This study brings a novel irreversible capacity-elimination method that cleverly utilizes waste graphite to develop a process for fabricating micron-thin, free-standing, and hosted metallic lithium films. We have demonstrated its pre-lithiation application in NCA622||CG-Si full cell. The infusion of molten metallic lithium into graphene oxide host tunable micrometer-scale thickness yields an ultra-thin Li@GO film. The unique combination of thinness, ultralow capacity, and hosted structure presents a realm of technological opportunities that go beyond the capabilities of existing thick Li metal electrodes. After pre-lithiation, not only was the active lithium consumed for initial SEI formation replenished (9.8 % for LCO||CG, 15.6 % for NCA622||CG-Si), but there was also an additional 4.5 % of active lithium on the cathode side. Through synchrotron in-situ XRD, the core mechanism for suppressing capacity degradation is to prevent the reduction of lattice parameters a(=b), and c and volume. Our tunable micron-thin and free-standing Li@GO films pave the way for future high-energy-density LIBs, as well as the recycling and reutilization of waste graphite.
Looking ahead, the advancement of this technology holds immense promise for enhancing the performance metrics of LIBs. Further optimization and integration of the thin Li@GO film into various LIBs architectures could lead to substantial gains in energy density, cycle life, and overall efficiency. Additionally, the environmentally friendly aspect of repurposing waste graphite for such applications aligns with the principles of sustainable energy storage solutions. Notably, during pre-lithiation on the cathode side, as investigated in NCA, the essence lies in the preparation of lithium-rich cathodes relative to the original cathodes. This process effectively enhances the Li ions intercalation capability of cathode materials, significantly elevating the potential of the positive electrodes (0.07 V for NCA622||CG-Si after pre-lithiation). Consequently, this drives a rise in the operational voltage of the entire battery system.