Silicon-carbon (Si/C) composite materials have been proven to be one of the most promising anode materials for the next generation of lithium-ion batteries (LIBs) due to their high theoretical capacity. However, the substantial volume changes during alloying/dealloying processes have posed significant challenges to the working lifespan of Si-based anodes. In this study, we designed a dual-carbon-layer-structured Si composite anode material (DCS-Si). Using ladderlike polysilsesquioxanes as a precursor, we employed a zinc thermal reaction to internally reduce the Si––Si framework to Si. Simultaneously, the phenyl groups directly connected to Si atoms served as a carbon source for the internally dense coating layer. The obtained product underwent further coating controllable pyrolysis reactions to form an external carbon coating layer. As anode for LIBs, DCS-Si delivered a reversible specific capacity exceeding 1000 mAh g. Even after 1350 cycles at a current density of 0.3 A g, the specific capacity remained above 500 mAh g. Moreover, even under a high current density of 3 A g, after nearly 1000 cycles, the capacity retention rate still exceeded 70%. Further testing of the full cell also indicated that DCS-Si is a highly promising high-energy-density anode, with potential applications in future commercial lithium-ion batteries.

中文翻译：

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梯状聚倍半硅氧烷衍生的双碳缓冲壳结构硅作为锂离子电池的稳定负极材料

硅碳（Si/C）复合材料因其高理论容量而被证明是下一代锂离子电池（LIB）最有前途的负极材料之一。然而，合金化/脱合金过程中巨大的体积变化对硅基阳极的工作寿命提出了重大挑战。在这项研究中，我们设计了一种双碳层结构的硅复合负极材料（DCS-Si）。使用梯状聚倍半硅氧烷作为前驱体，我们采用锌热反应将 Si––Si 骨架内部还原为 Si。同时，直接连接到Si原子的苯基充当内部致密涂层的碳源。所得产品进一步进行涂层可控热解反应，形成外部碳涂层。作为锂离子电池的阳极，DCS-Si 的可逆比容量超过 1000 mAh g。即使在0.3 A g的电流密度下循环1350次后，比容量仍保持在500 mAh g以上。而且，即使在3 A g的高电流密度下，经过近1000次循环后，容量保持率仍然超过70%。全电池的进一步测试还表明，DCS-Si是一种非常有前途的高能量密度负极，在未来的商业锂离子电池中具有潜在的应用前景。