Research progress on carbon materials as negative electrodes in sodium‐ and potassium‐ion batteries

Abstract Carbon materials, including graphite, hard carbon, soft carbon, graphene, and carbon nanotubes, are widely used as high‐performance negative electrodes for sodium‐ion and potassium‐ion batteries (SIBs and PIBs). Compared with other materials, carbon materials are abundant, low‐cost, and environmentally friendly, and have excellent electrochemical properties, which make them especially suitable for negative electrode materials of SIBs and PIBs. Compared with traditional carbon materials, modifications of the morphology and size of nanomaterials represent effective strategies to improve the quality of electrode materials. Different nanostructures make different contributions toward improving the electrochemical performance of electrode materials, so the synthesis of nanomaterials is promising for controlling the morphology and size of electrode materials. This paper reviews the progress made and challenges in the use of carbon materials as negative electrode materials for SIBs and PIBs in recent years. The differences in Na⁺ and K⁺ storage mechanisms among different types of carbon materials are emphasized.