Surprising Dependence of the Exfoliation of Graphite During Formation on Electrolyte Composition

Graphite is the most used lithium intercalation host for negative electrode of lithium-ion battery. Extensive research has been carried out to achieve high Coulombic Efficiency (CE) and long cycle life graphite anode. Here, LFP/graphite (graphite from Vendor 1) cells that undergo formation at 40 °C with either 1.2 M LiPF 6 dissolved in ethylene carbonate:dimethyl carbonate (EC:DMC), or carbonate:ethylmethyl (EC:EMC) have excellent first efficiency (FCE). However, when done 20 °C, EC:EMC carbonate:diethyl (EC:DEC) show much reduced FCE while EC:DMC retain FCE. We prove by a variety experiments caused solvent co-intercalation. explore impact temperature, different graphites, electrolyte additives, varied salt content on this effect. basic such as vinylene carbonate, are sufficient eliminate With well-designed system containing graphites co-intercalation absence additives perform equivalently better than do not additives.