Sodium-ion batteries attract significant interest for large-scale energy storage owing to abundant sodium reserves, while challenges remain in the high synthesis energy consumption, long synthesis period, and poor electrochemical performance of sodium-ion layered oxide materials. This study presents a general high-temperature thermal shock (HTS) strategy to synthesize and optimize sodium-ion layered oxides. The rapid ramping, sintering, and cooling processes minimize volatile sodium loss during HTS, facilitating the improvement of phase purity and effectively optimizing the microstructure of materials in a non-equilibrium state. As a proof of concept, Mn-based Na0.67MnO2 treated with HTS (NMOHTS) suppresses Mn ion vacancy within transition material layers, thereby increasing the redox centers and lowering the Mn 3d orbital energy level. Besides, the formation of transition metal layer stacking faults mitigates the structural transformation and Na+-vacancies ordering arrangement during cycling. Consequently, the energy density of the NMOHTS increases by 21.5 % to 559 Wh kg-1, with an outstanding rate capability of 108 mAh g-1 at 10C and an impressive capacity retention of 93.7 % after 300 cycles at 1C. In addition, we demonstrate the universality of HTS in synthesizing various other sodium-ion layered oxides, including nickel-based and iron-based cathodes, as well as in activating degraded materials.

中文翻译：

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用于高能量密度和高速率钠离子层状氧化物阴极的超快晶格工程


钠离子电池因其丰富的钠储量而引起了人们对大规模储能的极大兴趣，而钠离子层状氧化物材料的合成能耗高、合成周期长和电化学性能差等挑战仍然存在。本研究提出了一种合成和优化钠离子层状氧化物的通用高温热冲击 （HTS） 策略。快速升温、烧结和冷却过程最大限度地减少了 HTS 过程中挥发性钠的损失，有助于提高相纯度并有效优化非平衡状态下材料的微观结构。作为概念验证，用 HTS （NMOHTS） 处理的 Mn 基 Na0.67MnO2 抑制了过渡材料层内的 Mn 离子空位，从而增加了氧化还原中心并降低了 Mn 3d 轨道能级。此外，过渡金属层堆叠断层的形成减轻了循环过程中的结构转变和 Na+-空位有序排列。因此，NMOHTS 的能量密度增加了 21.5 %，达到 559 Wh kg-1，在 10C 下具有 108 mAh g-1 的出色倍率能力，在 1C 下循环 300 次后，容量保持率高达 93.7%。此外，我们还证明了 HTS 在合成各种其他钠离子层状氧化物（包括镍基和铁基阴极）以及活化降解材料方面的普遍性。