Solid Electrolyte Research Articles

Stabilizing the Bulk-Phase and Solid Electrolyte Interphase of Silicon Microparticle Anode by Constructing Gradient-Hierarchically Ordered Conductive Networks.

The poor bulk-phase and interphase stability, attributable to adverse internal stress, impede the cycling performance of silicon microparticles (µSi) anodes and the commercial application for high-energy-density lithium-ion batteries. In this work, a groundbreaking gradient-hierarchically ordered conductive (GHOC) network structure, ingeniously engineered to enhance the stability of both bulk-phase and the solid electrolyte interphase (SEI) configurations of µSi, is proposed. Within the GHOC network architecture, two-dimensional (2D) transition metal carbides (Ti3C2Tx) act as a conductive "brick", establishing a highly conductive inner layer on µSi, while the porous outer layer, composed of one-dimensional (1D) Tempo-oxidized cellulose nanofibers (TCNF) and polyacrylic acid (PAA) macromolecule, functions akin to structural "rebar" and "concrete", effectively preserves the tightly interconnected conductive framework through multiple bonding mechanisms, including covalent and hydrogen bonds. Additionally, Ti3C2Tx enhances the development of a LiF-enriched SEI. Consequently, the µSi-MTCNF-PAA anode presents a high discharge capacity of 1413.7 mAh g-1 even after 500 cycles at 1.0 C. Moreover, a full cell, integrating LiNi0.8Mn0.1Co0.1O2 with µSi-MTCNF-PAA, exhibits a capacity retention rate of 92.0% following 50 cycles. This GHOC network structure can offer an efficacious pathway for stabilizing both the bulk-phase and interphase structure of anode materials with high volumetric strain.

LiF‐Rich Solid Electrolyte Interfaces Guarantee the Cycle Stability of Metal‐Organic Frameworks for Lithium Storage

Metal‐organic framework materials (MOFs) with hierarchical porosity, structural tunability, and rich redox‐active centers have attracted intensive attention as potential substitutes for carbonaceous anode materials. However, the practical commercialization of MOFs still remains a challenge, due to uncontrollable performance degradation. Inspired by the prolonged lifespans of traditional anode materials with LiF‐rich solid electrolyte interface (SEI), the roles of LiF are examined in enhancing the cycle stability of MOFs, with copper benzenedicarboxylate (Cu‐BDC) as an example. By adjusting the electrolyte composition, the cycle performance of Cu‐BDC material is optimized, due to the generation of LiF‐rich SEI. In the optimal 3 M LiPF6 electrolyte, the formed SEI membrane is the thinnest, and the LiF content is the highest, so the Cu‐BDC shows a specific charge/discharge capacity of 378/387.2 mAh g−1 after 100 cycles at 100 mA g−1, comparing to less than 200 mAh g−1 in the electrolyte with 1% vinyl carbonate.

Balancing Ionic and Electronic Conduction at the LiFePO4 Cathode–Electrolyte Interface and Regulating Solid Electrolyte Interphase in Lithium‐Ion Batteries

AbstractRecently, in electric mobilities and stationary energy storage device applications, the development of long‐lasting, low‐cost, and high‐safety lithium‐ion batteries (LIBs) is widely studied. LiFePO4 (LFP) is a core cathode material for LIBs owing to its cost‐effectiveness and high safety. However, it exhibits low electronic conductivity and sluggish Li+ diffusion, hindering the application of LFP cathodes in high‐power battery industries. Herein, a triazole‐motivated electrolyte additive, 1‐(trimethylsilyl)−1H‐benzotriazole (TMSBTA) is presented, for mitigating iron dissolution via HF scavenging, reinforcing the robustness of the solid electrolyte interphase and constructing a cathode–electrolyte interface (CEI) to balance the ion and electron conduction of the CEI on the LFP cathode. Scanning probe microscopy performed in the conductive atomic force microscopy mode indicates that the electronically conductive CEI created by the oxidative decomposition of TMSBTA enables rapid and homogeneous lithiation and delithiation during cycling without morphological changes in the LFP particles. This study elucidates the design principles of the CEI on the LFP cathode and is expected to guide integrated electrolyte additive engineering for LFP‐containing LIBs.

Achieving Uniform Li Deposition and Suppressed Electrolyte Flammability in Li‐Metal Batteries via Designing Localized High‐Concentration Electrolytes

AbstractThe increasing need for energy storage devices with high energy density has led to significant interest in Li‐metal batteries (LMBs). However, the use of commercial electrolytes in LMBs is problematic due to their flammability, inadequate performance at low temperatures, and tendency to promote the growth of lithium dendrites and other flaws. This study introduces a localized high‐concentration electrolyte (LHCE) that addresses these issues by employing non‐flammable electrolyte components and incorporating carefully designed additives to enhance flame retardancy and low‐temperature performance. By incorporating additives to optimize the electrolyte, it is possible to attain inorganic‐dominated solid electrolyte interphases on both the cathode and anode. This achievement results in a uniform deposition of lithium, as well as the suppression of electrolyte decomposition and cathode deterioration. Consequently, this LHCE achieve over 300 stable cycles for both LiNi0.9Mn0.05Co0.05O2||Li cells and LiCoO2||Li cells, as well as 50 cycles for LiNi0.8Mn0.1Co0.1O2 (NCM811||Li) pouch cells. Furthermore, NCM811||Li cells maintain 84% discharge capacity at −20 °C, in comparison to the capacity at room temperature. The utilization of this electrolyte presents novel perspectives for the safe implementation of LMBs.

Stable Oxyhalide-Nitride Fast Ionic Conductors for All-Solid-State Li Metal Batteries.

Rechargeable all-solid-state lithium metal batteries (ASSLMBs) utilizing inorganic solid-state electrolytes (SSEs) are promising for electric vehicles and large-scale grid energy storage. However, the Li dendrite growth in SSEs still constrains the practical utility of ASSLMBs. To achieve a high dendrite-suppression capability, SSEs must be chemically stable with Li, possess fast Li transfer kinetics, and exhibit high interface energy. Herein, a class of low-cost, eco-friendly, and sustainable oxyhalide-nitride solid electrolytes (ONSEs), denoted as LixNyIz-qLiOH (where x = 3y + z, 0 ≤ q ≤ 0.75), is designed to fulfill all the requirements. As-prepared ONSEs demonstrate chemically stable against Li and high interface energy (>43.08 meV Å-2), effectively restraining Li dendrite growth and the self-degradation at electrode interfaces. Furthermore, improved thermodynamic oxidation stability of ONSEs (>3V vs Li+/Li, 0.45V for pure Li3N), arising from the increased ionicity of Li─N bonds, contributes to the stability in ASSLMBs. As a proof-of-concept, the optimized ONSEs possess high ionic conductivity of 0.52 mS cm-1 and achieve long-term cycling of Li||Li symmetric cell for over 500h. When coupled with the Li3InCl6 SSE for high-voltage cathodes, the bilayer oxyhalide-nitride/Li3InCl6 electrolyte imparts 90% capacity retention over 500 cycles for Li||1 mAh cm-2 LiCoO2 cells.

Novel yttrium and silicon co‐doped Li1.3+x+yAl0.3−xYxTi1.7Siy(P1−yO4)3 solid electrolyte for lithium batteries: Effect on ionic conductivity and crystal structure

AbstractDoping of superfast ionic conductors like NASICON has been shown to boost ionic conductivity and the efficiency of lithium batteries. NASICON‐type yttrium and silicon‐doped lithium aluminum titanium phosphate (LATP) solid electrolytes have been synthesized via the conventional solid‐state method at different sintering temperatures. Their intrinsic physical, chemical, and electrochemical properties are analyzed using x‐ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, x‐ray photoelectron spectroscopy, and electrochemical impedance spectroscopy. Yttrium and silicon co‐doped LATP (LAYTSP) powder sintered at 900°C exhibits homogeneous hexagonal morphology and better crystallinity than the pure LATP solid electrolyte synthesized by the same methodology. LAYSTP demonstrated a higher ionic conductivity of 5.98 × 10−6 S/cm at ambient conditions. Mixing 5%‐LiCl with LAYTSP‐900°C improved the ionic conductivity significantly up to 1.88 × 10−4 S/cm. Cell viability testing demonstrated that our cells exhibit long‐term stability and are suitable for applications requiring sustained high voltages.

Effect of Bias Potential on the Interface of a Solid Electrolyte and Electrode during XPS Depth Profiling Analysis.

Depth profiling is an essential method to investigate the physical and chemical properties of a solid electrolyte and electrolyte/electrode interface. In conventional depth profiling, various spectroscopic tools such as X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS) are utilized to monitor the chemical states along with ion bombardment to etch a sample. Nevertheless, the ion bombardment during depth profiling results in an inevitable systematic error, i.e., the accumulation of mobile ions at the electrolyte/electrode interface, known as the ion pile-up phenomenon. Here, we propose a novel method using bias potential, the substrate-bias method, to prevent the ion pile-up phenomena during depth profiling of a solid electrolyte. When the positive bias potential is applied on the substrate (electrode), the number of accumulating ions at the electrolyte/electrode interface is significantly reduced. The in-depth XPS analysis with the biased electrode reveals not only the suppression of the ion pile-up phenomena but also the altered chemical states at the interfacial region between the electrolyte and electrode depending on the bias. The proposed substrate-bias method can be a good alternative scheme for an efficient yet precise depth profiling technique for a solid electrolyte.

Pressure Tuning and Sn Particle Size Optimization for Enhanced Performance in PbSnF4-Based All-Solid-State Fluoride Ion Batteries.

All-solid-state fluoride ion batteries (ASSFIBs) show remarkable potential as energy storage devices due to their low cost, superior safety, and high energy density. However, the poor ionic conductivity of F- conductor, large volume expansion, and the lack of a suitable anode inhibit their development. In this work, PbSnF4 solid electrolytes in different phases (β- and γ-PbSnF4) are successfully synthesized and characterized. The ASSFIBs composed of β-PbSnF4 electrolytes, a BiF3 cathode, and micrometer/nanometer size (µ-/n-) Sn anodes, exhibit substantial capacities. Compared to the μ-Sn anode, the n-Sn anode with nanostructure exhibits superior battery performance in the BiF3/β-PbSnF4/Sn battery. The optimized battery delivers a high initial discharge capacity of 181.3 mAh g-1 at 8mA g-1 and can be reversibly cycled at 40mA g-1 with a high discharge capacity of over 100.0 mAh g-1 after 120 cycles at room temperature. Additionally, it displays high discharge capacities over 90.0 mAh g-1 with excellent cyclability over 100 cycles under -20°C. Detailed characterization has confirmed that reducing Sn particle size and boosting external pressure are crucial for achieving good defluorination/fluorination behaviors in the Sn anode. These findings pave the way to designing ASSFIBs with high capacities and superior cyclability under different operating temperatures.

Air-Stable and Low-Cost High-Voltage Hydrated Eutectic Electrolyte for High-Performance Aqueous Aluminum-Ion Rechargeable Battery with Wide-Temperature Range.

Aqueous aluminum-ion batteries (AAIBs) are considered as a promising alternative to lithium-ion batteries due to their large theoretical capacity, high safety, and low cost. However, the uneven deposition, hydrogen evolution reaction (HER), and corrosion during cycling impede the development of AAIBs, especially under a harsh environment. Here, a hydrated eutectic electrolyte (AATH40) composed of Al(OTf)3, acetonitrile (AN), triethyl phosphate (TEP), and H2O was designed to improve the electrochemical performance of AAIBs in a wide temperature range. The combination of molecular dynamics simulations and spectroscopy analysis reveals that AATH40 has a less-water-solvated structure [Al(AN)2(TEP)(OTf)2(H2O)]3+, which effectively inhibits side reactions, decreases the freezing point, and extends the electrochemical window of the electrolyte. Furthermore, the formation of a solid electrolyte interface, which effectively inhibits HER and corrosion, has been demonstrated by X-ray photoelectron spectroscopy, X-ray diffraction tests, and in situ differential electrochemical mass spectrometry. Additionally, operando synchrotron Fourier transform infrared spectroscopy and electrochemical quartz crystal microbalance with dissipation monitoring reveal a three-electron storage mechanism for the Al//polyaniline full cells. Consequently, AAIBs with this electrolyte exhibit improved cycling stability within the temperature range of -10-50 °C. This present study introduces a promising methodology for designing electrolytes suitable for low-cost, safe, and stable AAIBs over a wide temperature range.

Inorganic Composition Modulation of Solid Electrolyte Interphase for Fast Charging Lithium Metal Batteries.

The solid electrolyte interphase (SEI) with lithium fluoride (LiF) is critical to the performance of lithium metal batteries (LMBs) due to its high stability and mechanical properties. However, the low Li ion conductivity of LiF impedes the rapid diffusion of Li ions in the SEI, which leads to localized Li ion oversaturation dendritic deposition and hinders the practical applications of LMBs at high-current regions (>3 C). To address this issue, a fluorophosphated SEI rich with fast ion-diffusing inorganic grain boundaries (LiF/Li3P) is introduced. By utilizing a sol electrolyte that contains highly dispersed porous LiF nanoparticles modified with phosphorus-containing functional groups, a fluorophosphated SEI is constructed and the presence of electrochemically active Li within these fast ion-diffusing grain boundaries (GBs-Li) that are non-nucleated is demonstrated, ensuring the stability of the Li || NCM811 cell for over 1000 cycles at fast-charging rates of 5 C (11mA cm-2). Additionally, a practical, long cycling, and intrinsically safe LMB pouch cell with high energy density (400Wh kg-1) is fabricated. The work reveals how SEI components and structure design can enable fast-charging LMBs.

Electrolyte regulation achieving MoS2/C nanofiber for stable potassium-ion storage

Due to the pronounced expansion exhibited by sulfides in K-ion batteries (KIBs), achieving both high capacity and extended cycle life remains a formidable challenge. In our study, we utilized electrospinning to craft a self-standing MoS2/C electrode, and the incorporation of one-dimensional carbon was identified as a key factor significantly boosting its electronic conductivity. Addressing stability concerns, we meticulously regulated the salt concentration in ether solvents, revealing that the self-standing MoS2/C electrode exhibited outstanding electrochemical performance at a high-concentration electrolyte. After optimization, the MoS2/C electrode in 5 M ether electrolyte presents a capacity of 315 mA h g−1 after 50 cycles at 50 mA g−1. Impressively, even at 1 A g−1, the MoS2/C electrode still sustained a capacity of 200 mA h g−1 after 5000 cycles, exhibiting excellent electrochemical stability. According to our findings, decomposition occurs when the electrode material comes into contact with the electrolyte, resulting in the formation of a solid electrolyte interface (SEI) layer. In high-concentration electrolytes, a competitive mechanism between anions and ether solvent molecules takes place, with a tendency for preferential decomposition of highly concentrated anions. This behavior triggers the formation of a high-quality KF-rich SEI layer on the electrode interface, further suppressing the decomposition of subsequent electrolytes, which significantly improves the KIB’s electrochemical performance. We believe that this discovery will provide new insights for the development of high-performance KIBs.

Ion‐Conducting Molecular‐Grafted Sustainable Cellulose Quasi‐Solid Composite Electrolyte for High Stability Solid‐State Lithium‐Metal Batteries

AbstractCellulose‐based solid electrolyte possesses the characteristics of low cost, high strength, and sustainability, and has great potential in the field of solid‐state lithium metal batteries. However, the large hydrogen bonds between cellulose molecules make the molecular chains tightly arranged, and hinder the ion conduction, seriously limiting its further development. Herein, an ion‐conducting molecular grafting strategy is proposed for the fabrication of cellulose acetate quasi‐solid composite electrolyte (CLA‐CN‐LATP QCE) with a superior ionic conductivity of 1.25 × 10−3 S cm−1 at room temperature. Benefited from grafted functional molecules, the assembled symmetrical battery exhibits low polarization voltage and highly stable lithium stripping/plating cycling of more than 1200 h at 0.1 mA cm−2 current density. Moreover, it endows LFP|CLA‐CN‐LATP QCE|Li battery with excellent long‐cycle stability of 1500 cycles at 0.5 C and 25 °C and superior capacity retention of 92.1%. Importantly, this work provides an effective strategy for further opening the ion transport channel between cellulose molecular chains and improving the interface properties of electrolytes and electrodes.

Cation Distribution and Anion Transport in the La3Ga5-xGe1+xO14+0.5x Langasite Structure.

Exploration of compositional disorder using conventional diffraction-based techniques is challenging for systems containing isoelectronic ions possessing similar coherent neutron scattering lengths. Here, we show that a multinuclear solid-state Nuclear Magnetic Resonance (NMR) approach provides compelling insight into the Ga3+/Ge4+ cation distribution and oxygen anion transport in a family of solid electrolytes with langasite structure and La3Ga5-xGe1+xO14+0.5x composition. Ultrahigh field 71Ga Magic Angle Spinning (MAS) NMR experiments acquired at 35.2 T offer striking resolution enhancement, thereby enabling clear detection of Ga sites in different coordination environments. Three-connected GaO4, four-connected GaO4 and GaO6 polyhedra are probed for the parent La3Ga5GeO14 structure, while one additional spectral feature corresponding to the key (Ga,Ge)2O8 structural unit which forms to accommodate the interstitial oxide ions is detected for the Ge4+-doped La3Ga3.5Ge2.5O14.75 phase. The complex spectral line shapes observed in the MAS NMR spectra are reproduced very accurately by the NMR parameters computed for a symmetry-adapted configurational ensemble that comprehensively models site disorder. This approach further reveals a Ga3+/Ge4+ distribution across all Ga/Ge sites that is controlled by a kinetically governed cation diffusion process. Variable temperature 17O MAS NMR experiments up to 700 °C importantly indicate that the presence of interstitial oxide ions triggers chemical exchange between all oxygen sites, thereby enabling atomic-scale understanding of the anion diffusion mechanism underpinning the transport properties of these materials.

Recent Progress on Metal Organic Framework and Covalent Organic Framework Based Solid‐State Electrolyte Membranes for Lithium Battery Applications

AbstractLithium batteries have been widely utilized in wide‐ranging electronic devices, from smartphones to electric vehicles. This review explores a new area of advanced materials for energy storage application, especially focusing on solid electrolyte membranes for lithium battery. To enhance the overall performance of lithium batteries, researchers are studying solid electrolyte membranes, aiming to overcome the limitations of liquid electrolytes and other traditional membranes. Recently, metal‐organic frameworks (MOFs) and covalent‐organic frameworks (COFs) exhibit promising characteristics due to their highly organized porous nature and structural properties. These frameworks hold significant potential as a viable component for lithium battery systems, especially in advanced separator/electrolyte setups. Because of their adjustable structural design, MOFs and COFs have the capacity to enhance battery performance by facilitating ion movement, providing superior mechanical stability, and safety. This review provides insight into the recent progress achieved by integrating MOFs and COFs into solid electrolyte membranes for lithium batteries, highlighting their potential advantages, associated challenges, and future research avenues.

Performance of CuP2 Negative Electrode for Na‐Ion Batteries with CNTs As Stabilizer

AbstractTransition metal phosphides (TMPs) are promising anode materials for sodium ion battery, thanks to their high theoretical specific capacities. Nevertheless, they suffer from large volume change and from poor conductivity during prolonged cycling. Here we systematically investigate the role of different kinds of single/multi‐wall carbon nanotubes (SWCNTs/MWCNTs) as additives in order to stabilize copper phosphide particles (CuP2) as anode materials in sodium ion batteries (SIBs). All composites show enhancement in the overall capacity and cycling stability compared to the pristine CuP2 due to the well‐connected CNTs on and between the CuP2 particles. At a high currency density of 1 A g−1, CuP2@SWCNTs composite with 13 wt.% SWCNTs can deliver a specific capacity over 400 mAh g−1 for more than 60 cycles, much better than conventional hard carbon materials. The CNTs enhance the conductivity and reduce capacity loss caused by the volume variation of CuP2 based electrode materials. Post‐mortem analysis by scanning electron microscopy depicts a possible battery failure mechanism, whereby the solid electrolyte interface exists in the form of nanospheres distributing at the surface of the electrode. During the repeated cycling (volume change), more fractures and cracks occur resulting in continuous interfacial reactions and consumption of sodium and electrolyte.

Constructing Nano-Interlayer Inhibiting Interfacial Degradation toward High-Voltage PEO-Based All-Solid-State Lithium Batteries.

The interfacial instability between PEO-based solid electrolyte (SPE) and high-voltage cathode materials inhibits the longevity of high-energy-density all-solid-state polymer lithium metal batteries (ASSPLBs). Herein, for the first time it is demonstrated, that contact loss caused by gas generation from interfacial side reactions between the high-voltage cathode and solid polymer electrolyte (SPE) can also arise in ASSPLBs. To alleviate the interfacial side reactions, a LiNb0.6Ti0.5O3 (LNTO) layer is well coated on LiNi0.83Co0.07Mn0.1O2 (NCM83), denoted as (CNCM83). The LNTO layer with low electronic conductivity reduces the decomposition drive force of SPE. Furthermore, Ti and Nb in the LNTO layer spontaneously migrate inside the NCM83 surface to form a strong Ti/Nb─O bond, stalling oxygen evolution in high-voltage cathodes. The interfacial degradation phenomena, including SPE decomposition, detrimental phase transition and intragranular cracks of NCM83, and void formation between cathode and SPE, are effectively mitigated by the LNTO layer. Therefore, the growth rate of interfacial resistance (RCEI) decreases from 37.6 Ω h-0.5 for bare NCM83 to 2.4 Ω h-0.5 for CNCM83 at 4.2V. Moreover, 4.2V PEO-based ASSPLBs achieve impressive cyclability with high capacity retention of 135 mAh g-1 (75%) even after 300 cycles at 0.5 C.

An impedancemetric NH3 sensor based on Ag nanoparticle decorated NiFe2O4 sensing electrode prepared by electrochemical exsolution method

An impedancemetric NH3 sensor was prepared using Yttria-stabilized zirconia (YSZ) as the solid electrolyte and Ag nanoparticle decorated NiFe2O4 (NiFe2O4/Ag) prepared by electrochemical exsolution as the sensing electrode (SE). The feasibility of electrochemical exsolution was confirmed by XRD and TEM characterization. After a voltage of −2 V was applied across the sensor based on NiFe2Ag0.05O4.025 for 1000 s, a large number of Ag nanoparticles as the second phase appear on the surface of the NiFe2O4 particles and attached to the matrix. The effects of exsolution time, temperature, and voltage on the sensing performance of the sensor were investigated. After electrochemical exsolution, the response value and sensitivity of the sensor are significantly improved compared to the sensor before exsolution and the limit of detection (LOD) of the sensor is reduced from 50 ppm to 10 ppm at 500 °C. In addition, the reproducibility of the electrochemical exsolution is good, and the sensor exhibits good stability. More importantly, the immunity of the sensor to NOx is significantly improved using the electrochemical exsolution SE.

Design of Fluorinated Elastomeric Electrolyte for Solid-State Lithium Metal Batteries Operating at Low Temperature and High Voltage.

We demonstrate the low-temperature operation of solid-state lithium metal batteries (LMBs) through the development of a fluorinated and plastic-crystal-embedded elastomeric electrolyte (F-PCEE). The F-PCEE is formed via polymerization-induced phase separation between the polymer matrix and plastic crystal phase, offering a high mechanical strain (∼300%) and ionic conductivity (∼0.23 mS cm-1) at -10°C. Notably, strong phase separation between two phases leads to the selective distribution of lithium (Li) salts within the plastic crystal phase, enabling superior elasticity and high ionic conductivity at low temperatures. The F-PCEE in a Li/LiNi0.8Co0.1Mn0.1O2 full cell maintains 74.4 and 42.5% of discharge capacity at -10 and -20°C, respectively, compared to that at 25°C. Furthermore, the full cell exhibits 85.3% capacity retention after 150 cycles at -10°C and a high cut-off voltage of 4.5V, representing one of the highest cycling performances among the reported solid polymer electrolytes for low-temperature LMBs. We attribute the prolonged cycling lifetime of F-PCEE at -10°C to the great mechanical robustness to suppress the Li-dendrite growth and ability to form superior LiF-rich interphases. This study establishes the design strategies of elastomeric electrolytes for developing solid-state LMBs operating at low temperatures and high voltages. This article is protected by copyright. All rights reserved.

Formation of N‐Doped Carbon Nanofibers Decorated with MoP Nanoflakes for Dendrite‐Free Lithium Metal Anode

AbstractMetallic lithium (Li) is recognized as a promising candidate for anode material of Li‐ion batteries owing to high theoretical specific capacity and low redox potential. However, uncontrollable dendrite growth and huge volume expansion during Li plating/stripping processes hinder its practical application. Herein, N‐doped carbon nanofibers@MoP nanoflakes (NCNF@MoP) is developed as a potential host to address the above challenges. During the formation of solid electrolyte interphase, MoP nanoflakes can be changed into metallic Mo with high lithiophilicity and Li3P with high ionic conductivity. The whole composite host is transformed into a mixed ion/electron conducting network to reduce nucleation overpotential and accelerate diffusion kinetics at the electrode/electrolyte interface. As a proof of concept, the symmetric cell using NCNF@MoP host presents a long‐term cycling up to 2500 h with a low nucleation overpotential of 10 mV at 1 mA cm−2. Additionally, the Li‐NCNF@MoP||LiFePO4 full cell demonstrates a good capacity retention of 92.6% over 2200 cycles at a high current density of 5C (1 C = 169 mA g−1).

Operando insights into ammonium-mediated lithium metal stabilization: surface morphology modulation and enhanced SEI development

Lithium-ion batteries (LiBs) with graphite as an anode and lithiated transition metal oxide as a cathode are approaching their specific energy and power theoretical values. To overcome the limitations of LiBs, lithium metal anode with high specific capacity and low negative redox potential is necessary. However, practical application in rechargeable cells is hindered by uncontrolled lithium deposition manifesting, for instance, as Li dendrite growth which can cause formation of dead Li, short circuits and cell failure.The electrochemical behaviour of a protic additive (NH4PF6) in a carbonate-based electrolyte has been investigated by operando confocal Raman spectroscopy, in situ optical microscopy, and X-ray photoelectron spectroscopy, elucidating its functional mechanism. The ammonium cation promotes a chemical modification of the lithium metal anode-electrolyte interphase by producing an N-rich solid electrolyte interphase and chemically modifying the lithium surface morphology by electrochemical pitting. This novel method results in stable lithium deposition and stripping by a decreasing the local current density on the electrode, thus limiting dendritic deposition.