fig4

Figure 4. Mechanical properties and microstructure of dry LFP cathode films. (A) Stress-strain curve from UTM measurement and (B) micro-indentation test of dry LFP cathode films (LFP/CNT/PTFE = 94/3/3); (C) Stress-strain curve and (D) mechanical properties from UTM measurement; (E) Top view SEM images of dry LFP cathode films (LFP/CNT/PTFE = 94/4/2); left: S-LFP cathode film, middle: D-LFP Cathode film, right: L-LFP cathode film. LFP: LiFePO₄; UTM: universal testing machine; CNT: carbon nanotube; PTFE: polytetrafluoroethylene; SEM: scanning electron microscopy; S-LFP: small-sized LFP; L-LFP: large-sized LFP; D-LFP: developed LFP via two-step sxtrusion process.