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Hard carbon is a solid form of carbon that cannot be converted to graphite by heat-treatment, even at temperatures as high as 3000 °C. It is also known as char, or non-graphitizing carbon. More colloquially it can be described as charcoal.
Hard carbon is produced by heating carbonaceous precursors to approximately 1000 °C in the absence of oxygen. Among the precursors for hard carbon are polyvinylidene chloride , lignin and sucrose. Other precursors, such as polyvinyl chloride and petroleum coke, produce soft carbon, or graphitizing carbon. Soft carbon can be readily converted to graphite by heating to 3000 °C.
The physical properties of the two classes of carbons are quite different. Hard carbon is a low density material, with extremely high microporosity, while soft carbon has little microporosity. Hard carbon is extensively used as anode materials in lithium-ion batteries. and sodium-ion batteries
Manufacturers of hard carbon include Xiamen Tob New Energy , Kuraray and Stora Enso.