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Li2O2 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Li is bonded to four equivalent O atoms to form a mixture of distorted edge and corner-sharing LiO4 tetrahedra. There is three shorter (1.97 Å) and one longer (2.02 Å) Li–O bond length. O is bonded in a 5-coordinate geometry to four equivalent Li and one O atom. The O–O bond length is 1.52 Å.
Li2O2 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are two inequivalent Li sites. In the first Li site, Li is bonded to six equivalent O atoms to form edge-sharing LiO6 octahedra. All Li–O bond lengths are 2.17 Å. In the second Li site, Li is bonded in a 6-coordinate geometry to six equivalent O atoms. All Li–O bond lengths are 1.99 Å. O is bonded in a 7-coordinate geometry to six Li and one O atom. The O–O bond length is 1.55 Å.
Li2O2 is Tetraauricupride structured and crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Li is bonded in a body-centered cubic geometry to eight equivalent O atoms. There are four shorter (2.19 Å) and four longer (2.21 Å) Li–O bond lengths. O is bonded in a body-centered cubic geometry to eight equivalent Li atoms.
Li2O2 is Tetraauricupride structured and crystallizes in the tetragonal P4mm space group. The structure is three-dimensional. Li is bonded in a distorted body-centered cubic geometry to eight O atoms. There are a spread of Li–O bond distances ranging from 2.16–2.18 Å. There are two inequivalent O sites. In the first O site, O is bonded in a body-centered cubic geometry to eight equivalent Li atoms. In the second O site, O is bonded in a body-centered cubic geometry to eight equivalent Li atoms.
The use of lithium peroxide (Li2O2) as a cost-effective low-weight prelithiation cathode additive was successfully demonstrated. Through a series of studies on the chemical stability of Li2O2 and the activation process of Li2O2 on the cathode, we revealed that Li2O2 is more compatible with conventional electrolyte and cathode laminate slurry than lithium oxide. Due to the significantlysmaller size of commercial Li2O2, it can beused directly as a cathode additive. Moreover, the activation of Li2O2 on the cathode leads to the impedance growthof the cathode possibly resulting from the release of dioxygen andevacuation of Li2O2 inside the cathode. Withthe introduction of a new Li2O2 spread-coatingtechnique on the cathode, the capacity loss was suppressed. Si||NMCfull cells using Li2O2 spread-coated cathodedemonstrated a highly promising activation rate of Li2O2 and significantly enhanced specific capacity and cyclingstability compared to the uncoated full cells.
Li2O2(TiS2)2 crystallizes in the trigonal R3m space group. The structure is two-dimensional and consists of three Li2O2 sheets oriented in the (0, 0, 1) direction and three TiS2 sheets oriented in the (0, 0, 1) direction. In each Li2O2 sheet, Li1+ is bonded in a trigonal planar geometry to three equivalent O2- atoms. All Li–O bond lengths are 1.95 Å. O2- is bonded in a trigonal planar geometry to three equivalent Li1+ atoms. In each TiS2 sheet, Ti4+ is bonded to six S+1.50- atoms to form edge-sharing TiS6 octahedra. There are three shorter (2.41 Å) and three longer (2.43 Å) Ti–S bond lengths. There are two inequivalent S+1.50- sites. In the first S+1.50- site, S+1.50- is bonded in a 3-coordinate geometry to three equivalent Ti4+ atoms. In the second S+1.50- site, S+1.50- is bonded in a 3-coordinate geometry to three equivalent Ti4+ atoms.
Li2O2(TiSe2)2 is Hydrophilite-derived structured and crystallizes in the trigonal P3m1 space group. The structure is two-dimensional and consists of three Li2O2 sheets oriented in the (0, 0, 1) direction and three TiSe2 sheets oriented in the (0, 0, 1) direction. In each Li2O2 sheet, Li1+ is bonded in a trigonal planar geometry to three equivalent O2- atoms. All Li–O bond lengths are 2.01 Å. O2- is bonded in a trigonal planar geometry to three equivalent Li1+ atoms. In each TiSe2 sheet, Ti4+ is bonded to six Se+1.50- atoms to form edge-sharing TiSe6 octahedra. There are three shorter (2.54 Å) and three longer (2.56 Å) Ti–Se bond lengths. There are two inequivalent Se+1.50- sites. In the first Se+1.50- site, Se+1.50- is bonded in a 3-coordinate geometry to three equivalent Ti4+ atoms. In the second Se+1.50- site, Se+1.50- is bonded in a 3-coordinate geometry to three equivalent Ti4+ atoms.
Developing batteries with energy densities comparable to internal combustion technology is essential for a worldwide transition to electrified transportation. Li-O2 batteries are seen as the ‘holy grail’ of battery technologies since they have the highest theoretical energy density of all battery technologies. Current lithium-oxygen (Li-O2) batteries suffer from large charge overpotentials related to electronic resistivity of the insulating lithium peroxide (Li2O2) discharge product. One potential solution is the formation and stabilization of a lithium superoxide (LiO2) discharge intermediate that exhibits good electronic conductivity. However, LiO2 is reported to be unstable at ambient temperature despite its favorable formation energy at -1.0 eV/atom. In this paper, based on our recent work on the development of cathode materials for aprotic lithium oxygen batteries including two intermetallic compounds, LiIr3 and LiIr, that are found to form good template interfaces with LiO2, a simple goodness of fit R factor to gauge how well a template surface structure can support LiO2 growth is developed. The R factor is a quantitative measurement to calculate the geometric difference in the unit cells of specific Miller Index 2D planes of the template surface and LiO2. Using this as a guide, the R factors for LiIr3, LiIr, and La2NiO4+, are found to be good. This guide is attested by simple extension to other noble metal intermetallics with electrochemical cycling data including LiRh3, LiRh, and Li2Pd. Finally, the template concept is extended to main group elements and the R factors for LiO2 (111) and Li2Ca suggest that Li2Ca is a possible candidate for the template assisted LiO2 growth strategy.
A secondary battery including a cathode having a primary cathode active material and an alkaline source material selected from the group consisting of Na2O, Na2O2, Na2S, NaF, NaCl, NaBr, Li2O, Li2O2, Li2S, LiF, LiCl, LiBr, Na2O, Na2O2, Na2S, NaF, NaCl, and a mixture of any two or more thereof; an anode having an anode active material; an electrolyte; and a separator.
The rechargeable lithium-oxygen (Li-O 2 ) battery has the highest theoretical specific energy density of any rechargeable batteries and could transform energy storage systems if a practical device could be attained. However, among numerous challenges, which are all interconnected, are polarization due to sluggish kinetics, low cycle life, small capacity, and slow rates. Here, in this study, we report on use of KMnO 4 to generate a colloidal electrolyte made up of MnO 2 nanoparticles. The resulting electrolyte provides a redox mediator for reducing the charge potential and lithium anode protection to increase cycle life. This electrolyte in combination with a stable binary transition metal dichalcogenide alloy, Nb 0.5 Ta 0.5 S 2 , as the cathode enables the operation of a Li-O 2 battery at a current density of 1 mA center dot cm -2 and specific capacity ranging from 1000 to 10000 mA center dot h center dot g -1 (corresponding to 0.1-1 mA center dot h center dot cm -2 ) in a dry air environment with a cycle life of up to 150. This colloidal electrolyte provides a robust approach for advancing Li-air batteries.