Superstructure control of first-cycle voltage hysteresis in oxygen-redox cathodes

Negligible voltage hysteresis with strong anionic redox in conventional battery electrode

“…For example, Na2Mn3O7 displays a low voltage hysteresis of only about 50 mV, 25,26 and Na0.6[Li0.2Mn0.8]O2 shows a 0.2 V voltage hysteresis, which are significantly lower than those of Li-ion compounds 27,28 . Both systems, however, display low Coulombic efficiency during initial cycles.…”

Realizing Complete Solid‐Solution Reaction in High Sodium Content P2‐Type Cathode for High‐Performance Sodium‐Ion Batteries

“…It can be found that Ni 3d, Mn 3d, and O 2p are hybridized near Fermi level, indicating that oxygen might participate in the electrochemical reaction in the high voltage region. [17] P2-NLNMO also shows much better rate performance than P2-NNMO as demonstrated in 4, 121.9, 121.2, 115.8, 111.4, 104.8, 95.8, and 79.3 mA h g À1 at 0.1, 0.2, 0.5, 1, 2, 5, 10, and 20 C, respectively, while the P2-NNMO electrode exhibits much inferior rate performance, with only 8.8 mA h g À1 at 20 C. The superior rate performance of P2-NLNMO may be ascribed to the solid-solution reaction mechanism with fast Na + kinetics. [18] Na + mobility in P2-NLNMO will be discussed in detail in the latter parts.…”

Phosphoric acid and thermal treatments reveal the peculiar role of surface oxygen anions in lithium and manganese-rich layered oxides

“…13,14 Recently, extensive research efforts have been devoted to exploring the origin of the structural degradation of LMLOs upon high-voltage cycling. Several hypotheses have been proposed including layered-to-rock-salt/spinel phase transitions, 15,16 localization of oxygen electron holes 17 or formation of Mn-h 1 -O 2 species, 18 TM over-oxidation, 19,20 irreversible O 2 loss with surface densication, 21,22 Li 2 O removal with "MnO 2 -like" phase formation, 23 generation of peroxo-like O 2 mÀ (1 # m # 3)…”