Graphite anode: LiC₆, capacity, staging, SEI and lithium plating

Graphite is a stack of graphene layers 0.335 nm apart. During charging, Li⁺ ions are intercalated between the layers; fully lithiated graphite is LiC₆, one lithium for every six carbon atoms, giving a theoretical capacity of about 372 mAh g⁻¹ (Wu et al. 2026), or 371.9 mAh g⁻¹ per gram of carbon (calculated). In LiC₆ the interlayer spacing opens to about 0.370 nm (Wu et al. 2026), roughly a 10% expansion along the stacking axis (calculated from these values).

Lithium enters graphite mainly through the edge planes of the particles: passing straight through the carbon hexagons of the basal plane has a high energy barrier (Wu et al. 2026). The layered structure therefore makes lithium transport strongly anisotropic, and large particles, few edge sites or unfavourable particle orientation lengthen the diffusion path (Wu et al. 2026).

Lithium does not fill graphite layer by layer at random. It forms stages, ordered structures in which lithium-filled galleries are separated by a fixed number of empty ones, and the stage structure changes by stepwise increases or decreases in the number of graphene layers between adjacent lithium-filled interlayers (Yamamoto et al. 2023). Each transition appears as a peak in the differential capacity (dQ/dV) of a graphite electrode: four peaks for the staging transitions, ending in stage 1, LiC₆, at the full theoretical capacity of 372 mAh g⁻¹ (Chen et al. 2025).

All of this happens at a low potential, about 0.1 V vs Li⁺/Li (Clark et al. 2016). That is what gives graphite-based cells their high voltage, and it is also why graphite sits so close to the potential at which lithium metal is deposited.

At graphite’s low potential the organic electrolyte is not stable. On the first charge, before lithium intercalates, the electrolyte is reduced on the graphite surface: a shoulder near 0.7 V in the charging curve marks electrolyte reduction forming a primitive SEI-like layer (Chen et al. 2025), and on highly oriented pyrolytic graphite in LiPF₆ in ethylene carbonate/dimethyl carbonate, clusters grow on the step edges and terraces between 0.8 and 0.7 V vs Li⁺/Li from the reduction of solvent molecules (Wang et al. 2012). The reduction of ethylene carbonate (EC) is the initial stage of SEI growth (Gibson et al. 2021).

The resulting solid electrolyte interphase lets Li⁺ through (Wu et al. 2026) but protects the electrolyte from runaway reduction (Xia et al. 2017). EC remains irreplaceable as an electrolyte solvent for its balance of ionic conductivity and interfacial stability (Zhang et al. 2022). An EC-based electrolyte forms a protective SEI on graphite, whereas replacing EC entirely with fluoroethylene carbonate did not (Xia et al. 2017). Propylene carbonate, EC’s close relative, co-intercalates into graphite and exfoliates it (Xiang et al. 2015). EC has a cost: its high melting point of 36.4 °C limits low-temperature performance (Zhang et al. 2022).

Lithium plating occurs when the graphite electrode potential reaches 0 V vs Li/Li⁺ and below. Fast charging and low temperature polarize the graphite, partly because intercalation is slow, and drive its potential towards and below 0 V, so Li⁺ is reduced to lithium metal on the surface instead of entering the layers (Chen et al. 2025). Plated lithium reacts with the electrolyte to form more SEI, can grow dendrites that short-circuit the cell and lead to thermal runaway, becomes electrochemically inactive “dead lithium” and blocks intercalation sites (Chen et al. 2025).

Cold makes it much worse. Between 30 °C and −20 °C graphite still showed well-defined staging plateaus and near-theoretical capacity, but at −30 °C and −40 °C its potential crossed 0 V after only 160 and 106 mAh g⁻¹, compared with 412 mAh g⁻¹ at −20 °C (Chen et al. 2025). For fast charging, graphite is redesigned to shorten diffusion paths and add lithium entry points, through smaller particles, pores, expanded interlayers and more edge sites, at the cost of more surface area, more SEI and lower initial Coulombic efficiency (Wu et al. 2026).

Battery-grade graphite is made from three sources: natural graphite, synthetic graphite and, increasingly, graphite recycled from spent batteries. In a life cycle assessment, recycled graphite reduced the global warming potential of production by about 70% compared with the synthetic and natural routes (Kadivar et al. 2025). Graphite makes up 12–21 wt% of a lithium-ion battery (Niu et al. 2022). Spherical graphite is valued in commercial anodes for its processability and packing, which help electrode compaction density and uniformity (Wu et al. 2026).

Graphite is the anode in our overview of battery materials; in full cells it is paired with cathodes such as LiFePO₄ and layered NCM oxides (Wu et al. 2026).

For a paper, slide or poster, draw graphite side on as parallel graphene layers 0.335 nm apart, with Li⁺ entering at the particle edges, and show LiC₆ with lithium in every gallery and the spacing opened to about 0.370 nm; staging can be shown by filling every second, third or fourth gallery. Add a thin SEI layer on the surface and, for fast charging, metallic lithium deposits on top of it. The LabCanvas figure editor Library has a battery crystal object for graphite that you can drop into a figure, recolour and resize, and the LabCanvas 3D Studio has a graphite anode model that you can turn and export as a high-resolution image.