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The crystal structure of the 18650-type Li-ion cell constituents has been studied at ambient temperature by high-resolution neutron powder diffraction at different states of charge. The structure evolution occurring on the anode (graphite) site as a function of the cell state has been accurately monitored by simultaneous electrochemical measurements and powder diffraction. A set of 128 neutron powder diffraction patterns each over a 2θ angular range of 0.95 • -160 • has been collected during slow cell discharge/charge in a high-resolution mode. Severe deviations from the previously reported details of Li-intercalation into graphite have been observed, such as: structural evolution of the intercalated carbons depending either on charge or discharge; pronounced dependence of the interatomic spacings for the higher ordered Li x C 6 (incl. previously unknown ones). Instead of higher stages of Li-intercalation in the region of low Li-contents, which would have been observed by Bragg reflections at low 2θ angles, a modulation within the ab-planes is proposed, which is correlated between neighboured graphene layers and changes in dependence of the Li-content. On the basis of these results the phase diagram for lithium-intercalated carbons has been reconsidered and the alternative ordering model for the Li x C 6 (x < 0.5) has been proposed.Due to the rapid progress in the field of portable electronics and electric vehicles there is an increasing demand for smaller size, larger capacity, lighter weight and lower priced rechargeable batteries. Nowadays the Li-ion batteries are considered as the predominant cell technology due to their high voltage, high energy, good cycle life and excellent storage characteristics. However, despite their overall advantages, Li-ion cells have some drawbacks, which cannot be overcome and require systematic and detailed research, e.g. on issues concerning safety, stability of electrode materials, capacity improvements etc. The structural behavior of the electrode materials, its response on the Li intercalation/extraction as well as the information about transformations and their kinetics, is the key to address the issues mentioned above.In contrast to different kinds of commercially available cathode materials, graphite is nowadays the most often employed anode material in lithium ion batteries. Its general feature is the formation of a periodic arrangement of lithium containing and unoccupied layers in the a-b plane of the hexagonal graphite lattice during intercalation. [1][2][3] The knowledge about phase relationship in the lithium-carbon binary system is primarily based on reports by Dahn 4 and Ohzuku et al., 5 where X-ray powder diffraction along with electrochemical measurements have been used to characterize lithium-intercalated graphites. Despite the overall similarity of the setups and techniques used in latter reports, there are some discrepancies between the staging models, especially at the complicated carbon-rich edge. Further in-situ Xray diffraction studies of lithium intercala...

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Sodium‐deficient nickel–manganese oxides exhibit a layered structure, which is flexible enough to acquire different layer stacking. The effect of layer stacking on the intercalation properties of P3‐NaxNi0.5Mn0.5O2 (x=0.50, 0.67) and P2‐Na2/3Ni1/3Mn2/3O2, for use as cathodes in sodium‐ and lithium‐ion batteries, is examined. For P3‐Na0.67Ni0.5Mn0.5O2, a large trigonal superstructure with 2√3 a×2√3 a×2 c is observed, whereas for P2‐Na2/3Ni1/3Mn2/3O2 there is a superstructure with reduced lattice parameters. In sodium cells, P3 and P2 phases intercalate sodium reversibly at a well‐expressed voltage plateau. Preservation of the P3‐type structure during sodium intercalation determines improving cycling stability of the P3 phase within an extended potential range, in comparison with that for the P2 phase, for which a P2–O2 phase transformation has been found. Between 2.0 and 4.0 V, P3 and P2 phases display an excellent rate capability. In lithium cells, the P3 phase intercalates lithium, accompanied by a P3–O3 structural transformation. The in situ generated O3 phase, containing lithium and sodium simultaneously, determines the specific voltage profile of P3‐NaxNi0.5Mn0.5O2. The P2 phase does not display any reversible lithium intercalation. The P3 phase demonstrates a higher capacity at lower rates in lithium cells, whereas in sodium cells P3‐NaxNi0.5Mn0.5O2 operates better at higher rates. These findings reveal the unique ability of sodium‐deficient nickel–manganese oxides with a P3‐type structure for application as low‐cost electrode materials in both sodium‐ and lithium‐ion batteries.

New high‐capacity intercalation cathodes of Li2VxCr1−xO2F with a stable disordered rock salt host framework allow a high operating voltage up to 3.5 V, good rate performance (960 Wh kg−1 at ≈1 C), and cycling stability.

The cubic garnet-type solid electrolyte Li7La3Zr2O12 with aliovalent doping exhibits a high ionic conductivity.

Spatially-resolved neutron powder diffraction with a gauge volume of 2 × 2 × 20 mm3 has been applied as an in situ method to probe the lithium concentration in the graphite anode of different Li-ion cells of 18650-type in charged state. Structural studies performed in combination with electrochemical measurements and X-ray computed tomography under real cell operating conditions unambiguously revealed non-homogeneity of the lithium distribution in the graphite anode. Deviations from a homogeneous behaviour have been found in both radial and axial directions of 18650-type cells and were discussed in the frame of cell geometry and electrical connection of electrodes, which might play a crucial role in the homogeneity of the lithium distribution in the active materials within each electrode.

In-situ and operando neutron powder diffraction is well established method for studying structural changes in Li-ion electrode materials in real time during battery operation. Quality of diffraction data obtained in operando experiments depends on characteristics of diffractometer (brightness, space resolution) and design and assembly of electrochemical cell. Operando neutron diffraction experiments can be successfully performed with real batteries; however using special designed electrochemical cell allows us to exclude some undesirable reflexes of battery components from diffraction pattern, use Li-metal as counter electrode, decrease background from incoherent scattering elements, be almost independent from commercial machines for battery preparation and considerably reduce a mass of investigated materials. In this report we present special designed electrochemical cells developed for operando study of Li-ion electrode materials at time-of-flight neutron diffractometers at the IBR-2 neutron source (Dubna, Frank Laboratory of Neutron Physics). The cells are easily assembled in a glove box and demonstrate the excellent parameters of cyclabilities (with graphite electrodes, more than 700 cycles) and absence of leakage current. In dependence of scattering properties of studied materials the measured diffraction patterns can be analyzed by Rietveld method or Peak's profile data analysis. Several successful operando experiments on Li-ion electrode materials using these cells have been performed. In particular, investigation of LiNi0.8Co0.15Al0.05O2 (NCA) cathode material in the electrochemical cell allowed us to reveal the microstructural reasons of phase separation that occurs in cycled NCA during the first charge. The work is supported by Russian Science Foundation (project №14-12-00896). [1] A.