Interlayer-expanded carbon anodes with exceptional rates and long-term cycling via kinetically decoupled carbonization

Abstract

Conventional carbonization is often energy-intensive, time consuming, and characterized by tightly coupled sub-processes that yield hard-to-control structures and compromised performance. This study introduces a kinetically decoupled carbonization strategy tailored for carbon anodes in sodium-ion batteries. The process involves a pyrolysis (700°C, 1 h) followed by rapid high-temperature heating (1,950°C, 22 s), enabling efficient impurity removal and swift carbon crystallization with minimal graphitization, alongside an ∼80% energy reduction. The obtained expanded carbon (EC) exhibits larger grain sizes and expanded interlayer, rendering higher capacity, exceptional rate, and long-term stability (>6,000 cycles at a current rate of 10 C) than current carbon anodes. Mechanistic investigations reveal a wide intercalation potential range (2–0.01 V) in EC without inducing detrimental sodium clustering, thereby supporting expanded layers and easy intercalation for high capacity, fast charging, and robust stability. Our strategy provides a precise, energy-efficient pathway to develop desirable carbonaceous materials for batteries and advanced applications.