Electrochemical study of lithium insertion into carbon-rich polymer-derived silicon carbonitride ceramics

This paper presents the lithium insertion into carbon-rich polymer-derived silicon carbonitride (SiCN) ceramic synthesized by the thermal treatment of poly(diphenylsilylcarbodiimide) at three temperatures, namely 1100, 1300, and 1700 oC under 0.1 MPa Ar atmosphere. At lower synthesis temperatures, the material is X-ray amorphous, while at 1700 oC, the SiCN ceramic partially crystallizes. Anode materials prepared from these carbon-rich SiCN ceramics without any fillers and conducting additives were characterized using cyclic voltammetry and chronopotentiometric charging/discharging. We found that the studied silicon carbonitride ceramics demonstrate a promising electrochemical behavior during lithium insertion/extraction in terms of capacity and cycling stability. The sample synthesized at 1300 oC exhibits a reversible capacity of 392 mAh g-1. Our study confirms that carbon-rich SiCN phases are electrochemically active materials in terms of Li inter- and deintercalation.