With high theoretical specific capacity and relatively safe working potential, SnO₂ has drawn widespread attention as a promising candidate of advanced anode for next generation lithium-ion batteries. However, the practical application of SnO₂ anode in lithium-ion batteries is severely blocked by some shortcomings such as the inferior rate capability, fast capacity decay and low initial coulombic efficiency during charge/discharge process. Gratifyingly, there are many works which have demonstrated that the SnO₂ anode achieves extra improvement in lithium storage performance after being reduced to nanoscale and embedded into porous carbon matrixes. Herein, porous SnO₂@C micro-/nanospheres with a sandwiched buffer zone resulted from unevenly radial distribution of pores in carbon micro-/nanospheres are prepared for the first time. These SnO₂@C micro-/nanospheres consist of small SnO₂ nanoparticles embedded within porous carbon micro-/nanospheres with a sandwiched buffer zone. The results of this study indicate that the sandwiched buffer zone of carbon micro-/nanospheres and the confinement effect of nanopores on small SnO₂ nanoparticles synergistically contribute to outstanding structural stability and excellent electrochemical performance of thus porous SnO₂@C micro-/nanospheres. Besides, it is found that the lithium storage performance of the SnO₂@C micro-/nanospheres can be tuned by adjusting the SnO₂ contents. As a result, the as-prepared SnO₂@C micro-/nanospheres with an optimalizing SnO₂ content exhibit the best performance, delivering a high capacity of 955 mAh g⁻¹ at 200 mA g⁻¹ after 250 cycles as well as a high capacity of 836 mAh g⁻¹ at even 1000 mA g⁻¹ after 350 cycles.

具有较高的理论比容量和相对安全的工作潜力，SnO ₂作为下一代锂离子电池高级阳极的有前途的候选者已引起广泛关注。然而，SnO ₂阳极在锂离子电池中的实际应用受到一些缺点的严重阻碍，例如速率/速率能力差，容量衰减快以及在充电/放电过程中初始库仑效率低。令人欣慰的是，有许多工作表明，SnO ₂阳极在被还原成纳米级并嵌入多孔碳基体中后，锂的存储性能有了额外的提高。在此，多孔SnO ₂首次制备了由碳微/纳米球中孔隙的径向分布不均匀导致的具有夹层缓冲带的@C微/纳米球。这些SnO ₂ @C微球/纳米球由嵌入在多孔碳微球/纳米球中的小SnO ₂纳米颗粒组成，中间有一个缓冲区域。这项研究的结果表明，碳微/纳米球的夹层缓冲带和纳米孔对小SnO ₂纳米颗粒的约束作用协同作用，从而为多孔SnO ₂ @C微/纳米球提供了出色的结构稳定性和出色的电化学性能。此外，发现SnO ₂的锂存储性能可以通过调节SnO _2的含量来调节@C微球/纳米球。结果，所制备的具有最佳SnO ₂含量的SnO ₂ @C微球/纳米球表现出最佳性能，在250次循环后，在200 mA g ^-1时可提供955 mAh g ^-1的高容量，以及350次循环后，即使在1000 mA g ^-1时，也具有836 mAh g ^-1的高容量。