Diagnosis of high-Ni NCA/Gr-Si cells before rapid capacity drop by monitoring the heterogeneous degradation.

Understanding the degradation of lithium-ion batteries is of utmost significance for preventing unexpected capacity drops and addressing safety concerns. The manner in which batteries degrade during operation has a notable influence on their subsequent cycle performance. In particular, the rapid capacity drop related to the spatial heterogeneity of the anode degradation highlights the necessity of a health indicator for an accurate battery diagnosis. A novel health indicator established in this study, the Dominant degradation factors among Negative and Positive electrodes (DNP) scores, enables clear identification of degraded states despite comparable capacity levels. Specifically, batteries with heterogeneous anode degradation exhibited negative scores and the aggravation of the cycle performance. It is anticipated that this health indicator can provide a distinct evaluation of batteries based on their degraded states, supporting onboard battery management and the efficient allocation of resources for the battery reuse industry.

Gradient Lithium Metal Infusion in Ag-Decorated Carbon Fibers for High-Capacity Lithium Metal Battery Anodes.

Lithium (Li) metal is a promising anode material for high-energy-density Li batteries due to its high specific capacity. However, the uneven deposition of Li metal causes significant volume expansion and safety concerns. Here, we investigate the impact of a gradient-infused Li-metal anode using silver (Ag)-decorated carbonized cellulose fibers (Ag@CC) as a three-dimensional (3D) current collector. The loading level of the gradient-infused Li-metal anode is controlled by the thermal infusion time of molten Li. In particular, a 5 s infusion time in the Ag@CC current collector creates an appropriate space with a lithiophilic surface, resulting in improved cycling stability and a reduced volume expansion rate. Moreover, integrating a 5 s Ag@CC anode with a high-capacity cathode demonstrates superior electrochemical performance with minimal volume expansion. This suggests that a gradient-infused Li-metal anode using Ag@CC as a 3D current collector represents a novel design strategy for Li-metal-based high-capacity Li-ion batteries.

Reversible Na Plating/Stripping with High Areal Capacity Using an Electroconductive Liquid Electrolyte System.

Anode-free sodium-metal batteries (AFSMBs) are promising candidates for maximizing energy density and minimizing cost and safety hazards in the absence of metallic sodium during cell assembly. The practical implementation of AFSMBs is hindered by the low cycling stability of Na-metal plating and stripping, particularly under high areal capacities, due to unstable solid electrolyte interphase (SEI) layer formation with electrolyte decomposition and inactive dead Na formation. Here, we proposed an electroconductive electrolyte system consisting of liquid electrolytes that accept electrons at a certain energy level and form electronically conductive and solid electrolytes that prevent internal short circuit through low electronic conductivity. The electron acceptability and high electronic conductivity of the liquid electrolyte can suppress the irreversible electron transfer with electrolyte decomposition and reutilize the inactive dead metal, respectively. The functions of the system were demonstrated using a sodium biphenyl liquid electrolyte-NASICON solid electrolyte in a seawater battery (SWB) system, which features an infinite sodium source. The anode-free SWB cells achieved a high Coulombic efficiency of ≥99.9% for over 60 cycles at a high areal capacity of ∼24 mAh/cm2. This study provides insight into the Na plating/stripping properties in anode-free systems and proposes a significant strategy for improving the reversibility of metal anodes for various battery systems with solid electrolytes.

Selective separation of Xe/Kr and adsorption of water in a microporous hydrogen-bonded organic framework.

We have studied the adsorption properties of Xe and Kr in a highly microporous hydrogen-bonded organic framework based on 1,3,5-tris(4-carboxyphenyl)benzene, named HOF-BTB. HOF-BTB can reversibly adsorb both noble gases, and it shows a higher affinity for Xe than Kr. At 1 bar, the adsorption amounts of Xe were 3.37 mmol g-1 and 2.01 mmol g-1 at 273 K and 295 K, respectively. Ideal adsorbed solution theory (IAST) calculation predicts selective separation of Xe over Kr from an equimolar binary Xe/Kr mixture, and breakthrough experiments demonstrate the efficient separation of Xe from the Xe/Kr mixture under a dynamic flow condition. Consecutive breakthrough experiments with simple regeneration treatment at 298 K reveal that HOF-BTB would be an energy-saving adsorbent in an adsorptive separation process, which could be attributed to the relatively low isosteric heat (Q st) of adsorption of Xe. The activated HOF-BTB is very stable in both water and aqueous acidic solutions for more than one month, and it also shows a well-preserved crystallinity and porosity upon water/acid treatment. Besides, HOF-BTB adsorbs about 30.5 wt%, the highest value for HOF materials, of water vapor during the adsorption-desorption cycles, with a 19% decrease in adsorption amounts of water vapor after five cycles.

Efficient separation of C2 hydrocarbons in a permanently porous hydrogen-bonded organic framework.

A highly robust porous hydrogen-bonded organic framework (HOF) constructed by 4,4',4''-benzene-1,3,5-triyl-tris(benzoic acid) not only achieves the highest uptakes of ethylene and ethane among the HOF materials, but also exhibits unusual adsorption selectivity of C2H6 over other C2 gases. Besides, it exhibits the second highest acetylene uptake among all the reported HOF materials.

High-Affinity-Assisted Nanoscale Alloys as Remarkable Bifunctional Catalyst for Alcohol Oxidation and Oxygen Reduction Reactions.

A key challenge in developing fuel cells is the fabrication of low-cost electrocatalysts with high activity and long durability for the two half-reactions, i.e., the methanol/ethanol oxidation reaction (MOR/EOR) and the oxygen reduction reaction (ORR). Herein, we report a conductivity-enhanced bifunctional electrocatalyst of nanoscale-coated Pt-Pd alloys on both tin-doped indium (TDI) and reduced graphene oxide (rGO), denoted as Pt-Pd@TDI/rGO. The mass activities of Pt in the Pt-Pd@TDI/rGO hybrid toward MOR, EOR, and ORR are 2590, 1500, and 2690 mA/mg, respectively. The ORR Pt specific activity and mass activity of the electrocatalyst are 17 and 28 times larger, respectively, than commercial Pt/C catalysts. All these remarkable catalytic performances are attributed to the role of TDI in enhancing the catalytic activity by protecting Pt from oxidation as well as rapid mass/charge transfer due to the synergistic effect between surface Pt-Pd alloys and TDI/rGO.

Accelerated Bone Regeneration by Two-Photon Photoactivated Carbon Nitride Nanosheets.

Human bone marrow-derived mesenchymal stem cells (hBMSCs) present promising opportunities for therapeutic medicine. Carbon derivatives showed only marginal enhancement in stem cell differentiation toward bone formation. Here we report that red-light absorbing carbon nitride (C3N4) sheets lead to remarkable proliferation and osteogenic differentiation by runt-related transcription factor 2 (Runx2) activation, a key transcription factor associated with osteoblast differentiation. Accordingly, highly effective hBMSCs-driven mice bone regeneration under red light is achieved (91% recovery after 4 weeks compared to 36% recovery in the standard control group in phosphate-buffered saline without red light). This fast bone regeneration is attributed to the deep penetration strength of red light into cellular membranes via tissue and the resulting efficient cell stimulation by enhanced photocurrent upon two-photon excitation of C3N4 sheets near cells. Given that the photoinduced charge transfer can increase cytosolic Ca2+ accumulation, this increase would promote nucleotide synthesis and cellular proliferation/differentiation. The cell stimulation enhances hBMSC differentiation toward bone formation, demonstrating the therapeutic potential of near-infrared two-photon absorption of C3N4 sheets in bone regeneration and fracture healing.

Hemoglobin-carbon nanotube derived noble-metal-free Fe5C2-based catalyst for highly efficient oxygen reduction reaction.

High performance non-precious cathodic catalysts for oxygen reduction reaction (ORR) are vital for the development of energy materials and devices. Here, we report an noble metal free, Fe5C2 nanoparticles-studded sp(2) carbon supported mesoporous material (CNTHb-700) as cathodic catalyst for ORR, which was prepared by pyrolizing the hybrid adduct of single walled carbon nanotubes (CNT) and lyophilized hemoglobin (Hb) at 700 °C. The catalyst shows onset potentials of 0.92 V in 0.1 M HClO4 and in 0.1 M KOH which are as good as commercial Pt/C catalyst, giving very high current density of 6.34 and 6.69 mA cm(-2) at 0.55 V vs. reversible hydrogen electrode (RHE), respectively. This catalyst has been confirmed to follow 4-electron mechanism for ORR and shows high electrochemical stability in both acidic and basic media. Catalyst CNTHb-700 possesses much higher tolerance towards methanol than the commercial Pt/C catalyst. Highly efficient catalytic properties of CNTHb-700 could lead to fundamental understanding of utilization of biomolecules in ORR and materialization of proton exchange membrane fuel cells for clean energy production.

Activated carbon derived from waste coffee grounds for stable methane storage.

An activated carbon material derived from waste coffee grounds is shown to be an effective and stable medium for methane storage. The sample activated at 900 °C displays a surface area of 1040.3 m(2) g(-1) and a micropore volume of 0.574 cm(3) g(-1) and exhibits a stable CH4 adsorption capacity of ∼4.2 mmol g(-1) at 3.0 MPa and a temperature range of 298 ± 10 K. The same material exhibits an impressive hydrogen storage capacity of 1.75 wt% as well at 77 K and 100 kPa. Here, we also propose a mechanism for the formation of activated carbon from spent coffee grounds. At low temperatures, the material has two distinct types with low and high surface areas; however, activation at elevated temperatures drives off the low surface area carbon, leaving behind the porous high surface area activated carbon.

Rotated domains in chemical vapor deposition-grown monolayer graphene on Cu(111): an angle-resolved photoemission study.

Copper is considered to be the most promising substrate for the growth of high-quality and large area graphene by chemical vapor deposition (CVD), in particular, on the (111) facet. Because the interactions between graphene and Cu substrates influence the orientation, quality, and properties of the synthesized graphene, we studied the interactions using angle-resolved photoemission spectroscopy. The evolution of both the Shockley surface state of the Cu(111) and the π band of the graphene was measured from the initial stage of CVD growth to the formation of a monolayer. Graphene growth was initiated along the Cu(111) lattice, where the Dirac band crossed the Fermi energy (EF) at the K point without hybridization with the d-band of Cu. Then two rotated domains were additionally grown as the area covered with graphene became wider. The Dirac energy was about -0.4 eV and the energy of the Shockley surface state of Cu(111) shifted toward the EF by ~0.15 eV upon graphene formation. These results indicate weak interactions between graphene and Cu, and that the electron transfer is limited to that between the Shockley surface state of Cu(111) and the π band of graphene. This weak interaction and slight lattice mismatch between graphene and Cu resulted in the growth of rotated graphene domains (9.6° and 8.4°), which showed no significant differences in the Dirac band with respect to different orientations. These rotated graphene domains resulted in grain boundaries which would hinder a large-sized single monolayer growth on Cu substrates.