Recent advances in carbon-based anodes for high-performance sodium-ion batteries: Mechanism, modification and characterizations

Lithium-ion batteries (LIBs) are insufficient for large-scale energy storage due to limited lithium resources. Sodium-ion batteries (SIBs) are considered the most promising alternative to LIBs due to their abundant resources and potential for broad industrialization. However, the rapid development of SIBs is hindered by the availability of suitable anode materials. Most reported anode materials for SIBs are either expensive or have inherent flaws, making them unsuitable for large-scale production. Carbon materials have gained significant attention due to their sample resources, low cost, and diverse structures. However, the lack of a systematic discussion on the various structural configurations of carbon materials is a challenging issue. This review comprehensively investigated the preparation processes for nearly all carbon-based materials, including graphite, soft carbon, and hard carbon. It also proposed optimization strategies by thoroughly exploring the sodium storage mechanism of various carbon materials. In addition, based on advanced in-situ characterization technology, the solid electrolyte interface and structural changes of carbon materials during the electrochemical process were summarized. A creative analysis was conducted to establish a correlation relationship between the long-range and short-range ordered structure of carbon materials and their impact on important performance metrics such as initial coulombic efficiency, capacity, rate, cycle stability, and other relevant factors. Finally, this review presented personal insights into the challenges and issues faced by carbon materials, aiming to drive the advancement of SIBs.