Preparation of Cu/Expanded Graphite High-Performance Electromagnetic Wave Absorbing Materials by Spent Graphite Anode from Recycling Lithium-Ion Batteries

Abstract

With the widespread adoption of lithium-ion batteries and modern electronic components in both daily life and industrial production, there is a growing focus on the high-value recycling of spent lithium-ion batteries and the development of absorbents with high electromagnetic wave absorption capabilities. Efficiently recycling graphite from spent batteries through low-cost methods and utilizing it to prepare high-performance absorbents holds significant importance in addressing both the utilization of waste graphite and electromagnetic pollution issues simultaneously. This work presents a method to transform spent graphite into expanded graphite with a three-dimensional conductive structure using an enhanced Hummer's treatment and thermal reduction process. Subsequently, Cu/EG composite materials were efficiently prepared through straightforward mechanical ball milling and calcination. The unique honeycomb-like porous structure of expanded graphite facilitates the reflection and scattering of electromagnetic waves, electron transfer, and defect polarization. Additionally, the incorporation of copper nanoparticles improves the conduction loss and enhances interface polarization. The results demonstrate that Cu/EG composite materials exhibit excellent electromagnetic wave absorption performance. For the sample Cu/EG(1:3), the Ku band is effectively absorbed with a minimal reflection loss (RLmin) of -54 dB and an effective absorption bandwidth (EAB) of 5.28 GHz at a thickness of 2.2 mm, with a filler loading of just 15 wt. %. This work provides a novel strategy for the recycling of waste graphite and the design for manufacturing of electromagnetic wave absorption absorbents.

Keywords: Recycling lithium-ion batteries, Spent graphite, Expanded graphite, Electromagnetic wave absorbing materials