Carbide-Derived Niobium Pentoxide with Enhanced Charge Storage Capacity for Use as a Lithium-Ion Battery Electrode
Carbide-Derived Niobium Pentoxide with Enhanced Charge Storage Capacity for Use as a Lithium-Ion Battery Electrode
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DOI：
10.1021/acsaem.9b02549
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发表时间：
2020-05-26
影响因子：
6.4
通讯作者：
Presser, V
中科院分区：
文献类型：
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作者：
Budak, Oe;Geissler, M.;Presser, V
Nb2O5 已被探索作为一种有前景的锂离子电池 (LIB) 阳极材料，但根据晶体结构，据报道比容量通常约为或低于 200 mAh/g。我们首次推出粗晶 Nb2O5 材料，该材料可显着克服这种容量限制，有望实现高功率应用。我们的工作介绍了通过一步或两步本体转化过程获得的粗粒碳化物衍生 Nb2O5 相。通过在环境压力下由金属氯化物盐原位生产氯气，我们只需一步即可获得直接斜方 Nb2O5 以及碳化物衍生碳 (o-Nb2O5/CDC)。在真空条件下由金属氯化物盐原位形成氯气，产生覆盖剩余碳化物核的CDC，该碳化物核在CO2气体中热处理后可转化为碳壳覆盖的金属氧化物。两步过程产生了具有 CDC 的混合相四方和单斜 Nb2O5 (m-Nb2O5/CDC)。我们的综合衍射和光谱数据证实，碳化物衍生的 Nb2O5 材料显示出由于结构单元中缺氧而引起的晶面无序，并且在 m-Nb2O5/CDC 的情况下，出现严重的堆垛层错。这种缺陷工程允许获得非常高的比容量，超过传统 Nb2O5 的双电子转移过程。在 10 mA/g 的比电流下，所得的 m-Nb2O5/CDC 和 o-Nb2O5/CDC 的电荷存储容量在这两种情况下均约为 300 mAh/g，因此，这些值明显高于 Nb2O5 作为 LIB 阳极的最新技术。碳化物衍生的 Nb2O5 材料还显示出超过 500 个循环的强大循环稳定性，样品 m-Nb2O5/CDC 的容量衰减仅为 24%，o-Nb2O5/CDC 的容量衰减为 28%，这表明锂化和脱锂过程中膨胀/压缩程度较低。
Nb2O5 has been explored as a promising anode material for use as lithium-ion batteries (LIBs), but depending on the crystal structure, the specific capacity was always reported to be usually around or below 200 mAh/g. For the first time, we present coarse-grained Nb2O5 materials that significantly overcome this capacity limitation with the promise of enabling high power applications. Our work introduces coarse-grained carbide-derived Nb2O5 phases obtained either by a one-step or a two-step bulk conversion process. By in situ production of chlorine gas from metal chloride salt at ambient pressure, we obtain in just one step directly orthorhombic Nb2O5 alongside carbide-derived carbon (o-Nb2O5/CDC). In situ formation of chlorine gas from metal chloride salt under vacuum conditions yields CDC covering the remaining carbide core, which can be transformed into metal oxides covered by a carbon shell upon thermal treatment in CO2 gas. The two-step process yielded a mixed-phase tetragonal and monoclinic Nb2O5 with CDC (m-Nb2O5/CDC). Our combined diffraction and spectroscopic data confirm that carbide-derived Nb2O5 materials show disordering of the crystallographic planes caused by oxygen deficiency in the structural units and, in the case of m-Nb2O5/CDC, severe stacking faults. This defect engineering allows access to a very high specific capacity exceeding the two-electron transfer process of conventional Nb2O5. The charge storage capacities of the resulting m-Nb2O5/CDC and o-Nb2O5/CDC are, in both cases, around 300 mAh/g at a specific current of 10 mA/g, thereby, the values are significantly higher than that of the state-of-the-art for Nb2O5 as a LIB anode. Carbide-derived Nb2O5 materials also show robust cycling stability over 500 cycles with capacity fading only 24% for the sample m-Nb2O5/CDC and 28% for o-Nb2O5/CDC, suggesting low degree of expansion/compaction during lithiation and delithiation.