Figure 5: Electrode materials thermal stability.
From: Full open-framework batteries for stationary energy storage
Thermogravimetric analysis-mass spectrometry (TGA-MS) under inert (N2) atmosphere of (a) reduced (CuII—N≡C—FeII) and (b) oxidized (CuII—N≡C—FeIII) copper hexacyanoferrate shows that these materials is about 25 wt% of water and that HCN is not released from the structure for temperatures higher than 200 °C. Because of the lower stability of the Mn-C bond, (c) reduced (MnII—N≡C—MnII) and (d) oxidized (MnII—N≡C—MnIII) manganese hexacyanomanganate release HCN starting from 120 °C, temperature high enough for a water-based electrolyte. As general trend, the lower is the oxidation state, the higher is the stability of the material being CN a soft base it forms a stronger bond with soft metals, therefore with a lower oxidation state.
