Evaluation of Ti₃C₂T_x MXene-supported germanium sulfide as sodium-ion battery anodes: A comparison with reduced graphene oxide supports

We present a novel thin germanium sulfide-coated Ti₃C₂T_x MXene electrode and evaluate its material properties and electrochemical (EC) performance as an anode for sodium-ion batteries (SIBs). The material was synthesized by depositing amorphous germanium sulfide onto Ti₃C₂T_x MXenes via ammonium thiogermanate decomposition under low-pH conditions, with a nonionic surfactant added to prevent MXene flocculation and control particle size. Metal chalcogenide–MXene composites show great promise as SIB anodes, benefiting from MXenes' high electrical conductivity and the enhanced specific charge capacity provided by metal alloying and conversion reactions with sodium. However, MXene-based composite anodes for SIBs remain underexplored. The proposed germanium sulfide–Ti₃C₂T_x composite anode demonstrates outstanding performance, achieving a specific charge capacity of 540 mAh·g⁻¹ after 100 cycles at 1 A·g⁻¹, surpassing all previously reported metal chalcogenide–MXene anodes. Moreover, it exhibits excellent rate capability: a 30-fold increase in current density (from 0.1 to 3 A·g⁻¹) results in less than 15 % capacity loss. At high current densities (>1 A·g⁻¹), the GeS_x/MXene anode outperforms reduced graphene oxide (rGO)-supported GeS₂ anodes synthesized via a similar protocol. These findings highlight the potential of MXene-supported GeS₂ as a high-performance anode material for SIBs, paving the way for the development of next-generation MXene-based energy storage materials.