Constructing the correlation between optical microstructures and macroscopic properties of medium temperature coal pitch-derived cokes

Abstract

With the rapid development of the new energy industry, pitch-derived coke now shows greater potential than graphite anode. For investigate the correlation between optical microstructures and macroscopic properties of pitch coke, 6 pitch cokes with varying structures were prepared from medium temperature coal pitch (MTP) and its 5 fractions. Then, these pitch cokes were applied in lithium-ion batteries to evaluate their electrochemical performances. The results showed that the optical microstructures of pitch coke have significant influence on the macroscopic properties including electrochemical performances. In fact, pitch coke with high anisotropic index (DRAS) possesses high capacity and low powder resistivity. Its fibrous structure brings better oxidation resistance. While the mosaic structure contributes more to the improvement of the micro-strength intensity (MSI) of pitch coke. In addition, fine and medium mosaic structure have obvious influence on the rate performance and Warburg factor (σ) of pitch coke, respectively. Among several pitch cokes, BAI-TS-1400 has the best rate performance and initial coulombic efficiency (73.84 %). After 400 cycles at 0.05 A·g⁻¹, its capacity maintains 402.4 mAh·g⁻¹, exhibiting nice cycle stability. Thus, it’s a promising for lithium-ion battery anodes material. This work provides theoretical and experimental support for the high value-added utilization of pitch coke.