Hard Macrocellular Silica Si(HIPE) Foams Templating Micro/Macroporous Carbonaceous Monoliths: Applications as Lithium Ion Battery Negative Electrodes and Electrochemical Capacitors

By using Si(HIPEs) as hard, exotemplating matrices, interconnected macro-/ microporous carbon monolith-type materials with a surface area of around 600 m(2) g(-1) are synthesized and shaped. The carbonaceous foams exhibit a conductivity of 20 S cm(-1), addressed with excellent mechanical properties (Young's modulus of 0.2 GPa and toughness of 13 J g(-1), when the carbon core is optimized). The above-mentioned specificities, combined with the fact that the external shape and size can be easily designed on demand, are of primary importance for applications. The functionality of these carbonaceous monoliths is tested as both an electrochemical capacitor and a lithium ion negative electrode. The electrochemical capacitors' voltage-current profiles exhibit a non-ideal rectangular response, confirming the double-layer behavior of the carbon studied, while the charge-discharge current profile of the electric double-layer capacitor is directly proportional to the scan where the current response during charge and discharge exhibits high reversibility. When acting as a lithium ion negative electrode, after initial irreversibility, a good cyclability is obtained, associated with a stable capacity of 200 mA h g(-1) during the first 50 cycles at a reasonable current density (C/10).