With the increasing demand for high energy density in energy-storage systems, a high-voltage cathode is essential in rechargeable Li-ion and Na-ion batteries. The operating voltage of a triclinic-polymorph Na₂CoP₂O₇, also known as the rose form, is above 4.0 V (vs. Na/Na⁺), which is relatively high compared to that of other cathode materials. Thus, it can be employed as a potential high-voltage cathode material in Na-ion batteries. However, it is difficult to synthesize a pure rose phase because of its low phase stability, thus limiting its use in high-voltage applications. Herein, compositional-engineered, rose-phase Na_2-2xCo_1+xP₂O₇/C (x = 0, 0.1 and 0.2) nanopowder are prepared using a wet-chemical method. The Na_2-2xCo_1+xP₂O₇/C cathode shows high electrochemical reactivity with Na ions at 4.0 V, delivering high capacity and high energy density.

随着储能系统对高能量密度的需求不断增加，高压阴极在可再充电锂离子和钠离子电池中必不可少。三斜晶多晶型物Na ₂ CoP ₂ O ₇，也称为玫瑰形式，其工作电压高于4.0 V（相对于Na / Na ⁺），与其他阴极材料相比，该电压相对较高。因此，它可用作Na离子电池中潜在的高压阴极材料。但是，由于纯玫瑰相的低相稳定性，因此难以合成，因此限制了其在高压应用中的使用。此处，成分工程化的玫瑰相Na _2-2x Co _{1 + x} P ₂ O ₇使用湿化学方法制备/ C（x = 0、0.1和0.2）纳米粉。Na _2-2x Co _{1 + x} P ₂ O ₇ / C阴极在4.0 V电压下与Na离子具有高电化学反应性，可提供高容量和高能量密度。