Nanosheet-assembled hierarchical Li4Ti5O12 microspheres for high-volumetric-density and high-rate Li-ion battery anode
Nanosheet-assembled hierarchical Li4Ti5O12 microspheres for high-volumetric-density and high-rate Li-ion battery anode
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DOI：
10.1016/j.ensm.2019.05.036
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发表时间：
2019-09
影响因子：
20.4
通讯作者：
Dongdong Wang;Haodong Liu;Mingqian Li;Xuefeng Wang;Shuang Bai;Yang Shi;Jianhua Tian;Zhongqiang S
中科院分区：
文献类型：
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作者：
Dongdong Wang;Haodong Liu;Mingqian Li;Xuefeng Wang;Shuang Bai;Yang Shi;Jianhua Tian;Zhongqiang S
快速充电（高倍率）是锂离子电池 (LIB) 的关键需求。虽然纳米结构电极可以实现优异的倍率性能，但其振实密度通常较低，这导致体积能量密度较低并限制了其实际应用。在这里，我们报道了纳米片组装的Li4Ti5O12（LTO）分级微球，它可以同时实现高振实密度、高倍率性能和长循环寿命。这些微球通过简单的溶剂热反应和短的热退火过程以高产率制备。对此类LTO微球的形成机制进行了系统研究，以了解其形态演变和相变过程。这些精心设计的分层微球在纳米和微米尺度上具有受控特征，可实现致密的颗粒堆积、轻松的锂离子扩散和高结构鲁棒性。最佳的LTO微球可以提供极高的倍率性能（例如，50C下155mAh g−1）和优异的循环稳定性（50C下2000次循环后容量保持率为99.5%，30C下3000次循环后容量保持率为95.4%），振实密度为1.32gcm−3。此外，LiNi0.5Mn1.5O4正极在全电池中也证明了它们的优越性能，在3C下循环1000次后容量保持率为93.4%。这些结果表明，使用这种高体积密度的 LTO 作为高倍率和长寿命锂离子电池的阳极材料具有巨大的前景。
Fast-charging (high-rate) is a critical need for lithium-ion batteries (LIBs). While superior rate performance can be achieved by nanostructured electrodes, their tap density is often low, which leads to low volumetric energy density and limits their practical applications. Here, we report nanosheet-assembled Li4Ti5O12(LTO) hierarchical microspheres which can simultaneously achieve high tap density, high rate performance and long cycle life. These microspheres were prepared with high yield by facile solvothermal reaction followed by a short thermal annealing process. The formation mechanism of such LTO microspheres was systematically investigated to understand their morphology evolution and phase transformation process. These well-designed hierarchical microspheres with controlled features on both nanometer- and micrometer-scales enable dense particle packing, easy lithium-ion diffusion and high structure robustness. Optimal LTO microspheres can offer extremely high rate capability (e.g., 155 mAh g−1at 50 C), and excellent cycling stability (99.5% capacity retention after 2000 cycles at 50 C, 95.4% capacity retention after 3000 cycles at 30 C) with a tap density of 1.32 g cm−3. Furthermore, their superior performance was also demonstrated with LiNi0.5Mn1.5O4cathode in full cells, which showed 93.4% of capacity retention after 1000 cycles at 3C. These results suggest the great promise of using such high-volumetric-density LTO as an anode material for high-rate and long-life LIBs.