Identification of LixSn Phase Transitions During Lithiation of Tin Nanoparticle-Based Negative Electrodes from Ex Situ 119Sn MAS NMR and Operando 7Li NMR and XRD

Frerichs, Joop Enno; Ruttert, Mirco; Böckmann, Steffen; Winter, Martin; Placke, Tobias

doi:10.1021/acsaem.1c01405

Cited by 10 publications

(9 citation statements)

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“…During discharge/charge, the 119 Sn NMR resonance for metallic Sn does not change in width, nor the center of mass, which strongly suggests that metallic Sn particles do not participate in further reactions. DFT and ex situ studies of 119 Sn NMR during Li–Sn alloying reveal that isotropic 119 Sn shifts are very sensitive to alloying (e.g., LiSn has two resonances at 5969 and 5429 ppm compared to a single resonance at 6915 ppm for pure β-Sn). , We would expect similar 119 Sn NMR spectrum changes if K–Sn alloying were taking place.…”

Section: Resultsmentioning

confidence: 93%

“…DFT and ex situ studies of 119 Sn NMR during Li−Sn alloying reveal that isotropic 119 Sn shifts are very sensitive to alloying (e.g., LiSn has two resonances at 5969 and 5429 ppm compared to a single resonance at 6915 ppm for pure β-Sn). 52,53 We would expect similar 119 Sn NMR spectrum changes if K−Sn alloying were taking place.…”

Section: Synthesis and Characterization Of Tin Phosphidementioning

confidence: 97%

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Phase Transformations and Phase Segregation during Potassiation of Sn_xP_y Anodes

et al. 2022

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K-ion batteries (KIBs) have the potential to offer a cheaper alternative to Li-ion batteries (LIBs) using widely abundant materials. Conversion/alloying anodes have high theoretical capacities in KIBs, but it is believed that electrode damage from volume expansion and phase segregation by the accommodation of large K-ions leads to capacity loss during electrochemical cycling. To date, the exact phase transformations that occur during potassiation and depotassiation of conversion/alloying anodes are relatively unexplored. In this work, we synthesize two distinct compositions of tin phosphides, Sn 4 P 3 and SnP 3 , and compare their conversion/alloying mechanisms with solid-state nuclear magnetic resonance (SSNMR) spectroscopy, powder X-ray diffraction (XRD), and density functional theory (DFT) calculations. Ex situ 31 P and 119 Sn SSNMR analyses reveal that while both Sn 4 P 3 and SnP 3 exhibit phase separation of elemental P and the formation of KSnP-type environments (which are predicted to be stable based on DFT calculations) during potassiation, only Sn 4 P 3 produces metallic Sn as a byproduct. In both anode materials, K reacts with elemental P to form K-rich compounds containing isolated P sites that resemble K 3 P but K does not alloy with Sn during potassiation of Sn 4 P 3 . During charge, K is only fully removed from the K 3 P-type structures, suggesting that the formation of ternary regions in the anode and phase separation contribute to capacity loss upon reaction of K with tin phosphides.

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Section: Resultsmentioning

confidence: 93%

Section: Synthesis and Characterization Of Tin Phosphidementioning

confidence: 97%

Phase Transformations and Phase Segregation during Potassiation of Sn_xP_y Anodes

et al. 2022

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“…7 Li NMR spectroscopy enables the direct observation of all lithium-containing compounds in the bulk of the active material particles. [49,50] Specifically, the 7 Li chemical shift is sensitive to changes in the chemical surrounding of the 7 Li nuclei, and therefore, ideally suited for the given challenge of elucidating the WE composition at different potentials during the lithiation as well as delithiation. The 7 Li MAS NMR spectra of SiN 0.5 were measured for WEs extracted at different potentials during the lithiation and delithiation in the first cycle as indicated in Figure 4a.…”

Section: Resultsmentioning

confidence: 99%

Active Buffer Matrix in Nanoparticle‐Based Silicon‐Rich Silicon Nitride Anodes Enables High Stability and Fast Charging of Lithium‐Ion Batteries

Kilian

Wankmiller

Sybrecht

et al. 2022

Adv Materials Inter

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first and foremost are defined by both anode and cathode material properties.Silicon is considered the most attractive high-capacity anode material for the next generation of LIBs, showing a low working potential and a high theoretical storage capacity of 3579 mAh g −1 . [1,2] Additional advantages include better rate performance compared to graphite, [3,4] high natural abundance, and low cost. [5][6][7] In spite of these clear advantages, the implementation of silicon-based anodes has not yet been accomplished, mainly due to two major challenges: the continuous solid electrolyte interphase (SEI) growth and the pulverization of the anode material. These challenges have their origin in the high capacity of Si and the alloying reaction with Li that inevitably leads to huge volume expansion of up to 300% in a fully lithiated state. [8] The volume changes during charging and discharging lead to mechanical instability of the anode, noticeable by severe cracking and eventually a loss of electrical contact of active material. [9,10] Thus, silicon-based electrodes show rapid degradation and failure after only a few cycles, while the application of nanomaterials, such as nanowires, nanoparticles, or thin films, have been shown to circumvent distinct mechanical failure. [11][12][13][14] Whereas nanostructures mitigate challenges related to, for example, fracturing and pulverization, they do promote irreversible capacity losses and capacity fading associated with excessive SEI build-up during cycling, owing to their usually A very promising way to improve the stability of silicon in lithium-ion battery (LIB) anodes is the use of nanostructured silicon-rich silicon nitride (SiN x ), known as a conversion-type anode material. To investigate the conversion mechanism in this material in detail, SiN 0.5 nanoparticles are synthesized and examined as LIB anodes using a combination of ex situ X-ray photoelectron spectroscopy and solid-state 7 Li MAS NMR measurements. During the initial cycle, the conversion of SiN 0.5 nanoparticles results in the formation of lithium silicides and a buffer matrix consisting of different lithium nitridosilicates and lithium nitride. These phases can be reversibly lithiated and contribute to the total reversible capacity of the silicon nitride active material. The structure of the material after conversion is best described by an amorphous solid solution. Further, it is shown that silicon-rich silicon nitrides possess improved rate capability because of the higher ionic conductivity of the buffer matrix compared to pure silicon, and very fine dispersion of silicon clusters throughout the buffer matrix. Thus, unlike most conversion materials, the silicon-rich silicon nitride exhibits an additional intrinsic active functionality of the buffer matrix that goes far beyond the mere reduction of electrolyte contact area and volume expansion.

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“…Moreover, the isotropic 119 Sn shifts of the intermetallic Li−Sn phases are spread over a much wider range (7300 to −200 ppm) compared to the 7 Li resonances (100−0 ppm) and are thus less effected by a possible signal overlap caused by the formation of several Li−Sn species. 36,37 These important features potentially offer a more straightforward 119 Sn signal assignment and, thus, are a key strategy for an accurate determination and characterization of the Li−Sn phases formed during and at the end of the lithiation process. 36 Here, we investigate the electrochemical performance of TiSnSb-based negative electrodes in terms of cycling stability and Coulombic efficiency (CE) in a full-cell setup versus a lithium nickel cobalt manganese oxide (LiNi 1/3 Co 1/3 Mn 1/3 O 2 , NCM111) positive electrode.…”

Section: Introductionmentioning

confidence: 99%

“…As we have recently reported, 119 Sn NMR is a powerful tool for the investigation of Sn-containing lithiation products as the 119 Sn NMR signals display a characteristic magnetic shift anisotropy, which can be used as a fingerprint for the identification of the respective Li–Sn intermetallic phases. Moreover, the isotropic 119 Sn shifts of the intermetallic Li–Sn phases are spread over a much wider range (7300 to −200 ppm) compared to the 7 Li resonances (100–0 ppm) and are thus less effected by a possible signal overlap caused by the formation of several Li–Sn species. , These important features potentially offer a more straightforward 119 Sn signal assignment and, thus, are a key strategy for an accurate determination and characterization of the Li–Sn phases formed during and at the end of the lithiation process …”

Section: Introductionmentioning

confidence: 99%

Lithiation Mechanism and Improved Electrochemical Performance of TiSnSb-Based Negative Electrodes for Lithium-Ion Batteries

et al. 2021

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Lithium alloying materials are promising candidates to replace the current intercalation-type graphite negative electrode materials in lithium-ion batteries (LIBs) due to their high specific capacity and relatively low cost. Here, we investigate the electrochemical performance of TiSnSb regarding its charge/discharge cycling stability as a negative electrode material in LIB cells. To assess a more practical performance with respect to a limited active lithium content in LIB full-cells, we evaluate the impact of pre-lithiation for TiSnSb with respect to the cycling stability in a NCM111||TiSnSb cell setup. The observation of the individual electrode potentials reveals comprehensive insights into the ongoing cell chemistry, showing that clear performance improvements can be achieved via pre-lithiation. Furthermore, the lithiation mechanism of TiSnSb is systematically studied via ex situ 7Li magic-angle spinning (MAS) nuclear magnetic resonance (NMR), ex situ X-ray diffraction, and static ex situ 119Sn wideband uniform rate smooth truncation Carr–Purcell Meiboom–Gill (CPMG) WCPMG NMR experiments. For comprehensive references regarding the isotropic 7Li shift of the Li–Sb intermetallic phases, all thermodynamically stable Li–Sb intermetallics of the binary Li–Sb systems have been synthesized and subsequently characterized by 7Li MAS NMR. Combined, our measurements for lithiated TiSnSb do not give any evidence for the formation of Li–Sn and Li–Sb intermetallics related to crystalline bulk phases (Li7Sn3, Li7Sn2, Li3Sb, and Li2Sb) as has been previously reported. In contrast, unique insights obtained from static ex situ 119Sn WCPMG NMR and ex situ XRD measurements reveal the formation of ternary Li–Sb–Sn species during lithiation, which can be assigned to the intermetallic phase Li2.8SbSn0.2. Additionally, the 7Li MAS NMR measurements combined with the observed discharge capacity reveal a second Li species, which we assign to an amorphous Li–Sn phase.

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Identification of Li_xSn Phase Transitions During Lithiation of Tin Nanoparticle-Based Negative Electrodes from Ex Situ ¹¹⁹Sn MAS NMR and Operando ⁷Li NMR and XRD

Cited by 10 publications

References 67 publications

Phase Transformations and Phase Segregation during Potassiation of Sn_xP_y Anodes

Phase Transformations and Phase Segregation during Potassiation of Sn_xP_y Anodes

Active Buffer Matrix in Nanoparticle‐Based Silicon‐Rich Silicon Nitride Anodes Enables High Stability and Fast Charging of Lithium‐Ion Batteries

Lithiation Mechanism and Improved Electrochemical Performance of TiSnSb-Based Negative Electrodes for Lithium-Ion Batteries

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Identification of LixSn Phase Transitions During Lithiation of Tin Nanoparticle-Based Negative Electrodes from Ex Situ 119Sn MAS NMR and Operando 7Li NMR and XRD

Cited by 10 publications

References 67 publications

Phase Transformations and Phase Segregation during Potassiation of SnxPy Anodes

Phase Transformations and Phase Segregation during Potassiation of SnxPy Anodes

Active Buffer Matrix in Nanoparticle‐Based Silicon‐Rich Silicon Nitride Anodes Enables High Stability and Fast Charging of Lithium‐Ion Batteries

Lithiation Mechanism and Improved Electrochemical Performance of TiSnSb-Based Negative Electrodes for Lithium-Ion Batteries

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Identification of Li_xSn Phase Transitions During Lithiation of Tin Nanoparticle-Based Negative Electrodes from Ex Situ ¹¹⁹Sn MAS NMR and Operando ⁷Li NMR and XRD

Phase Transformations and Phase Segregation during Potassiation of Sn_xP_y Anodes

Phase Transformations and Phase Segregation during Potassiation of Sn_xP_y Anodes