Thermodynamically stable low-Na O3 cathode materials driven by intrinsically high ionic potential discrepancy,Energy & Environmental Science

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Thermodynamically stable low-Na O3 cathode materials driven by intrinsically high ionic potential discrepancy
Energy & Environmental Science ( IF 32.4 ) Pub Date : 2024-08-22 , DOI: 10.1039/d4ee02359e
Meng Li _{1,

2} , Haoxiang Zhuo _{3,

4} , Yang Xu _{1,

5} , Qihang Jing _{1,

2} , Yanlong Wu ₃ , Yang Gu ₁ , Zhou Liao _{1,

6} , Kuan Wang ₁ , Miao Song ₇ , Xiaona Li ₆ , Jianwen Liang ₁ , Changtai Zhao ₁ , Yingying Jiang ₁ , Tianci Wu ₂ , Dongsheng Geng _{2,

8} , Jiangtao Hu ₉ , Xueliang Sun ₆ , Biwei Xiao _{1,

3,

4}

Affiliation

The thermodynamically stable window for an O3-type layered sodium cathode material is largely determined by its Na stoichiometry; a spontaneous transition to the P-type structure occurs when it is relatively low. With such limitation, the capacity and stability of O3-structured materials become restricted and a potentially promising class of O3-type materials that garner the structural stability of P2-type materials is underexplored. This work discovers that a large ionic potential discrepancy within the transition metal layer acts as a driving force that pushes the Na-ions from prismatic coordination to octahedral coordination. Utilizing this strategy, we have explored a class of off-stoichiometric O3-type materials with exceptionally low Na-stoichiometry (generally forming P2-type structures with higher thermodynamic stability) yet having the structural parameter features of P-type materials. These materials demonstrate rapid O3–P3 phase transition while maintaining a stable solid solution reaction at high voltages, resulting in an impressive P-phase range of 81.4%, thus showing superior performance compared with conventional O3-type materials. This principle provides a great extension to the existing family of layered cathode materials for sodium-ion batteries.

中文翻译：

由本质上高离子势差驱动的热力学稳定的低Na O3阴极材料

O3型层状钠正极材料的热力学稳定窗口很大程度上取决于其Na化学计量；当它相对较低时，会自发转变为 P 型结构。由于这种限制，O3 结构材料的容量和稳定性受到限制，并且具有 P2 型材料结构稳定性的一类潜在有前途的 O3 型材料尚未得到充分探索。这项工作发现，过渡金属层内较大的离子电势差异充当驱动力，推动钠离子从棱柱配位转变为八面体配位。利用这一策略，我们探索了一类非化学计量的O3型材料，其具有极低的Na化学计量（通常形成具有更高热力学稳定性的P2型结构），同时具有P型材料的结构参数特征。这些材料表现出快速的 O3-P3 相变，同时在高电压下保持稳定的固溶反应，导致令人印象深刻的 81.4% 的 P 相范围，从而与传统的 O3 型材料相比表现出优越的性能。这一原理为现有的钠离子电池层状阴极材料系列提供了极大的扩展。

更新日期：2024-08-22

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