Fig. 1

Crystal structure of LiFePO4 along perspective of 1D diffusion channels of Li ions[4]"

Fig. 2

LiFePO4 modification strategy in recent years"

Fig. 3

(a)～(c) CV curves of LiFePO4 under different scan rates of 1.4 mV/s, 2.8 mV/s, and 4.2 mV/s at temperature ranging from 253～313 K; (d)～(f) image plot of diffraction patterns for (111), (211), (020), (311), and (121) reflections during two CV cycles under different scan rates of 1.4 mV/s, 2.8 mV/s, and 4.2 mV/s at a temperature of 293 K, corresponding current curves are plotted to right; LFP represent for LiFePO4; (g)～(i) selected individual diffraction patterns for two CV cycles at 1.4 mV/s, 2.8 mV/s, and 4.2 mV/s[14]"

Fig. 4

SEM images for synthesized (a) LiFePO4 and (b) LiFe0.77Mn0.23PO4 particles; (c) first cycle charge/discharge profile, (d) cycled capacity at various charge/discharge rates, and (e) electrochemical impedance spectra for LiFePO4 and LiFe0.77Mn0.23PO4[22]"

Fig. 5

(a) First charge/discharge curves of Cl-doped LFP/C and LFP/C electrodes at 0.1 C; discharge curves of different current density: (b) LFP/C; (c) Cl-doped LFP/C; (d) rate ability of LFP/C and Cl-doped LFP/C; (e) cycling performance of Cl-doped LFP/C and LFP/C at 0.1 C and 10 C, respectively[28]; (f) initial charge/discharge curves of undoped and F-doped LiFePO4/C samples at 0.1 C rate; (g) initial charge/discharge curves of LiFePO4/C and LiFePO4-xFx/C (x = 0.15) samples at 0.1C rate, (h) rate and cycle performances of undoped and F-doped LiFePO4/C samples; i) cycle performances of LiFePO4-xFx/C (x = 0.15) sample at high-rate 20 C, 30 C[29]"

Fig. 6

(a) Schematic illustration of te synthesis process of MT-LFP materials; SEM images of the as-prepared undoped LFP (b) and (c); MT-LFP (d) and (e); Nitrogen adsorption (closed symbols)-desorption (open symbols) isotherms (f); pore diameter distribution curves (g) of as-prepared undoped LFP and MT-LFP samples; (h) charge-discharge curves of LFP and (i) MT-LFP at different rates; (j) rate capabilities of LFP and MT-LFP at various rates; cycling performance of LFP and MT-LFP cathodes at a charge/discharge rate of 0.5 C (k), 1 C (l), and 5C (m)[30]"

Table 1

A sum up of electrochemical performance of LiFePO4 modified by elemental doping"

Fig. 7

Schematic illustration of synthesis and structure of LFP/graphite composite. (a) synthesis of LFP/graphite composite by intercalating graphite with FeCl3 followed by formation of LFP within the graphite layers; (b) schematics of LFP/graphite based cathode and a commercial LFP cathode, continuous conductive network provided by graphite confers better performance on LFP/graphite electrode; structure and morphology of LFP/graphite composite: (c), (d) SEM and EDS mapping, (e), (f) SEM images, and (g), (h) TEM images of LFP/graphite composite; (i) inset in panel g is SAED of a LFP particle; (j) SEM and (k) TEM images of porous graphite particle after etching away LFP particles from LFP/graphite composite[43]"

Fig. 8

Overview of electrochemical properties of LiFePO4 coated by different materials"

Fig. 9

(a) Schematic of fabrication process of N-Co/N-Li2O composites; (b) initial charge potential profiles of electrodes made with various Co/Li2O nanocomposites: M-Co/N-Li2O composite, SM-Co/N-Li2O composite and N-Co/N-Li2O composite; (c) charge/discharge potential profiles of N-Co/N-Li2O electrode after first charge process; (d) initial charge potential profiles of LiFePO4 electrodes with different amounts of N-Co/N-Li2O additive in half-cell configurations; initial charge/ discharge potential profiles (e) and cycling performance (f) of LiFePO4/ graphite full cells with and without N-Co/N-Li2O additive[72]"