Developing novel materials is crucial to overcoming the performance degradation of lithium-ion batteries (LIBs) for low-temperature applications. In this work, we demonstrate a novel copper zinc tin sulfide (Cu 2 ZnSnS 4 , CZTS) thin film with nanowalls structure as the anode material in thin-film LIBs for low-temperature applications. The quaternary CZTS synthesized by a simple hydrothermal method shows a higher reversible capacity of 475 mAh g −1 after 200 cycles at −10 °C with the EC/ DEC/DMC-based electrolyte in comparison with the graphite electrode (110 mAh g −1 after 100 cycles at −10 °C). The effects of temperature and electrolyte systems including EC/DEC-and EC/ DEC/DMC-based electrolytes on the cycling performance are studied. The faster Li-ion transport in the electrolyte−electrode interface of the CZTS anode material is obtained in the EC/DEC/DMC-based electrolyte at −10 °C. In addition, the depthprofiling XPS results of the CZTS anode reveal that a solid electrolyte interphase (SEI) layer with less carbon content is formed in the EC/DEC/DMC-based electrolyte likely associated with the interfacial stability at low temperature. The enhanced cycling performance of CZTS could be attributed to its improved interfacial stability and Li + diffusion, along with the formation of an interconnected active material architecture at low temperature.

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The widespread use of energy storage technologies has created a high demand for the development of novel anode materials in Li-ion batteries (LIBs) with high areal capacity and faster electron-transfer kinetics. In this work, carbon-coated Cu 2 ZnSnS 4 with a hierarchical 3D structure (CZTS@C) is used as an anode material for LIBs. The CZTS@C microstructures with enhanced electrical conductivity and improved Li-ion diffusivity exhibit high areal and gravimetric capacities of 2.45 mA h/cm 2 and 1366 mA h/g, respectively. The areal capacity achieved in the present study is higher than that of previously reported CZTS-based materials. Moreover, in situ X-ray diffraction results show that lithium ions are stored in CZTS through the insertion reaction, followed by the alloying and conversion reactions at ∼1 V. The structural evolution of Li 2 S and Cu–Sn/Cu–Zn alloy phases occurs during the conversion and alloying reactions. The present work provides a cost-effective and simple method to prepare bulk CZTS and highlights the conformal carbon coating over CZTS, which can enhance the electrical and ionic conductivities of CZTS materials and increase the mass loading (1–2.3 mg/cm 2 ). The improved stability and rate capability of CZTS@C anode materials can therefore be achieved.

Controlled cracking pattern formation in carbon-coated CZTS (CZTS@C) thin-film as high-power anodes for next-generation thin-film LIBs applications.

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