Boosting Initial Coulombic Efficiency of Coal-Based Carbon Anodes with Cross-Linked Polymeric Binder for Sodium-Ion Batteries
Yating Zhang, Yanping Hu, Youyu Zhu, Xue Li, Peng Chang, Keke Li, Yicheng Wang, Yuan Liu
Abstract
Benefiting from abundant resources, low price, and high carbon content, coal is considered as one of the most promising precursors of carbon-based anode materials for sodium-ion batteries. However, the application of coal-based carbon anode materials has been enormously restricted due to its poor sodium storage capacity and low initial Coulombic efficiency (ICE). In this work, a cross-linked polymeric binder [sodium alginate (SA)/ poly(acrylic acid) (PAA)] combining the molecular structure advantages of SA and PAA has been successfully designed. The SA/PAA binder has a strong interaction with coal-based carbon materials through covalent bonds, which can validly reduce its defect sites and inhibit the decomposition of the electrolyte. In addition, the cross-linking structure of the SA/PAA binder improves the bonding capacity and mechanical property of the coal-based carbon anode materials, significantly enhancing their rate and cycling performance. Simultaneously, the inclusion of a binder with Na-ions can compensate for the irreversible loss of sodium in coal-based carbon anode materials, thereby achieving higher ICE (82.08%) and reversible capacity (361.4 mA h g –1 at 0.1C). Therefore, the SA/PAA binder can be considered as a candidate binder for sodium-ion batteries, considering its desirable mechanical properties and electrochemical performances.