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A study was conducted on the local coordination of low-spin Ni (super 3+) probes in trigonal LiAl(sub y)Co(sub 1-y)O2 using high-frequency EPR spectroscopy. The maximum effect of Jahn-Teller distortion is achieved when the Ni (super 3+) ion falls in a pure Al environment.

Occupancy of gallium in octahedral sites of layered LiGa (sub y) Co (sub 1-y) O (sub 2) obtained at 3GPa is detected by using (super71) Ga MAS NMR spectroscopy. The Electron paramagnetic resonance spectra of Ni (sub 3+) probes in the series show a reinforcement of local tetragonal distortion of NiO (sub 6) octahedra in the trigonal LiGa (sub y) Co (sub 1-y) O (sub 2) as compared to that in LiCoO (sub 2).

Spinel lithium titanate, Li 4 Ti 5 O 12 (LTO), emerges as a "universal" electrode material for Li-ion batteries and hybrid Li/Na-, Li/Mg-, and Na/Mg-ion batteries functioning on the basis of intercalation. Given that LTO operates in a variety of electrolyte solutions, the main challenge is to understand the reactivity of the LTO surface toward single- and dual-cation electrolytes at the molecular level. This study first reports results on ion desolvation and electrolyte solvent/salt degradation on an LTO surface by means of periodic DFT calculations. The desolvation stages are modeled by the adsorption of mono- and binuclear complexes of Li + , Na + , and Mg 2+ with a limited number of ethylene carbonate (EC) solvent molecules on the oxygen-terminated LTO (111) surface, taking into account the presence of a PF 6 - counterion. Alongside cation adsorption, several degradation reactions are discussed: surface-catalyzed dehydrogenation of EC molecules, simultaneous dehydrogenation and fluorination of EC, and Mg 2+ -induced decay of PF 6 - to PF 5 and F - . Data analysis allows the rationalization of existing experimentally established phenomena such as gassing and fluoride deposition. Among the three investigated cations, Mg 2+ is adsorbed most tightly and is predicted to form a thicker fluoride-containing film on the LTO surface. Gassing, characteristic for carbonate-based electrolytes with LTO electrodes, is foreseen to be suppressed in dual-cation batteries. The latter bears promise to outperform the single-ion ones in terms of durability and safety., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)

To double the energy density of lithium- and sodium-ion batteries there is a need to activate simultaneously cationic and anionic redox reactions at the intercalation-type electrodes. In contrast to the cationic redox activity, the oxygen redox activity enforces an enhancement in the surface reactivity of the oxides leading to their poor reversibility and cycling stability. Herein, we propose a new concept to stabilize oxygen redox activity by using oxygen-storage materials as an efficient buffer supplying and receiving oxygen during alkali ion intercalation. As a proof-of-concept, the study is focused on CeO 2 as a modifier of sodium nickel-manganese oxide with a three-layer sequence, P 3-Na 2/3 Ni 1/2 Mn 1/2 O 2 . The CeO 2 -modified P 3-Na 2/3 Ni 1/2 Mn 1/2 O 2 displays a drastic increase in the reversible capacity following the order Na + intercalation < Li + intercalation < Li + ,Na + cointercalation.

The development of lithium and sodium ion batteries without using lithium and sodium metal as anodes gives the impetus for elaboration of low-cost and environmentally friendly energy storage devices. In this contribution we demonstrate the design and construction of a new type of hybrid sodium-lithium ion cell by using unique electrode combination (Li4Ti5O12 spinel as a negative electrode and layered Na3/4Co1/3Ni1/3Mn1/3O2 as a positive electrode) and conventional lithium electrolyte (LiPF6 salt dissolved in EC/DMC). The cell operates at an average potential of 2.35 V by delivering a reversible capacity of about 100 mAh/g. The mechanism of the electrochemical reaction in the full sodium-lithium ion cell is studied by means of postmortem analysis, as well as ex situ X-ray diffraction analysis, HR-TEM, and electron paramagnetic resonance spectroscopy (EPR). The changes in the surface composition of electrodes are examined by ex situ X-ray photoelectron spectroscopy (XPS).