Low-cost room-temperature sodium-ion batteries (SIBs) are expected to promote the development of stationary energy storage applications. However, due to the large size of Na⁺, most Na⁺ host structures resembling their Li+ counterparts show sluggish ion mobility and destructive volume changes during Na ion (de)intercalation, resulting in unsatisfactory rate and cycling performances. Herein, we report a new type of sodium iron phosphate (Na_0.71Fe_1.07PO₄), which exhibits an extremely small volume change (~ 1%) during desodiation. When applied as a cathode material for SIBs, this new phosphate delivers a capacity of 78 mA·h·g⁻¹ even at a high rate of 50 C and maintains its capacity over 5,000 cycles at 20 C. In situ synchrotron characterization disclosed a highly reversible solid-solution mechanism during charging/discharging. The findings are believed to contribute to the development of high-performance batteries based on Earth-abundant elements.

Open image in new window

低成本的室温钠离子电池（SIB）有望促进固定式储能应用的发展。但是，由于Na ^+的尺寸较大，大多数类似其Li +对应物的Na ⁺主体结构在Na离子（脱嵌）过程中显示出缓慢的离子迁移率和破坏性的体积变化，导致速率和循环性能不理想。在本文中，我们报道了一种新型的磷酸铁钠（Na _0.71 Fe _1.07 PO ₄），其在除尘过程中表现出极小的体积变化（〜1％）。当用作SIB的阴极材料时，这种新型磷酸盐的容量为78 mA·h·g ^-1即使在50 C的高速率下，也能在20 C的条件下保持5,000个循环以上的容量。原位同步加速器的特性揭示了在充电/放电过程中具有高度可逆的固溶机理。据信，这些发现有助于开发基于富含地球元素的高性能电池。

在新窗口中打开图像