Enhancing the electrochemical performance of lithium ion batteries using mesoporous Li3V2(PO4)3/C microspheres

Abstract

Mesoporous Li 3 V 2 (PO 4 ) 3 -carbon (LVP-C) microspheres are synthesized using Baker's yeast cells as both mesoporous structure templates and amorphous carbon sources. We find that the vanadium cations are combined with the negatively charged hydrophilic groups and are self-assembled both on the yeast cell wall surface and inside the cell by electrostatic interaction and metabolism regulation, respectively. The self-assembly leads to the formation of LVP-C microspheres with diameters of 1-8 mm. These microspheres are composed of densely aggregated nanoparticles (20-40 nm) as well as interconnected nanopores (2-15 nm), and hence they are of mesoporous nature. The nanoparticles can be easily brought into contact with electrolyte, and the open mesoporous structure allows lithium ions to easily penetrate into the microspheres. The carbon network (16.4 wt.%) on the surface of the Li 3 V 2 (PO 4 ) 3 nanoparticles facilitates electron diffusion. The mesoporous LVP-C microspheres have a high discharge capacity (about 126.7 mAh g À1 ), only 2% capacity loss of the initial value at the 50th cycle at a current density of 0.2 C, and a high rate capacity of 100.5 mAh g À1 at 5 C in the region of 3.0-4.3 V. The apparent Li + diffusion coefficient is found to be 6.76 Â 10 À10 cm 2 s À1 . The microspheres could be an ideal cathode-active material that fulfills the requirements of rechargeable lithium batteries for high power applications.

Lithium diffusion in Li3V2(PO4)3-based electrodes: a joint analysis of electrochemical impedance, cyclic voltammetry, pulse chronoamperometry, and chronopotentiometry data

“…(14) and (16) at the potentials close to maximum lithiated (3.5 V) and delithiated (4.1 V) states Table 2 The results of the E,t curves processing of the Li 3 V 2 (PO 4 ) 3 electrode using Eqs. (13) and (15) modeling the transfer of lithium in the two sublayers of the electrode material's particle Choice of the equivalent circuit and analysis of the impedance spectra…”

“…It is worth to note that in several studies [9,12], authors refuted the said circuit and suggested to use significantly different, obviously more suitable circuit. The authors of several other works [11,12,15,20,23], in principle, refused to use any circuit; considering the presence in the spectrum of pure diffusion segment and linearizing experimental points in the coordinates Z W ∼1= ffiffiffi ω p , they found Warburg's constant and therefrom by Warburg formula extracted the value of lithium diffusion coefficient (D).…”

“…A considerable number of articles are devoted to issues of ion transport in Li 3 V 2 (PO 4 ) 3 electrode [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25], which engage for this purpose impedance spectroscopy method. However, the analysis of impedance data in these studies is quite superficial.…”

Superior electrochemical properties of spherical-like Co2(OH)3Cl-reduced graphene oxide composite powders with ultrafine nanocrystals

“…6c shows the Nyquist impedance plots for the four samples obtained after the 100th cycle in a fully charged state. The medium-frequency semicircle is assigned to the charge-transfer resistance (R ct ), whereas the line inclined at %45°to the real axis corresponds to lithium diffusion within the electrodes [52][53][54]. The Co 2 (OH) 3 Cl/RGO powder electrode had a smaller charge transfer resistance than the others.…”

The Electrochemical Performance of Li3V2(PO4)3/Graphene Nano-powder Composites as Cathode Material for Li-ion Batteries

“…However, despite of these advantages, the intrinsic low electronic conductivity of about 2.3 × 10 −8 Scm −1 at room temperature, which is major drawback for the application of the LIBs, limits its rate capability [6,10]. In order to improve the low electronic conductivity, many efforts such as minimizing the particle size, doping with metal or surface coating with conducting materials were conducted [11][12][13][14][15][16][17][18][19][20][21][22]. Although the carbon coating is generally employed as a useful method towards improving the electronic conductivity of the LVP, it is difficult to cover uniformly the carbon on the surface of the LVP particles.…”