Extended Data Fig. 5: Li plating and significant amount of unreacted Si observed from XPS, XRD, and XPS depth profile of SiG anode after lithiation process.
From: Fast cycling of lithium metal in solid-state batteries by constriction-susceptible anode materials
(a) XPS measurement of Li 1 s signal from SiG in an NMC-SEs-SiG solid state battery with nominal NP ratio = 1.5 after the 1st charge at 0.5 C-rate at room temperature, showing the existence of Li metal. Since no Li layer was assembled on the anode side initially, this further confirms the plating of Li metal to the current collector side of the SiG layer from charging the cathode. (b) XRD of SiG from the above charged battery, clearly showing the Si phase rather than the lithiated alloying phase. (c) XPS depth profile of SiG anode after the 1st charge at higher milling energy for longer duration to investigate across the entire SiG electrode. The majority of Si peak throughout the SiG layer indicates that the lithiation of Si across the entire anode is significantly constricted. The sputtered thickness is estimated based on the 0.7 nm/s sputtering rate for Si, giving the number (µm) on the right side that is the thickness sputtered away from the current collector side. Note that the total thickness of the original SiG layer is ~10 µm. The battery is with the structure of SiG-LPSCl-LGPS-LPSCl-NMC83 (loading = 25 mg/cm2) with a nominal NP ratio of 1 and charged at 4.1 V at 0.5 C-rate at room temperature.
