EV Batteries with Hard Carbon Anodes

Carbon-coated hardly graphitizable carbon for high performance lithium-ion batteries. The carbon coating layer has an average thickness of 4-30 nm and improves battery performance compared to uncoated graphite or thicker carbon coatings. The coating thickness provides both high discharge capacity and initial efficiency. The coating promotes electrolyte stability, prevents particle deactivation, and enhances conductivity. The coated carbon has specific structural features like high sp2 carbon orientation and spacing.

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Non-graphitizable carbonaceous material for fully charged lithium-ion batteries with high charge/discharge efficiency and capacity. The material has an oxygen content of 0.25% mass or less. It enables high charge/discharge performance and capacity in lithium-ion batteries that are fully charged compared to traditional graphitizable carbon anodes. The low oxygen content prevents overcharging issues. The material is made by acid treating a plant-derived carbon precursor followed by firing in an inert gas at 1100-1400°C.

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Electrochemical device with improved energy density and reduced lithium precipitation in lithium-ion batteries using a specific range of ratios for hard carbon content and capacity balance. The hard carbon used as the negative electrode active material has a molar H/C ratio of 0.05-0.18. The capacity balance between negative and positive electrodes is 0.95-1.05. This range of ratios improves ion transmission speed, energy density, and prevents lithium segregation.

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Fast-charging lithium battery negative electrode material that combines the high capacity of graphite with the fast charging capability of hard carbon. The material is prepared by melting a resin and asphalt mixture, pre-carbonizing it, grinding it to a specific size range, and then graphitizing. The resulting material has high capacity density and can charge at 10C rates.

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Nonaqueous electrolyte secondary battery with improved cycle life and energy density by using non-graphitizable carbon in the negative electrode. The carbon expands and contracts less during charging/discharging compared to graphite, preventing electrode structure deterioration. However, keeping the capacity ratio of non-graphitizable carbon to negative electrode capacity between 5-65% balances benefits like lower resistance and overvoltage against issues like increased initial resistance and lower energy density from high carbon levels.

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An anode material for lithium-ion batteries with improved cycle stability and reduced expansion during charging and discharging. The anode material has a porosity of 10% or less and a target region ratio C of 15% or greater. It is prepared by mixing active material, carbon source, and solvent, followed by heat treatment and densification to form an aggregate with dispersed active particles. Additives like metal oxide, conductivity enhancer, and coupling agent can be added during mixing. Carbon coating is also done after densification. The aggregate structure with low porosity and dispersed active particles inhibits volume expansion during lithium ion intercalation/deintercalation.

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Composite negative electrode material for lithium-ion batteries with improved energy density, rate performance, and cycle life. The composite material has a core-shell structure where the core is a carbon nanotube/graphite composite and the shell is made of hard carbon. This design provides high ionic and electronic conductivity from the nanotube/graphite core, and the hard carbon shell further improves rate performance and structural stability. By optimizing the core-shell composition, it allows lithium-ion batteries with higher energy density, better rate performance, and cycle life compared to conventional graphite anodes.

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Negative electrode material for lithium-ion batteries with improved first Coulombic efficiency and cycle life. The material is hard carbon with a unique multi-level pore structure. The core has micropores (2nm) and the surface has macropores (55nm). This reduces the specific surface area compared to conventional hard carbon to lower water/oxygen absorption. It also prevents pore collapse during cycling. The micropores store lithium and the macropores provide high-rate capability. The pore ratios are micropores:mesopores:macropores = 50%:50%. This reduces water ingress while maintaining lithium storage capacity. The hard carbon can also be coated with hydrophobic molecular sieves or doped with silica to further improve water resistance.

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Preparation method for high performance hard carbon negative electrode material for sodium-ion batteries. The method involves carbonizing plant material to create a porous carbon structure. Then, organic pyrolytic carbon is embedded or attached inside or on the porous carbon. Carbon nanotubes are interspersed between the porous carbon and pyrolytic carbon. Finally, roasting is done to form parallel graphite structure with the nanotubes. This improves rate performance of the hard carbon anode material by increasing electrical conductivity and ion storage sites.

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Carbon material for high-performance lithium-ion battery anodes that provides improved charge/discharge performance and lifespan compared to conventional anode materials. The carbon material has a specific fiber content range of 0.58 to 0.78. This carbon raw material is ground and graphitized to create the anode active material. The ground carbon particles have a size range of 5 to 30 microns and the graphitized anode has a high graphitization degree, low orientation, and interplanar spacing. The anode material prepared this way has enhanced charge/discharge capacity, charge output, and discharge output compared to conventional anodes made from other carbon materials. It also has lower expansion during charging/discharging. The manufacturing method avoids the assembly process used in some anode materials to achieve similar benefits.

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A negative electrode material for lithium-ion batteries that has low average potential for lithium removal, improving battery energy density. The material is a hard carbon with a specific microporous structure. The carbon has a delithiation potential between 0.15-0.40 V vs Li/Li+ when used with a metallic lithium counter electrode. The micropores allow lithium intercalation during charging, providing reversible capacity. The optimized pore structure enables high capacity, low voltage, and good lithium ion diffusion. This carbon material is used as the negative electrode active material in lithium-ion batteries to provide higher energy density compared to conventional graphite electrodes.

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Hard carbon composite material for lithium-ion batteries with improved electrochemical performance. The composite is made by hydrothermally embedding lithium ions into a hard carbon precursor, followed by dehydration carbonization. The embedded lithium improves first cycle efficiency. The composite also has a tight coating of soft carbon on the surface to prevent phase separation. The hard carbon/lithium composite has low surface area and pore volume, reducing side reactions and improving cycle life. The hydrothermal embedding and surface coating steps are key to the performance benefits.

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Preparing hard carbon negative electrode material for low temperature lithium-ion batteries by breaking the long-range crystal structure of the carbon precursor to increase interlayer spacing. The method involves heating the carbon precursor (like graphite, coal, or wood) at low oxygen levels to reduce oxygen content. This prevents oxidation that can destroy the carbon structure. The reduced oxygen precursor is then subjected to high temperatures to break the long-range crystal order. This creates short-range disorder with increased interlayer spacing in the carbon. The resulting hard carbon electrode material has improved lithium ion storage capacity and performance at low temperatures compared to conventional graphite electrodes.

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A three-dimensional anode for lithium-ion batteries that improves rate performance and reduces dendrite formation during fast charging. The anode has a 3D structure with vertical channels between the major surfaces. It contains a mixture of graphite and hard carbon, or just graphite or hard carbon, to balance energy density and power performance. The channels reduce concentration gradients during charging to prevent excessive polarization and Li plating. The tunable channel geometry helps mitigate issues like dendrite growth and capacity loss that can occur in thicker anodes.

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Hard carbon negative electrode material for lithium-ion batteries with improved first coulombic efficiency, capacity, and cycle life. The hard carbon precursor is coated with a lithium-containing substance and asphalt before carbonization. This reduces surface area, side reactions, and first irreversible capacity loss. The lithium substance provides lithium for SEI formation during battery preparation, preventing consumption of lithium from electrolyte/positive. The asphalt reduces surface area further. This results in higher first coulombic efficiency, capacity, and cycle life compared to uncoated hard carbon.

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Anode structure for lithium-ion batteries that improves cycle life and initial efficiency. The anode has an inner core of hard carbon surrounded by a graphite outer layer. This configuration prevents localized carbon degradation in the core during cycling, which improves cycle life. The graphite outer layer provides initial efficiency. The hard carbon center reduces central carbon loss during cycling compared to using graphite alone.

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Power storage element like lithium-ion batteries that have a high capacity retention after cycling when using non-graphitizable carbon in the negative electrode. The key is to balance the density of the non-graphitizable carbon in the negative electrode and the pore ratio of the separator. The true density of the non-graphitizable carbon should be between 0.56 and 0.83 g/cm3, and the separator pore ratio should be 50% or more. This prevents lithium plating and improves capacity retention when using non-graphitizable carbon with deep charge depth.

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Lithium ion battery negative electrode material with high fast charging performance, high energy density, good low-temperature retention rate, and long cycle life. The material has a unique core-shell structure with a continuous cavity layer between the inner hard carbon and outer soft carbon coatings. The thin cavity layer allows efficient lithium ion transfer between the coatings. Coating order and carbonization conditions are optimized to achieve this structure.

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Anode material for lithium-ion batteries with improved low-temperature power performance compared to conventional graphite anodes. The anode material contains hard carbon, graphite, polyethylene glycol, lithium carbonate, phenolic resin, and a dispersant. The hard carbon and graphite are strongly mixed before adding the other components. The mixed powder is dispersed in alcohol/water, heated to remove the dispersant, then added water and lithium carbonate to form a slurry. Calcining this slurry in a protective atmosphere produces the anode material. The strong mixing of hard carbon and graphite before coating improves the low-temp power by preventing polarization.

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A high-rate lithium ion battery negative electrode material with improved performance for high-rate charging and discharging. The material has a core-shell structure with a hard carbon coating on the negative electrode substrate. The hard carbon coating is formed by carbonizing a hard carbon source like glucose, along with niobium and nitrogen sources. The niobium and nitrogen react at high temperatures to form composite structures on the surface of the negative electrode. This coating provides benefits like larger interlayer spacing for better rate performance, reduced stress on lithium ion insertion, and improved high-rate charge/discharge compared to uncoated negative electrodes.

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