Intercalation Rate Research Articles

A Need for Speed: Characterizing Fast Charging Failure Mechanisms in Lithium-Ion Batteries (LIBs) Using X-Ray Microtomography (XRM)

The charging rate of traditional lithium-ion batteries is severely limited by a process known as lithium plating, whereby the rate of oxidation of lithium at the positive electrode exceeds the rate of lithium intercalation into the negative electrode active material, leading lithium ions to preferentially reduce and subsequently deposit as lithium metal at the surface of the material. Such plating further slows intercalation, causing an exponential buildup of metal at the electrode interface to the severe detriment of the system’s long-term cyclability, stability, and safety due to the formation of dead lithium and secondary SEI, as well as the increased risk of catastrophic shorting and thermal runaway. It is therefore imperative that the nucleation and growth pathways of lithium plating be fully understood and characterized to properly inform the development of novel, fast charge-capable lithium-ion battery designs.This work discusses the use of X-ray microtomography to characterize both lithium plating on and lithiation within a graphite electrode at various charge rates. Due to the heterogeneity of these processes, the time and length scales at which they occur vary throughout the electrode and are heavily influenced by the current applied. For the first time ever, we are able to observe such phenomena as they occur using a method we call “rapid scan” X-ray microtomography to improve the temporal resolution of our scans and create operando, actionable datasets that capture the onset and growth of lithium plating and lithiation in three dimensions. Such insights are subsequently compared with and validated against trends observed post-fast charging using a more traditional tomographic approach.In this manner, we observe and quantify the onset of lithium plating and its growth on both a local and global scale. We are also able to characterize and compare the primary (during-charge) and secondary (post-charge) intercalation of lithium into graphite and find that as much as 70% of plated lithium can be recovered if the system is allowed to rest for 30 minutes prior to discharge. Finally, we combine these two unique datasets to better understand the relationship between regional plating, active material lithiation, and charge rate, and how each of these components impacts the cyclability of the system as a whole.

Current Transient-Based Electrochemical Method for Detecting Li Plating during Fast-Charging of Li-Ion Batteries

Li metal plating in Li-ion batteries (LIBs) has been recognized as a major obstacle for realizing fast-charging of LIBs, as Li metal deposits on graphite anodes often cause drastic capacity loss and may trigger internal short-circuiting, raising safety concerns. Therefore, extensive research efforts have been devoted to developing methods for detecting plated Li. However, proposed methods often required specialized equipment or sophisticated experimental methods, which cannot be implemented in practical cell operation conditions. Recently, diagnostic methods based on characteristic electrochemical signals of plating have been attracted significant research interest as they enable non-destructive, in operando detection that can be directly applied to the state-of-the-art battery management systems.Herein, we present an electrochemical method for detecting Li plating based on the cell current transient during constant-voltage (CV) charging. To study the electrochemical behavior of full cells under fast-charging conditions, a three-dimensional (3D) full-cell model is constructed with a stochastically generated anode. To generate the geometry of graphite anodes with realistic particle shapes, we employ 3D Voronoi tessellation and Catmull-Clark subdivision methods. In the model, we assume that the plating/stripping reaction of Li-metal is partially reversible, to reflect the highly irreversible nature of Li metal deposits.To extract the characteristic signal of Li plating from the electrochemical behavior of full cells, we simulate the charging process of full cells with three different reaction modes for the graphite anode: (i) intercalation reaction, (ii) intercalation and irreversible Li plating reaction, and (iii) intercalation and partially reversible Li plating/stripping reactions. The results of electrochemical modeling show that, without the Li stripping reaction, the cell current monotonously decreases as CV charging proceeds. Conversely, the cell with partially reversible Li plating/stripping reactions exhibits a characteristic peak in the cell current profile. The amount of plated Li metal and reaction current profiles suggest that the peak appears with the depletion of plated Li. Upon the depletion of plated Li, the Li stripping reaction current, which contributes to the cell current in an opposite direction to the intercalation reaction current, rapidly decreases, causing a transient increase in the cell current during CV charging. As a result, a peak or plateau appears in the current profile of the cell that experiences Li plating and stripping during charging. The effect of the reaction rates of intercalation, Li plating, and Li stripping reactions on the characteristic signal is further explored by electrochemical modeling. Specifically, the amount of plated Li and the reaction rate for Li stripping critically affect the detectability of the peak/plateau in the cell profile. Based on the simulation results, we demonstrate that the peak/plateau in cell current profiles during CV charging can be utilized as a characteristic electrochemical signal of Li plating. Moreover, experimental studies with [LiNi0.8Co0.1Mn0.1O2|graphite] full cells are conducted to demonstrate the practical applicability of the proposed electrochemical method for detecting Li plating during fast-charging cycling.

Lithium-Ion Intercalation By Coupled Ion-Electron Transfer Mechanism

Ion intercalation in intercalation solids is crucial for energy storage device, including Li-ion batteries. Despite significant advancements in understanding Li-ion diffusion and discoveries of new electrodes and electrolytes, the molecular process of ion intercalation across electrode-electrolyte interfaces remains poorly understood. Li intercalation kinetics has been traditionally treated by the empirical Butler-Volmer kinetics, but remains poorly measured and understood. In this study, we developed experimental electrochemical methods to probe Li+ (de-)intercalation kinetics, and provided unique experimental evidence to support the microscopic mechanism of Li+ intercalation, described by the coupled ion-electron transfer mechanism. Current-voltage responses and reaction-limited capacities, indicative of small and large overpotentials, respectively, were measured across various electrode materials, including common LixCoO2 and NMCs, and were consistent with the proposed theory. A universal dependence of the intercalation rate on the lithium-ion filling fraction was revealed, as well as temperature and electrolyte effects, consistent with the theoretical description that classical ion transfer from the electrolyte is coupled with quantum-mechanical electron transfer from the electrode. Our findings suggest that the proposed mechanism applies to a variety of intercalation materials used in energy storage, and governs the power density at low and moderate applied current densities. The possibility of modifying the reaction-limited current with electrodes and electrolytes opens new directions for interfacial engineering of Li-ion batteries.

Model-Based Interpretation of Thermal-Gradient Effects in Li-Ion Cells

The present study develops a combined experimental and modeling approach to study temperature gradients in Li-ion batteries. Although through-plane temperature differences may be small (ΔT ≈ 1-10 °C), large interelectrode thermal gradients (∇T ≈ 1,000-10,000 °C/m) can be present and have been found to significantly affect Li-ion battery performance and degradation [1,2]. Figure 1 illustrates a thin pouch cell (order of 300 microns thick) sandwiched between cool and warm plates. The cell uses a graphite anode and a NMC622 cathode. By maintaining the temperature of the cool and warm blocks, a thermal gradient can be enforced across the cell. Depending on how the cell is positioned, the cell’s cathode or anode can be on the cool or warm side. Experiments include overpotential analysis and galvanostatic intermittent titration technique (GITT) at different states of charge. Results show different behaviors as the thermal gradient is applied and the directionality of the thermal gradient changes.This presentation presents a pseudo-two-dimensional (P2D) model [3] that has been modified to represent the experimental conditions, including the thermal gradients. The model considers the temperature dependencies of thermodynamic properties, electrolyte conductivities, electrode diffusion coefficients, intercalation rates, etc. [4]. The model captures some, but not all, of the measured behaviors. Thus, an important objective is to investigate physical and chemical behaviors that are not included in typical P2D models. For example, off-diagonal Onsager contributions could be significant in the presence of high temperature gradients. The results predict how thermal gradients can contribute to Li-ion concentration fluxes (Soret contribution), and thus affect battery performance. The scientific intent is to understand the thermal gradient behaviors and thus assist battery design guidelines and battery-management control considerations. Acknowledgments The authors thank the Office of Naval Research (Dr. Michele Anderson) for financial support (ONR award numbers: N00014-23-1-2694 and N00014-22-1-2411) of this work.

Application of modified kaolinite in improving thermal stability of polydimethylsiloxane

AbstractThis research investigated the chemical structure and morphology of the hydrogenated tallow amine (HTA)‐intercalated kaolinite by XRD, FT‐IR, and TEM measurements. The experimental outcomes show that intercalation of kaolinite by HTA, with an intercalation rate of 63.2%, expands the interlayer distance with a subsequent dominant basal XRD peak at 2θ ≈ 7.9°. Furthermore, a composite was created from the HTA‐intercalated kaolinite and polydimethylsiloxane (PDMS) through a favorable interaction between the end silanol groups of PDMS and the modified kaolinite surface. Thermogravimetry‐differential scanning calorimetry results indicate that introducing the HTA‐intercalated kaolinite into the PDMS matrix increases the thermal stability of the composite from 178 to 343 °C. However, the thermal stability of the composite is lower than that of other published materials. The synthesis of kaolinite/PDMS composite with enhanced structural and thermal stability outcomes has been provided via a simple and effective solution method that should have further applications.

Controllable Design of Metal-Organic Framework-Derived Vanadium Oxynitride for High-Capacity and Long-Cycle Aqueous Zn-Ion Batteries.

Introducing N atoms in vanadium oxides (VOx) of aqueous Zn-ion batteries (ZIBs) can reduce their bandgap energy and enhance their electronic conductivity, thereby promoting the diffusion of Zn2+. The close-packed vanadium oxynitride (VON) generated often necessitates the intercalation of water molecules for restructuring, rendering it more conducive for zinc ion intercalation. However, its dense structure often causes structural strain and the formation of by-products during this process, resulting in decreased electrochemical performance. Herein, carbon-coated porous V2O3/VN nanosheets (p-VON@C) are constructed by annealing vanadium metal-organic framework in an ammonia-contained environment. The designed p-VON@C nanosheets are efficiently converted to low-crystalline hydrated N-doped VOx during subsequent activation while maintaining structural stability. This is because the V2O3/VN heterojunction and abundant oxygen vacancies in p-VON@C alleviate the structural strain during water molecule intercalation, and accelerate the intercalation rate. Carbon coating is beneficial to prevent p-VON@C from sliding or falling off during the activation and cycling process. Profiting from these advantages, the activated p-VON@C cathode delivers a high specific capacity of 518 mAh g-1 at 0.2 A g-1 and maintains a capacity retention rate of 80.9% after 2000 cycles at 10 A g-1. This work provides a pathway to designing high-quality aqueous ZIB cathodes.

Evolution mechanism and non-destructive assessment of thermal safety for lithium-ion batteries during the whole lifecycle

The thermal safety variations of lithium-ion batteries during operational usage pose a significant threat to the safe application of electric vehicles. This work initially investigates the battery thermal safety evolution mechanism under different degradation paths. Lithium plating is identified as the critical common degradation mechanism leading to the decline of battery thermal safety through multi-angle characterization analysis. However, lithium plating generated by different formation mechanism has different impact on the battery thermal stability. The most severe degradation of battery thermal safety is caused by lithium plating which is induced by the limited lithium intercalation rate under low-temperature cycling and high-rate cycling. Further, the mechanism of internal degradation on the battery thermal safety is elucidated through multi-scale thermal test analysis. It is indicated that lithium plating and transition metal dissolution are crucial factors leading to the decreased thermal stability of the anode and cathode respectively, which consequently results in a significant reduction of T1 and T2. Furthermore, based on the principle of internal degradation synchronously affecting electrochemical characteristics and thermal stability characteristics, the mapping relationship between the observation indicators of electrochemical characteristics and the characterization parameters of thermal safety is established, realizing the non-destructive assessment of battery thermal safety during the whole lifecycle.

Lithium-ion battery sudden death: Safety degradation and failure mechanism

Environmental pollution and energy scarcity have acted as catalysts for the energy revolution, particularly driving the rapid progression of vehicle electrification. Lithium-ion batteries play a fundamental role as the pivotal components in electric vehicles. Nevertheless, battery sudden death poses substantial challenges to battery design and management. This work comprehensively investigates the failure mechanism of cell sudden death under different degradation paths and its impact on cell performances. Multi-angle characterization analysis shows that lithium plating is the primary failure mechanism of battery sudden death under different degradation paths. However, the formation mechanisms of lithium plating differ in various degradation paths. In the path-L and path-F, the limited lithium intercalation rate in graphite leads to lithium plating, while localized anode drying and uneven potential distribution are the causes in the path-H and path-R. Furthermore, sudden death significantly reduces the cell electrochemical performances and thermal safety, but the cell performance evolution varies under different degradation paths. Sudden death primarily affects the anode interface polarization process in the path-L and path-F, with a more severe impact on cell thermal safety. However, sudden death mainly affects the charge transfer process, with a relatively milder impact on cell thermal safety. These findings can provide valuable insights for optimizing battery design and management.

Lithium recovery from brine by PEG-modified porous LiFePO4/FePO4 electrode system

Lithium recovery from high Mg/Li brine through the electrochemical intercalation /de-intercalation technology has attracted great attention due to its good selectivity. To obtain higher equipment capacity, the LiFePO4/FePO4 electrodes with higher coating density are applied for lithium extraction. Unfortunately, it also brings a problem of slow diffusion of Li+ within the electrode, which limits the intercalation rate of lithium. To solve the problem of Li+ diffusion, a PEG-modified porous LiFePO4 electrode was prepared for lithium recovery. After modification, a “microcracks-microporosity” composite structure appears on the electrode, and the agglomeration of electrode materials reduces due to the dispersing effect of PEG. Therefore, the diffusion resistance of Li+ within the electrode decreases, and the electrode polarization reduces. Using the PEG-modified porous LiFePO4/FePO4 system to recover lithium, the Li+ intercalation rate reaches 4.45 g(Li)·m−2·h−1, while that of unmodified electrode is only 2.10 g(Li)·m−2·h−1. Besides, the intercalation of Na+ was significantly reduced from 0.28 to 0.07 of Na/Fe ratio in FePO4 cathode, which means better selectivity and circularity. Therefore, the application of PEG-modified porous electrode systems can efficiently recover lithium from brines.

Film electrode Li1-xMn2O4/C/PAA-c-CMCLi-b-PVDF by double cross-linking for selective extraction of Li+

Because of its excellent stabilities, polyvinylidene fluoride (PVDF) is commonly employed as a binder in electrode fabrication. However, poor adhesion and hydrophilicity limit its applicability. Herein, PVDF as the hydrophobic framework, polyacrylic acid (PAA), and carboxymethylcellulose lithium (CMCLi) composite binders were cross-linked with phytic acid and Li1-xMn2O4/C were used in the formulation. After 100 electrochemical cycles, the film electrode Li1-xMn2O4/C/PAA-c-CMCLi-b-PVDF exhibits excellent adhesion (0.93 N cm−1) and a low capacity fading rate (8.2 %). Furthermore, this film electrode demonstrated a high intercalation capacity (32.14 mg g−1), a short intercalation equilibrium time (within 2 h), and a fast Li+ intercalation rate, which can be attributed to the synergistic effect of electrolyte permeability enhanced by hydrophilic functional groups (–OH and –COOH), dispersibility of electrode material particles improved by high slurry rheology, and the high transport efficiency of –COOH for Li+. These promising results suggest that this double cross-linked Li1-xMn2O4/C/PAA-c-CMCLi-b-PVDF film electrode is suitable for the selective extraction of Li+.

Alkaline Metal Intercalates of VSe2 by Electrochemical Intercalation

AbstractWe report on the series of the alkali metal intercalates of VSe2 synthesised by electrochemical means in an aqueous environment. For all alkali metals we find water‐conintercalated structures (stage I and stage II), of which only the sodium structure had been reported so far. The new structures are analyzed by powder X‐ray diffraction and Rietveld refinement. Their (meta‐)stability is investigated in terms of the open circuit potential, revealing the sensitivity towards oxygen. Except for the lithium intercalate these structures transform into water‐free alkali metal intercalates under vacuum. In addition, scanning electron microscopy reveals the impact of different electrochemical intercalation techniques yielding different intercalation rates. This paves the way for future single crystal investigations.

Study on Intercalated Melt-blown Nonwovens Based on Product Performance Control Mechanism

There are many factors affecting the preparation of intercalation melt-blown nonwovens, and scientists are committed to studying the conditions required for optimal product performance. Therefore, in order to study the optimal conditions, this paper first uses multiple linear regression to explore the correlation between intercalation rate and the change rule. It is found that intercalation rate is related to the change rule of thickness and filtration resistance, but has nothing to do with other indicators. In order to explore the relationship between process parameters and structure variables, a multi-layer perceptron (BP neural network) model with process parameters as input and structure variables as output is established. The relationship between input and output is obtained by using the trained network and the functional relationship is calculated. By analyzing the function, it is found that the correlation between the receiving distance and thickness and porosity is stronger than the positive correlation between the hot air speed and the compression resilience is stronger than the negative correlation between the hot air speed. The correlation between hot air velocity and thickness and porosity is weaker than that of receiving distance, and the correlation between hot air velocity and compressive resilience is weaker than that of receiving distance.

Influence of coal-measure kaolinite with different types on the preparation of kaolinite nanotube

Coal-measure kaolinite with different types were selected to explore the influence of raw mineral on the preparation of intercalation compounds and kaolinite nanotubes. Types of coal-measure kaolinite were feldspar-pseudomorph kaolinite (HSS), worm-like kaolinite (XY), brain striatum kaolinite (CBM), mica-pseudomorph kaolinite (CBM) and crypto crystalline kaolinite (HW and HY), respectively. And the average crystal size of coal-measure kaolinite after grinding of HSS, XY, CBM, HW and HY were 2.60 μm, 6.81 μm, 3.28 μm, 0.52 μm and 0.32 μm, respectively. Characterization methods of XRD, FTIR and SEM were utilized to reveal the change in the crystal structure of kaolinite before and after intercalation reactions, the vibrational pattern of the chemical bond and the surface morphology characteristics of raw minerals and kaolinite nanotubes. Results showed that intercalation effects were significantly different among the selected coal-measure kaolinite, and the intercalation rates of intercalation compound of HSS-KD, XY-KD, CBM-KD, HW-KD and HY-KD were 80.71%, 83.33%, 82.99%, 55.13% and 65.23%, respectively. That is to say, Intercalation rates of feldspar-pseudomorph kaolinite, worm-like kaolinite, brain striatum kaolinite and mica-pseudomorph kaolinite were significantly higher than those of crypto crystalline coal-measure kaolinite which were reflected from intercalation compound of coal-measure kaolinite/dimethyl sulfoxide. Furthermore, the intercalation rates of the precursor intercalation compounds affect the intercalation effect of macromolecular intercalation agents and the yield of kaolinite nanotubes. According to the SEM patterns of kaolinite nanotubes, yield of kaolinite nanotube of HSS, XY, CBM, HW and HY were 80%, 88%, 72%, 28% and 35%, respectively. It could be concluded that yield of kaolinite nanotube of coarse crystalline coal-measure kaolinite was higher than that of crypto crystalline coal-measure kaolinite.

Closed-loop fast charging strategy of lithium-ion batteries based on temperature limitation and lithium precipitation

The safe fast-charging of lithium-ion batteries is one of the key technological challenges constraining the rapid development of electric vehicles. The development of larger-capacity, larger-sized batteries has presented new challenges to the advancement of safe fast-charging technology. The primary risks of fast charging are lithium plating and thermal runaway. The essence of safe fast charging lies in the control of temperature and lithium-ion intercalation rates into the lattice. In this paper, a new charging method that balances lithium plating prevention and maximum temperature control is proposed through experimental testing and Simulink-Fluent co-simulation. The results show that compared to traditional charging methods, this charging strategy can save 48.2 precents of the charging time. And it can control the maximum battery temperature to stay within 50 °C. This charging strategy can guarantee high-speed charging rates while taking into account battery safety. This method provides new perspectives for further advancing fast-charging technologies in the electric vehicle industry.

Effects of nitrite ion intercalated CaAl and MgAl layered double hydroxides on the properties of concrete mortar

Nitrite ion intercalated Ca-Al and Mg-Al layered double hydroxides (LDHs) had been successfully synthesized by two modified methods in order to improve intercalation rate of nitrite ion and the effects of the obtained LDHs on the mechanical properties, anticorrosion properties of concrete mortar were discussed. The results revealed that two kinds of LDHs exhibited the improved crystallinity and uniform morphology, and Ca-Al LDH synthesized by hydrothermal method (H-C-LDH) exhibited better properties. The intercalated LDHs had different degrees of improvement in the mechanical properties, chloride penetration resistance and permeability resistance of cement mortars without apparent decline in the fluidity, especially for 2% H-C-LDH sample. Electrochemical tests also showed that the intercalated LDH led to a more positive potential and larger charge transfer resistance, and H-C-LDH sample expressed the best corrosion resistance. The exchanged ions and X-ray diffraction (XRD) results confirmed that synthetic LDHs could reduce the corrosion risk of carbon steel by providing physical barrier, chloride ion absorption and inhibitor release.

Facile recyclable process of high-quality single layer graphene oxide via waste graphite anode scrap

Here we report a facile reusable method for graphene oxide (GO) from the oxidation of waste graphite anode scrap (WGAS), which was synthesized by Couette–Taylor flow reactor. The toroidal motion of fluids generated by the mechanical and structural specificity of the reactor increased the intercalation rate and oxidation efficiency of the WGAS, resulting in high production yield (95 ± 1%) of GO within 90 min reaction time. In addition, the as-synthesized GO nanosheets were extensively characterized using a variety of techniques, which allowed the identification of two-dimensional monolayers (∼1.3 nm) and successfully functionalized high-quality graphene oxides. Our approach of the high-efficiency oxidation and exfoliation of recycled GO with WGAS may find potential application in numerous industrial fields, such as catalysis and electrodes in energy conversion and storage systems, and conductive materials in electronic devices.

Impact of the increase in tuition fees and demographic factors on medical student intercalation rates between 2006 and 2020

No quantitative research has assessed the trends in English medical student intercalation. In addition, the impacts of the increase in tuition fees, introduced in 2012, and demographic factors on intercalation rates are unknown. Freedom of information requests were sent to all UK universities. Regression analysis compared intercalation rates before (2006-2012) and after (2012-2020) the tuition fee increase. Student's t-tests compared demographics of medical students who intercalated. Questionnaires were sent to all UK universities to explore reasons for intercalating. In total, 101,085 students from seven universities responded. The intercalation rate increased from 4.70% to 10.53% (mean percentage difference (MPD) 5.84; 95% confidence interval (CI) 2.94-8.73). Intercalating students were more likely to be <25 years of age (MPD 33.36%; 95%CI 28.34-38.39), without a previous degree (MPD 8.56%; 95% CI 7.00-10.11) and without a disability (MPD 3.15%; 95% CI 0.88-5.42). In total, 389 completed questionnaires were received from 10 universities. Medical students believed an intercalated degree made them a better doctor. The proportion of students who intercalated was greater following the increase in tuition fees. This might be explained by the value medical that students placed on the skills and opportunities that accompany an intercalated degree.

Effect of original crystal size of kaolinite on the formation of intercalation compounds of coal-measure kaolinite

Coarse crystalline (14.8–19.8 µm) and crypto crystalline (0.51–0.92 µm) coal-measure kaolinite were selected to explore the effect of original crystal sizes on intercalation. Characterization methods of SEM, XRF, XRD, FT-IR, and TG-DTG were utilized to study the original crystal size distribution, chemical composition, crystal structure changes, vibrational characteristics of functional groups, and thermal stability before and after intercalation. The test results reflected that the original crystal size significantly affects the formation of intercalated compounds. Coal-measure kaolinite intercalation compounds have been successfully prepared. Nonlinear fitting curves between the different characterization methods and the original average crystal size showed a significant positive correlation. The results showed that the intercalation effect of coarse crystalline was more significant than those of crypto crystalline, that is to say, the larger the original crystal sizes of coal-measure kaolinite, the higher the intercalation rate, the higher the grafting rate and the more pronounced the mass loss rate. Based on the theory of surface energy and surface charge of mineral particles, the electrical double layer theory which was different from the previous researchers was proposed to explain the intrinsic mechanism of the effect of original crystal size on intercalation.

Copolymer intercalated hydrotalcite sustained release-type fluid loss additive for water-based drilling fluid: Synthesis, characterization, and performance evaluation

The polyanionic copolymer fluid loss additive (PSADM) intercalated hydrotalcite sustained release-type fluid loss additive (PSADM–LDH) was fabricated through in situ intercalation polymerization to alleviate the deterioration of filtration and rheological properties of water-based drilling fluid (WBDF) under extreme geological conditions (e.g., high-temperature and alt-gypsum formations). The PSADM between layers of LDH can be slowly exchanged by anions in WBDF to give full play to its original efficiency. Results of FT–IR, TG and XRD demonstrate that the PSADM successfully intercalated the layers of LDH, and the intercalation rate was approximately 14 wt%. In addition, results of filtration measurements of WBDF demonstrate that the PSADM–LDH significantly decreased the filtration volume, even though after thermal rolling at 200 °C the filtration volume of brine drilling fluids contained 2 wt% PSADM–LDH was reduced by approximately 50% compared with PSADM. Moreover, the introduction of PSADM–LDH enhanced the thixotropy of WBDF because of forming a dynamic reversible gel structure by copolymer and charged clay colloidal particles (LDH and bentonite), which is conducive to giving full play to the water power of the bit, and carrying and suspending the drill cutting well in the annulus. Therefore, PSADM–LDH has broad application prospects for exploring and developing super-deep reservoirs.

Engineering stable carbon sponge with moderate interlayer spacing and porous architecture for rapid K+-intercalation

The practical application of graphitic carbon materials in potassium-ion batteries (PIBs) is severely hindered by slow K+-intercalation kinetics and severe volume changes during (de)potassiation process. It is challenging but necessary to achieve satisfactory carbon anode with good structural stability and rapid K+-intercalation rate at low potential. Herein, we theoretically investigated the relationship between K intercalation behavior and carbon interlayer spacing by density functional theory (DFT) calculation and ab initio molecular dynamics (AIMD) simulation, and proposed that kinetics of K intercalation improves gradually with the expanding of interlayer spacing. We accordingly constructed a free-standing carbon sponge material with moderate interlayer spacing and porous hollow structure, which achieves synergistically boosting K+-intercalation rate at low potential and enhancing structural stability. As a result, the porous hollow carbon sponge provides rapid K+-intercalation rate at high current density and accommodate volume variety to ensure excellent structural stability during the long-term (de)potassiation process (over 1000 cycles). Moreover, the full cell is successfully assembled with outstanding cycling performance (over 500 cycles) and high voltage output (2.0–3.7 V). This work provides a novel strategy for developing high-performance graphitic carbon anode with rapid K+-intercalation rate and high structural stability for PIBs.