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11 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

A Novel NASICON‐Type Na 4 MnCr(PO 4 ) 3 Demonstrating the Energy Density Record of Phosphate Cathodes for Sodium‐Ion Batteries

Abstract Sodium‐ion batteries (SIBs) have attracted incremental attention as a promising candidate for grid‐scale energy‐storage applications. To meet practical requirements, searching for new cathode materials with high energy density is of great importance. Herein, a novel Na superionic conductor (NASICON)‐type Na 4 MnCr(PO 4 ) 3 is developed as a high‐energy cathode for SIBs. The Na 4 MnCr(PO 4 ) 3 nanoparticles homogeneously embedded in a carbon matrix can present an extraordinary reversible capacity of 160.5 mA h g −1 with three‐electron reaction at ≈3.53 V during the Na + extraction/insertion process, realizing an unprecedentedly high energy density of 566.5 Wh kg −1 in the phosphate cathodes for SIBs. It is intriguing to reveal the underlying mechanism of the unique Mn 2+ /Mn 3+ , Mn 3+ /Mn 4+ , and Cr 3+ /Cr 4+ redox couples via X‐ray absorption near‐edge structure spectroscopy. The whole electrochemical reaction undergoes highly reversible single‐phase and biphasic transitions with a moderate volume change of 7.7% through in situ X‐ray diffraction and ex situ high‐energy synchrotron X‐ray diffraction. Combining density functional theory (DFT) calculations with the galvanostatic intermittent titration technique, the superior performance is ascribed to the low ionic‐migration energy barrier and desirable Na‐ion diffusion kinetics. The present work can offer a new insight into the design of multielectron‐reaction cathode materials for SIBs.

Zhang, Jian↗
DOE OSTI2020

Materials Data on MnCr(PO4)2 by Materials Project

CrMn(PO4)2 crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. Cr4+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with four equivalent MnO6 octahedra, corners with four PO4 tetrahedra, and an edgeedge with one PO4 tetrahedra. The corner-sharing octahedral tilt angles are 49°. There are a spread of Cr–O bond distances ranging from 1.97–2.10 Å. Mn2+ is bonded to six O2- atoms to form distorted MnO6 octahedra that share corners with four equivalent CrO6 octahedra, corners with four PO4 tetrahedra, and an edgeedge with one PO4 tetrahedra. The corner-sharing octahedral tilt angles are 49°. There are a spread of Mn–O bond distances ranging from 1.90–2.28 Å. There are two inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one MnO6 octahedra, corners with three equivalent CrO6 octahedra, and an edgeedge with one MnO6 octahedra. The corner-sharing octahedra tilt angles range from 43–54°. There are a spread of P–O bond distances ranging from 1.52–1.57 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one CrO6 octahedra, corners with three equivalent MnO6 octahedra, and an edgeedge with one CrO6 octahedra. The corner-sharing octahedra tilt angles range from 45–56°. There are a spread of P–O bond distances ranging from 1.51–1.58 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Cr4+ and one P5+ atom. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to one Mn2+ and one P5+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Cr4+, one Mn2+, and one P5+ atom. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Cr4+, one Mn2+, and one P5+ atom. In the fifth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Cr4+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Mn2+ and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MnCr(PO4)2 by Materials Project

CrMn(PO4)2 crystallizes in the trigonal R3 space group. The structure is three-dimensional. there are three inequivalent Cr4+ sites. In the first Cr4+ site, Cr4+ is bonded to six O2- atoms to form distorted CrO6 octahedra that share corners with six PO4 tetrahedra, a faceface with one CrO6 octahedra, and a faceface with one MnO6 octahedra. There are three shorter (2.08 Å) and three longer (2.09 Å) Cr–O bond lengths. In the second Cr4+ site, Cr4+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with six PO4 tetrahedra and a faceface with one CrO6 octahedra. There is three shorter (1.94 Å) and three longer (2.03 Å) Cr–O bond length. In the third Cr4+ site, Cr4+ is bonded to six O2- atoms to form distorted CrO6 octahedra that share corners with six PO4 tetrahedra and faces with two MnO6 octahedra. All Cr–O bond lengths are 2.08 Å. There are three inequivalent Mn2+ sites. In the first Mn2+ site, Mn2+ is bonded to six O2- atoms to form distorted MnO6 octahedra that share corners with six PO4 tetrahedra and a faceface with one CrO6 octahedra. There are three shorter (1.96 Å) and three longer (2.10 Å) Mn–O bond lengths. In the second Mn2+ site, Mn2+ is bonded to six O2- atoms to form distorted MnO6 octahedra that share corners with six PO4 tetrahedra and a faceface with one CrO6 octahedra. There are three shorter (1.95 Å) and three longer (2.09 Å) Mn–O bond lengths. In the third Mn2+ site, Mn2+ is bonded to six O2- atoms to form distorted MnO6 octahedra that share corners with six PO4 tetrahedra and a faceface with one CrO6 octahedra. There are three shorter (1.95 Å) and three longer (2.10 Å) Mn–O bond lengths. There are two inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three CrO6 octahedra and corners with three MnO6 octahedra. The corner-sharing octahedra tilt angles range from 27–54°. There is two shorter (1.51 Å) and two longer (1.57 Å) P–O bond length. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three CrO6 octahedra and corners with three MnO6 octahedra. The corner-sharing octahedra tilt angles range from 31–54°. There are a spread of P–O bond distances ranging from 1.51–1.58 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to one Mn2+ and one P5+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Cr4+, one Mn2+, and one P5+ atom. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to one Cr4+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one Cr4+, one Mn2+, and one P5+ atom. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to one Mn2+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to two Cr4+ and one P5+ atom. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to one Cr4+, one Mn2+, and one P5+ atom. In the eighth O2- site, O2- is bonded in a bent 150 degrees geometry to one Mn2+ and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MnCr(Ni2Sn)2 by Materials Project

CrMn(Ni2Sn)2 is Tungsten-derived structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Cr is bonded in a distorted body-centered cubic geometry to eight Ni and six equivalent Sn atoms. There are six shorter (2.63 Å) and two longer (2.64 Å) Cr–Ni bond lengths. All Cr–Sn bond lengths are 3.03 Å. Mn is bonded in a distorted body-centered cubic geometry to eight Ni and six equivalent Sn atoms. There are two shorter (2.62 Å) and six longer (2.63 Å) Mn–Ni bond lengths. All Mn–Sn bond lengths are 3.04 Å. There are five inequivalent Ni sites. In the first Ni site, Ni is bonded in a distorted body-centered cubic geometry to three equivalent Cr, one Mn, and four equivalent Sn atoms. There are three shorter (2.62 Å) and one longer (2.63 Å) Ni–Sn bond lengths. In the second Ni site, Ni is bonded in a distorted body-centered cubic geometry to one Cr, three equivalent Mn, and four equivalent Sn atoms. The Ni–Cr bond length is 2.64 Å. There are one shorter (2.63 Å) and three longer (2.64 Å) Ni–Sn bond lengths. In the third Ni site, Ni is bonded in a distorted body-centered cubic geometry to one Cr, three equivalent Mn, and four equivalent Sn atoms. There are one shorter (2.63 Å) and three longer (2.64 Å) Ni–Sn bond lengths. In the fourth Ni site, Ni is bonded in a distorted body-centered cubic geometry to three equivalent Cr, one Mn, and four equivalent Sn atoms. There are three shorter (2.62 Å) and one longer (2.63 Å) Ni–Sn bond lengths. In the fifth Ni site, Ni is bonded in a distorted body-centered cubic geometry to three equivalent Cr, one Mn, and four equivalent Sn atoms. All Ni–Cr bond lengths are 2.63 Å. The Ni–Mn bond length is 2.62 Å. There are three shorter (2.62 Å) and one longer (2.63 Å) Ni–Sn bond lengths. Sn is bonded in a 8-coordinate geometry to three equivalent Cr, three equivalent Mn, and eight Ni atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MnCr by Materials Project

CrMn crystallizes in the orthorhombic Cmmm space group. The structure is three-dimensional. Cr is bonded in a 8-coordinate geometry to four equivalent Cr and four equivalent Mn atoms. All Cr–Cr bond lengths are 2.46 Å. All Cr–Mn bond lengths are 2.44 Å. Mn is bonded in a 8-coordinate geometry to four equivalent Cr and four equivalent Mn atoms. All Mn–Mn bond lengths are 2.46 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

A High-Energy NASICON-Type Cathode Material for Na-Ion Batteries

Over the last decade, Na-ion batteries have been extensively studied as low-cost alternatives to Li-ion batteries for large-scale grid storage applications; however, the development of high-energy positive electrodes remains a major challenge. Materials with a polyanionic framework, such as Na superionic conductor (NASICON)-structured cathodes with formula Na x M 2 (PO 4 ) 3 , have attracted considerable attention because of their stable 3D crystal structure and high operating potential. Herein, a novel NASICON-type compound, Na 4 MnCr(PO 4 ) 3 , is reported as a promising cathode material for Na-ion batteries that deliver a high specific capacity of 130 mAh g –1 during discharge utilizing high-voltage Mn 2+/3+ (3.5 V), Mn 3+/4+ (4.0 V), and Cr 3+/4+ (4.35 V) transition metal redox. In addition, Na 4 MnCr(PO 4 ) 3 exhibits a high rate capability (97 mAh g –1 at 5 C) and excellent all-temperature performance. In situ X-ray diffraction and synchrotron X-ray diffraction analyses reveal reversible structural evolution for both charge and discharge.

25 ENERGY STORAGE↗
DOE OSTI2023

Oxidation Behavior of Heat-Resistant Type $\mathrm{HK}$ Steel ($\mathrm{HK30Nb}$) at 800 °C

We report the cyclic oxidation behavior of HK30Nb heat-resistant steel processed by laser powder bed fusion (LPBF) was compared to its cast counterpart during exposures in air and air + 10% H 2 O at 800 °C. The specific finer microstructure and lower Mn of the LPBF alloy resulted in lower oxidation rates in dry air and faster establishment of a continuous Cr 2 O 3 scale in air + 10% H 2 O compared to coarse-grained cast HK30Nb with higher Mn. Differences in alloy mechanical strength and therefore their ability to accommodate high temperature and oxidation-induced stresses as well as differences in thermal expansion coefficients between the alloy and the formed oxides (Cr 2 O 3 only for the LPBF and Cr 2 O 3 and MnCr 2 O 4 for the cast specimens) during temperature cycling were found to result in a greater extent of spallation for the LPBF than for the cast alloy in dry air at 800 °C.

36 MATERIALS SCIENCE↗
DOE OSTI2022

A phase-field study of stainless-steel oxidation from high-temperature carbon dioxide exposure

An electrochemical phase-field model has been developed to investigate the oxidation mechanisms of the 21-2N valve stainless steel alloy exposed to carbon dioxide at 973 K. Three oxide phases observed in oxidation experiments are included in the model: Mn 3 O 4 , Cr 2 O 3 , and MnCr 2 O 4 . Local charge neutrality and the conserved current condition are assumed to include the impact of the electric potential on oxidation, though it is found to be negligible when the system is electrically isolated. The sensitivity of the oxidation processes to the values of the diffusion mobilities is examined, and the oxidation rate is calibrated against experimental data by modifying the sensitive mobilities. We find that both inward oxygen and outward metal diffusion are important for oxidation. Furthermore, by investigating the impact of the order of the initial oxide layers, we find that Cr 2 O 3 serves as a barrier to outward Mn diffusion. Moreover, controlling the initial oxide layer order can be used to limit oxidation.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Oxidation kinetics and microstructure evolution of high Mn stainless-steel alloy in CO 2 at 700 °C

Oxidation kinetics and scale formation were examined in 21–2N Stainless Steel alloys in a CO 2 environment at 700 °C. Several characterization techniques were used to identify the morphology, crystallographic structure, and chemical composition of the oxide scale formation during exposures up to 1925 h. High manganese content played an important role in homogenous oxide scale formation of Mn 3 O 4 and MnCr 2 O 4 at the scale/gas and scale/alloy interfaces and as an FCC stabilizer in the alloy. Depletion of Mn resulted in an FCC to BCC phase transformation at the scale/alloy interface. No carburization was observed, indicating that the oxide layer is preventing carbon uptake.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MnCrB2 by Materials Project

(MnCr)B2 crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. Cr4+ is bonded in a 7-coordinate geometry to seven B3- atoms. There are a spread of Cr–B bond distances ranging from 2.17–2.23 Å. Mn2+ is bonded in a 7-coordinate geometry to seven B3- atoms. There are a spread of Mn–B bond distances ranging from 2.16–2.25 Å. There are two inequivalent B3- sites. In the first B3- site, B3- is bonded in a 9-coordinate geometry to three equivalent Cr4+, four equivalent Mn2+, and two equivalent B3- atoms. Both B–B bond lengths are 1.79 Å. In the second B3- site, B3- is bonded in a 9-coordinate geometry to four equivalent Cr4+, three equivalent Mn2+, and two equivalent B3- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Impact of Hydrogen Combustion on the Oxidation-induced Degradation of Heavy-duty Diesel Engine Piston Materials

High temperature ferritic-martensitic steels are candidate materials for heavy-duty diesel engine pistons. The envisioned transition to hydrogen blended fuels is expected to alter the post-combustion atmosphere in the engines, primarily resulting in a higher water vapor content (> 20 vol%) and potentially higher exhaust gas temperatures. The oxidation resistance of existing and newly developed alloys will be a critical life-limiting mechanism under these conditions. In the present work, the oxidation behavior of candidate piston alloys was evaluated in air+10 vol.% H2O and air+30 vol.% H2O at 700°C. Thermal cyclic (1h cycle) exposures were conducted for two variants of commercial UNSS42200 ferritic-martensitic steel and two developmental alloy steels for up to 300h. The developmental alloys each have similar compositions but with one containing elevated Cu levels of 3 wt.%, A significant reduction in resistance to breakaway oxidation was observed for the commercial alloys in the higher water vapor atmosphere. Microstructural characterization (optical metallography, scanning electron microscopy and electron microprobe analysis) revealed the formation of thick Fe-rich oxides even for the high Cr (~12 wt.%) steels after an initial stage of protective oxidation with MnCr-rich spinels. The impact of the evaporation-induced loss of Cr on the time and temperature dependent compositional changes in the alloys was correlated with experimental findings. For the developmental alloys, Cu additions appear to play a role in significantly reducing oxidation kinetics in air+30 vol.% H2O at 700°C.

Pillai, Rishi [ORNL] (ORCID:0000000243688197)↗