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We investigated the electrochemical properties of composite cathodes obtained by mixing LiNi 0.5 Mn 1.5 O 4 (LNMO), reduced graphene oxide (RGO) and carbon black (C65). Electrochemical electrode characterization was carried out in ethylene carbonate: dimethyl carbonate and 1 M LiPF 6 by galvanostatic charge/discharge cycles up to 4.8 V vs. Li + /Li and impedance spectroscopy. We demonstrate that RGO improves the electrode/electrolyte interface stability at high potentials and, consequently, the cycling stability of LNMO cathodes in the presence of C65 with 92% capacity retention after 100 cycles at 1 C. The reciprocal effect of RGO and C65 is also beneficial for rate capability, which retained a specific capacity of 75 mAh g −1 at 10 C. The electric contact between particles is promoted by C65 s conductive percolating network; RGO enhances the electrical conductivity of the composite electrode and hinders undesirable reactions between LNMO and the electrolyte. Despite RGO's lower electronic resistivity with respect to C65, the addition of RGO alone to LNMO is not sufficient to assure good performance. The mixing procedure without C65 promotes the agglomeration of graphene nanosheets rather than their distribution among LNMO particles and aggregates, limiting the electron and Li + transport in the cathode material. The appealing properties of graphene have attracted great attention in several research fields. Its superior electric conductivity, chemical stability and high flexibility make it of great interest as electrode material and additive in energy storage and conversion systems. [13][14][15][16][17][18][19] For example, the addition of graphene to lithium metal phosphates, which display low electrical conductivity (near 10 −9 -10 −7 S cm −1 ), boosts electronic conductivity, enhances microstructure via the formation of a three-dimensional network that shortens the lithium ion diffusion distance, and improves morphology by hindering grain growth.Directly adding graphene during conventional or non-conventional syntheses is often pursued. Graphene oxide (GO) is usually added to the precursors of the cathode materials so that the synthesis of the latter and GO reduction occur simultaneously during pyrolysis under reducing atmosphere.1 LiN 0.5 Mn 1.5 O 4 (LNMO)/graphene composites have recently been developed [20][21][22] by suspending mildly oxidized graphene and LNMO in ethanol to obtain graphene-wrapped LNMO. Graphene acts as a protective layer that minimizes the Mn 2+ dissolution in electrolyte and limits the unwanted parasitic electrode reactions, which affect both capacity and coulombic efficiency.Large-size battery production needs bulk syntheses of cathode materials and viable, inexpensive methods of preparing the composite electrode with graphene. Simple mixing of cathode composite components that include graphene might be a preferable, albeit nonoptimal, procedure. We thus investigated several mixing procedures for LNMO-based composites with reduced graphene oxide (RGO) and carbon black. The results o...

The aluminium foams present very interesting properties due to their low density. However, the presence of cells and the complex geometry are critical aspects considering the corrosion behaviour. A suitable method to increase the corrosion resistance is desirable. The cataphoretic deposited paint could be a useful way due to the possibility to obtain a protective and homogenous paint layer also with complex geometry. Other solution could be the application of an enamel layer, which shows high protection properties together with a good resistance at high temperature. The aim of this paper is the evaluation of the protection performance of these kinds of coatings. The corrosion behaviour of coated samples is evaluated by acetic acid salt spray exposure test and by electrochemical measurements. Both layers, organic coating and enamel, show a high increase of corrosion behaviour in comparison of uncoated aluminium foam.

We explored the effect of reduced graphene oxide (RGO) on LiNi 0.5 Mn 1.5 O 4 (LNMO) and on 0.6LiMnPO 4 -0.4Li 3 V 2 (PO 4 ) 3 (LMVP) composite cathodes with carbon black (C65). We demonstrated that the effect of RGO depends on the cathode active material. Indeed, RGO improves cycling stability of LNMO cathodes by improving electrode/electrolyte interface stability at high potentials. On the contrary, RGO worsens the performance of LMVP/C65 and it has no effect on LMVP electrodes when it is produced in situ during LMVP synthesis in presence of graphene oxide. Our study indicates that at least 10 wt. % of C65 is necessary for good performance of the poor conductive LMVP.