High electrochemical stability and safety make Na⁺ superionic conductor (NASICON)-class cathodes highly desirable for Na-ion batteries (SIBs). However, their practical capacity is limited, leading to low specific energy. Furthermore, the low electrical conductivity combined with a decline in capacity upon prolonged cycling (>1000 cycles) related to the loss of active material-carbon conducting contact regions contributes to moderate rate performance and cycling stability. The need for high specific energy cathodes that meet practical electrochemical requirements has prompted a search for new materials. Herein, we introduce a new carbon-coated Na₃VFe_0.5Ti_0.5(PO₄)₃ (NVFTP/C) material as a promising candidate in the NASICON family of cathodes for SIBs. With a high specific energy of ∼457 Wh kg⁻¹ and a high Na⁺ insertion voltage of 3.0 V versus Na⁺/Na, this cathode can undergo a reversible single-phase solid-solution and two-phase (de)sodiation evolution at 28 C (1 C = 174.7 mAh g⁻¹) for up to 10,000 cycles. This study highlights the potential of utilizing low-cost and highly efficient cathodes made from Earth-abundant and harmless materials (Fe and Ti) with enriched Na⁺-storage properties in practical SIBs.

中文翻译：

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Na3VFe0.5Ti0.5(PO4)3 阴极纳米结构：克服钠离子电池多电子反应的能垒

高电化学稳定性和安全性使得Na ⁺超离子导体（NASICON）级正极非常适合钠离子电池（SIB）。然而，它们的实际容量有限，导致比能量较低。此外，低电导率加上与活性材料-碳导电接触区域损失相关的长时间循环（>1000次循环）时容量下降，有助于适度的倍率性能和循环稳定性。对满足实际电化学要求的高比能阴极的需求促使人们寻找新材料。在此，我们介绍了一种新型碳涂层Na ₃ VFe _0.5 Ti _0.5 (PO ₄ ) ₃ (NVFTP/C) 材料，作为SIB 阴极NASICON 系列中的有前途的候选材料。该阴极具有〜457 Wh kg ^-1的高比能和3.0 V（相对于Na ⁺ /Na）的高Na ⁺插入电压，可以在以下温度下经历可逆的单相固溶体和两相（脱）钠化演化。 28 C (1 C = 174.7 mAh g ⁻¹ ) 最多 10,000 次循环。这项研究强调了在实际 SIB 中利用由地球丰富且无害的材料（铁和钛）制成的低成本、高效阴极的潜力，这些材料具有丰富的 Na ^{+存储特性。}