Up-scalable synthesis, structure and charge storage properties of porous microspheres of LiFePO4@C nanocomposites

Abstract

Novel porous micro-spherical aggregates of LiFePO 4 @C nanocomposites have been synthesized in large quantities via an improved sol-gel method combined with spray drying technology (sol-gel-SD method), which required no surfactants or templates. With this new procedure, a precursor was prepared through the process of sol-gel and subsequent spray drying. A series of analyses, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray (EDX), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and a combined system focused ion beam (FIB)/SEM were performed after the as-obtained LiFePO 4 @C was heat-treated at 700 C for 12 h. The as-obtained LiFePO 4 @C had a large specific surface area (20.2 m 2 g À1 ), with an average nano-size of 32 nm and a main pore diameter of 45 nm. Contact with electrolyte occurred easily, which facilitated the electrical and lithium ion diffusion. In comparison with nano-sized LiFePO 4 @C particles prepared by a sol-gel method, the current product presented a high coulombic efficiency of 97.2%, a large reversible capacity of 133.8 mAh/g and an excellent capacity retention rate close to 100% after 50 cycles. The sol-gel-SD method provides an additional strategy to easily deal with gelatin and shows potential for use in the preparation of similar superstructures of other composites.

High-rate and long-term cycling capabilities of LiFe0.4Mn0.6PO4/C composite for lithium-ion batteries

“…4a, corresponding to the one obtained by Bhuvaneswari [33]. Figure 5b shows the XPS spectrum of Fe element on the surface of the LiFe 0.4 Mn 0.6 PO 4 /C composite, and two distinct peaks at binding energies of 710.5 and 724.7 eV corresponding to Fe2p 3/2 and Fe2p 1/2 are observed in the spectrum of Fe2p, which is characteristic of Fe 2+ in LiFePO 4 [34][35][36]. The XPS spectrum of LiFe 0.4 Mn 0.6 PO 4 /C composite shows the Mn 2p 1/2 and 2p 3/2 as 653.2 and 640.9 eV indicating Mn 2+ state [25,37], as shown in Fig.…”

Additive-free synthesis of 3D porous V2O5 hierarchical microspheres with enhanced lithium storage properties

“…19,20 Recently, the electrode materials with these structures have been found to be the most suitable for improving the electrochemical performance of LIBs. 15,21,[27][28][29][30] It is therefore highly desirable to prepare microsized V 2 O 5 spherical structures composed of nanostructures 60 for the design of high-performance LIBs with both high volumetric energy density and high gravimetric energy density, as well as good rate capability.…”

Improved performance of porous LiFePO4/C as lithium battery cathode processed by high energy milling comparison with conventional ball milling

“…In order to overcome these drawbacks of LiFePO 4 , different fabrication approaches can be adopted for example controlling the particle size and making homogeneous polycrystalline LiFePO 4 nanoparticles without agglomerations [7,8]. An electrode consisting of carbon coated with homogenously distributed pores is also appealing since it can provide fast electronic conduction and ion conduction at reasonable rates [4,9]. It is well documented that electrochemical performance of LiFePO 4 is improved when homogeneous porous structure is achieved [4,5,9e12].…”