An ultrathin Al₂O₃ layer of varying thickness is deposited on biomass-derived hard carbon by atomic layer deposition (ALD). This hard carbon is used as an anode for sodium-ion batteries. The structures and morphologies of the hard carbon remain unchanged even with an increase in the cycle number of Al₂O₃ ALD. Improved electrochemical performance of the hard carbon is obtained when 20 cycles of Al₂O₃ ALD are applied. Compared with the pristine samples, the initial irreversible capacity loss is reduced from 108 to 97 mAh g^–1, and columbic efficiency and plateau region capacity are improved from 67 to 72% and 150 to 172 mAh g^–1, respectively. The samples also exhibit a higher capacity, 296 mAh g^–1, than the pristine sample, 277 mAh g^–1, after 100 charge–discharge cycles at 0.2 C current density (1 C = 250 mA g^–1). Moreover, the discharge capacity of the pristine samples increases from 100 to 130 mAh g^–1 at 4 C rate. The enhanced electrochemical performances arise from the complete protection of the ultrathin Al₂O₃ layer on the electrode to alleviate solid electrolyte interphase (SEI) layer formation. Consequently, the SEI layer and charge transfer resistance are reduced. The Na-ion diffusivity below 0.1 V is then improved, which dominates the high rate performance.

中文翻译：

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超薄人造固体电解质界面层涂层生物质衍生硬碳作为钠离子电池的阳极

通过原子层沉积 (ALD) 在源自生物质的硬碳上沉积不同厚度的超薄 Al ₂ O ₃层。这种硬碳被用作钠离子电池的阳极。即使增加Al ₂ O ₃ ALD的循环次数，硬碳的结构和形态也保持不变。当应用 20 次 Al ₂ O ₃ ALD循环时，硬碳的电化学性能得到改善。与原始样品相比，初始不可逆容量损失从 108 降低到 97 mAh g ^-1，库伦效率和平台区容量从 67% 提高到 72%，从 150 提高到 172 mAh g ^-1， 分别。在 0.2 C 电流密度 (1 C = 250 mA g ^-1 ) 下100 次充放电循环后，这些样品还表现出比原始样品 277 mAh g ^-1更高的容量 296 mAh g ^-1。此外，原始样品的放电容量在 4 C 倍率下从 100 增加到 130 mAh g ^-1。增强的电化学性能源于对电极上超薄 Al ₂ O ₃层的完全保护，以减轻固体电解质界面 (SEI) 层的形成。因此，SEI层和电荷转移电阻降低。然后改善了低于 0.1 V 的 Na 离子扩散率，这在高倍率性能中占主导地位。