A series of P3-phase Na_0.67Ni_0.33−xZn_xMn_0.67O₂ (x = 0, 0.06, 0.09, and 0.12) samples have been synthesized and investigated as cathode materials for sodium-ion batteries. The partial substitution of Ni with Zn in the P3-phase Na_0.67Ni_0.33Mn_0.67O₂ lattice can markedly improve the electrochemical performance. A Na_0.66Ni_0.24Zn_0.09Mn_0.67O₂ cathode material with an optimized Zn content of x = 0.09 can deliver an initial reversible discharge specific capacity of 127.4 mA h g⁻¹ and Coulomb efficiency of 89.2% at 10 mA g⁻¹ in a voltage range of 2.0−4.25 V. When the current density increases to 100 mA g⁻¹, Na_0.67Ni_0.24Zn_0.09Mn_0.67O₂ delivers an initial reversible discharge specific capacity of 106.1 mA g⁻¹, and capacity retention is 68.05% after 50 cycles, which is much higher than those of other samples with different Zn content. The structural characterization reveals that Zn-substituted Na_0.67Ni_0.24Zn_0.09Mn_0.67O₂ increases the lattice parameters and crystallite size, and decreases the lattice strain, which is beneficial for the structural stability whether before or after the cycle. In addition, the charge–transfer impedance (R_ct) and cathodic electrolyte interphase impedance (R_CEI) of Na_0.67Ni_0.24Zn_0.09Mn_0.67O₂ are significantly decreased after cycling compared with the undoped Zn electrode, which should be partially responsible for the improvement of the electrochemical performance of the Zn-doped electrode.

Graphical Abstract

中文翻译：

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提高钠离子电池用锌取代 P3-Na0.67Ni0.33Mn0.67O2 正极材料的储钠性能

已合成一系列 P3 相 Na _0.67 Ni _{0.33− x} Zn _x Mn _0.67 O ₂ ( x  = 0, 0.06, 0.09 和 0.12) 样品并作为钠离子电池的正极材料进行了研究。在P3相Na _0.67 Ni _0.33 Mn _0.67 O ₂晶格中Ni被Zn部分取代可以显着提高电化学性能。具有优化的 Zn 含量x的 Na _0.66 Ni _0.24 Zn _0.09 Mn _0.67 O _{2正极材料}^{= 0.09 可以在 2.0-4.25 V 的电压范围内提供 127.4 mA h g -1} 的初始可逆放电比容量和 10 mA g ^-1的库仑效率为 89.2% 。当电流密度增加到 100 mA g ^-1时， Na _0.67 Ni _0.24 Zn _0.09 Mn _0.67 O ₂的初始可逆放电比容量为106.1 mA g ^-1，循环50次后容量保持率为68.05%，远高于其他不同Zn含量的样品。结构表征表明，Zn取代Na _0.67 Ni _0.24 Zn _0.09 Mn_0.67 O ₂增加了晶格参数和微晶尺寸，降低了晶格应变，有利于循环前后的结构稳定性。此外，与未掺杂的 Zn 电极相比，Na _0.67 Ni _0.24 Zn _0.09 Mn _0.67 O _{2的电荷转移阻抗（} R _ct）和阴极电解质界面阻抗（R _CEI ）在循环后显着降低，这应该是部分原因Zn掺杂电极的电化学性能的改善。

图形概要