Lithium transition metal phosphates have become of great interest as storage cathodes for rechargeable lithium batteries because of their high energy density, low raw materials cost, environmental friendliness and safety. Their key limitation has been extremely low electronic conductivity, until now believed to be intrinsic to this family of compounds. Here we show that controlled cation non-stoichiometry combined with solid-solution doping by metals supervalent to Li+ increases the electronic conductivity of LiFePO4 by a factor of approximately 10(8). The resulting materials show near-theoretical energy density at low charge/discharge rates, and retain significant capacity with little polarization at rates as high as 6,000 mA x g(-1). In a conventional cell design, they may allow development of lithium batteries with the highest power density yet.

Electronically conductive phospho-olivines as lithium storage electrodes

The olivine LiFePO4 now stands as a competitive candidate of cathode material for the next generation of a green and sustainable lithium-ion battery system due to its long life span, abundant resources, low toxicity, and high thermal stability. In this review, we focus on LiFePO4 and discuss its structure, synthesis, electrochemical behavior, mechanism, and the problems encountered in its application. The major goal is to highlight some recent development of LiFePO4 with high rate capability, high energy density, and excellent cyclability resulting from conductive coating, nanocrystallization, or preparation.

Development and challenges of LiFePO4 cathode material for lithium-ion batteries

Ultimate Limits to Intercalation Reactions for Lithium Batteries

The rapidly expanding field of nonaqueous multivalent intercalation batteries offers a promising way to overcome safety, cost, and energy density limitations of state-of-the-art Li-ion battery technology. We present a critical and rigorous analysis of the increasing volume of multivalent battery research, focusing on a wide range of intercalation cathode materials and the mechanisms of multivalent ion insertion and migration within those frameworks. The present analysis covers a wide variety of material chemistries, including chalcogenides, oxides, and polyanions, highlighting merits and challenges of each class of materials as multivalent cathodes. The review underscores the overlap of experiments and theory, ranging from charting the design metrics useful for developing the next generation of MV-cathodes to targeted in-depth studies rationalizing complex experimental results. On the basis of our critical review of the literature, we provide suggestions for future multivalent cathode studies, including a...

Odyssey of Multivalent Cathode Materials: Open Questions and Future Challenges

4. Laplacian of the Electron Density 1592 5. AIM Properties 1593 IV. Topological Analyses of Experimental Densities 1593 A. Experimental versus Theoretical Topology 1593 1. Carbon−Carbon Bond 1593 2. Polar Bonds 1594 B. Reproducibility of the Experimental Topology 1596 1. Amino Acids and Oligopeptides 1596 2. Model Ambiguities 1598 C. Applications to Molecular Crystals 1599 1. Aromaticity in Carbon-Based Ring Systems 1599

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Chemical applications of X-ray charge-density analysis.

The electron density distribution and 3d-orbital electron occupancies for the Fe atom in synthetic triphylite, LiFePO 4 , have been analysed using single-crystal X-ray diffraction data measured at T=298 K with Mo Kα (λ=0.71069 A) radiation to a resolution corresponding to (sin θ max /λ)=1.078 A -1 . Measurements of 3265 reflections gave 944 unique data [R int (I)=0.036] with I>2σ(I). For an atomic multipole density model fitted by least-squares methods R(F)=0.0174 for all unique reflections. The Fe atom 3d-orbital occupancies have been derived from the multipole population coefficients using point-group-specific relations

Multipole analysis of the electron density in triphylite, LiFePO4, using X-ray diffraction data

Multipole Analysis of the Electron Density in Triphylite LiFePO4 using X-ray Diffraction Data

The static deformation electron density, Laplacian of the electron density and critical points in the electron density were analyzed in topaz Al2[SiO4]F2, using high-precision X-ray diffraction data. The electron deformation density, positive values of the Laplacian at (3,−1) bond critical points and the net atomic charges indicate a closed-shell-type interaction in the polyhedra. Anion valence-shell charge depletions are revealed. Maxima in the Laplacian of the electron density are displaced towards the close-packed plane owing to the mutual repulsion of the anion valence shells. The relationship between the topological features of the electron density and the close-packing concept is discussed. Shifts of the critical points from the internuclear vectors reflect the strain in the structure.

N. K. Hansen

Papers

Multipole analysis of the electron density in triphylite, LiFePO4, using X-ray diffraction data

Multipole Analysis of the Electron Density in Triphylite LiFePO4 using X-ray Diffraction Data

Multipole Analysis of the Electron Density in Topaz Using X-ray Diffraction Data