Porous Ge@C materials via twin polymerization of germanium( ii ) salicyl alcoholates for Li-ion batteries

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2016, Vol.4 (7), p.2705-2719
• Main Authors: Kitschke, Philipp, Walter, Marc, Rüffer, Tobias, Seifert, Andreas, Speck, Florian, Seyller, Thomas, Spange, Stefan, Lang, Heinrich, Auer, Alexander A., Kovalenko, Maksym V., Mehring, Michael
• Format: Article
• Language: English
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/C5TA09891B

The germylenes, germanium( ii ) 2-(oxidomethyl)phenolate ( 1 ), germanium( ii ) 4-methyl-2-(oxidomethyl)phenolate ( 2 ) and germanium( ii ) 4-bromo-2-(oxidomethyl)phenolate ( 3 ) were synthesized and their thermally induced twin polymerization to give organic–inorganic hybrid materials was studied. The compounds 1–3 form oligomers including dimers, trimers and tetramers as a result of intermolecular coordination of the benzylic oxygen atom to germanium. The structural motifs were studied by single crystal X-ray diffraction analysis and DFT-D calculations. Thermally induced twin polymerization of these germylenes gave hybrid materials based on germanium-containing phenolic resins. Carbonization of these resins under reductive conditions resulted in porous materials that are composed of germanium and carbon (Ge@C materials), while oxidation with air provided non-porous germanium dioxide. The porous Ge@C materials were tested as potential anode materials for rechargeable Li-ion batteries. Reversible capacities of 540 mA h g −1 were obtained at a current density of 346 mA g −1 without apparent fading for 100 cycles, which demonstrates that germanium is well accessible in the hybrid material.