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Understanding intercalation chemistry for sustainable aqueous zinc–manganese dioxide batteries

Rechargeable aqueous Zn-MnO 2 technology combines one of the oldest battery chemistries with favourable sustainability characteristics, including safety, cost and environmental compatibility. However, the ambiguous charge storage mechanism presents a challenge to fulfil the great potential of this energy technology. In this work, we leverage on advanced electron microscopy, electrochemical analysis and theoretical calculations to look into the intercalation chemistry within the cathode material, or α-MnO 2 more specifically. We show that Zn 2+ insertion into the cathode is unlikely in the aqueous system; rather, the charge storage process is dominated by proton intercalation to form α-H x MnO 2 . We further reveal anisotropic lattice change as a result of entering protons proceeding from the surface into the bulk of α-MnO 2 , which accounts for the structural failure and capacity decay of the electrode upon cycling. Our work not only advances the fundamental understanding of rechargeable zinc batteries but also suggests the possibility to optimize proton intercalation kinetics for better-performing cell designs. A rechargeable aqueous Zn-MnO 2 battery features a combination of favourable sustainability characteristics from safety to cost. The authors deploy advanced characterizations and theoretical calculations to provide fresh insight into the charge storage mechanism, which not only closes an ongoing debate but suggests ways forward.

25 ENERGY STORAGE↗

Synthesis and structural characterization of 2,2’-bipyridine zinc formate: Analysis of formate bonding and hydrosilylation of CO 2 and carbonyl compounds

The zinc formate compound (bipy)Zn(O 2 CH) 2 is obtained via the reaction of Zn(O 2 CH) 2 with 2,2’-bipyridine (bipy). In addition, (bipy)Zn(O 2 CH) 2 may be formed from zinc hydride via addition of bipy followed by addition of (i) HCO 2 H and (ii) CO 2 . The molecular structure of (bipy)Zn(O 2 CH) 2 has been determined by X-ray diffraction, thereby demonstrating that it exists as a monomeric species with a distorted tetrahedral zinc center and monodentate formate ligands. Analysis of the bonding within the formate ligand indicates that the zinc–formate moiety is not best represented by a Zn–O–C(=O)H resonance structure, but instead possesses a significant ionic component that reduces the C=O bond order and increases the C–O bond order. The formate compound (bipy)Zn(O 2 CH) 2 participates in hydrosilylation transformations involving CO 2 and carbonyl compounds.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Secondary zinc-manganese dioxide batteries for high power applications

In an embodiment, a secondary Zn—MnO 2 battery comprises a battery housing, a MnO 2 cathode, a Zn anode, and an electrolyte solution. The MnO 2 cathode, the Zn anode, and the electrolyte solution are disposed within the battery housing, and the MnO 2 cathode comprises a MnO 2 cathode mixture and a current collector. The MnO 2 cathode mixture is in electrical contact with at least a portion of an outer surface of the current collector, and the MnO 2 cathode has a porosity of from about 5 vol. % to about 90 vol. %, based on the total volume of the MnO 2 cathode mixture of the MnO 2 cathode.

Ingale, Nilesh↗

A tunable band gap of the layered semiconductor Zn 3 In 2 S 6 under pressure

The band gap is an important property of a semiconductor, and a candidate material with a highly tunable band gap under external tuning parameters will offer wider applications in optoelectronic devices and photocatalytic fields. Here, we show that the layered semiconductor Zn 3 In 2 S 6 possesses a band gap that is highly tunable with pressure. In situ optical absorption shows that the band gap unexpectedly widens with pressure up to ~13 GPa. Sudden gap narrowing then occurs above 14 GPa, which is followed by progressive gap decreases on further compression and the gap finally closes above 20 GPa. Our study, encompassing X-ray diffraction, Raman spectroscopy experiments and theoretical calculations revealed that the selective responses of the different bonds are responsible for the band gap increase in the low-pressure ranges. We show that the pressure-induced irreversible amorphization is responsible for the sudden gap narrowing whereas the semiconductor–metallic transition is related to the amorphous–amorphous transition at high-pressure due to a change in the local coordination number of Zn atoms. This work demonstrates the high tunability of the electronic and optical properties of layered ternary semiconductors under pressure, providing a potential way for wider applications of this class of materials.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

Influence of metal organic framework glasses on thermoelectric properties of AgSb 0.96 Zn 0.04 Te 2 alloy

In recent years, a significant number of chalcogenides-based thermoelectric (TE) materials have been investigated theoretically and experimentally. However, the efficiency of TE materials is often limited by physical and chemical stability issues. Therefore, it is crucial to identify additive materials that can reduce thermal conductivity and improve the efficiency of crystalline TE materials. One well-known approach to lower thermal conductivity is introducing porosity into the material structure, which helps scatter phonon energy. Metal-organic framework (MOF) crystalline materials, known for their porosity and physical and chemical stability, offer unique advantages in TE applications. In this study, we investigate the influence of 20 weight% amorphous Zeolitic Imidazolate Framework (ZIF)-62 to p-type AgSb 0.96 Zn 0.04 Te 2 (ASTZ), a well-known TE material. We synthesized composites, ASTZ, ASTZ-Zn, and ASTZ-Co, by sintering ASTZ with amorphous ZIF-62(Zn) and ZIF-62(Co) respectively. The addition of amorphous ZIF-62(Zn) leads to a significant enhancement in the Seebeck coefficient of ASTZ increasing from 151 µV/K to 229 µV/K at 586K. Moreover, the thermal conductivity of the ASTZ TE materials drops drastically from 0.491 Wm -1 K -1 to around 0.22 Wm -1 K -1 at 623K with the addition of either amorphous ZIF-62(Zn) or ZIF-62(Co). Remarkably, ASTZ containing amorphous ZIF-62(Zn) achieves a maximum thermoelectric figure of merit (zT max ) of approximately 0.078 at 573K, surpassing any MOF-based thermoelectric material reported to date. In conclusion, these findings highlight the potential of amorphous ZIF-62 as an effective additive for enhancing the properties of thermoelectric materials.

36 MATERIALS SCIENCE↗

Molten Salts-Driven Discovery of a Polar Mixed-Anion 3D Framework at the Nanoscale: Zn 4 Si 2 O 7 Cl 2 , Charge Transport and Photoelectrocatalytic Water Splitting

Mixed-anion compounds widen the chemical space of attainable materials compared to single anionic compounds, but the exploration of their structural diversity is limited by common synthetic paths. Especially, oxychlorides rely mainly on layered structures, which suffer from low stability during photo(electro)catalytic processes. Herein we report a strategy to design a new polar 3D tetrahedral framework with composition Zn 4 Si 2 O 7 Cl 2 . We use a molten salt medium to enable low temperature crystallization of nanowires of this new compound, by relying on tetrahedral building units present in the melt to build the connectivity of the oxychloride. These units are combined with silicon-based connectors from a non-oxidic Zintl phase to enable precise tuning of the oxygen content. This structure brings high chemical and thermal stability, as well as strongly anisotropic hole mobility along the polar axis. These features, associated with the ability to adjust the transport properties by doping, enable to tune water splitting properties for photoelectrocatalytic H 2 evolution and water oxidation. This work then paves the way to a new family of mixed-anion solids

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Synthesis and structural characterization of 2,2′:6′,2″-terpyridine zinc formate: Hydroboration and hydrosilylation of CO 2 and carbonyl compounds

The zinc formate compound (terpy)Zn(O 2 CH) 2 is obtained via the reaction of Zn(O 2 CH) 2 with 2,2′:6′,2″-terpyridine (terpy) and has been structurally characterized by X-ray diffraction as possessing formate ligands that coordinate via a κ 1 -monodentate coordination mode, which is in accord with IR spectroscopic studies. In terms of reactivity, (terpy)Zn(O 2 CH) 2 participates in catalytic transformations involving CO 2 and carbonyl compounds via hydrosilylation and hydroboration reactions. For example, (terpy)Zn(O 2 CH) 2 achieves hydroboration of Me 2 CO and Ph 2 CO by HBpin to afford R 2 C(H)OBpin, and triple insertion of Ph 2 CO, PhC(O)Me, Me 2 CO and PhCHO into the Si–H bonds of PhSiH 3 to afford PhSi[OCH(R)R’] 3 . In addition, CO 2 also undergoes hydroboration and hydrosilylation by HBpin and (MeO) 3 SiH in the presence of (terpy)Zn(O 2 CH) 2 to afford HCO 2 Bpin and HCO 2 Si(OMe) 3 , respectively.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Bioremediation of copper in sediments from a constructed wetland ex situ with the novel bacterium Cupriavidus basilensis SRS

The H-02 constructed wetland was designed to remove metals (primarily copper and zinc) to treat building process water and storm water runoff from multiple sources associated with the Tritium Facility at the DOE-Savannah River Site, Aiken, SC. The concentration of Cu and Zn in the sediments has increased over the lifetime of the wetland and is a concern. A bioremediation option was investigated at the laboratory scale utilizing a newly isolated bacterium of the copper metabolizing genus Cupriavidus isolated from Tim’s Branch Creek, a second-order stream that eventually serves as a tributary to the Savannah River, contaminated with uranium and other metals including copper, nickel, and mercury. Cupriavidus basilensis SRS is a rod-shaped, gram-negative bacterium which has been shown to have predatory tendencies. The isolate displayed resistance to the antibiotics ofloxacin, tetracycline, ciprofloxacin, select fungi, as well as Cu 2+ and Zn 2+ . Subsequent ribosomal sequencing demonstrated a 100% confidence for placement in the genus Cupriavidus and a 99.014% match to the C. basilensis type strain. When H-02 wetland samples were inoculated with Cupriavidus basilensis SRS samples showed significant (p < 0.05) decrease in Cu 2+ concentrations and variability in Zn 2+ concentrations. Over the 72-h incubation there were no significant changes in the inoculate densities (10 6 –10 8 cells/ML) indicating Cupriavidus basilensis SRS resiliency in this environment. This research expands our understanding of the Cupriavidus genus and demonstrates the potential for Cupriavidus basilensis SRS to bioremediate sites impacted with heavy metals, most notably copper.

54 ENVIRONMENTAL SCIENCES↗

Effect of operating parameters on H 2 /CO 2 conversion to methanol over Cu-Zn oxide supported on ZrO 2 polymorph catalysts: Characterization and kinetics

Kinetic aspects of the operating parameters for the catalytic conversion of H 2 /CO 2 to methanol over two novel catalysts were evaluated to understand the effect of the polymorphic ZrO 2 phase composed of Cu 0/+ -ZnO sites at the atomic level and its impact on the reaction mechanism. The catalysts were characterized by in situ and ex-situ XRD, N 2 adsorption/desorption isotherms, FRX, TPR, TPD-N 2 O, in situ XANES, TPD-CO 2 , and in situ DRIFTS techniques. The influence of different reaction variables such as the GHSV, temperature, pressure, and H 2 /CO 2 ratio were studied using a fixed bed continuous plug flow reactor. The Cu-ZnO catalyst supported on the tetragonal zirconia polymorph exhibited the highest methanol yield due to the lower activation energy when compared to the catalyst with a greater amount of the monoclinic phase. In addition, the catalysts were reused for 8 cycles of 6 hours to evaluate their stability, which can translate into lower costs for large-scale methanol production. As a result, the estimation of the kinetic parameters over Cu-Zn oxide supported on ZrO 2 polymorphs was significant for understanding the reaction mechanism, as well as to provide a pathway for scaling-up of the process.

36 MATERIALS SCIENCE↗

Electron irradiation effects on the optical properties of Hf- and Zn-doped β -Ga 2 O 3

Optical and electrical properties of Hf- and Zn-doped β-Ga 2 O 3 samples, which are n-type and insulating, respectively, were altered via high-energy electron irradiation at 2.5 or 0.5 MeV. The β-Ga 2 O 3 :Hf samples irradiated with 2.5 MeV electrons experienced a color change from blue to yellow and a large drop in conductivity, attributed to the creation of gallium vacancies, which compensate donors. This irradiation resulted in the absence of free carrier absorption and the presence of Cr 3+ photoluminescence (PL). PL mapping prior to irradiation revealed optically active ZnO precipitates that formed during the growth of β-Ga 2 O 3 :Zn. These precipitates have a 384 nm (3.23 eV) stacking fault emission in the core; in the outer shell of the precipitate, the PL blue-shifts to 377 nm (3.29 eV) and a broad defect band is observed. After 0.5 MeV electron irradiation, the defect band broadened and increased in intensity. The blue PL band (435 nm) of β-Ga 2 O 3 was enhanced for both Hf- and Zn-doped samples irradiated with 0.5 MeV. This enhancement is correlated with an increase in oxygen vacancies.

36 MATERIALS SCIENCE↗

Materials Data on ZnC2(Br2N3)2 by Materials Project

Zn(CN3)2(Br)4 crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of four diaziridinimine molecules, eight hydrobromic acid molecules, and two zinc dust molecules.

36 MATERIALS SCIENCE↗

Materials Data on ZnH2(CO2)2 by Materials Project

Zn(HCOO)2 crystallizes in the monoclinic P2_1 space group. The structure is three-dimensional. there are six inequivalent Zn2+ sites. In the first Zn2+ site, Zn2+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing ZnO6 octahedra. The corner-sharing octahedral tilt angles are 68°. There are a spread of Zn–O bond distances ranging from 2.07–2.17 Å. In the second Zn2+ site, Zn2+ is bonded to six O2- atoms to form a mixture of distorted edge and face-sharing ZnO6 octahedra. There are a spread of Zn–O bond distances ranging from 2.08–2.18 Å. In the third Zn2+ site, Zn2+ is bonded to six O2- atoms to form a mixture of face and corner-sharing ZnO6 octahedra. The corner-sharing octahedral tilt angles are 68°. There are a spread of Zn–O bond distances ranging from 2.06–2.28 Å. In the fourth Zn2+ site, Zn2+ is bonded to six O2- atoms to form edge-sharing ZnO6 octahedra. There are a spread of Zn–O bond distances ranging from 2.11–2.17 Å. In the fifth Zn2+ site, Zn2+ is bonded to six O2- atoms to form edge-sharing ZnO6 octahedra. There are a spread of Zn–O bond distances ranging from 2.09–2.20 Å. In the sixth Zn2+ site, Zn2+ is bonded to six O2- atoms to form edge-sharing ZnO6 octahedra. There are a spread of Zn–O bond distances ranging from 2.06–2.20 Å. There are twelve inequivalent C2+ sites. In the first C2+ site, C2+ is bonded in a trigonal planar geometry to one H1+ and two O2- atoms. The C–H bond length is 1.11 Å. There is one shorter (1.25 Å) and one longer (1.29 Å) C–O bond length. In the second C2+ site, C2+ is bonded in a trigonal planar geometry to one H1+ and two O2- atoms. The C–H bond length is 1.11 Å. There is one shorter (1.26 Å) and one longer (1.29 Å) C–O bond length. In the third C2+ site, C2+ is bonded in a trigonal planar geometry to one H1+ and two O2- atoms. The C–H bond length is 1.11 Å. There is one shorter (1.25 Å) and one longer (1.29 Å) C–O bond length. In the fourth C2+ site, C2+ is bonded in a trigonal planar geometry to one H1+ and two O2- atoms. The C–H bond length is 1.11 Å. There is one shorter (1.26 Å) and one longer (1.28 Å) C–O bond length. In the fifth C2+ site, C2+ is bonded in a trigonal planar geometry to one H1+ and two O2- atoms. The C–H bond length is 1.10 Å. There is one shorter (1.26 Å) and one longer (1.29 Å) C–O bond length. In the sixth C2+ site, C2+ is bonded in a trigonal planar geometry to one H1+ and two O2- atoms. The C–H bond length is 1.10 Å. There is one shorter (1.27 Å) and one longer (1.28 Å) C–O bond length. In the seventh C2+ site, C2+ is bonded in a trigonal planar geometry to one H1+ and two O2- atoms. The C–H bond length is 1.10 Å. There is one shorter (1.26 Å) and one longer (1.28 Å) C–O bond length. In the eighth C2+ site, C2+ is bonded in a trigonal planar geometry to one H1+ and two O2- atoms. The C–H bond length is 1.10 Å. There is one shorter (1.26 Å) and one longer (1.29 Å) C–O bond length. In the ninth C2+ site, C2+ is bonded in a trigonal planar geometry to one H1+ and two O2- atoms. The C–H bond length is 1.11 Å. There is one shorter (1.26 Å) and one longer (1.29 Å) C–O bond length. In the tenth C2+ site, C2+ is bonded in a trigonal planar geometry to one H1+ and two O2- atoms. The C–H bond length is 1.10 Å. There is one shorter (1.25 Å) and one longer (1.29 Å) C–O bond length. In the eleventh C2+ site, C2+ is bonded in a trigonal planar geometry to one H1+ and two O2- atoms. The C–H bond length is 1.10 Å. There is one shorter (1.26 Å) and one longer (1.29 Å) C–O bond length. In the twelfth C2+ site, C2+ is bonded in a trigonal planar geometry to one H1+ and two O2- atoms. The C–H bond length is 1.10 Å. There is one shorter (1.26 Å) and one longer (1.28 Å) C–O bond length. There are twelve inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one C2+ atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one C2+ atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one C2+ atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one C2+ atom. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one C2+ atom. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one C2+ atom. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one C2+ atom. In the eighth H1+ site, H1+ is bonded in a single-bond geometry to one C2+ atom. In the ninth H1+ site, H1+ is bonded in a single-bond geometry to one C2+ atom. In the tenth H1+ site, H1+ is bonded in a single-bond geometry to one C2+ atom. In the eleventh H1+ site, H1+ is bonded in a single-bond geometry to one C2+ atom. In the twelfth H1+ site, H1+ is bonded in a single-bond geometry to one C2+ atom. There are twenty-four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to two Zn2+ and one C2+ atom. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to one Zn2+ and one C2+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to two Zn2+ and one C2+ atom. In the fourth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Zn2+ and one C2+ atom. In the fifth O2- site, O2- is bonded in a bent 120 degrees geometry to one Zn2+ and one C2+ atom. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Zn2+ and one C2+ atom. In the seventh O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Zn2+ and one C2+ atom. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to two Zn2+ and one C2+ atom. In the ninth O2- site, O2- is bonded in a trigonal planar geometry to two Zn2+ and one C2+ atom. In the tenth O2- site, O2- is bonded in a bent 120 degrees geometry to one Zn2+ and one C2+ atom. In the eleventh O2- site, O2- is bonded in a 1-coordinate geometry to two Zn2+ and one C2+ atom. In the twelfth O2- site, O2- is bonded in a bent 120 degrees geometry to one Zn2+ and one C2+ atom. In the thirteenth O2- site, O2- is bonded in a 3-coordinate geometry to two Zn2+ and one C2+ atom. In the fourteenth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Zn2+ and one C2+ atom. In the fifteenth O2- site, O2- is bonded in a 3-coordinate geometry to two Zn2+ and one C2+ atom. In the sixteenth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Zn2+ and one C2+ atom. In the seventeenth O2- site, O2- is bonded in a 3-coordinate geometry to two Zn2+ and one C2+ atom. In the eighteenth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Zn2+ and one C2+ atom. In the nineteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Zn2+ and one C2+ atom. In the twentieth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Zn2+ and one C2+ atom. In the twenty-first O2- site, O2- is bonded in a 3-coordinate geometry to two Zn2+ and one C2+ atom. In the twenty-second O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Zn2+ and one C2+ atom. In the twenty-third O2- site, O2- is bonded in a distorted trigonal planar geometry to two Zn2+ and one C2+ atom. In the twenty-fourth O2- site, O2- is bonded in a bent 120 degrees geometry to one Zn2+ and one C2+ atom.

36 MATERIALS SCIENCE↗

Materials Data on ZnH2(CO2)2 by Materials Project

Zn(HCOO)2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are four inequivalent Zn2+ sites. In the first Zn2+ site, Zn2+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing ZnO6 octahedra. The corner-sharing octahedra tilt angles range from 65–69°. There are a spread of Zn–O bond distances ranging from 2.07–2.17 Å. In the second Zn2+ site, Zn2+ is bonded to six O2- atoms to form edge-sharing ZnO6 octahedra. There are a spread of Zn–O bond distances ranging from 2.06–2.20 Å. In the third Zn2+ site, Zn2+ is bonded to six O2- atoms to form corner-sharing ZnO6 octahedra. The corner-sharing octahedral tilt angles are 69°. There are a spread of Zn–O bond distances ranging from 2.09–2.18 Å. In the fourth Zn2+ site, Zn2+ is bonded to six O2- atoms to form corner-sharing ZnO6 octahedra. The corner-sharing octahedral tilt angles are 65°. There are a spread of Zn–O bond distances ranging from 2.10–2.19 Å. There are six inequivalent C2+ sites. In the first C2+ site, C2+ is bonded in a trigonal planar geometry to one H1+ and two O2- atoms. The C–H bond length is 1.10 Å. There is one shorter (1.26 Å) and one longer (1.28 Å) C–O bond length. In the second C2+ site, C2+ is bonded in a trigonal planar geometry to one H1+ and two O2- atoms. The C–H bond length is 1.11 Å. There is one shorter (1.25 Å) and one longer (1.29 Å) C–O bond length. In the third C2+ site, C2+ is bonded in a trigonal planar geometry to one H1+ and two O2- atoms. The C–H bond length is 1.11 Å. There is one shorter (1.25 Å) and one longer (1.29 Å) C–O bond length. In the fourth C2+ site, C2+ is bonded in a trigonal planar geometry to one H1+ and two O2- atoms. The C–H bond length is 1.10 Å. There is one shorter (1.26 Å) and one longer (1.29 Å) C–O bond length. In the fifth C2+ site, C2+ is bonded in a trigonal planar geometry to one H1+ and two O2- atoms. The C–H bond length is 1.10 Å. There is one shorter (1.25 Å) and one longer (1.29 Å) C–O bond length. In the sixth C2+ site, C2+ is bonded in a trigonal planar geometry to one H1+ and two O2- atoms. The C–H bond length is 1.11 Å. There is one shorter (1.25 Å) and one longer (1.29 Å) C–O bond length. There are six inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one C2+ atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one C2+ atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one C2+ atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one C2+ atom. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one C2+ atom. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one C2+ atom. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to two Zn2+ and one C2+ atom. In the second O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Zn2+ and one C2+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to two Zn2+ and one C2+ atom. In the fourth O2- site, O2- is bonded in a trigonal planar geometry to two Zn2+ and one C2+ atom. In the fifth O2- site, O2- is bonded in a trigonal planar geometry to two Zn2+ and one C2+ atom. In the sixth O2- site, O2- is bonded in a bent 120 degrees geometry to one Zn2+ and one C2+ atom. In the seventh O2- site, O2- is bonded in a bent 120 degrees geometry to one Zn2+ and one C2+ atom. In the eighth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Zn2+ and one C2+ atom. In the ninth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Zn2+ and one C2+ atom. In the tenth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Zn2+ and one C2+ atom. In the eleventh O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Zn2+ and one C2+ atom. In the twelfth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Zn2+ and one C2+ atom.

36 MATERIALS SCIENCE↗

Materials Data on ZnP2C4NO8 by Materials Project

(C)2Zn(PO4)2C2N crystallizes in the orthorhombic Fdd2 space group. The structure is three-dimensional and consists of eight aziridine molecules, sixteen methane molecules, and one Zn(PO4)2 framework. In the Zn(PO4)2 framework, Zn2+ is bonded to four O2- atoms to form ZnO4 tetrahedra that share corners with four equivalent PO4 tetrahedra. There is two shorter (1.95 Å) and two longer (1.96 Å) Zn–O bond length. P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent ZnO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.53–1.57 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Zn2+ and one P5+ atom. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Zn2+ and one P5+ atom. In the third O2- site, O2- is bonded in a single-bond geometry to one P5+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one P5+ atom.

36 MATERIALS SCIENCE↗

Zinc-Doped High-Nickel, Low-Cobalt Layered Oxide Cathodes for High-Energy-Density Lithium-Ion Batteries

High-Ni layered oxides with Ni contents greater than 90% are promising cathode candidates for high-energy-density Li-ion batteries. However, drastic electrode-electrolyte reactions and mechanical degradation issues limit their cycle life and practical viability. We demonstrate here that LiNi 0.94 Co 0.04 Zn 0.02 O 1.99 (NCZ), obtained by incorporating 2 mol% Zn 2+ into an ultrahigh-Ni baseline cathode material LiNi 0.94 Co 0.06 O 2 (NC), delivers superior cell performance. NCZ retains 74% of the initial capacity after 500 cycles in full cell assembled with graphite anode, outperforming NC (62% retention). NCZ also possesses a higher average discharge voltage relative to NC with an outstanding average voltage retention of over 99% after 130 cycles in half cells. Bulk structural investigations unveil that Zn doping promotes a smoother phase transition, suppresses anisotropic lattice distortion, and maintains the mechanical integrity of cathode particles. Furthermore, NCZ shows an enhanced interphase stability after long-term cycling, in contrast to the seriously degraded surface chemistry in NC. Finally, this work provides a practically viable approach for designing higher-energy-density high-Ni layered oxide cathodes for lithium-ion batteries.

25 ENERGY STORAGE↗

Unraveling the Dissolution-Mediated Reaction Mechanism of α-MnO 2 Cathodes for Aqueous Zn-Ion Batteries

Aqueous Zn/α-MnO 2 batteries have attracted immense interest owing to their high energy density, low cost, and safety, making them desirable for future large-scale energy application. Despite these merits, the comprehensive understanding of their reaction mechanism has been elusive due to the limitations of standard bulk characterization. Here, via transmission electron microscopy, the dissolution-mediated reaction mechanism of a Zn/α-MnO 2 system is discovered and explored in full scope to involve reversible formation of Zn 4 SO 4 (OH) 6 · x H 2 O and “birnessite-like” Zn-MnO x phase upon cycling. Overall, α-MnO 2 acts primarily as a source for cell activation through dissolution and thus is not directly involved in the Zn redox chemistry. Overall, this microscopic study offers a unique knowledge on the unconventional reaction chemistry of Zn/α-MnO 2 batteries.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗