The structure and electrochemical properties of carbonized polyacrylonitrile microspheres

• A hard carbon microsphere material was prepared by a stabilization–carbonization method.
• Such carbon microsphere has a uniform walnut kernel structure.
• The anode material presents excellent rate capability and cycling stability.

A hard carbon microsphere (HCS) material with a uniform walnut kernel structure was prepared using polyacrylonitrile (PAN) asa a carbon precursor by a stabilization–carbonization method. The PAN–HCS preserves the original ellipsoidal shapes of natural polyacrylonitrile granules. Structural analysis shows that PAN–HCS is a kind of disordered carbon containing micropores and graphite-like micro-crystallites. The effects of heat-treatment temperature varying from 800 to 1500 °C on electrochemical performance were systemically studied. PAN–HCS–1250 obtained at 1250 °C as a negative material for lithium-ion batteries exhibits a reversible capacity of about 350 mAh g− 1 at 20 mA g− 1 with an excellent rate capability and cycling stability.