The electrochemical performance of negative active materials employed in sodium-ion batteries is dependent on the amount of Na⁺ available in the test cells. As such, electrodes that exhibit long cycle-life and high coulombic efficiency (CE) in half-cells could suffer from fast capacity fading in full-cells as a result of unstable solid electrolyte interphase (SEI) and mechanical degradation leading to loss of active materials. In this work, the performance of Sb–graphite composite active materials prepared by extended ball-milling was evaluated in sodium half-cells and various types of symmetric cells (SCs). In half-cell tests, the composite electrodes provided specific capacities in the range 350–600 mAh g⁻¹ at C/20 with initial CE of 82%. A stable capacity of 380 mAh g⁻¹ was observed in the subsequent 100 cycles with the CE increasing to nearly 99%. However, self-discharge tests on half-cells and galvanostatic cycling of SCs revealed poor capacity retention as a result of parasitic reaction occurring through the SEI layer. Contrary to half-cells, the SCs revealed that Sb electrodes suffered from sharp capacity losses when a limited amount of Na⁺ ions was available in the cells. This is also characteristic of full-cells in which the sodium ions are supplied by the positive electrode.

钠离子电池中使用的负极活性材料的电化学性能取决于测试电池中可用的 Na ⁺量。因此，在半电池中表现出长循环寿命和高库仑效率 (CE) 的电极可能会由于不稳定的固体电解质中间相 (SEI) 和机械降解导致活性损失而遭受全电池快速容量衰减。材料。在这项工作中，通过扩展球磨制备的 Sb-石墨复合活性材料在钠半电池和各种类型的对称电池 (SCs) 中的性能进行了评估。在半电池测试中，复合电极在 C/20 下提供了 350-600 mAh g ^{-1 的}比容量，初始 CE 为 82%。稳定的容量为 380 mAh g在随后的 100 个循环中观察到^-1，CE 增加到接近 99%。然而，半电池的自放电测试和 SCs 的恒电流循环表明，由于通过 SEI 层发生寄生反应，容量保持率很差。与半电池相反，SC 显示当电池中可用的 Na ⁺离子数量有限时，Sb 电极会遭受急剧的容量损失。这也是由正极提供钠离子的全电池的特征。