices, and eight composites were fabricated by increasing SG loadings [0, 10, 20, and 30 parts per hundred rubber (phr)]. The effects of these SG loadings on the composites' morphological, physical, thermal, wettability, mechanical, dynamic mechanical, vibration-damping, and acoustic properties were thoroughly investigated. The findings demonstrate significant improvements with increasing SG loading, particularly in the BR/SG30 composite. By reinforcing 30 phr of SG into the BR matrix, the density, hardness, thermal degradation, and sound-insulating properties improved by approximately 3.50%, 15.64%, 6.05%, and 5%, respectively, compared to the NR/SG0 composite. The damping ratio (ξ) of MSBB + BR/SG30 was approximately 18.04 at the second vibration mode, and the overall sound power level of MSBB was reduced by about 12.20 dB(A) when the BR/SG30 composite layer was applied, highlighting its potential for real-world vibration and noise control applications. These results underscore the significant role of SG as a sustainable reinforcing filler in enhancing the properties of rubber composites, particularly in the BR matrix, making it a promising option for applications requiring effective vibration and noise control. This research opens new possibilities for using SG in various engineering applications, inspiring further exploration and innovation.