3D Self-Doped N-Sponge Carbon Framework for Highly Reversible Lithium Electroplating/Stripping

Lithium metal has become an ideal anode for high-energy-density lithium-ion batteries due to its unique theoretical capacity and potential advantages. However, the volume effect, uneven deposition, and dendrite growth of lithium metal can seriously shorten the service life of the battery. A 3D structural design and a lithium-friendly interface are considered effective ways to improve lithium metal negative electrodes. Hence, this article successfully prepared a sponge carbon (SC) scaffold rich in N-sites using melamine as the raw material. Pyridine N and pyrrole N, which can enhance surface activity, are distributed in the SC structure and can serve as lithium nucleation sites to promote the uniform deposition of lithium metal. Compared with hard carbon (HC), SC exhibits significant improvements in polarization potential and cycle life. The deposition overpotential of the SC battery is only 36 mV, and its cycle life is as long as 1800 h, while it maintains a high Coulombic efficiency of over 98%. Even at a high deposition capacity of 10 mAh cm–2, SC can still stably deposit for over 1000 h. In addition, the 3D flexible carbon skeleton of SC provides a large space for buffering the volume expansion of lithium metal, which effectively suppresses the growth of lithium dendrites. The full-cell performance results demonstrate that the SC still retains a capacity retention rate of 98.4% after 200 cycles at 1 C, whereas the capacity retention rate of HC drops to 73.5%. Moreover, the long cycle performance and rate capability of SC full cells are both superior to those of HC full cells. This article improves the reversibility of lithium metal deposition/stripping by constructing a 3D self-doped N-sponge carbon skeleton and provides a reference for the development of long-life lithium metal batteries.