Synthesis of LiCoPO4/C nanocomposite fiber mats as free-standing cathode materials for lithium-ion batteries with improved electrochemical properties
Synthesis of LiCoPO4/C nanocomposite fiber mats as free-standing cathode materials for lithium-ion batteries with improved electrochemical properties
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DOI：
10.1016/j.electacta.2022.140400
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发表时间：
2022-04-23
影响因子：
6.6
通讯作者：
Taniguchi, Izumi
中科院分区：
文献类型：
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作者：
Belgibayeva, Ayaulym;Nagashima, Takeru;Taniguchi, Izumi
采用喷雾热解法制备的纳米结构磷酸钴锂微粒，通过静电纺丝和两步热处理成功合成了磷酸钴锂/碳（LiCoPO₄/C）纳米复合纤维毡。研究了预氧化温度对合成材料物理性能的影响。在425℃预氧化，随后在氮气气氛中700℃退火的纤维毡含有7 wt.%的碳，磷酸钴锂纳米粒子的小团聚体均匀地嵌入到几百纳米的碳纤维中。这种纤维毡具有338 m² g⁻¹的高比表面积和0.71 cm³ g⁻¹的大中孔体积。它可直接用作锂电池的无粘结剂和集流体的自支撑电极。该电池在0.1C下的初始放电容量为115 mAh g⁻¹。进一步研究了二氧化硅涂层对磷酸钴锂/碳纳米复合纤维毡电化学性能的影响。最后，含2 wt.%二氧化硅的二氧化硅包覆的磷酸钴锂/碳（15 wt.%）纳米复合纤维毡比未包覆的具有更优的容量保持率，其在0.05C下的初始放电容量分别达到126 mAh g⁻¹，在1C下达到100 mAh g⁻¹。
LiCoPO4/C nanocomposite fiber mats were successfully synthesized by electrospinning with a two-step heat treatment using nanostructured LiCoPO4 microparticles prepared by spray pyrolysis. The effects of the pre-oxidation temperature on the physical properties of the synthesized materials were studied. The fiber mats pre-oxidized at 425 C and subsequently annealed at 700 C in a N-2 atmosphere contained 7 wt.% carbon and the small agglomerates of LiCoPO4 nanoparticle were evenly incorporated in carbon fibers with a few hundred nanometers. This fiber mat had a high specific surface area of 338 m(2) g(-1) and a large meso-macropore volume of 0.71 cm3 g-1. It was directly used as a free-standing electrode without a binder and a current collector for lithium batteries. The cell exhibited an initial discharge capacity of 115 mAh g(-1) at 0.1 C. The effects of SiO2 coating on the electrochemical properties of LiCoPO4/C nanocomposite fiber mats were further studied. Finally, the SiO2- coated LiCoPO4/C (15 wt.%) nanocomposite fiber mat with 2 wt.% SiO2 demonstrated superior capacity retention to uncoated ones, and the initial discharge capacities reached 126 mAh g(-1) at 0.05 C and 100 mAh g(-1) at 1 C, respectively.