GeP₃/Ketjen Black Composite: Preparation <i>via </i>Ball Milling and Performance as Anode Material for Sodium-ion Batteries

Metal phosphides have been studied as prospective anode materials for sodium-ion batteries (SIBs) due to their higher specific capacity compared to other anode materials.However, rapid capacity decay and limited cycle life caused by volume expansion and low electrical conductivity of phosphides in SIBs remain still unsolved.To address these issues, GeP 3 was first prepared by high-energy ball milling, and then Ketjen black (KB) was introduced to synthesize composite GeP 3 /KB anode materials under controlled milling speed and time by a secondary ball milling process.During the ball milling process, GeP 3 and KB form strong chemical bonds, resulting in a closely bonded composite.Consequently, the GeP 3 /KB anodes was demonstrated excellent sodium storage performance, achieving a high reversible capacity of 933.41 mAhg -1 at a current density of 0.05 Ag -1 for a special formula of GeP 3 /KB-600-40 sample prepared at ball milling speed of 600 r/min for 40 h.Even at a high current density of 2 Ag -1 over 200 cycles, the capacity remains 314.52 mAhg -1 with a retention rate of 66.6%.In conclusion, this work successfully prepares GeP 3 /KB anode-carbon composite for electrodes by high-energy ball milling, which can restrict electrode volume expansion, enhance capacity, and improve cycle stability of SIBs.