Figure 8: Analysis of sodium insertion to α-C radical.
From: Highly durable organic electrode for sodium-ion batteries via a stabilized α-C radical intermediate
(a) Na1s XPS spectra of the TSAQ electrode under different states. The sodium atom content is 9.2%, 13.1%, 15.8%, 8.4% and 2.5% at the state of discharge to 1.0 V, discharge to 0.5 V, discharge to 0.05 V, recharge to 1.5 V and fully recharge to 3 V, respectively. Sodium ratio (Na-1:Na-2:Na-3): 1.0 V (≈1:0:0); 0.5 V (2:1:0.3); 0.05 V (2:1:1); and 1.5 V (2:1:0.1). Black (raw), red (simulation), olive (background), blue (1,072.0 eV, Na-1), magenta (1,071.3 eV, Na-2) and violet (1,070.8 eV, Na-3). (b) Solid-state 23Na nuclear magnetic resonance (NMR) spectrum of the TSAQ electrode after discharged to 0.05 V. Black (raw), dark yellow (simulation), red (a, −9.01 p.p.m.), magenta (b, −7.11 p.p.m.) and olive (c, 5.23 p.p.m.).
