Tuning structural stability and lithium-storage properties by d -orbital hybridization substitution in full tetrahedron Li 2 FeSiO 4 nanocrystal

Mechanism of Exact Transition between Cationic and Anionic Redox Activities in Cathode Material Li2FeSiO4

“…2). It is found that when x goes from 0 to 1.5, the band gap E g changes from 2.91 eV (x = 0) to 3.60 eV and 0.57 eV for x = 1 and x = 1.5, respectively, in sharp contrast with the previous DFT+U results 36,47 and consistent with the semiconducting phase as reported by experiments 48,49 . Our results naturally explain that Li (2-x) FeSiO 4 always keeps a poor electronic conductivity and rate capability during electrochemical cycling 51 .…”

“…We note that almost all of the previous experimental [41][42][43][44][45] and theoretical studies 36,37 held that during the whole delithiation process in Li (2-x) However, previous DFT studies (with standard exchange-correlation functionals and Hubbard-like U correction) even predict a metallic state for Li (2-x) FeSiO 4 during delithiation 36,47 , in sharp contrast to the semiconducting phase as reported by experiments 48,49 . Clearly, the uncertainty about the Fe valence state and whether there is an 9 oxygen redox activity is imperative for the full understanding of the whole delithiation process in Li 2 FeSiO 4 .…”

Insight into cations substitution on structural and electrochemical properties of nanostructured Li2FeSiO4/C cathodes

“…This material possesses an excellent voltage window, best energy storage capability, safe operation, and environmental friendliness due to the presence of Fe and Si ion combination in its structural unit. The cost‐effective LFSO cathode material with the stable structure created significant attention when compared with the existing conventional cathodes such as LiMO 2 (M = Ni, Co, and Mn), LiMn 2 O 4 , and olivine‐type LiFePO 4 . The lower electronegativity of Si (2.03) in Li 2 FeSiO 4 when compared with P (2.39) in the LiFePO 4 cathode, can effectively reduce de‐intercalation voltage during the formation of Fe 2+ to Fe 3+ redox pair .…”

“…created significant attention when compared with the existing conventional cathodes such as LiMO 2 (M = Ni, Co, and Mn), LiMn 2 O 4 , and olivine-type LiFePO 4 . 5 The lower electronegativity of Si (2.03) in Li 2 FeSiO 4 when compared with P (2.39) in the LiFePO 4 cathode, 3 can effectively reduce de-intercalation voltage during the formation of Fe 2+ to Fe 3+ redox pair. 3 Despite many advantages, the LFSO suffers from low electronic/ionic conductivity, poor diffusion rate (~10 −17 cm −1 ), structural distortion, and capacity fading which limits high rate electrochemical performances when used as the cathode material for LIBs.…”

A review on first principles based studies for improvement of cathode material of lithium ion batteries

“…Strain is widely used to tune the band structure of materials [186,187] . First principles based DFT calculations have been employed to study the stability of Li 2 FeSiO 4 under different value of external mechanical pressure, it has been seen a transformation from monoclinic LFS to orthorhombic LFS at the perpendicular pressure of 0.38 GPa.…”