RESUMEN

The performance of lithium-ion batteries largely depends on the stability of the solid electrolyte interphase (SEI) layer formed on the anode surface. Strategies to improve SEI robustness often rely on optimizing its composition through electrolytic additives. Recently, the amalgamation of fluorinated cosolvents with nitride sources as additives has been shown to enable the construction of sustainable fluorinated-nitrided SEI layers (FN-SEI). Furthermore, the presence of lithiophilic nitrides embedded in lithium fluoride (LiF) was found to contribute toward stability of a beneficial amorphous phase for interfacial passivation. However, there is a lack of understanding on how key indicators of mechanical longevity, like plasticity and fracture resistance, may evolve in such multiphase SEI building blocks. Herein, in conjunction with first-principles calculations, a reactive force field (ReaxFF) has been developed for deriving new mechanistic insights into the intriguing FN-SEI. Our studies demonstrate that owing to a significant elasticity mismatch, the hard nitride phases have a propensity to affect the native deformation modes when embedded in a soft amorphous LiF-rich matrix. Impact of the volume fraction and distribution of the nitride (Li3N) phases are discussed from the perspective of how they interfere with the propagation of shear bands. Interestingly, brittle-ductile-brittle regimes are recognized along the nitride infusion window, providing a glimpse into the effect of phase distribution on the structural toughness of the LiF-Li3N-enhanced SEI.

RESUMEN

The lithiation/delithiation properties of α-Si3 N4 and ß-Si3 N4 are compared and the carbon coating effects are examined. Then, ß-Si3 N4 at various fractions is used as the secondary phase in a Si anode to modify the electrode properties. The incorporated ß-Si3 N4 decreases the crystal size of Si and introduces a new NSiO species at the ß-Si3 N4 /Si interface. The nitrogen from the milled ß-Si3 N4 diffuses into the surface carbon coating during the carbonization heat treatment, forming pyrrolic nitrogen and CNO species. The synergistic effects of combining ß-Si3 N4 and Si phases on the specific capacity are confirmed. The operando X-ray diffraction and X-ray photoelectron spectroscopy data indicate that ß-Si3 N4 is partially consumed during lithiation to form a favorable Li3 N species at the electrode. However, the crystalline structure of the hexagonal ß-Si3 N4 is preserved after prolonged cycling, which prevents electrode agglomeration and performance deterioration. The carbon-coated ß-Si3 N4 /Si composite anode shows specific capacities of 1068 and 480 mAh g-1 at 0.2 and 5 A g-1 , respectively. A full cell consisting of the carbon-coated ß-Si3 N4 /Si anode and a LiNi0.8 Co0.1 Mn0.1 O2 cathode is constructed and its properties are evaluated. The potential of the proposed composite anodes for Li-ion battery applications is demonstrated.

RESUMEN

Lithium (Li) metal is a promising anode for high-energy-density batteries; however, its practical viability is hampered by the unstable metal Li-electrolyte interface and Li dendrite growth. Herein, a mixed ion/electron conductive Li3N-Mo protective interphase with high mechanical stability is designed and demonstrated to stabilize the Li-electrolyte interface for a dendrite-free and ultrahigh-current-density metallic Li anode. The Li3N-Mo interphase is simultaneously formed and homogeneously distributed on the Li metal surface by the surface reaction between molten Li and MoN nanosheets powder. The highly ion-conductive Li3N and abundant Li3N/Mo grain boundaries facilitate fast Li-ion diffusion, while the electrochemically inert metal Mo cluster in the mosaic structure of Li3N-Mo inhibits the long-range crystallinity and regulates the Li-ion flux, further promoting the rate capability of the Li anode. The Li3N-Mo/Li electrode has a stable Li-electrolyte interface as manifested by a low Li overpotential of 12 mV and outstanding plating/stripping cyclability for over 3200 h at 1 mA cm-2. Moreover, the Li3N-Mo/Li anode inhibits Li dendrite formation and exhibits a long cycling life of 840 h even at 30 mA cm-2. The full cell assembled with LiFePO4 cathode exhibits stable cycling performance with 87.9% capacity retention for 200 cycles at 1C (1C = 170 mA g-1) as well as high rate capability of 83.7 mAh g-1 at 3C. The concept of constructing a mixed ion/electron conductive interphase to stabilize the Li-electrolyte interface for high-rate and dendrite-free Li metal anodes offers a viable strategy to develop high-performance Li-metal batteries.

RESUMEN

Inorganic-rich solid-electrolyte interphases (SEIs) on Li metal anodes improve the electrochemical performance of Li metal batteries (LMBs). Therefore, a fundamental understanding of the roles played by essential inorganic compounds in SEIs is critical to realizing and developing high-performance LMBs. Among the prevalent SEI inorganic compounds observed for Li metal anodes, Li3N is often found in the SEIs of high-performance LMBs. Herein, we elucidate new features of Li3N by utilizing a suspension electrolyte design that contributes to the improved electrochemical performance of the Li metal anode. Through empirical and computational studies, we show that Li3N guides Li electrodeposition along its surface, creates a weakly solvating environment by decreasing Li+-solvent coordination, induces organic-poor SEI on the Li metal anode, and facilitates Li+ transport in the electrolyte. Importantly, recognizing specific roles of SEI inorganics for Li metal anodes can serve as one of the rational guidelines to design and optimize SEIs through electrolyte engineering for LMBs.

RESUMEN

As a new class of solid electrolytes, halide solid electrolytes have the advantages of high ionic conductivity at room temperature, stability to high-voltage cathodes, and good deformability, but they generally show a problem of being unstable to a lithium anode. Here, we report the use of Li3N as an interface modification layer to improve the interfacial stability of Li2ZrCl6 to the Li anode. We found that commercial Li3N can be easily transformed into an α-phase and a ß-phase by ball-milling and annealing, respectively, in which ß-phase Li3N simultaneously has high room-temperature ionic conductivity and good stability to both Li and Li2ZrCl6, making it a good choice for an artificial interface layer material. After the modification of the ß-Li3N interfacial layer, the interfacial impedance between Li2ZrCl6 and the Li anode decreased from 1929 to ∼400 Ω. At a current density of 0.1 mA cm-2, the overpotential of the Li symmetric cell decreased from 250 to ∼50 mV, which did not show an obvious increase for at least 300 h, indicating that the ß-Li3N interface layer effectively improves the interfacial stability between Li2ZrCl6 and Li.

RESUMEN

The high dehydrogenation temperature of aluminum hydride (AlH3 ) has always been an obstacle to its application as a portable hydrogen source. To solve this problem, lithium nitride is introduced into the aluminum hydride system as a catalyst to optimize the dehydrogenation drastically, which reduces the initial dehydrogenation temperature from 140.0 to 66.8 °C, and provides a stable hydrogen capacity of 8.24, 6.18, and 5.75 wt.% at 100, 90, and 80 °C within 120 min by adjusting the mass fraction of lithium nitride. Approximately 8.0 wt.% hydrogen can be released within 15 min at 100 °C for the sample of 10 wt.% doping. Moderate dehydrogenation temperature slows down the inevitable self-dehydrogenation process during the ball-milling process, and the enhanced kinetics at lower temperature shows the possibility of application in the fuel cell.

RESUMEN

The practical implementation of the lithium metal anode is hindered by obstacles such as Li dendrite growth, large volume changes, and poor lifespan. Here, copper nitride nanowires (Cu3 N NWs) printed Li by a facile and low-cost roll-press method is reported, to operate in carbonate electrolytes for high-voltage cathode materials. Through one-step roll pressing, Cu3 N NWs can be conformally printed onto the Li metal surface, and form a Li3 N@Cu NWs layer on the Li metal. The Li3 N@Cu NWs layer can assist homogeneous Li-ion flux with the 3D channel structure, as well as the high Li-ion conductivity of the Li3 N. With those beneficial effects, the Li3 N@Cu NWs layer can guide Li to deposit into a dense and planar structure without Li-dendrite growth. Li metal with Li3 N@Cu NWs protection layer exhibits outstanding cycling performances even at a high current density of 5.0 mA cm-2 with low overpotentials in Li symmetric cells. Furthermore, the stable cyclability and improved rate capability can be realized in a full cell using LiCoO2 over 300 cycles. When decoupling the irreversible reactions of the cathode using Li4 Ti5 O12 , stable cycling performance over 1000 cycles can be achieved at a practical current density of ≈2 mA cm-2 .

RESUMEN

The construction of all-solid-state batteries is now easier after the successful synthesis of sulfur-based solid electrolytes with extremely high ionic conductivities. Utilizing lithium metal as the anode in these batteries requires a protective solid electrolyte layer to prevent corrosion due to the highly reactive nature of lithium. Li3 N coating on lithium metal is a promising way of preventing the degradation of the electrolyte during charge and discharge. In this study, utilization of a Li3 N-coated lithium anode and Li7 P3 S11 solid electrolyte are reported, where a quaternary reduced graphene oxide (rGO)/S/carbon black/Li7 P3 S11 composite is used as cathode in the assembled cell. Our results indicate that protecting the Li metal with a Li3 N coating does not affect the electrochemical characteristics of the cell and extends the cycle life of the battery. A cell assembled with a protective layer was shown to having 306 mAh g-1 capacity after 120 cycles at 160 mAh g-1 current density, whereas a cell without protective layer had a capacity of 260 mAh g-1 .

RESUMEN

Lithium carbonate on the surface of garnet blocks Li+ conduction and causes a huge interfacial resistance between the garnet and electrode. To solve this problem, this study presents an effective strategy to reduce significantly the interfacial resistance by replacing Li2CO3 with Li ion conducting Li3N. Compared to the surface Li2CO3 on garnet, Li3N is not only a good Li+ conductor but also offers a good wettability with both the garnet surface and a lithium metal anode. In addition, the introduction of a Li3N layer not only enables a stable contact between the Li anode and garnet electrolyte but also prevents the direct reduction of garnet by Li metal over a long cycle life. As a result, a symmetric lithium cell with this Li3N-modified garnet exhibits an ultralow overpotential and stable plating/stripping cyclability without lithium dendrite growth at room temperature. Moreover, an all-solid-state Li/LiFePO4 battery with a Li3N-modified garnet also displays high cycling efficiency and stability over 300 cycles even at a temperature of 40 °C.

RESUMEN

3D porous carbon-coated Li3 N nanofibers are successfully fabricated via the electrospinning technique. The as-prepared nanofibers exhibit a highly improved hydrogen-sorption performance in terms of both thermodynamics and kinetics. More interestingly, a stable regeneration can be achieved due to the unique structure of the nanofibers, over 10 cycles of H2 sorption at a temperature as low as 250 °C.

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