The selected cathode is dataset record 107116. The archive contains 64 LiFePO4 polymorphs. The equilibrium path has a transition at x = 1/3, with plateaus of 3.3245966200 V and 3.2788983737 V. A calculation restricted to the two endpoint compounds gives 3.2941311225 V and misses the intermediate assemblage. At x = 1/3 the equilibrium products are 1/9 Fe7(PO4)6 and 1/9 Li3Fe2(PO4)3 per initial FePO4 inventory. This is an equilibrium prediction from the frozen library, not an assertion of experimentally reversible intercalation.

The spreadsheet and reference.json provide the complete numerical result. Phase coefficients refer to reduced formulas. Energy-equivalent degenerate decompositions are accepted under the published balance and energy tolerances.
