Hard Carbon Nanosheets with Uniform Ultramicropores and Accessible Functional Groups Showing High Realistic Capacity and Superior Rate Performance for Sodium‐Ion Storage

from graphitic layers is manifested as the low-potential plateau region (0.01-0.10 V), contributing to stable insertion capacity; meanwhile, the surface desodiation process of the CO and OH groups corresponds to the high-potential plateau region (0.40-0.70 V), contributing to a fast capacitive storage.