A multipurpose laboratory diffractometer for <i>operando</i> powder X-ray diffraction investigations of energy materials

Geßwein, Holger; Stüble, Pirmin; Weber, Daniel; Binder, Joachim R.; Mönig, Reiner

doi:10.1107/s1600576722003089

Cited by 9 publications

(9 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The reasonable assumption of Vegard behavior allows for a rough estimation of the Ni content of the spinel phase based on the variation of the lattice parameters. As discussed before, [ 27 ] PXRD data from different studies is difficult to compare. Relative differences of LNMO materials published within individual studies, in contrast, are quite reliable, as it can be assumed that uniform measurement conditions and evaluation techniques were used.…”

Section: Discussionmentioning

confidence: 99%

“…The crystal structures of the LNMO and the secondary phases were investigated by means of powder X‐ray diffraction (PXRD). The room temperature measurements were carried out on an advanced laboratory diffractometer (Typ 5021, Huber) equipped with a microfocus rotating anode X‐ray generator (Rigaku MM007, Mo‐ K a radiation, parallel collimated beam, Ø ≈ 2 mm) and a 2D Pilatus 300K‐W detector, with a sample to detector distance of 0.7 m. [ 27 ] Measurements were carried out in an angular range of 7° < 2θ < 47°. In order to reliably track small changes in the lattice parameter, all samples, together with a standard reference material (LaB 6 NIST SRM 660c) were packed separated from each other, into a single glass capillary with a diameter of 0.5 mm.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

On the Composition of LiNi_0.5Mn_1.5O₄ Cathode Active Materials

Stüble

Mereacre

Geßwein

et al. 2023

Advanced Energy Materials

Self Cite

View full text Add to dashboard Cite

A characteristic advantage over state-of-the-art Ni-rich cathode active materials such as LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM-622) or LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM-811) is that LNMO is cobalt free and the redox capacity of nickel is used in its entirety. The latter could become more important considering rising nickel prices. Based on realistic full cell capacities of 120 mAh g −1 for LNMO and 170 mAh g −1 for the NCM materials, 43.8 Ah per mol Ni is obtained for LNMO, whereas NCM-622 and NCM-811 only yield 27.5 and 20.7 Ah mol −1 , respectively. The specific energy density of LNMO vs. graphite full cells is likewise highly competitive. For LNMO, up to 464 Wh kg −1 are expected, which exceeds the energy densities of corresponding NCM-622 and NCM-811 cells, yielding 416 and 448 Wh kg −1 , respectively. [2] Despite these favorable features, commercialization of LNMO cathode materials never succeeded. Up to date, it was not possible to build competitive cells with graphite anodes, as the degradation of these full cells has not been brought under control. [3,4] The problem, however, is not the stability of LNMO itself, but the dissolution and disproportionation of Mn(III) from LNMO, which leads to continuous decomposition reactions on the anode side and ongoing loss of cyclable lithium. [3,5,6] LNMO is nevertheless a very stable cathode material, which does not tend to decompose or release oxygen during cycling. [7] There is scientific consensus that LNMO crystallizes as an ordered or disordered spinel phase in the space groups P4 3 32 or Fd3m, respectively, or as intermediate, partial ordered phases. The term "order" refers to the distribution of transition metal cations on the octahedral sites of the spinel structure. In the ordered structure, Mn and Ni predominantly occupy the Wyckoff positions 12d and 4a, while in the disordered structure, they are statistically distributed over the 16c octahedral site. [8,9] Whether an LNMO material is predominantly ordered or disordered is commonly associated with the calcination temperature. Temperatures below 730 °C are reported to favor the formation of the ordered phase, whereas at higher temperatures disordered crystal structures are reported to occur. [10] LNMO phases with the composition LiNi 0.5 Mn 1.5 O 4 , where Mn is Mn(IV) exclusively, are reported to be obtained by calcining LNMO materials at 700 °C. [11] Increasing calcination temperatures however, lead to a partial reduction of Mn(IV) to Mn(III), which becomes obvious from an increasing Mn 3+ /Mn 4+ LiNi 0.5 Mn 1.5 O 4 (LNMO) cathode active materials for lithium-ion batteries have been investigated for over 20 years. Despite all this effort, it has not been possible to transfer their favorable properties into applicable, stable battery cells. To make further progress, the research perspective on these spinel type materials needs to be updated and a number of persisting misconceptions on LNMO have to be overcome. Therefore, the current knowledge on LNMO is summarized and controversial points are addressed by detaile...

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

On the Composition of LiNi_0.5Mn_1.5O₄ Cathode Active Materials

Stüble

Mereacre

Geßwein

et al. 2023

Advanced Energy Materials

Self Cite

View full text Add to dashboard Cite

show abstract

“…The exchange reaction was studied by in situ XRD using a custom-built diffractometer, the specifics of which were reported previously . For sample preparation, a 1:1 wt mixture of NNO-600 and LiNO 3 was ground in a mortar and filled into a sapphire capillary.…”

Section: Methodsmentioning

confidence: 99%

“…The exchange reaction was studied by in situ XRD using a custom-built diffractometer, the specifics of which were reported previously. 57 For sample preparation, a 1:1 wt mixture of NNO-600 and LiNO 3 was ground in a mortar and filled into a sapphire capillary. The mixture was then heated at a rate of 1 K min −1 under an O 2 atmosphere, with each XRD pattern being the accumulated signal over 5 min.…”

Section: ■ Conclusionmentioning

confidence: 99%

Low-Temperature Ion Exchange Synthesis of Layered LiNiO₂ Single Crystals with High Ordering

et al. 2023

Self Cite

View full text Add to dashboard Cite

Layered Ni-rich oxide cathode materials are being explored in an effort to boost the energy density of lithium-ion batteries, especially for automotive applications. Among them, the ternary-phase LiNiO2 (LNO) is a promising candidate but brings along various issues, such as poor structural stability. The material is prone to disordering (Li off-stoichiometry) when prepared by conventional solid-state synthesis, leading to the presence of Ni2+ in the Li layer. These point defects negatively affect the utilization of the Li inventory, thereby limiting the practical specific capacity. In this work, we report on a two-step synthesis approach that avoids the formation of nickel substitutional defects. First, NaNiO2 (NNO) is prepared, showing no such defects due to larger differences in ionic radii between Ni2+/Ni3+ and Na+. NNO is then subjected to Na+/Li+ exchange under mild conditions. In so doing, monolithic LNO particles free of NiLi • defects can be produced at relatively low temperatures. Notably, this route allows for tailoring of the grain size, a strategy that may be used to gain insights into the structure–size–property relations in single-crystalline LNO.

show abstract

“…Hence, for studying solid-state synthesis reactions in particular there are several advantages: not only is the larger amount of sample more comparable to real synthesis conditions in the laboratory but also the loss of Li precursors through reaction with the quartz capillary can be reduced. This loss of precursors has been observed in previous studies and presents a significant issue, due to the small amount of sample and large contact surface with the tube (Geßwein et al, 2022;Bianchini, Fauth et al, 2020). Li 4 SiO 4 impurities were observed, undermining the targeted stoichiometry of the final LiNiO 2 product.…”

mentioning

confidence: 57%

In situ neutron diffraction to investigate the solid-state synthesis of Ni-rich cathode materials

Goonetilleke¹,

Suard²,

Bergner³

et al. 2023

J Appl Crystallogr

View full text Add to dashboard Cite

Studying chemical reactions in real time can provide unparalleled insight into the evolution of intermediate species and can provide guidance to optimize the reaction conditions. For solid-state synthesis reactions, powder diffraction has been demonstrated as an effective tool for resolving the structural evolution taking place upon heating. The synthesis of layered Ni-rich transition-metal oxides at a large scale (grams to kilograms) is highly relevant as these materials are commonly employed as cathodes for Li-ion batteries. In this work, in situ neutron diffraction was used to monitor the reaction mechanism during the high-temperature synthesis of Ni-rich cathode materials with a varying ratio of Ni:Mn from industrially relevant hydroxide precursors. Rietveld refinement was further used to model the observed phase evolution during synthesis and compare the behaviour of the materials as a function of temperature. The results presented herein confirm the suitability of in situ neutron diffraction to investigate the synthesis of batches of several grams of electrode materials with well-controlled stoichiometry. Furthermore, monitoring the structural evolution of the mixtures with varying Ni:Mn content in real time reveals a delayed onset of lithiation as the Mn content is increased, necessitating the use of higher annealing temperatures to achieve layering.

show abstract

A multipurpose laboratory diffractometer for operando powder X-ray diffraction investigations of energy materials

Cited by 9 publications

References 37 publications

On the Composition of LiNi_0.5Mn_1.5O₄ Cathode Active Materials

On the Composition of LiNi_0.5Mn_1.5O₄ Cathode Active Materials

Low-Temperature Ion Exchange Synthesis of Layered LiNiO₂ Single Crystals with High Ordering

In situ neutron diffraction to investigate the solid-state synthesis of Ni-rich cathode materials

Contact Info

Product

Resources

About

A multipurpose laboratory diffractometer for operando powder X-ray diffraction investigations of energy materials

Cited by 9 publications

References 37 publications

On the Composition of LiNi0.5Mn1.5O4 Cathode Active Materials

On the Composition of LiNi0.5Mn1.5O4 Cathode Active Materials

Low-Temperature Ion Exchange Synthesis of Layered LiNiO2 Single Crystals with High Ordering

In situ neutron diffraction to investigate the solid-state synthesis of Ni-rich cathode materials

Contact Info

Product

Resources

About

On the Composition of LiNi_0.5Mn_1.5O₄ Cathode Active Materials

On the Composition of LiNi_0.5Mn_1.5O₄ Cathode Active Materials

Low-Temperature Ion Exchange Synthesis of Layered LiNiO₂ Single Crystals with High Ordering