High-capacity Si-based microspheres are being spotlighted as a promising substitute for commercial spherical graphite anodes in the development of high-energy lithium-ion batteries. Nevertheless, the formidable challenge of their severe mechanochemical degradation during the (de)lithiation process remains unaddressed currently. Herein, we present a Si-based microsphere prepared by the oxygen pumping mechanism under a cost-efficiently low-temperature (250 °C) molten salt reduction environment. By optimally controlling oxygen gradient distribution, the resulted Si-based microspheres exhibit the unique coherent architecture ranging from ordered crystalline Si core to disordered SiO2(v) shell. Their structural coherence but regional difference in function achieves a perfect combination of structural compatibility and optimized chemo-mechanical effect, endowing the obtained Si-based microspheres with a nearly intact morphology after 1500 cycles and a 97 % capacity retention after 1000 cycles at 2 A g-1. Our design broadens research directions for Si anode material design, which will accelerate the practical application of micro-sized Si anode materials.

中文翻译：

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硅基微球作为超稳定储锂负极的梯度设计


在高能锂离子电池的开发中，高容量硅基微球作为商用球形石墨阳极的有前途的替代品而受到关注。然而，它们在（脱）锂化过程中严重机械化学降解的巨大挑战目前仍未得到解决。在此，我们提出了一种在经济高效的低温 （250 °C） 熔盐还原环境中通过氧气泵送机构制备的硅基微球。通过最佳控制氧梯度分布，所得的 Si 基微球表现出独特的相干结构，范围从有序的结晶 Si 核到无序的 SiO2（v） 壳层。它们的结构相干性但功能上的区域差异实现了结构相容性和优化的化学机械效应的完美结合，使获得的硅基微球在 1500 次循环后具有几乎完整的形态，在 2 A g-1 下循环 1000 次后具有 97% 的容量保留。我们的设计拓宽了硅负极材料设计的研究方向，这将加速微型硅负极材料的实际应用。