Graphite Limiter Research Articles

Study on Electrochemical Characteristics of Crystal Structure Changes Effects of Silicon Anode Materials for Lithium Ion Batteries

Graphite is widely used as a representative anode material in commercialized lithium-ion secondary batteries. However, with a theoretical capacity of 370 mAh/g, it is difficult to manufacture high-capacity/high-density lithium-ion secondary batteries. Therefore, research is actively underway to find high-capacity substances to replace graphite. Silicon anode materials are currently attracting attention as next-generation high-capacity cathode materials. Silicon forms Li4.4Si when fully charged through an alloying/dealloying process with lithium during the reaction. Graphite is intercalation/deintercalation in reaction with lithium and LiC6 is formed when fully charged. That's why silicon has a theoretical capacity of 3800 mAh/g, about 10 times that of graphite.However, silicon is a high-capacity electrode material that overcomes the theoretical capacity limit of graphite, and has the disadvantage of experiencing volume expansion of about 400% during repeated charge/discharge cycles. Problems such as material cracks due to volume expansion can affect the safety of the battery. Various studies are being conducted to solve silicon-related challenges to effectively utilize silicon materials. Previous studies have explored the use of binders or additives to mitigate volume expansion. In addition, various types of silicon materials such as Si alloy and SiOx are being developed to suppress volume expansion through matrix formation. Nevertheless, despite the development of silicon materials, structural changes in the charging and discharging process of silicon remain unclear.This study aims to analyze the structural changes that occur during the charging and discharging process of silicon. The experiment evaluates the electrochemical characteristics of crystalline silicon and amorphous silicon and compares the behavior and structural changes during charging/discharging. The volumetric expansion measurements are performed with electrochemical characterization, and ex-situ X-ray diffraction (XRD) and transmission electron microscope (TEM) analyses are performed for comparison with crystal structural changes.

Layered CoS@NC in situ loaded onto Ti3C2Tx MXene as an efficient lithium-ion battery anode.

Due to its large capacity and relatively high conductivity, cobalt sulfide has been considered an excellent electrode material for lithium-ion batteries, but its extreme volume change during charging and discharging and lower conductivity than graphite limits its development. In this work, composite nanosheets of MXene and N-doped carbon-confined cobalt sulfide nanosheets (CoS@NC/MXene) were synthesized by growing the Co metal-organic framework of ZIF-67 onto MXene sheets, followed by sulfidation treatment. Different from normal ZIF-67 generally prepared in methanol, this work fabricates ZIF-67 in aqueous solution, which induces ZIF-67 to undergo some degree of hydrolysis and form more dispersed Co layered hydroxides mounted onto MXene. Also, the MXene incorporation imparts better water stability to ZIF-67(Co) and helps maintain its morphology during the sulfidation. CoS@NC/MXene has a conductive network supported by MXene and enhanced by NC, as well as a 3D hierarchical porous structure offered by the rational combination of its components. These favorable characteristics allow CoS@NC/MXene to deliver a capacity of 691 mA h g-1 at 200 mA g-1 in the 100th cycle and retain the specific capacity of 382 mA h g-1 at a higher current density of 8000 mA g-1.

Unraveling the Lithium Storage Mechanism at Low Potentials in Niobium Pentoxide Anodes for Lithium-Ion Batteries

State-of-the-art lithium-ion anodes based on graphite exhibits high specific capacity and a low de-/lithiation potential, thus, enabling very high energy densities at full-cell level. However, the rather sluggish lithiation kinetics render them less suitable for fast-charging batteries[1]. A potential alternative that has gathered increasing interest in recent years is Nb2O5, but the commonly employed lower cut-off voltage of 1.0 V vs. Li+/Li in combination with the lower capacity compared to graphite limit the achievable energy density[2,3].Herein, the extended lithiation to lower cut-off voltages is reported, resulting in increased capacities while maintaining a very stable cycle life. Remarkably, this behavior is generally independent from the initial polymorph, and both monoclinic and orthorhombic Nb2O5 show a substantial increase in capacity for several hundred cycles. To elucidate the underlying storage mechanism, comprehensive characterization via operando/ex-situ X-ray diffraction (XRD), operando Raman spectroscopy, operando isothermal microcalorimetry (IMC), ex-situ X-ray absorption spectroscopy (XAS), and ex-situ X-ray photoelectron spectroscopy (XPS) was conducted. It appears that the occurrence of an additional phase transition at low potentials plays a decisive role for the enhanced capacity and superior cycling stability. Reference [1] J. Asenbauer, T. Eisenmann, M. Kuenzel, A. Kazzazi, Z. Chen, D. Bresser, Sustain. Energy Fuels 2020, 4, 5387–5416.[2] P. Jing, K. Liu, L. Soule, J. Wang, T. Li, B. Zhao, M. Liu, Nano Energy 2021, 89, 106398.[3] T. Li, G. Nam, K. Liu, J. H. Wang, B. Zhao, Y. Ding, L. Soule, M. Avdeev, Z. Luo, W. Zhang, T. Yuan, P. Jing, M. G. Kim, Y. Song, M. Liu, Energy Environ. Sci. 2022, 15, 254–264.

Co/CoO particle within F, N-codoped mesoporous carbon framework for anode of lithium-ion batteries

Lithium-ion batteries (LIBs) have attracted immense attention as a main power supplier for electronic devices because they have a high energy density and long cycle life. Graphite has mainly been used for the anode material of LIBs, because it is chemically stable, has a high electrical conductivity, and is inexpensive. However, the low theoretical specific capacity of graphite limits the application of LIBs. One prospective strategy for achieving high-performance anodes is a hybrid composite structure, which utilizes various materials. Herein, a novel composite structure of a Co/CoO particle within an F, N-codoped mesoporous carbon framework was synthesized using a biomass impregnation process followed by a carbonization step. During the impregnation process, the biomass absorbed Co(NO3)2·6H2O and the NH4F precursor, which facilitated the formation of Co(OH)2 and CoO. During the carbonization, CoO particles were partially reduced to Co/CoO, and embedded into the F, N-codoped mesoporous carbon framework. The resulting Co/CoO/C 4M anode exhibited superior anode performances, including a high specific capacity of 557.37 mA h/g after 100 cycles at a current density of 100 mA/g and an excellent fast lithium-ion storage capability of 403.17 mA h/g after 1000 cycles at 2000 mA/g. The Co/CoO/C 4M anode can provide a reasonable reference point for hybrid composited anode materials for use in accomplishing high-performance and long-cyclable LIBs.

First-principles study of Li adsorption and diffusion in naphyne

The Li adsorption and diffusion properties in naphyne are explored by first-principles calculations. The porous structure of naphyne facilitates the adsorption of Li atoms, and the adsorption performance of large pores is better than that of small pores. The average open circuit potential is 0.78 V and the maximum Li storage capacity of bulk naphyne is up to 620 mAh/g, much larger than the up limit of the popular graphite. Upon Li intercalation, the interlayer spacing dilatation of bulk naphyne is only 1.78 %, implying that naphyne would not undergo significant structural degradation during cycling. The average adsorption energy between Li and naphyne in LiC3.6 is −2.38 eV/Li, which is feasible to realize their free migration. The porous structure enables Li atoms to diffuse either parallel or perpendicular to the naphyne plane. About 0.41–0.70 eV barriers are needed to overcome for the three-dimensional Li diffusion. Compared to commercial graphite, the higher Li capacity, the smaller structural distortion, and the unique three-dimensional diffusion performance of Li atoms make naphyne a promising candidate as the anode material of LIB.

Quantized thermoelectric Hall plateau in the quantum limit of graphite as a nodal-line semimetal

We performed thermoelectric Hall conductivity ${\ensuremath{\alpha}}_{xy}$ measurements on single-crystal graphite in the quantum limit up to 13 T. Both electrical and thermoelectric transport measurements were performed on the same crystal to extract pure ${\ensuremath{\alpha}}_{xy}$, avoiding any sample quality dependence. The ${\ensuremath{\alpha}}_{xy}$ converges to a plateau in the quantum limit with a linear dependence on temperature. This behavior is analogous to the quantized thermoelectric Hall effect (QTHE) observed in three-dimensional Dirac/Weyl nodal-point semimetals, and experimentally confirms a theoretical proposal on the QTHE in semimetals with nodal lines as in graphite.

Comparative Analysis of Spectroscopic Studies of Tungsten and Carbon Deposits on Plasma-Facing Components in Thermonuclear Fusion Reactors

Studies on the erosion products of tungsten plasma-facing components (films, surfaces, and dust) for thermonuclear fusion reactors by spectroscopic methods are considered and compared with those of carbon deposits. The latter includes: carbon–deuterium CDx (x ~ 0.5) smooth films deposited at the vacuum chamber during the erosion of the graphite limiters in the T-10 tokamak and mixed CHx-Me films (Me = W, Fe, etc.) formed by irradiating a tungsten target with an intense H-plasma flux in a QSPA-T plasma accelerator. It is shown that the formerly developed technique for studying CDx films with 15 methods, including spectroscopic methods, such as XPS, TDS, EPR, Raman, and FT-IR, is universal and can be supplemented by a number of new methods for tungsten materials, including in situ analysis of the MAPP type using XPS, SEM, TEM, and probe methods, and nuclear reaction method. In addition, the analysis of the fractality of the CDx films using SAXS + WAXS is compared with the analysis of the fractal structures formed on tungsten and carbon surfaces under the action of high-intensity plasma fluxes. A comparative analysis of spectroscopic studies on carbon and tungsten deposits makes it possible to identify the problems of the safe operation of thermonuclear fusion reactors.

Effect of fluoro and hydroxy analogies of diglyme on sodium-ion storage in graphite: a computational study.

Diglyme co-intercalation with sodium ion (Na+) into graphite can enable the use of graphite as a potential anode for sodium-ion batteries (NIBs). However, the presence of diglyme molecules in Na+ intercalated graphite limits Na+ storage capacity and increases volume changes. In this work, the effect of functionalising diglyme molecules with fluoro and hydroxy groups on Na+ storage properties in graphite were computationally studied. It was found that the functionalisation can significantly alter the binding between sodium and the solvent ligand as well as between the sodium-solvent complex and the graphite. The hydroxy-functionalised diglyme exhibits the strongest binding to the graphite of the other functionalised diglyme compounds considered. The calculations also reveal that the graphene layer affects the electron distribution on the diglyme molecule and Na, so the diglyme complexed Na binds more strongly to the graphene layer than the Na alone. We also propose a mechanism for the early stages of the intercalation mechanism that involves a reorientation of the sodium-diglyme complex and suggest how the solvent can be designed to optimise the co-intercalation process.

Tannin-Derived Hard Carbon for Stable Lithium-Ion Anode.

Graphite anodes are well established for commercial use in lithium-ion battery systems. However, the limited capacity of graphite limits the further development of lithium-ion batteries. Hard carbon obtained from biomass is a highly promising anode material, with the advantage of enriched microcrystalline structure characteristics for better lithium storage. Tannin, a secondary product of metabolism during plant growth, has a rich source on earth. But the mechanism of hard carbon obtained from its derivation in lithium-ion batteries has been little studied. This paper successfully applied the hard carbon obtained from tannin as anode and illustrated the relationship between its structure and lithium storage performance. Meanwhile, to further enhance the performance, graphene oxide is skillfully compounded. The contact with the electrolyte and the charge transfer capability are effectively enhanced, then the capacity of PVP-HC is 255.5 mAh g−1 after 200 cycles at a current density of 400 mA g−1, with a capacity retention rate of 91.25%. The present work lays the foundation and opens up ideas for the application of biomass-derived hard carbon in lithium anodes.

Formation of the Structure and Properties of Deposited Multilayer Specimens from Austenitic Steel under Various Heat Removal Conditions

The effect of side limiters (shaping blocks) on the formation of the structure and hardness of AISI 308LSi stainless steel workpieces obtained by multilayer build-up welding in an argon environment has been studied. The studies were carried out on specimens deposited using graphite limiters, copper limiters and without limiters. As a result of numerical simulation, it was found that the lowest temperatures of the specimen metal are observed when using copper limiters, and the highest when using graphite limiters (different thermal conductivity of materials) in comparison with the temperatures of the specimen obtained without limiters. With the use of graphite limiters, most of the specimen’s metal is in the temperature range of austenite formation (45%) and a more uniform growth of structural elements is observed, without sharp transitions between the deposited layers, in contrast to the other two types of specimens. The high value of the thermal conductivity of copper leads to an increase in the difference in the size of the dendrites between the central and peripheral side parts of the deposited specimen. The highest values of hardness are observed in the specimen obtained using graphite blocks, due to the more active diffusion of δ-ferrite into austenite by an average of 12%, compared with the other investigated specimens, despite the overall increase in size dendrites. The technology of electric arc multilayer build-up welding with the use of shaping graphite blocks makes it possible to produce a workpiece with a uniform structure and properties. The above makes it a promising direction in electric arc additive manufacturing.

Improvement of lower hybrid current drive systems for high-power and long-pulse operation on EAST

Aiming at high-power and long-pulse operation up to 1000 s, some improvements have been made for both 2.45 GHz and 4.6 GHz lower hybrid (LH) systems during the recent 5 years. At first, the guard limiters of the LH antennas with graphite tiles were upgraded to tungsten, the most promising material for plasma facing components in nuclear fusion devices. These new guard limiters can operate at a peak power density of 12.9 MW/m2. Strong hot spots were usually observed on the old graphite limiters when 4.6 GHz system operated with power >2.0 MW [B. N. Wan et al., Nucl. Fusion57(2017) 102019], leading to a reduction of the maximum power capability. With the new limiters, 4.6 GHz LH system, the main current drive (CD) and electron heating tool for EAST, can be operated with power >2.5 MW routinely. Long-pulse operation up to 100 s with 4.6 GHz LH power of 2.4 MW was achieved in 2021 and the maximal temperature on the guard limiters measured by an infrared (IR) camera was about 540 °C, much below the permissible value of tungsten material (∼1200 °C). A discharge with a duration of 1056 s was achieved and the 4.6 GHz LH energy injected into the plasma was up to 1.05 GJ. Secondly, the fully-active-multijunction (FAM) launcher of 2.45 GHz system was upgraded to a passive-active-multijunction (PAM), for which the density of optimum coupling was relatively low (below the cut-off value). Good coupling with reflection coefficient ∼3% has been achieved with plasma-antenna distance up to 11 cm for the new PAM. Finally, in order to eliminate the effect of ion cyclotron range of frequencies (ICRF) wave on 4.6 GHz LH wave coupling, the location of the ICRF launcher was changed to a port that is located 157.5° toroidally from the 4.6 GHz LH system and is not magnetically connected.

Thermo-mechanical limits of a magnetically driven fast-ion loss detector in the ASDEX Upgrade tokamak

A real-time control system is being developed for a magnetically driven Fast-Ion Loss Detector (FILD) at the ASDEX Upgrade tokamak. The insertion of the diagnostic head will be adjusted in real-time to react to changes in the graphite head temperature, plasma position and appearance of MHD instabilities. The graphite probe head of the detector is exposed to an intense heat flux (located ∼3–5 cm from separatrix). The control algorithm performance is constrained by: the graphite head sublimation temperature, the ultimate stress limit, the reaction time of the controller and the retraction time. In this work, the temperature and thermal induced stress distribution on the probe head are assessed to determine what temperature-related magnitude is the limiting factor. The heat flux at the probe head has been estimated using the time-averaged parallel heat flux measured at the divertor target via infrared thermography. A field line tracing algorithm determines which regions of the probe head receives a weighted heat flux due to shadowing (self-induced or from other structures) and the incidence angle of the field lines. A finite element model is used to simulate the temporal evolution of the graphite head temperature and to obtain the induced thermal stress. The temperature spatial distribution at the probe head is validated against measurements of the probe head for different FILD systems showing a good agreement. These measurements have been obtained from visible cameras with an infrared filter. The model concludes that the maximum stress (∼100 MPa) does not overcome the graphite mechanical limit (170 MPa) and that the probe head is not affected by fatigue. Therefore, the graphite sublimation temperature (2000 °C) is set as the limiting factor of the new control system.

Investigations on the thermal stability of microstructures generated by different thermal electron beam surface treatments

AbstractSurface treatments are frequently used to improve the wear and/or corrosion resistance of metal components. In the case of cast iron, the material‐specific graphite limits both its treat‐ability and load‐bearing behaviour. A promising option for overcoming these limitations is provided by combination processes, in which near‐surface graphite is first removed in an initial liquid‐phase surface treatment – such as, e. g., remelting, alloying or cladding using electron beam (EB) – before application of thermochemical processes or hard coatings. A prerequisite for this is sufficient thermal resistance of these microstructures. This was investigated by means of annealing tests. The ranges of temperature used for annealing are based on those typically used for hard coating (250 °C–500 °C), nitriding (400 °C–600 °C) and boriding (600 °C–860 °C). The metastable microstructures produced as a result of rapid solidification during the electron beam liquid‐phase treatments differ in their alloy content and, therefore, in their microstructural components. Hardness measurements after annealing provided an initial indication of thermal stability. Based on these measurements, interesting treatment conditions were analysed in more detail using scanning electron microscopy and x‐ray diffraction. The focus of interest was on the formation of secondary graphite and the dissolution of ledeburitic carbides and other intermetallic phases.

Practical Approach to Enhance Compatibility in Silicon/Graphite Composites to Enable High-Capacity Li-Ion Battery Anodes

There is an urgent need to improve the energy density of Li-ion batteries to enable mass-market penetration of electric vehicles, grid-scale energy storage, and next-generation consumer electronics. Silicon–graphite composites are currently the most plausible anode material to overcome the capacity limit of graphite or poor cycling performance of silicon. One serious and unrecognized limitation to the use of the composite as an anode is the incompatibility of hydrophobic (natural) graphite with the hydrophilic Si, which adversely affects battery performance. Herein, we report a novel, practical approach to modify the graphite resulting in the formation of a hard carbon coating and graphene sheets that give rise to higher compatibility with Si nanoparticles in the composite. Electrochemical and battery testing of the composite (10 wt % Si) anode shows higher reversible capacity (10% at C/12 and 20% at C/2) than the composite with unmodified graphite reaching ∼600 mAh/g with 95% retention after 100 cycles. The enhanced battery performance is explained by the uniform distribution of Si nanoparticles at the modified graphite surface due to the presence of graphene conductive networks and a thin, oxygen-rich, amorphous carbon layer on the surface of graphite particles, as evidenced by transmission electron microscopy (TEM) images and X-ray photoelectron spectra (XPS). This work provides a new approach to prepare graphite compatible materials that can work with hydrophilic components other than silicon for various applications other than batteries.

Diamine molecules double lock-link structured graphene oxide sheets for high-performance sodium ions storage

Graphite has been commercialized as a material of lithium ions batteries because of its abundant source, low cost and excellent conductivity while the small interlayer spacing of graphite limits its application for Na+ insertion/extraction. Herein, an emerging and effective approach—chain-like H2N(CH2)xNH2 locked between graphene oxide (GO) sheets to expand the interlayer spacing of graphene with enhanced stability of layered structure was demonstrated by a dehydration condensation reaction. The as-obtained H2N(CH2)xNH2, which can link GO (xDM-GO), exhibits a lock-link structure, resulting in expanded interlayer spacing, with which the excellent Na+ storage performance with a high specific discharge capacity of 158.1 mAh g−1 at 0.1 A g−1 and outstanding capacity retention of 82.2% at a current density of 1 A g−1 can be achieved. The effects of interlayer spacing on Na+ diffusion coefficient and the rate capability were investigated, for which 0.95 nm is the most suitable interlayer spacing for the Na+ insertion/extraction. The novel strategy demonstrates an effective way to controllably tune the interlayer spacing with the improved structure stability of GO, resulting in the best Na+ insertion/extraction behavior with the excellent Na+ storage performance.

Graphite creep negation during flash spark plasma sintering under temperatures close to 2000 °C

Graphite creep has high importance for applications using high pressures (100 MPa) and temperatures close to 2000 °C. In particular, the new flash spark plasma sintering process (FSPS) is highly sensitive to graphite creep when applied to ultra-high temperature materials such as silicon carbide. In this flash process taking only a few seconds, the graphite tooling reaches temperatures higher than 2000 °C resulting in its irreversible deformation. The graphite tooling creep prevents the flash spark plasma sintering process from progressing further. In this study, a finite element model is used to determine FSPS tooling temperatures. In this context, we explore the graphite creep onset for temperatures above 2000 °C and for high pressures. Knowing the graphite high temperature limit, we modify the FSPS process so that the sintering occurs outside the graphite creep range of temperatures/pressures. 95% dense silicon carbide compacts are obtained in about 30 s using the optimized FSPS.

The application of limiter target electrostatic measurement system in J-TEXT tokamak

The limiter target electrostatic measurement system including limiter grounding current sensors and Langmuir probes have been newly developed for the measurement of the limiter target area on the Joint-Texas Experimental tokamak (J-TEXT). Current sensors fixed between graphite limiters and the vacuum vessel walls are used to measure the currents between limiters and vessel wall. Simultaneously, a rectangular poloidal array containing 54 Langmuir probes is embedded in the graphite tiles of limiters for a more localized measurement. Based on this system, the effect of both the plasma’s inherent behavior, including plasma motion and the 2/1 tearing mode, and the electrode biasing on probe and sensor signals have been observed and analyzed in the experiments.

Novel approach of pulsed-glow discharge wall conditioning in the ADITYA Upgrade tokamak

In the ADITYA Upgrade tokamak, glow discharge wall conditioning (GDC) is performed regularly during the high-temperature plasma operation cycle using hydrogen (H) and helium (He) gases. H GDC is carried out after long durations (few hours) of plasma operations on every plasma operation day in automatic mode to control oxygen (O) and carbon (C) containing impurities. This leads to high retention of H gas on graphite limiter plates and stainless steel (SS) vessel walls. Subsequently, the high outgassing of H requires a prolonged pumping time and high H recycling during plasma discharges affects the plasma performance in respect to H fueling control of the plasma. To overcome the above-mentioned issues with continuous H GDC for longer durations, a new approach involving pulsed glow discharge wall conditioning (P-GDC) has been introduced in the ADITYA-U tokamak to reduce the residual H and He concentration in SS vessel walls and graphite limiter plates. To facilitate the fast initiation of a discharge in the case of P-GDC, a source of free electrons from a hot filament has been introduced in the vessel. A fast feedback controlled pulsed-gas-fueling system has been developed to initiate a glow discharge in each gas-feed pulse at various operating pressures from 1 × 10−4 Torr to 10−3 Torr in the presence of an applied DC voltage. The different P-GDC experiments have been carried out with H, He and argon as the working gases and the results are compared with traditional continuous GDC. The P-GDC experiments have been optimized to provide beneficial wall conditioning for plasma operations. In this paper, the design, development and operation of P-GDC has been described along with the preliminary studies of its effect on the measured impurity line radiation during a plasma discharge.

Overview of operation and experiments in the ADITYA-U tokamak

The first Indian tokamak, ADITYA, operated for over two decades with a circular poloidal limiter, has been upgraded to a tokamak named ADITYA Upgrade (ADITYA-U) to attain shaped-plasma operations with an open divertor in single and double-null configurations. Experimental research using ADITYA-U has made significant progress since the last FEC in 2016. After installation of a plasma facing component and standard tokamak diagnostics in ADITYA-U, the Phase-I plasma operations were initiated in December 2016 with a graphite toroidal belt limiter. Ohmically heated circular plasmas supported by filament pre-ionization with plasma parameters Ip ~ 80–95 kA, duration ~80–180 ms, with a maximum toroidal field ~1 T and chord averaged electron density ~2.5 × 1019 m−3, have been obtained. The runaway electron (RE) generation, transport and mitigation experiments, along with magneto hydrodynamic (MHD) activities and density enhancement with H2 gas puffing experiments were carried out in Phase-I, which was completed in March 2017. Preparation for the Phase-II operation in ADITYA-U includes calibration of magnetic diagnostics followed by commissioning of major diagnostics and installation of a baking system. After repeated cycles of baking the vacuum vessel up to ~135 °C, the Phase-II operations resumed in February 2018 and are continuing to achieve plasma parameters close to the design parameters of circular limiter plasmas, using real-time plasma position control. The plasma current has been raised to ~135 kA in Phase-II, with a maximum chord averaged electron density of ~4 × 1019 m−3. Hydrogen gas breakdown has been observed in more than 2000 discharges, including Phase-I and Phase-II operations, without a single failure. Several experiments have been carried out, including the control of REs with the fuelling of supersonic molecular beam injection as well as sonic H2 gas puffing during current flat-top, MHD mode studies using multiple periodic gas puffs, and radiative improved modes using neon gas puffs. The experimental results from Phase-I and Phase-II operations of the ADITYA-U tokamak are discussed in this paper.

Depth resolved analysis of hydrogen in W7-X graphite components using laser-induced ablation-quadrupole mass spectrometry (LIA-QMS)

A deep understanding of the plasma-wall interaction processes in fusion devices like Wendelstein 7-X is necessary for an efficient plasma operation and a long lifetime of the plasma-facing components.In this work we present an approach employing residual gas analysis after picosecond laser-induced ablation (ps LIA-QMS) of graphite limiter tiles, exposed in the first plasma operational phase of Wendelstein 7-X, for depth-resolved and quantitative hydrogen content analysis. A series of poloidal and toroidal locations are analyzed at three of the five limiters, showing up to 2.3 × 1022 hydrogen atoms/m2 in net-deposition areas after a total plasma exposure of about 311 s in mixed hydrogen and helium operation. Shallow implantation of hydrogen is observed in erosion zones, where a low fuel content is present due to the high surface temperature during plasma operation. The hydrogen content spans between (1.1 and 3.7) × 1021 hydrogen atoms/m2 in the net-erosion areas. Moreover, oxygen has been analyzed and its appearance in both the implantation and deposition zone was verified. Results are compared to thermal desorption spectrometry and to simultaneously performed laser-induced breakdown spectroscopy (LIBS) measurements.