It is crucial to develop stable energy sources for rechargeable sodium-ion batteries using simple synthesis methods. Herein, we report a facile route for synthesizing phase-pure carbon-coated Na₂FeSiO₄ polyanionic cathodes using conventional solid-state methods at 700 ^°C under inert atmosphere. X-ray diffraction results reveal that there are no impurities in the highly crystalline Na₂FeSiO₄ particles, resulting from the heat of combustion provided by the organic chelating agent. The electrochemical behaviour of Na₂FeSiO₄ particles is tested within 1.5–4.5 V at 0.25 C. The Na₂FeSiO₄ cathode delivered 119 mAh g⁻¹ at 0.25 C and maintained ∼85% of its initial capacity after 200 cycles after activation process. Even at high current densities of 3.5 C, the material outperforms other orthosilicates-based cathodes reported with capacities of 55 mAh g⁻¹ discharge capacity along with ∼80% retention after 1000 cycles. The enhanced performance of carbon-coated Na₂FeSiO₄ particles is ascribed to the improved electronic conductivity by the incorporation of carbon and the presence of void space between the particles. This void space contains more electrolytes and eliminates the stress formed during the cycling process, thus improving stability even at high rates. This is the first report on obtaining phase pure metal orthosilicate material with negligible impurities using simple solid-state method along with such exponential electrochemical performances.

使用简单的合成方法为可充电钠离子电池开发稳定的能源至关重要。本文中，我们报告了在惰性气氛下，使用常规固态方法在700 ^° C下合成相纯碳涂层的Na ₂ FeSiO ₄聚阴离子阴极的简便方法 。X射线衍射结果表明，在高度结晶的Na ₂ FeSiO ₄颗粒中没有杂质，这是由于有机螯合剂提供的燃烧热引起的。在0.25 C和1.5-4.5 V范围内测试了Na ₂ FeSiO ₄颗粒的电化学行为。Na ₂ FeSiO ₄阴极在0.25 C下输送119 mAh g ^-1，并在激活过程200个循环后保持其初始容量的〜85％。即使在3.5 C的高电流密度下，该材料也优于其他基于正硅酸盐的阴极，报道的容量为55 mAh g ^-1放电容量，在1000次循环后保留率约为80％。碳包覆的Na ₂ FeSiO ₄的增强性能通过掺入碳和颗粒之间存在空隙空间，可将颗粒归因于改善的电导率。该空隙空间包含更多的电解质，并消除了循环过程中形成的应力，从而即使在高速率下也提高了稳定性。这是关于使用简单的固态方法获得具有可忽略不计的杂质的相纯金属原硅酸盐材料以及这种指数电化学性能的第一份报告。