Experimental phase diagram of lithium-intercalated graphite

First-order transitions to dilute stage 1 from stages 2-4 and from mixed stages are observed in Li-graphite compounds in the range 430-1020 K. The resulting ($T$,$x$) phase boundary agrees generally with predictions by Safran and others except for a sharp peak of very stable stage-2 compositions around $x\sim 0.4$. The commensurability energy does not contribute to this peak since both low-$T$ and high-$T$ phases are disordered.