石墨Graphite

层内 C–C 键长 142 pm，层间距 335 pm，常见六方石墨按 ABAB 方式堆叠。层内离域 π 电子使石墨沿层平面导电导热，垂直方向则差得多（各向异性）。层间作用力弱，层易滑移，所以石墨可作润滑剂、能在纸上留下痕迹。小分子或离子可插入层间形成石墨插层化合物，这是锂离子电池负极（LiC₆）的工作原理。

In-layer C–C bonds are 142 pm and layers are 335 pm apart, usually stacked ABAB in hexagonal graphite. Delocalised π electrons within the layers make graphite conduct electricity and heat along the planes but much less across them (anisotropy). Weak forces between layers let them slide, so graphite lubricates and marks paper. Small molecules or ions can slip between the layers to form intercalation compounds, the working principle of the lithium-ion battery anode (LiC₆).

16 世纪英国坎伯兰发现大型纯石墨矿，当时误认为是铅矿，称为“黑铅”，用于制作铅笔，所以铅笔芯至今仍叫“铅”。1779 年舍勒证明它是碳。1789 年德国矿物学家维尔纳根据希腊语 graphein（书写）命名为 graphite。1896 年艾奇逊发明以焦炭高温石墨化制造人造石墨的方法。

In the sixteenth century a large deposit of pure graphite was found at Borrowdale in Cumberland, England; mistaken for lead ore, it was called black lead and used for pencils, which is why pencil 'lead' still bears the name. Scheele showed in 1779 that it is carbon, and in 1789 the German mineralogist Werner named it graphite, from Greek graphein, to write. In 1896 Acheson patented making synthetic graphite by heating coke to graphitising temperatures.

石墨用于锂离子电池负极（最大增长领域）、电弧炉电极、耐火材料和坩埚、铅笔芯、润滑剂、刹车片和核反应堆中子慢化剂（如早期反应堆和 RBMK 堆）。膨胀石墨用于密封材料，石墨纤维和碳纤维用于高强度复合材料。中国是全球最大的天然石墨生产国。

Graphite is used in lithium-ion battery anodes (the fastest-growing use), arc-furnace electrodes, refractories and crucibles, pencil leads, lubricants, brake linings and as a neutron moderator in reactors such as early piles and the RBMK. Expanded graphite makes seals, and graphite and carbon fibres go into high-strength composites. China is the largest producer of natural graphite.