Electronic and Ionic Wirings Versus the Insertion Reaction Contributions to the Polarization in LiFePO4 Composite Electrodes

International audienceThe different contributions to the polarization of a LiFePO4 electrode are experimentally discriminated in this work. The electrode total resistance is dominated at high rate by the contribution of the electronic and the ionic wires, the former being more important in the case of electrodes with low compaction, while the latter being more important in the case of electrodes with high compaction. A porosity in the 35%-40% range allows to minimize the electrode polarization. At low rate, the electrode resistance is dominated by the resistance to lithium insertion into the active mass and follows the predictions of M. Gaberscek and J. Jamnik [ Solid State Ionics , 177 , 2647 (2006)] . We show here that the resistance to lithium insertion decreases with the increase of the specific current, a feature that suggests an increase of the active particle conductivity with rate. The easy-handling methodology described in this work should enable a more rational optimization of the electrode formulation and processing conditions for better electrochemical performance

Toward the Aqueous Processing of Li4Ti5O12: A Comparative Study with LiFePO4

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New Tools for a Rationale Optimization of Thick LiFePO4 Composite Electrodes

LGEP 2010 ID = 650International audienc

New tools for a rationale optimization of C-LiFePO4 composite electrodes

LGEP 2010 ID = 64

CuSbS2 as a negative electrode material for sodium ion batteries

International audienceCuSbS2 was tested as a negative electrode material for sodium-ion batteries. The material synthesized by ball milling offers a specific charge of 730 mAh g−1, close to the theoretical value (751 mAh g−1), over a few cycles. The reaction mechanism was investigated by means of operando X-ray diffraction, 121Sb Mössbauer spectroscopy, and Cu K-edge X-ray absorption spectroscopy. These studies reveal a sodiation mechanism that involves an original conversion reaction in two steps, through the formation of a ternary phase, CuSb(1−x)S(2−y), as well as a NaxS alloy and Sb, followed by an alloying reaction involving the previously formed Sb. The desodiation process ends with the reformation of the ternary phase, CuSb(1−x′)S(2−y′), deficient in Sb and S; this phase is responsible for the good reversibility observed upon cycling