Aerosol-Assisted Synthesis of Colloidal Aggregates with Different Morphology: Toward the Electrochemical Optimization of Li₃VO₄ Battery Anodes Using Scalable Routes

Abstract

The improvement of properties through strict morphology control often requires the use of difficult to scale up synthesis routes. Thus, a compromise between scalability and morphology control is required to partially exploit the advantages of this control in materials functionality. Here, we show that a scalable and continuous route (aerosol route) is able to produce Li3VO4 colloidal aggregates with different morphology (spherical and platelet-like) using easy to handle economic precursors (V2O5, LiOH, and LiNO3 in stoichiometric amounts). The key for these differences in morphology resides on controlling the nature of the intermediate stages that can occur during particle formation in aerosol synthesis. We also show that the electrochemical response of Li3VO4 is strongly dependent on morphology. Thus, optimization of morphology allows building anodes that to our knowledge outperform other reported Li3VO4 anodes and even compete with most of the reported Li3VO4/C composites at adequate high rates (2–8 A/g). Finally, we have developed a simple and scalable coating protocol (suspensions with solid concentrations of 100 g/L are used) that additionally improves the long-term stability of the optimized anodes. Combination of the two scalable methods leads to Li3VO4 anodes that operating at a safe cutoff voltage of 0.2 V can retain a high capacity (280 mAh/g) with excellent coulumbic efficiency (>99.9%), even after 500 cycles at a competitive rate (2 A/g discharge–charge).

Vanadate‐Based Materials for Li‐Ion Batteries: The Search for Anodes for Practical Applications

“…Tartaj at al. reported the preparation of Li 3 VO 4 via an aerosol method, which consists of the initial formation of solution contains of V 2 O 5 , LiOH, LiNO 3 , and H 2 O 2 , and the subsequent spraying at 300 and 700 °C . Zhao et al fabricated porous Li 3 VO 4 /C by initially dissolving [VO‐(acac) 2 ] and LiOH in distilled water, and then the sample was freeze‐dried and heated at 550 °C for 2 h in N 2 atmosphere .…”

“…4) Li 3 VO 4 is low‐cost compared with graphite and Li 4 Ti 5 O 12 . However, Li 3 VO 4 also suffers from several drawbacks, mainly referring to: 1) Li 3 VO 4 is hydrophilic and therefore require highly dry condition for sample preparation and storage; 2) the poor electronic conductivity of Li 3 VO 4 may cause large polarization upon charge/discharge; 3) the low initial coulombic efficiency. All these, make it challenging for practical application.…”

“…Though it cannot be easily scaled up because the requirement of high reaction temperature and pressure that ordinary reaction container cannot bear, it takes the advantage of morphology variety when comparing with solid‐state reaction method. The main challenge for one‐step solution synthesis of Li 3 VO 4 is the hydrophilic property, which correlates intimately with the fabrication conditions such as the precursors (mainly refers to Li and V sources) and solvent (i.e., DI water and organic solvent). Notably, Li source was dominated by LiOH, while V 2 O 3 and NH 4 VO 3 were usually adopted as V source.…”

“…However, it is debatable. Since much higher specific capacities have been reported recently . Remarkably, it was found in Ni et al's study that stable cycling with reversible capacity of ≈540 mAh g −1 over 300 cycles can be achieved for Li 3 VO 4 /C composite with homogeneous hybridization between Li 3 VO 4 and C at nanoscale .…”

Si‐Doping Mediated Phase Control from β‐ to γ‐Form Li3VO4 toward Smoothing Li Insertion/Extraction

“…However, in the last three decades, few insertion anode alternatives are available with good promise of commercial requirements and higher energy than graphite, which becomes a bottleneck for the development of next generation LIBs. [9,10] The current reported works on Li 3 VO 4 are mainly focused on decreasing the particle size to improve its reaction activity by exploring different synthesis methods, [11][12][13][14] or enhancing its conductivity by carbon coating or compositing. [6] It shows a theoretical capacity of 394 mA h g −1 when inserted 2 mole Li per formula, higher than graphite and nearly two times that of Li 4 Ti 5 O 12 .…”