Group 14 patents: They talk about hard carbon, and use s carbon/phosphorous precursor to produce the carnon particles with cavities to accommodate the Si.
WO2018165610A1 DECOMPOSITION OF SILICON-CONTAINING PRECURSORS ON POROUS SCAFFOLD MATERIALS
https://worldwide.espacenet.com/patent/search/family/063448802/publication/WO2018165610A1?q=WO2018165610A1Embodiments of the present invention generally relate to methods of manufacturing novel materials exhibiting extremely durable intercalation of lithium. The novel materials comprise a porous scaffold, for example a carbon having a pore volume comprising micropores, mesopores, and/or macropores, wherein said volume is impregnated with silicon. Suitable precursors for the carbon scaffold include, but are not limited to, sugars and polyols, organic acids, phenolic compounds, and amine compounds. Suitable precursors for the silicon include, but are not limited to, silane, disilane, trisilane, and tetrasilane. The silicon-impregnated porous scaffold can be further coated to reduce any remaining surface area, for example, coated with carbon or conductive polymer. Such silicon- impregnated carbon materials and carbon- or conductive polymer-coated silicon- impregnated carbon materials exhibit remarkable durability with respect to their intercalation of lithium.
WO2014201275A2 HIGH CAPACITY HARD CARBON MATERIALS COMPRISING EFFICIENCY ENHANCERS
https://worldwide.espacenet.com/patent/search/family/051063877/publication/WO2014201275A2?q=pa%20%3D%20%22group%2014%22%20AND%20nftxt%20%3D%20%22anode%22
the current invention is directed to novel polymeric materials, and novel hard carbon materials derived therefrom which exhibit optimized lithium storage and utilization properties. The novel polymeric materials are organic in nature and comprise efficiency enhancers, for instance phosphorus. The novel carbon materials find utility in any number of electrical energy storage devices, for example as electrode material in lithium-based electrical energy storage devices (e.g., lithium ion batteries). Electrodes comprising the carbon materials display high reversible capacity, high first cycle efficiency, high power performance or any combination thereof. The present inventors have discovered that such improved electrochemical performance is related, at least in part, to the carbon materials' physical and chemical properties such as surface area, pore structure, crystallinity, surface chemistry, chemical composition and other properties as discussed in more detail herein. Specific modulation of the final carbon properties can be achieve through fine control of the initial polymeric material and/or through modification of the carbonization process. Furthermore, certain electrochemical modifiers can be incorporated on the surface of and/or in the carbon material to further tune the desired properties.
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traditional lithium based energy storage devices comprise graphitic anode material. The disadvantages of graphitic carbon are numerous in lithium ion batteries. For one, the graphite undergoes a phase and volume change during battery operation. That is, the material physically expands and contracts when lithium is inserted between the graphene sheets while the individual sheets physically shift laterally to maintain a low energy storage state. Secondly, graphite has a low capacity. Given the ordered and crystalline structure of graphite, it takes six carbons to store one lithium ion. The structure is not able to accommodate additional lithium. Thirdly, the movement of lithium ions is restricted to a 2D plane, reducing the kinetics and the rate capability of the material in a battery. This means that graphite does not perform well at high rates where power is needed. This power disadvantage is one of the limiting factors for using lithium ion batteries in all-electric vehicles.
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