LiCoO2 with double porous structure obtained by electrospray deposition and its evaluation as an electrode for lithium-ion batteries

International audienceAn in-situ temperature-controlled Raman spectroscopy aided unique electrode fabrication technique has been developed for Li-ion battery applications, ensuring superior electrochemical quality of the multi-porous LiCoO2 films with higher stoichiometric purity of high temperature (HT)-LiCoO2 phase, by observing the structural changes during the fabrication process and thus confirming the transformation from the low temperature (LT)-LiCoO2 phase. This much desired simple process is not only free of any sort of binders or carbon additives but also works at atmospheric pressure, leading to a very simple deposition technique using a homemade and inexpensive set-up. Also, the time of depositions were varied and resultant films we investigated for their electrochemical performance. The high-resolution scanning electron microscope (SEM) observation has revealed not only a μm-size porous structure but also three-dimensional cross-link with 10 nm-level pores of the material, which ensured the much-desired porosity for high-performance cathodes

P2-Na0.67Mn0.85Al0.15O2 and NaMn2O4 Blend as Cathode Materials for Sodium-Ion Batteries Using a Natural β-MnO2 Precursor

International audienceSodium-ion batteries (NIBs) are promising candidates for specific stationary applications considering their low-cost and costeffective energetic property compared to lithium-ion batteries (LIBs). Additional cost cutbacks are achievable by employing natural materials as active cathode materials for NIBs. In this work, we report the use of natural pyrolusite (β-MnO 2) as a precursor for the synthesis of a NaMnO blend (a mixture of layered P2-Na 0.67 Mn 0.85 Al 0.15 O 2 without any doping technique combined with a post-spinel NaMn 2 O 4 without any highpressure synthesis). The synthesized powder was characterized by XRD, evidencing these two phases, along with two additional phases. Tests for Na-ion insertion registered a reversible discharge capacity of 104 mA h/g after 10 cycles with a well-defined plateau at 2.25 V. After 500 cycles at a C/4 current density, a high Coulombic efficiency between 96 and 99% was achieved, with an overall 25% capacity retention loss. These pilot tests are encouraging; they provide economic relief since the natural material is abundant (low-cost). Desirable, energetic assurances and ecological confirmations are obtainable if these materials are implemented in large-scale stationary applications. The synthesis technique does not use any toxic metals or toxic solvents and has limited side product formation

Co3-xMnxO4 as a High Capacity Anode Material for Lithium Ion Batteries

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Mechanism of the Delithiation/Lithiation Process in LiFe_0.4Mn_0.6PO₄: in Situ and ex Situ Investigations on Long-Range and Local Structures

LiFe_0.4Mn_0.6PO₄ olivine was prepared by a sol–gel route, using citric acid as a chelating agent and NH₄H₂PO₄ as a phosphorus source. Sucrose was used as the source for the carbon-coating of the particles. The correlation between the physicochemical and the electrochemical properties of this positive electrode material was investigated. The electrochemical tests showed an initial discharge capacity of 121 mAh/g at a C/20 rate with a good reversibility of the lithiation/delithiation reactions. In situ XRD on Li_<i>x</i>Fe_0.4Mn_0.6PO₄ reveals the occurrence of new phases upon cycling, which disappeared again at the end of discharge. The single phase observed after one complete cycle is identical to the pristine one. In situ XAS spectroscopy in combination with ⁵⁷Fe Mössbauer and ⁷Li NMR spectroscopy were used to investigate the changes in the local structure and the oxidation states of the transition metals and thus to complete the overall characterization of the lithiation/delithiation mechanism. All results reveal a high reversibility of the reactions in this electrode material