Comparative studies on the lithium and sodium ions storages in semi-coke derived carbon anode materials

Abstract

The same carbon material usually shows different electrochemical performances as the anodes in lithium-ion and sodium-ion batteries, and the underneath mechanisms are remained to be debated. In the work, we prepared more than ten kinds of carbon materials with semi-coke as precursor through calcination in Ar atmosphere at different temperatures from 600 to 2800 °C. The carbon materials prepared at the temperatures from 600 to 1000 °C showed manifest specific capacities for Li and Na ion storage. The ones got at the temperatures from 1200 to 1400 °C delivered a higher Na ion storage capacity than that of Li ion. Oppositely, the carbon materials obtained at the temperatures from 1600 to 2800 °C exhibit higher Li ion storage capacity than that of the Na ion. The structure evolution demonstrates that low-temperature carbon (600–1000 °C) assume excellent long cycling stability for both LIBs and SIBs, but they exhibited lower initial coulombic efficiency (ICE) due to the residual more oxygen-containing groups. The medium-temperature carbon (1200–1400 °C) assume certain nano-sized closed pores that are essential for Na ion storage as a quasi-metallic state, but not the Li ion. This nano-sized closed pores structural features enhance the reversible capacity of medium-temperature carbon but negatively impact their kinetic properties. In contrast, the high-temperature carbon (1600–2800 °C) show graphite gallery that affords with a long cycling performance and high ICE for LIBs, but not for SIBs. This work provides a protocol for synthesizing various carbon materials from semi-coke, offers insights into the electrochemical mechanisms of lithium and sodium storage, and establishes a framework for designing suitable anode materials for LIBs and SIBs.