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Highlights: [•] Zn is employed as dopant in LiNi0.5Mn1.5O4. [•] The effects of Zn doping on structure and performance are investigated. [•] LiZn0.08Ni0.42Mn1.5O4 shows excellent rate capability and cyclic performance. [•] The mechanism of performance improvement by Zn doping is examined. [ABSTRACT FROM AUTHOR]

Highlights: [•] Cation-incorporated Li3V2(PO4)3/C have been systematically investigated. [•] Cation incorporation in Li3V2(PO4)3 does not change the monoclinic structure but form solid solution. [•] Fe-incorporation shows the best electrochemical performance whereas Ni-incorporation shows the poorest performance. [•] A clear profile of cation incorporation with Fe, Co, Ni, Mn ions in Li3V2(PO4)3/C is obtained. [ABSTRACT FROM AUTHOR]

Highlights: [•] A polymer-assisted sol–gel method is developed to fabricate porous nanoscaled LiMn2O4. [•] Porous nanoscaled LiMn2O4 cathode exhibits superior rate capability and excellent cyclability. [•] Morphology, Li+ diffusion coefficient and Mn dissolution are examined to explain the high performance. [Copyright &y& Elsevier]

Abstract: Ti-incorporated LiFe1−x Ti x PO4 (0≤ x ≤0.2) samples have been prepared via a two-step solid-state reaction route. The samples have systematically been investigated with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, scanning electron microscope (SEM), transmission electron microscope (TEM), cyclic voltammetry (CV) and charge/discharge measurements. The incorporation of Ti in LiFePO4 significantly enhances the electrochemical performance; the carbon-coated LiFe0.9Ti0.1PO4 sample shows the best performance. It is confirmed that LiFe1−x Ti x PO4 with x ≤0.05 are of single phase while those with 0.07≤ x ≤0.2 contain impurity phases: LiTi2(PO4)3 and TiP2O7. The impurities influence not only the electronic conductivity, but also the total specific capacity. Appropriate amount of titanium incorporation is favorable for the improvement in electrochemical performance. [Copyright &y& Elsevier]

Abstract: Nonstoichiometry and Na incorporation are designed to attain controllable impurity phases Li4P2O7 and Li3PO4 in LiFePO4. The effects of Li4P2O7 and Li3PO4 on structure and electrochemical performance have been investigated. Both Li4P2O7 and Li3PO4 impurities are observed in (Fe, P)-deficient LiFe0.9P0.95O4−δ . With Na+ incorporation, Li4P2O7 phase disappears while Li3PO4 content increases. Proved by X-ray photoelectron spectroscopy, nonstoichiometry and Na-incorporation do not change the chemical state of Fe(II). Our experiments indicate that Li4P2O7 and Li3PO4 show different effects on the electrochemical performance. Li4P2O7 leads to degradation of cyclability, whereas a small amount of Li3PO4 is beneficial for the improvement in capacity and rate capability. The 1% Na-doped LiFe0.9P0.95O4−δ composite exhibits the best electrochemical performance. We ascribe the improvement to the structural stabilization caused by the existence of Li3PO4. [Copyright &y& Elsevier]

Abstract: Na+ and Cl− co-doped LiFePO4/C composites were prepared via a simple solid state reaction. The structure, valence state and electrochemical performance were carefully investigated. Rietveld refinement on X-ray diffractions reveals that Na+ and Cl− have successfully been introduced into the lattice of LiFePO4. X-ray photoelectron spectroscopy proves that the co-doping of Na+ and Cl− does not change the chemical state of Fe(II). Experimental results further show that the co-doping contributes to induce the lattice distortion, modify the particle morphology, and increase the electronic conductivity. Considerably enhanced capacity, coulombic efficiency and rate capability were obtained in the co-doped LiFePO4. The specific capacities are 157mAhg−1 at 0.2C, 115mAhg−1 at 10C and 98mAhg−1 at 20C for the (Na+, Cl−) co-doped LiFePO4/C cathode material. The improvement can be ascribed to the enhanced electronic conductivity and electrode kinetics due to the micro-structural modification promoted by co-doping. [Copyright &y& Elsevier]

Abstract: A simple and efficient strategy was employed to enhance high-rate performance for carbon-coated LiFePO4 (C-LFP) by incorporating with conducting polymer polyaniline (PANI). C-LFP was synthesized via a solid state reaction whereas PANI was formed in situ by chemical oxidative polymerization of aniline with ammonium persulfate as an oxidizer to achieve the C-LFP/PANI composites. Specific capacities as high as 165mAhg−1 at 0.2C, 133mAhg−1 at 7C and 123mAhg−1 at 10C were obtained in C-LFP/7wt.% PANI composite. Moreover, the composite exhibits remarkably improved cyclability as compared with the parent C-LFP. The mechanism has been carefully investigated for the improvement in the electrochemical performance. Experimental results show that the charge transfer impedance decreases significantly and the cathode surface becomes much smooth over cycling with modification of conductive PANI. The incorporated PANI can work not only as an additional host for Li+-ion insertion/extraction, but also as a binder to modify the electrode surface and a container for electrolyte to penetrate into C-LFP particles. [Copyright &y& Elsevier]