Elucidating High Initial Coulombic Efficiency, Pseudocapacitive Kinetics and Charge Storage Mechanism of Antiperovskite Carbide NiZnC@rGO Anode for Fast Sodium Storage in Ether Electrolyte.

To explore novel electrode materials with in-depth elucidation of initial coulombic efficiency (ICE), kinetics, and charge storage mechanisms is of great challenge for Na-ion storage. Herein, a novel 3D antiperovskite carbide NiZnC@rGO anode coupled with ether-based electrolyte is reported for fast Na-ion storage, exhibiting superior performance than ester-based electrolyte. Electrochemical tests and density functional theory (DFT) calculations show that NiZnC@rGO anode with ether-based electrolyte can promote charge/ion transport and lower Na diffusion energy barrier, thereby improving ICE, reversible capacity, rate, and cycling performance. Cross-sectional-morphology and depth profiling surface chemistry demonstrate that not only a thinner and more homogeneous reaction interface layer with less side effects but also a superior solid electrolyte interface (SEI) film with a high proportion of inorganic components are formed in the ether-based electrolyte, which accelerates Na transport and is the significant reason for the improvement of ICE and other electrochemical properties. Meanwhile, electrochemical and ex situ measurements have revealed conversion, alloying, and co-intercalation hybrid mechanisms of the NiZnC@rGO anode based on ether electrolyte. Interestingly, the Na-ion capacitors (SICs) designed by pairing with activated carbon (AC) cathode exhibit favorable electrochemical performance. Overall, this work provides deep insights on developing advanced materials for fast Na-ion storage.