Effect of crystallite size on the intercalation pseudocapacitance of lithium nickel vanadate in aqueous electrolyte

Micro- and Nanocrystalline Inverse Spinel LiCoVO4 for Intercalation Pseudocapacitive Li+ Storage with Ultrahigh Energy Density and Long-Term Cycling

“…Among a variety of intercalation host materials for Li-ion battery, spinel and inverse spinel-type structures earned special interest as Li + hosts permitting three-dimensional pathways for rapid Li + diffusion accompanying a low energy barrier. , So far, only a few lithium-based vanadates such as monoclinic LiV 3 O 8 and cubic LiNiVO 4 with well-defined ion conducting channels in the crystal structure demonstrated a pseudocapacitive Li + intercalation/extraction mechanism in aqueous electrolytes. The effect of crystallite size on the Li + storage properties of inverse spinel LiNiVO 4 has been reported in our previous work . Nanocrystalline structure contributes an increased number of lattice sites for Li + accommodation with expanded solid–solution limits.…”

“…It is found that H-LCVO has decreased R s -value compared to S-LCVO electrode in 1 M LiOH aqueous electrolyte. The reduced R s -value of H-LCVO electrode could be endorsed to the small crystallite size of the active material, which minimizes the Li + diffusion path length, thereby boosting the Li + movement in the electrolyte. , In addition, the lack of a semicircle in the high-frequency region of the Nyquist plot entails negligible charge-transfer resistance for both electrodes. The slopes of the straight lines in the low-frequency region of both S-LCVO and H-LCVO electrodes were greater than 45°, indicating characteristic capacitor behavior. ,, …”

“…An equivalent circuit used to fit the impedance curve is given in Figure 4d, which includes components of bulk solution resistance (R s ), charge-transfer resistance (R ct ), a constant phase element (CPE) to represent the double layer capacitance, a Warburg diffusion element (W), and a pseudocapacitive element (C p ) from the Li + diffusion The reduced R s -value of H-LCVO electrode could be endorsed to the small crystallite size of the active material, which minimizes the Li + diffusion path length, thereby boosting the Li + movement in the electrolyte. 25,38 In addition, the lack of a semicircle in the high-frequency region of the Nyquist plot entails negligible charge-transfer resistance for both electrodes.…”

“…The effect of crystallite size on the Li + storage properties of inverse spinel LiNiVO 4 has been reported in our previous work. 25 Nanocrystalline structure contributes an increased number of lattice sites for Li + accommodation with expanded solid−solution limits. The combination of ionselective channels and nanocrystalline structure exhibited a possible way for high-rate Li + storage.…”

“…Recently, Li + storage via intercalation pseudocapacitance received significant attention considering its ability to overcome the slow intrinsic Li + solid-state diffusion limited battery kinetics with a surface process. , However, intercalation pseudocapacitive Li + storage is hardly observed in most metal oxides. To date, only a few transition metal oxides such as Nb 2 O 5 , − α-MoO 3 , TiO 2 , H 3 Ti 6 O 13 , LiFePO 4 , LiV 3 O 8 , LiFeTiO 4 , and LiNiVO 4 , etc., exhibited Li + storage through intercalation pseudocapacitance mechanism. The significance of this new class of pseudocapacitance is that Li + storage in battery materials can be attained at rapid rates comparable to that of electrochemical capacitors.…”