Mixed-carbon-coated LiMn0.4Fe0.6PO4 nanopowders with excellent high rate and low temperature performances for lithium-ion batteries

Abstract

Ascorbic acid acts as both an antioxidant and a surfactant to form organic groups (first carbon source) on the surface of as-solvothermal products, in which the-OH (or H 2 O) groups of glucose (second carbon source) are closely bonded to the surface to form a uniform adsorption layer. Uniform mixed-carbon-coated LiMn 0.4 Fe 0.6 PO 4 nanopowders are formed after calcination, which demonstrate excellent electrochemical performances.

Sandwich, Vertical‐Channeled Thick Electrodes with High Rate and Cycle Performance

“…Meanwhile, we note that one additional cathodic peak (3.6 V) appears for both electrodes. This would arise from the incomplete Li intercalation in MnPO 4 engendering the formation of Mn 3+ ‐containing FePO 4 , which can be intercalated by Li at ≈3.6 V versus Li/Li + to form some intermediate LiFePO 4 . Besides, two peak currents ( I p ) from anodic and cathodic processes of LFMP‐IGF are larger than those of LFMP‐TGF.…”

“…Furthermore, the elemental mapping images (Figure g–j and Figure S2: Supporting Information) indicate that LFMP NPs were uniformly embedded within the rGO skeleton, and Mn has been doped into the Fe site in LiFe 0.7 Mn 0.3 PO 4 crystals. The higher voltage given by the redox couple Mn 2+ /Mn 3+ would contribute to increase the energy density of the electrode . In addition, the cross‐section of LFMP‐IGF is shown in Figure d.…”

“…The mechanical robustness of LFMP‐IGF would arise from its unique pore anisotropy. From top view (Figure a), the honeycomb pores are well organized with each other to maximize the elastic strength; from side view (Figure d), the multilayered face‐to‐face stacked configuration along the compression direction could strengthen the interlayer π–π interaction during bending deformation, thereby its mechanical stiffness is greatly enhanced . In addition, the anisotropic distributed LFMP NPs inside the sandwich layers were tightly bonded within the interconnected graphene framework after annealing at 700 °C, so that the cork‐like LFMP‐IGF can act as a whole to further improve its structure rigidity …”

“…a) Cycling performance combined with Coulombic efficiency of LFMP‐IGF‐3 at 1C; b) retention of specific capacity at 1C as a function of mass loading for three LFMP‐IGF electrodes after 500 cycles; c) areal capacity versus C‐rate of LFMP‐IGF‐4‐6; d) comparison of specific capacity of LFMP‐IGF‐1,‐3 and LFMP‐Al‐1, ‐11 from 0.2C to 20C; e) comparison of SCWEM of LFMP‐IGF with the reported research‐level LFMP cathodes: black, blue, pink, and orange histograms referring to refs. , , , and , respectively; or other slurry‐casted 3D carbon‐based free‐standing LFP electrodes: Wood‐templated framework, Ultrathin graphite foam and reduced graphene oxide/polyacrylic acid (RGO/PAA) aerogel, f) photos of the pouch cell show the structure stability and flexibility of the LFMP‐IGF electrode under folding test.…”

Preparation of Enhanced‐Performance LiMn0.6Fe0.4PO4/C Cathode Material for Lithium‐Ion Batteries by using a Divalent Transition‐Metal Phosphate as an Intermediate

“…For example, Chen et al reported LiMn 0.4 Fe 0.6 PO 4 /C nanopowders with excellent high-rate and low-temperature performance, which delivered 128 mAh g À1 at ah igh currentr ate of 20 Ca nd 107 mAh g À1 at À20 8C. [22] Chen et al produced LiMn 0.6 Fe 0.4 PO 4 /C microspheres using oxalates and as pray-drying method, which showed ar eversible capacity of about 152 mAh g À1 after 500 cycles at 1C, indicative of outstanding cycle stability. [23] Sun et al synthesized LiMn 0.5 Fe 0.5 PO 4 /C microsized spheres using coprecipitated phosphate as precursor,w hich retained 85 %o ft heir capacity at 55 8C.…”