A Passionfruit-Like Carbon-Confined Cu_2ZnSnS_4 Anode for Ultralong-Life Sodium Storage

摘要

The sodium-ion battery (SIB) is one of the new generation of electrochemical energy storage devices, although its life-time needs to be improved. To assemble an SIB with an ultralong life-time, passionfruit-like Cu2ZnSnS4 nanoparticles confined with nitrogen-doped carbon (CZTS@C) are synthesized. As an alternative anode for an SIB, the CZTS@C anode exhibits a reversible capacity of 461 mA h g(-1) at a current density of 50 mA g(-1) after 140 charge/discharge cycles and excellent cycling stability (e.g., a capacity of 146 mA h g(-1) at 4 A g(-1) even after 1000 charge/discharge cycles). Such high performance originates from multiple electrons involved in the electrochemical reactions of the CZTS@C anode, as verified by in situ X-ray diffraction measurements. As a conductive maskant, the carbon shell enhances the electric conductivity of the CZTS@C anode and further behaves as a blocked layer to maintain the structural integrity of this anode, namely to avoid the loss of active components. Several heterostructures that promote the reaction kinetics of the Na+ storage are formed in the subsequent charging process, as proved by ex situ transmission electron microscopy. The remarkable performance based on this low-cost CZTS anode may pave the way to develop commercial SIBs.