Li Absorption Research Articles

Analysis of the interfacial reaction between Si-based anodes and electrolytes in Li-ion batteries.

To ensure optimal operation of electrochemical energy storage devices, a precise design of the interfaces formed between the electrodes and the electrolyte is essential. Si is a promising anode active material for Li-ion batteries owing to its high theoretical capacity; however, the large volume change associated with Li absorption and release hinders its practical applications. The development of high-performance storage batteries depends on the construction of an electrode-electrolyte interface that facilitates Li+ movement. To this aim, the authors have developed Si-specific interface observation methods. In this feature article, we review and discuss recent advances in the reaction behavior of Si-based anodes, particularly at the Si electrode-electrolyte interface.

Spectroscopic Observations of the GALEX Nearby Young Star Survey Sample. I. Nearby Moving Group Candidates

The GALEX Nearby Young Star Search (GALNYSS) yielded the identification of more than 2000 late-type stars that, based on their ultraviolet and infrared colors and pre-Gaia proper motions, are potentially of age<200 Myr and lie within ~120 pc of Earth. We present the results of a campaign of medium- and high-resolution optical spectroscopy of 471 GALNYSS stars aimed at confirming their youth and their potential membership in nearby young stellar moving groups. We present radial velocity (RV), Li absorption, and H-alpha emission measurements for these spectroscopically observed GALNYSS stars, and assess their Li absorption and optical emission-line properties and infrared excesses. Our RV measurements are combined with literature and Gaia DR3 RV measurements and Gaia DR3 astrometry and photometry to obtain the spatiokinematics and color-magnitude positions of GALNYSS stars. We use these results to assess membership in the TW Hya, Tuc-Hor, Carina, Columba, and Argus Associations and the β Pic and AB Dor moving groups. We have identified 132 stars as candidate members of these seven groups; roughly half of these candidates are newly identified on the basis of data presented here. At least one-third of the 132 candidates are spectroscopic and/or photometric binaries and/or have comoving (visual) binary companions in Gaia DR3. The contingent of young, low-mass stars in the solar vicinity we identify here should provide excellent subjects for future direct imaging exoplanet surveys and studies of the early evolution of low-mass stars and their planetary progeny.

Green recycling of short-circuited garnet-type electrolyte for high-performance solid-state lithium batteries

Solid-state lithium batteries (SSLBs) solve safety issues and are potentially energy-dense alternatives to next-generation energy storage systems. Battery green recycling routes are responsible for the widespread use of SSLBs due to minimizing environmental contamination, reducing production costs, and providing a sustainable solution for resources, e.g., saving rare earth elements (La, Ta, etc.). Herein, a solid-state recycling strategy is proposed to achieve green recycling of the crucial component solid-state electrolytes (SSEs) in spent SSLBs. The short-circuited garnet Li6.5La3Zr1.5Ta0.5O12 (LLZTO) is broken into fine particles and mixed with fresh particles to improve sintering activity and achieve high packing density. The continuous Li absorption process promotes sufficient grain fusion and guarantees the transformation from tetragonal phase to pure cubic phase for high-performance recycled LLZTO. The Li-ion conductivity reaches 5.80 × 10-4 S cm−1 with a relative density of 95.9%. Symmetric Li cell with as-recycled LLZTO shows long-term cycling stability for 700 h at 0.3 mA cm−2 without any voltage hysteresis. Full cell exhibits an excellent cycling performance with a discharge capacity of 141.5 mA h g−1 and a capacity retention of 92.1% after 400 cycles (0.2C). This work develops an environmentally friendly and economically controllable strategy to recycle SSE from spent SSLBs, guiding future directions of SSLBs large-scale industrial application and green recycling study.

WITHDRAWN: Li3N-rich SEI for lithiophilic carbon cloth/ZnO nanorod arrays host enabling stable lithium metal anode

In this work, a 3D lithiophilic carbon cloth (CC)/ZnO nanorod arrays skeleton and an Li 3 N-rich SEI layer induced by the Mg 3 N 2 -containin electrolyte are co-designed to achieve stable Li metal anode. • The ZnO nanorod arrays is applied to improve the wettability between carbon cloth and molten Li to achieve uniform Li absorption. • High lithiophilic LiZn alloy enforces a uniform Li deposition within the 3D framework. • Li 3 N-rich SEI layer insures a low Li + diffusion energy barrier and inhibits the interfacial side reactions. • The as-prepared composite Li anode offers a long lifespan even at 5 mA cm -2 or 15 mAh cm -2 . Lithium (Li) metal anode offers highest theoretical-specific-capacity among all typical anodes, yet its further utilization is significantly suppressed due to a series of critical challenges, such as uncontrolled Li dendrite growth, continuous side reactions, and unlimited volume variation. In this work, a 3D lithiophilic nature carbon cloth (CC)/ZnO nanorod arrays skeleton and an Li 3 N-rich SEI layer induced by the Mg 3 N 2 -containin electrolyte are co-designed to guide homogenous Li deposition. It is revealed that ZnO nanorods are converted into highly lithiophilic LiZn alloy to induce homogeneous Li deposition within the skeleton and optimize the Li + flux. In addition, the Mg 3 N 2 -containing electrolyte derives an Li 3 N-rich SEI and abundant Mg lithiophilic seeds on the surface, thus reducing the diffusion barrier and deposition barrier. As a result, the CC-ZnO-Mg 3 N 2 /Li anode can deliver a high-capacity of 2205 mA h g −1 , and it also shows a lower nucleation overpotential and a long-running lifespan even at an ultrahigh current density (5 mA cm −2 , 1000 cycles) or an ultrahigh areal capacity (15 mA h cm −2 , >1000 h). In addition, the as-assembled LiFePO 4 ||CC-ZnO-Mg 3 N 2 /Li and LiNi 0.8 Co 0.1 Mn 0.1 O 2 (4.4 mA h cm −2 )||CC-ZnO-Mg 3 N 2 /Li full cells present the improved cycling stability and rate performances. This work gives a new sight to design stable Li composite anode and highlights the critical role of the interfacial stability toward cycling properties of composite Li metal anode.

Lithiophilic pore-gradient structured and oxygen-enriched carbon fiber as dense lithium nucleation enabler for stable lithium metal batteries

Lithium (Li) metal is the ultimate anode material for next generation batteries, thanks to its ultrahigh theoretical specific capacity and lowest reduction potential. However, an unstable solid electrolyte interphase caused by uneven Li deposition and infinite volume expansion of Li obstruct the commercialization of Li metal anodes. Herein, we introduce a unique strategy to tune lithiophobic carbon fiber (CF) to lithiophilic pore-gradient structured and oxygen-enriched carbon fiber (PGOCF) as dense Li nucleation enabler. The simultaneous regulation of surface chemistry and structure of CF is simply achieved by using CoAl layered double hydroxide as an etchant-protectant agent in thermal treatment, in which the porosifying role of Co and the protecting role of Al elements synergistically affect the morphology of PGOCF. The O enriched PGOCF (the atomic O ratio of 10.55%) can exhibit strong Li absorption, lowering Li nucleation barrier, and the pore-gradient structure of PGOCF can effectively lower Li nuclei-substrate contact angle, leading to dense and uniform Li electrodeposition. As a result, PGOCF exhibits an impressive electrochemical performance. When paired with a LiFePO4 cathode, Li@PGOCF delivers a specific capacity of 138.3 mA h g−1 at 2C with an exceptional capacity retention of 98.3% for 500 cycles.

Recycling garnet-type electrolyte toward superior cycling performance for solid-state lithium batteries

Green-sustainable approaches prompt urgent attention for recycling end-of-life spent solid-state lithium batteries (SSLBs), which are candidates for next-generation energy storage systems. Here, we propose a green method of deformation-driven re-sintering (DDR) to recycle spent SSLBs with emphasis on garnet-type solid-state electrolyte (SSE) recovery. The recycled fine SSE particles via DDR provide sufficient sintering activity for grain fusion and promote Li absorption with the Li2O atmosphere. The severe deformation accelerates the phase transformation process from the tetragonal phase to cubic phase and inhibits the proton/lithium exchange process. The homogeneous distribution of Li-ions eliminates discontinuous connection areas, facilitating the establishment of fast ionic pathways. The critical current density of DDR-SSE reaches 1.24 mA·cm−2, indicating a stable process of the stripping and plating lithium. SSLBs assembled by the DDR-SSE and LiFePO4 cathode show a superior cycling performance with a discharge capacity of 126.7 mAh·g−1 and capacity retention of 89.7% after 400 cycles (0.5 C) at room temperature. The work firstly provides a feasible green-sustainable method for spent SSEs with high performances, promoting the environmental benignity and economic viability for the sustainable solution of resources.

Regulating Li nucleation/growth via implanting lithiophilic seeds onto flexible scaffolds enables highly stable Li metal anode

Lithium (Li) metal is deemed as an ideal and promising star anode for high energy storage but its application still is impeded due to uncontrollable Li dendrite growth and tremendous dimension change. Although the flexible and conductive three-dimensional (3D) skeleton can improve the structural and interfacial stability of Li anode, its inherently lithiophobic feature usually brings a high nucleation barrier, uneven Li+ flux, and large concentration polarization, leading to inhomogeneous Li plating/stripping. Here, we develop target material (denoted as Mo2C NPs@CC) consisting of well-distributed molybdenum carbide nanoparticles (Mo2C NPs) with intrinsic lithiophilicity serving as lithiophilic seeds implanted onto the carbon cloth, breaking the dilemma of ordinary 3D conductive skeletons. The Mo2C NPs with large Li absorption energy provide plentiful lithiophilic sites for guiding the uniform and thin Li-nuclei layer formation, thereby realizing flat Li growth and stable electrode/electrolyte interface. Moreover, the high electronic conductivity of Mo2C-modified 3D scaffolds can balance the lithiophilicity, ensuring the fast electron transport in the whole electrode, effectively lowering the local current density, and providing enough space for buffering volume change, and synergistically suppresses the growth of Li dendrites. As a result, a prolonged lifespan of 5000 cycles with low voltage hysteresis of 10 mV at current density of 2 mA cm−2 with area capacity (Ca) of 1 mA h cm−2 has been achieved, giving rational guidance for designing high-performance composite Li anodes.

Experimental evidence for onset of L1–L3M5 transition at Z = 75 through measurements of fluorescence and Coster–Kronig yields for W and Re

L shell fluorescence and Coster–Kronig yields for W and Re were deduced from synchrotron radiation induced X-ray line intensities measured at different incident energies across the Li absorption edge energies of both elements based on HFS and DHF models.

Spatially Controlled Lithium Deposition on Silver‐Nanocrystals‐Decorated TiO2 Nanotube Arrays Enabling Ultrastable Lithium Metal Anode

Abstract3D scaffolds and heterogeneous seeds are two effective ways to guide Li deposition and suppress Li dendrite growth. Herein, 3D TiO2 nanotube (TNT) arrays decorated using ultrafine silver nanocrystals (7–10 nm) through cathodic reduction deposition are first demonstrated as a confined space host for lithium metal deposition. First, TiO2 possesses intrinsic lithium affinity with large Li absorption energy, which facilitates Li capture. Then, ultrafine silver nanocrystals decoration allows the uniform and selective nucleation in nanoscale without a nucleation barrier, leading to the extraordinary formation of lithium metal importing into 3D nanotube arrays. As a result, Li metal anode deposited on such a binary architecture (TNT‐Ag‐Li) delivers a high Coulomb efficiency at around 99.4% even after 300 cycles with a capacity of 2 mA h cm−2. Remarkably, TNT‐Ag‐Li exhibits ultralow overpotential of 4 mV and long‐term cycling life over 2500 h with a capacity of 2 mAh cm–2 in Li symmetric cells. Moreover, the full battery with 3D spaced Li nanotubes anode and LiFeO4 cathode exhibits a stable and high capacity of 115 mA h g–1 at 5 C and an excellent Coulombic efficiency of ≈100% over 500 cycles.

Isotopic analysis and plasma diagnostics for lithium detection using combined laser ablation–tuneable diode laser absorption spectroscopy and laser-induced breakdown spectroscopy

Laser-Induced Breakdown Spectroscopy (LIBS) enables rapid stand-off measurements of potentially hazardous material which is particularly favourable for applications in the nuclear industry. Isotopic characterisation with LIBS remains challenging because of the narrow separation of isotopic emission lines, which demands large, high resolution spectrometers. To address this, laser ablation (LA)-Tuneable Diode Laser Absorption Spectroscopy (TDLAS) has been combined with LIBS to analyse laser-produced plasma of lithium. Isotope ratio calculations were performed by fitting multiple peaks to the Li absorption spectra, achieving a relative error of 13% at later delay times after line broadening had reduced. Double-pulsed laser ablation resulted in narrower absorption peaks but more noise in the absorption spectra. LIBS and LA-TDLAS spectra were used simultaneously to calculate plasma temperature and electron density for both single- and double-pulsed laser ablation. The Doppler broadening of absorption peaks from LA-TDLAS was used to calculate the plasma temperature after long time delays of 200 μs and the temperature followed an exponential decay which was extrapolated back to early delay times in order to predict the temperature throughout the plasma lifecycle. The electron density was calculated using the Stark broadening of emission peaks from the LIBS spectra, which were temperature-corrected by accounting for the Doppler broadening. Both single- and double-pulsed-laser ablation plasmas exhibited maximum electron densities of around 1016 to 1017 cm−3, although the decay rate was reduced by around a factor of 2 using DP-laser ablation. We have shown that the combination of emission and absorption spectroscopy with LIBS and LA-TDLAS is useful for isotopic analysis and calculating laser ablation plasma properties. We have demonstrated that double pulsed laser ablation has the potential to enable more isotopic pairs to be analysed due to the narrower absorption linewidth.

The GTC exoplanet transit spectroscopy survey

Exoplanets with relatively clear atmospheres are prime targets for detailed studies of chemical compositions and abundances in their atmospheres. Alkali metals have long been suggested to exhibit broad wings due to pressure broadening, but most of the alkali detections only show very narrow absorption cores, probably because of the presence of clouds. We report the strong detection of the pressure-broadened spectral profiles of Na, K, and Li absorption in the atmosphere of the super-Neptune WASP-127b, at 4.1σ, 5.0σ, and 3.4σ, respectively. We performed a spectral retrieval modeling on the high-quality optical transmission spectrum newly acquired with the 10.4 m Gran Telescopio Canarias (GTC), in combination with the re-analyzed optical transmission spectrum obtained with the 2.5 m Nordic Optical Telescope (NOT). By assuming a patchy cloudy model, we retrieved the abundances of Na, K, and Li, which are super-solar at 3.7σ for K and 5.1σ for Li (and only 1.8σ for Na). We constrained the presence of haze coverage to be around 52%. We also found a hint of water absorption, but cannot constrain it with the global retrieval owing to larger uncertainties in the probed wavelengths. WASP-127b will be extremely valuable for atmospheric characterization in the era of James Webb Space Telescope.

Is the Young Star RZ Piscium Consuming Its Own (Planetary) Offspring?

Abstract The erratically variable star RZ Piscium (RZ Psc) displays extreme optical dropout events and strikingly large excess infrared emission. To ascertain the evolutionary status of this intriguing star, we obtained observations of RZ Psc with the European Space Agency’s X-ray Multi-Mirror Mission (XMM-Newton), as well as high-resolution optical spectroscopy with the Hamilton Echelle on the Lick Shane 3 m telescope and with HIRES on the Keck I 10 m telescope. The optical spectroscopy data demonstrate that RZ Psc is a pre-main sequence star with an effective temperature of 5600 ± 75 K and log g of 4.35 ± 0.10. The ratio of X-ray to bolometric luminosity, , lies in the range −3.7 to −3.2, consistent with ratios typical of young, solar-mass stars, thereby providing strong support for the young star status of RZ Psc. The Li absorption line strength of RZ Psc suggests an age in the range 30–50 Myr, which in turn implies that RZ Psc lies at a distance of ∼170 pc. Adopting this estimated distance, we find the Galactic space velocity of RZ Psc to be similar to the space velocities of stars in young moving groups near the Sun. Optical spectral features indicative of activity and/or circumstellar material are present in our spectra over multiple epochs, which provide evidence for the presence of a significant mass of circumstellar gas associated with RZ Psc. We suggest that the destruction of one or more massive orbiting bodies has recently occurred within 1 au of the star, and we are viewing the aftermath of such an event along the plane of the orbiting debris.

On the Iron Abundance Anomaly in K-dwarf and Hyades Stars

Abstract Using standard 1D-LTE model atmosphere analysis, we provide an in-depth investigation of iron abundance as derived from neutral and singly ionization iron lines (Fe i, ii) in nearby star clusters. Specifically, we replicate the discrepancy regarding Δ[Fe/H], wherein the difference of Fe ii–Fe i increases for stars of the same cluster with decreasing T eff, reaching an astonishing 1.0 dex at T eff ∼ 4000 K. Previous studies have investigated this anomaly in the Pleiades and Hyades clusters with no concrete solution. In this analysis, we probe two samples: 63 wide binary field stars where the primary star is of Sun-like temperatures and the secondary is a K-dwarf, ranging from 4231 K ≤ T eff ≤ 6453 K, and 33 Hyades stars of temperatures 4268 K ≤ T eff ≤ 6072 K. Previous studies have found discrepancies on the order of 1.0 dex. However, we find that these studies have neglected line-blending effects of certain Fe ii lines, namely λ = {4508.29 Å, 4993.34 Å, 5197.58 Å, 5325.55 Å, 5425.26 Å, 6456.38 Å}. When these lines are removed from the line-list, we find Δ[Fe/H] decreases to ∼0.6 dex in the field binaries and ∼0.3 dex in the Hyades. The reason for this remaining trend is investigated by probing NLTE effects, as well as age and activity considerations using Ca ii H+K emission and Li absorption, but these results appear to be small to negligible.

Synchrotron radiation induced X‐ray production cross sections of 66Dy at energies across its Li (i = 1–3) subshell absorption edges

The X‐ray production (XRP) cross sections for the 66Dy Lk (k = l, α, η, β2,6,7,15, β1,6, β1,3,4,6, β2,7,15, γ1,5, γ2,3) emission lines have been measured by tuning the incident synchrotron radiation at energies over the range 7.8–9.2 keV and ~10–370 eV above the respective Li (i = 1–3) absorption edges. These measurements aim to check the reliability of the independent particle approximation models used to generate the theoretical data sets of different physical parameters required to calculate the XRP cross sections and also investigate the influence of many body effects on the photoionization process. The measured values have been compared with 4 sets of XRP cross sections calculated using the Dirac–Fock model‐based X‐ray emission rates, 2 sets of the Li (i = 1–3) subshell photoionization cross sections deduced from the self‐consistent Dirac–Hartree–Fock model‐based values and the nonrelativistic Hartree–Fock–Slater model‐based values, and 2 sets of the fluorescence (ωi) and Coster–Kronig (fij) yields. The present measured Lγ2,3 (originating from decay of the L1 subshell vacancies) XRP cross sections are found to be significantly higher than different sets of theoretical values, whereas a good agreement is generally observed for the various other XRP cross sections and relative intensities.

Measurements of fluorescence and Coster-Kronig yields for 66Dy using synchrotron radiation induced selective photoionization method

The L shell fluorescence (ω1, ω2, ω3) and Coster-Kronig (f12, f13, f23) yields for 66Dy have been deduced from the Li (i=1–3) sub-shell X-ray intensities measured at different incident photon energies across its Li absorption edge energies. Three sets of photoionization cross sections used for determination of these yields include two sets of theoretical values based on the non-relativistic Hartree-Fock-Slater model and the self-consistent Dirac-Hartree-Fock model, and the third one is that deduced from independently measured mass attenuation coefficients of 66Dy. The present experimental fluorescence and Coster-Kronig yields deduced using the self-consistent Dirac-Hartree-Fock model based photoionization cross sections have been found to be in good agreement with the semi-empirical values tabulated by Krause [1] and the Dirac-Hartree-Slater model based values.

L X-ray intensity ratio measurements using selective L sub-shell photo-ionisation on synchrotron

Lα/Lℓ, Lβ /Lℓ and Lγ/Lℓ intensity ratios have been measured for elements in the range 66≤Z≤83 at tuned photon energies on synchrotron beam line-16 at Indus-2, India. For each element, three incident energies Ei were E3; EL3 < E3 <EL2, E2; EL2 < E2 <EL1 and E1; E1>EL1 where ELi are Li absorption edge energies of the element. Emitted L X-ray spectrum of an element constitutes a number of X-ray lines generally grouped into four main groups due to limited resolution of available detectors as Lℓ(L3-M1), Lα(L3-M4,5), Lβ( L1-M2,3,4,5,N4; L2-M3,4; L3-N1,4,5,O1,4,5) and Lγ(L2-N1,4,O1,4; L1-N2,3,5,O3,2). Lα and Lℓ both comprise only the lines feeding L3 level and Lβ group comprises X-ray lines feeding all the three sub-shells where as Lγ involves contribution from L1 and L2 feedings. Only E3 excitation gives the ratios free from intra sub-shell Coster-Kronig (CK) transitions while excitations E2 and E1 give CK affected Lβ/Lℓ and Lγ/Lℓ X-ray intensity ratios and Lα/Lℓ still remains free from CKs. The pattern of intensity ratios at three excitation energies of elements was well interpreted in terms of on/off of CK transitions (Bambynek et al., 1972; Campbell, 2003) and outer shell electron filling configuration (Scofield, 1973).

L sub-shell fluorescence cross-section measurements for elements, Z = 62–67, at tuned photon energies

L sub-shell X-ray fluorescence (XRF) cross-sections for 6 elements with Z= 62-67 have been measured at tuned photon energies on synchrotron Beamline-16, Indus-2, RRCAT, India. Three incident photon energies at the intervals of 0.1keV were tuned in each region; > EL1, < EL1 & >EL2 and <EL2 & >EL3 where ELi are Li (i= 1-3) absorption edge energies of element. No single measurement is available in literature for present incident photon energies and elements, therefore, certainty and reliability of the measurements have been judged from three different aspects. One, from comparison of measured cross-sections with calculated theoretical values. Second, evaluation of Coster-Kronig yield (fij’s) and fluorescence yield (ωi’s) fine parameters from measured XRF cross-sections with formulations derived from total intensity of X-rays originating from individual sub-shells that generated a data set for fij’s and ωi’s of six elements for comparison with available theoretical/empirical/experimental values. Third, from trends of total measured L XRF cross-sections with photon energy for the elements. The results were found affected by the 4f electron filling in the elements.

Characterization of close visual binaries from the AstraLux Large M Dwarf Survey

We present VLT/SINFONI J, H+K spectra of seven close visual pairs in M dwarf binary/triple systems, discovered or observed by the AstraLux M dwarf survey. We determine the spectral types to within 1.0 subclasses from comparison to template spectra and the strength of K-band water absorption, and derive effective temperatures. The results are compared to optical spectral types of the unresolved binary/multiple systems, and we confirm that our photometric method to derive spectral types in the AstraLux M dwarf survey is accurate. We look for signs of youth such as chromospheric activity and low surface gravity, and find an age in the range 0.25-1 Gyr for the GJ 852 system. Strong Li absorption is detected in optical spectra of the triple system J024902 obtained with FEROS at the ESO-MPG 2.2m telescope. The equivalent width of the absorption suggests an age consistent with the beta Pic moving group. However, further observations are needed to establish group membership. Ongoing orbital monitoring will provide dynamical masses and thus calibration of evolutionary models for low mass stars.

Li Storage Performance for the Composite Structure Of Graphene and Boron Fullerene

We study the stability and performance of Li absorption on the composite structure (B80C72) of boron fullerene and graphene by first-principles calculations. Our results show that the Li storage capacity of the composite structure is estimated to be at least Li54B80C72, which is steady with improved dispersibility and electronic conductivity. The composite structure could have the potential application as the anode material of Li-ion batteries with high Li storage capacity and great mechanical property.

WARM DUST AROUND COOL STARS: FIELD M DWARFS WITHWISE12 OR 22 μm EXCESS EMISSION

Using the SDSS DR7 spectroscopic catalog, we searched the WISE AllWISE catalog to investigate the occurrence of warm dust, as inferred from IR excesses, around field M dwarfs (dMs). We developed SDSS/WISE color selection criteria to identify 175 dMs (from 70,841) that show IR flux greater than typical dM photosphere levels at 12 and/or 22 $\mu$m, including seven new stars within the Orion OB1 footprint. We characterize the dust populations inferred from each IR excess, and investigate the possibility that these excesses could arise from ultracool binary companions by modeling combined SEDs. Our observed IR fluxes are greater than levels expected from ultracool companions ($>3\sigma$). We also estimate that the probability the observed IR excesses are due to chance alignments with extragalactic sources is $<$ 0.1%. Using SDSS spectra we measure surface gravity dependent features (K, Na, and CaH 3), and find $<$ 15% of our sample indicate low surface gravities. Examining tracers of youth (H$\alpha$, UV fluxes, and Li absorption), we find $<$ 3% of our sample appear young, indicating we are observing a population of field stars $\gtrsim$ 1 Gyr, likely harboring circumstellar material. We investigate age-dependent properties probed by this sample, studying the disk fraction as a function of Galactic height. The fraction remains small and constant to $|Z| \sim 700$ pc, and then drops, indicating little to no trend with age. Possible explanations for disks around field dMs include: 1) collisions of planetary bodies, 2) tidal disruption of planetary bodies, or 3) failed planet formation.