Electrospun Single‐Phase Na_1.2V₃O₈ Materials with Tunable Morphologies as Cathodes for Rechargeable Lithium‐Ion Batteries

Abstract

Single‐phase Na1.2V3O8 materials with single and hierarchical nanobelt morphologies were prepared by using a versatile electrospinning technique by altering the sintering profiles. On the basis of characterization by field‐emission scanning electron microscopy and high‐resolution transmission electron microscopy, the formation mechanisms of products with tunable morphologies are discussed. The products obtained are employed as cathode materials for lithium‐ion batteries. Their electrochemical activities are demonstrated through galvanostatic cycling and cyclic voltammetry. The non‐agglomerated, single nanobelts with exposed (100) facets, which serve as channels for facile lithium diffusion, are capable of exhibiting higher maximum capacities of approximately 218 mAh g−1 compared to hierarchical nanobelts with a maximum capacity of approximately 197 mAh g−1 versus Li/Li+ at a current density of 200 mA g−1. Their associated reversible capacities are approximately 207 and 173 mAh g−1, respectively, after 100 cycles. Single nanobelts with individual belt‐like structures and preferred facet orientation also exhibit better rate capabilities.

Hydrothermal synthesis of sodium vanadate nanobelts as high-performance cathode materials for lithium batteries

“…After 50 cycles, the electrodes can maintain a specific capacity of 222 and 209 mA h g À1 , respectively, indicating the high specific capacity and good cycling performance of Na 0.76 V 6 O 15 nanobelts. The capacity increasing trend at the first few cycles is also found in the previous literature, which may be associated with activation process and the wetting of electrode [23,26,35,36]. The cycling performances of Na 0.76 V 6 O 15 electrode are also evaluated at the higher current densities of 1000 and 1500 mA g À1 .…”

Electrospun Single Crystalline Fork-Like K2V8O21 as High-Performance Cathode Materials for Lithium-Ion Batteries

“…The as-obtained KVO nanofibers lost mass weight owing to the decomposition of metallic precursor and PVP during the annealing process, leading to the significant surface rupture and the formation of K 2 V 8 O 21 simultaneously. The mass loss within the range of 25–200°C was attributed to the loss of volatile components, such as residual solvent (DMF, H 2 O) and adsorbed moisture (Ko et al, 2015). At 332.2°C, there was a prominent DSC exothermic peak with a dramatic mass-loss.…”

NaV3O8 Nanoplates as a Lithium‐Ion‐Battery Cathode with Superior Rate Capability and Cycle Stability

“…21.3 C; 1C= 300 mA g À1 ), whereas the N-NVO electrode delivered ac apacity of 83.3 mAh g À1 .W hen the current density finally returned to 0.1 Ag À1 ,acapacity of 231.2 mAh g À1 could be recovered forN P-NVO.F rom the charge/discharge profiles of the NP-NVO cathode at various rates, shown in Figure 4d,w ef ind that the discharge/charge plateausa tl ow current density agreesw ell with the CV curves in Figure 4a.M oreover, the average operation voltage was still above 2.1 Ve ven at 6.4 Ag À1 .I nc ontrast, the average discharge voltage of N-NVO dropped below 2.0 Vatt his high current rate ( Figure S2). [34] Clearly, the electrochemical performance of our NP-NVO electrode is superior to that of their cathodes. [26] Ko et al synthesized single-phase Na 1.2 V 3 O 8 with single nanobelt morphology by using an electrospinning technique;t he as-obtained cathode had an initial discharge capacity of approximately 156 mAh g À1 at ac urrent density of 200 mA g À1 ,a nd its retention at the 100th cycle was approximately 207 mAh g À1 .…”

“…First, the radius of Na + is larger than Li + ,a nd hence NaV 3 O 8 has al arger interlayer distance than LiV 3 O 8 ,w hich may allow Li ions to be readily inserted and removed. [24][25][26][29][30][31][32][33][34] Huang and co-workerss ynthesized single-crystalline Na 2 V 6 O 16 ·xH 2 O nanowires by using ah ydrothermalm ethoda nd tested their lithium-storage properties;t he cathode hasa ni nitial specific discharge capacity of 235.2 mAh g À1 at 30 mA g À1 ,with acapacity retention of 91.1 %a fter 30 cycles. [27,28] The electrochemical performances of NaV 3 O 8 have been studied in both Li-ion and Na-ion batteries.…”

“…[27,28] The electrochemical performances of NaV 3 O 8 have been studied in both Li-ion and Na-ion batteries. [24][25][26][29][30][31][32][33][34] Huang and co-workerss ynthesized single-crystalline Na 2 V 6 O 16 ·xH 2 O nanowires by using ah ydrothermalm ethoda nd tested their lithium-storage properties;t he cathode hasa ni nitial specific discharge capacity of 235.2 mAh g À1 at 30 mA g À1 ,with acapacity retention of 91.1 %a fter 30 cycles. [24] Recently,T ang et al fabricated NaV 3 O 8 nanoflakes by using VO 2 nanoflakes as atemplate;t he NaV 3 O 8 nanoflakes delivered ad ischarge capacity of 210 mAh g À1 ,w ith stable cycling for 30 cycles when used as ac athode materialf or LIBs.…”