Li Xinyan, Li Chao, Zhang Xin, Sun Jianguo, Liu Ximeng, Song Kepeng, Han Jiuhui, Wang John, Song Chen Jun
School of Materials and Energy, University of Electronic Science and Technology of China, 610054, Chengdu, Sichuan, China.
Department of Materials Science and Engineering, National University of Singapore, 117574, Singapore, Singapore.
Angew Chem Int Ed Engl. 2024 Nov 4;63(45):e202412533. doi: 10.1002/anie.202412533. Epub 2024 Sep 20.
Alloy-type materials are attractive for anodes in sodium-ion batteries (SIBs) owing to their high theoretical capacities and overall performance. However, the accumulation of stress/strain during repeated cycling results in electrode pulverization, leading to rapid capacity decay and eventual disintegration, thus hindering their practical applications. Herein, we report a 3D coral-like Sb-Cu alloy nanoarray with gradient distribution of both elements. The array features a Sb-rich bottom and a Cu-rich top with increasing Sb and decreasing Cu concentrations from top to bottom. The former is the active component that provides the high capacity, whereas the latter serves as an inert additive that acts against volume variation. The gradual transition in composition within the electrode introduces a ladder-type volume expansion effect, facilitating a smooth distribution and effective release of stress, thereby ensuring the wanted mechanical stability and structural integrity. The as-developed nanoarray affords a high reversible capacity (460 mAh g at 0.5 C), stable cycling (89 % retention over 120 cycles at 1.0 C), and superior rate capability (354 mAh g at 10 C). The concentration dual-gradient strategy paves a new pathway of designing alloy-type materials for SIBs.
合金型材料因其高理论容量和整体性能，对钠离子电池（SIBs）的阳极具有吸引力。然而，在反复循环过程中应力/应变的积累会导致电极粉化，从而导致容量迅速衰减并最终解体，阻碍了它们的实际应用。在此，我们报道了一种具有两种元素梯度分布的三维珊瑚状Sb-Cu合金纳米阵列。该阵列的特点是底部富含Sb，顶部富含Cu，从顶部到底部Sb浓度增加而Cu浓度降低。前者是提供高容量的活性成分，而后者作为一种惰性添加剂，可抵抗体积变化。电极内成分的逐渐转变引入了阶梯式体积膨胀效应，有利于应力的平滑分布和有效释放，从而确保所需的机械稳定性和结构完整性。所制备的纳米阵列具有高可逆容量（0.5 C时为460 mAh g）、稳定的循环性能（1.0 C下120次循环后保持率为89%）和优异的倍率性能（10 C时为354 mAh g）。浓度双梯度策略为设计用于SIBs的合金型材料开辟了一条新途径。
