Preparation and electrochemical properties of a Li2CuO2–Li2NiO2 solid solution as a lithium-intercalation electrode

First principles study of Li diffusion inI-Li2NiO2structure

“…Assuming that d is approximately 3 Å, corresponding to the distance of a hop along path B, and ‫ء‬ is about 10 13 Hz, which is in the range of phonon frequencies and consistent with typical values, 26 D for the path B can be approximated to be 10 −10 ͑cm 2 / s͒ at a temperature of 300 K. Considering that D for the commercially used Li x CoO 2 has been found to be within the range of 10 −13 to 10 −7 ͑cm 2 / s͒ at room temperature, 27 path B can be an acceptably fast Li diffusion path for cathode applications.…”

“…The higher potential was attributed to the structural aspect of relatively long Li-Li distance in I-Li 2 NiO 2 . 12,13 Even though we found that the undoped I-Li 2 NiO 2 gradually transforms to layeredlike structure upon cycling, therefore loses its capability to hold two lithium at high potential, 13 I-Li 2 NiO 2 structure provides a tactical idea how we can store more than two lithium per transition metal in a reasonable potential range in terms of a crystal structure.…”

Investigating Li2NiO2–Li2CuO2 Solid Solutions as High-Capacity Cathode Materials for Li-Ion Batteries

“…15−17 The crystal lattice of all three compounds contains a CuO 4 square unit, which shares edges with tetrahedral LiO 4 in Li 2 CuO 2 , one tetrahedral LiO 4 and one octahedral LiO 6 in Li 1.5 CuO 2 , and only octahedral LiO 6 in LiCuO 2 , therefore, its delithiation process is mainly characterized by a gradual change in Li environment from tetrahedral to octahedral coordination. 14 18 Recently, Ruther et al performed a comprehensive study on the electrochemical reaction mechanism of Li 2 Cu 0.5 Ni 0.5 O 2 using a suite of characterization techniques, revealing a reversible Ni 2+ / Ni 3+ redox reaction coupled with O 2 evolution at a high charge voltage (>3.9 V) and Cu 2+ to Cu + reduction at a low discharge voltage (<1.8 V). 21 Oxygen oxidation was also proposed and gas evolution was detected by other groups, 25,31 but no quantification work has been performed to isolate the evolved gas species and correlate the oxygen redox with electrochemistry.…”

“…Variation in the XRD peak position and intensity between 29 and 35°might correlate with the size difference between nickel and copper ions and lithium content. 20,27 On the other hand, the distinct diffraction peak around 18 4 ]. Combined with our hard XAS results, we are certain about the formation of layered R3̅ m phase at these charge states.…”

Enhanced cycling performance of surface-doped LiMn2O4 modified by a Li2CuO2-Li2NiO2 solid solution for rechargeable lithium-ion batteries

“…Recently, modification of LiMn 2 O 4 by a layer of media containing Li + ions and/or electron conductors such as LiNbO 3 [1], LiNi 0.5 Mn 1.5 O 4 [26,27] [29], and Li 4 Ti 5 O 12 [30], was used to improve electrochemical properties by accelerating Li ions transport and/or the charge transfer on the surface of the cathode material. Li 2 CuO 2 , exhibiting an Immm orthorhombic phase, possesses a relatively large amount of lithium per unit formula, with the lithium ions located between one-dimensional chains of edge-sharing [CuO 4 ] square planar units, facilitating rapid transfer of Li + ions [31,32]. Li 2 CuO 2 delivers a high capacity of 200 mAh g -1 and an average discharge voltage of 2.5 V, along with undamaged one-dimensional [CuO 4 ] chains during cycling [33].…”