Ultrafast nano-spherical single-crystalline LiMn_0.792Fe_0.198Mg_0.010PO₄solid-solution confined among unbundled interstices of SGCNTs

Abstract

Spherical LiMn 0.792 Fe 0.198 Mg 0.010 PO 4 nanocrystals, which are highly dispersed and encapsulated within the interstices of supergrowth (single-walled) carbon nanotubes (SGCNTs), were successfully synthesized by in situ material processing technology called "ultra-centrifuging (UC) treatment". TEM images of these LiMn 0.792 Fe 0.198 Mg 0.010 PO 4 /SGCNT composites suggest the direct attachment of the LiMn 0.792 Fe 0.198 Mg 0.010 PO 4 nanocrystals (10-40 nm) onto the surface of highly conductive SGCNTs. Mgdoping brought out 10% increase of Li + capacity in Mn sites with 200% increase of Li + diffusivity and 50% decrease of electrical resistance owing to such peculiar "nano-nano LiMn 0.792 Fe 0.198 Mg 0.010 PO 4 /SGCNT composites". The synthesized LiMn 0.792 Fe 0.198 Mg 0.010 PO 4 /SGCNT composites overcome the inherent restrictions of one-dimensional diffusion and deliver a high electrochemical capacity density of ca. 54 mA h g À1 per composite (corresponding to 77 mA h g À1 per pure LiMn 0.792 Fe 0.198 Mg 0.010 PO 4 ) at a high rate of 50 C, while showing excellent cycle life, retaining 84% of the initial capacity over 3000 cycles.

Ultrafast Cathode Characteristics of Nanocrystalline-Li3V2(PO4)3/Carbon Nanofiber Composites

“…[30][31][32][33][34] This may be partially explained by the catalytic influence of the co-existing LVP nanocrystals on the CNF oxidative decomposition. On the other hand, the smaller temperature shift of LVP/CNF (89 Electrochemical performances.-The charge-discharge tests were performed to investigate the electrochemical characteristic of our Li 3 V 2 (PO 4 ) 3 /CNF composites.…”

“…Both the in-situ synthesis steps were achieved via our original method, referred to as ultracentrifuging (UC) treatment, and a subsequent instantaneous heat-treatment (post-UC). [29][30][31][32][33][34] The UC treatment is a buildup synthetic scheme involving: i) unbundling of the carbon matrix, ii) in-situ sol-gel reaction of the V 2 O 3 precursors on the exposed carbon surface, iii) restructuring of the carbon matrix. We applied this UC treatment to the synthesized V 2 O 3 /CNF in order to transform the V 2 O 3 nanocrystals into the LVP precursors on the surface of the CNF.…”

A novel nanoporous Fe-doped lithium manganese phosphate material with superior long-term cycling stability for lithium-ion batteries

“…We have compared the long-term cycle performance with that of other groups in the last three years as shown in Figure 3f. 19,25,28,[38][39][40][41][42] Moreover, the HNM-LMFP/C/G electrode shows a good structure stability after long-term cycling even at a relatively high charge/discharge rate as shown in Figure S9. To our best of knowledge, the cycling performance of HNM-LMFP/C/G in this paper is the best long-term cyclablity for the lithium manganese phosphate cathode materials till now.…”

“…Although the LiMn 0.792 Fe 0.0198 Mg 0.010 PO 4 /SGCNTs composite in Ref. 39 cycled over 1000 cycles, this cathode composite contained too much inactive single-walled carbon nanotubes (30 wt%) and just delivered a discharge capacity of 82 mAh·g -1 at the discharge rate of 1 C. The electrochemical impedance spectroscopy (EIS) measurement for the Nano-LMFP/C/G and HNM-LMFP/C/G electrodes was performed in order to better understand the superior cycling performance of the cathode materials. The EIS curves shown in Figure S10 are composed of a depressed semicircle in the high-frequency region and a straight sloping line in the lowfrequency region, which can be assigned to the charge-transfer process and the semi-infinite Warburg diffusion process, respectively.…”

Enhanced electrochemical properties of ZnO-coated LiMnPO4 cathode materials for lithium ion batteries

“…Moreover, some researchers focused on dual substitution [11][12][13]. Besides that, LiMn 2 O 4 was incorporated with LiMnPO 4 by one-step polyol-assisted pyro-synthesis [14].…”