Stable Solid Electrolyte Interphase Research Articles

Inhibiting Residual Solvent induced side reactions in Vinylidene Fluoride-based Polymer Electrolytes enables ultra-stable Solid-State Lithium Metal Batteries.

Residual solvents in vinylidene fluoride (VDF)-based solid polymer electrolytes (SPEs) have been recognized as responsible for their high ionic conductivity. However, side reactions by the residual solvents with the lithium (Li) metal induce poor stability, which has been long neglected. This study proposes a strategy to achieve a delicate equilibrium between ion conduction and electrode stability for VDF-based SPEs. Specifically, 2,2,2-Trifluoro-N, N-dimethylacetamide (FDMA) is developed as the non-side reaction solvent for poly(vinylidene fluoride-co-hexafluoropropylene) (PVHF)-based SPEs, achieving both high ionic conductivity and significantly improved electrochemical stability. The developed FDMA solvent fosters the formation of a stable solid electrolyte interphase (SEI) through interface reactions with Li metal, effectively mitigating side reactions and dendrite growth on the Li metal electrode. Consequently, the Li||Li symmetric cells and Li||LiFePO4 cells demonstrate excellent cycling performance, even under limited Li (20μm thick) supply and high-loading cathodes (>10mg cm-2, capacity >1 mAh cm-2) conditions. The stable Li||LiCoO2 cells operation with a cutoff voltage of 4.48V indicates the high-voltage stability of the developed SPE. This study offers valuable insights into developing advanced VDF-based SPEs for enhanced lithium metal battery performance and longevity. This article is protected by copyright. All rights reserved.

Amphoteric Supramolecular Nanofiber Separator for High‐Performance Sodium‐Ion Batteries

The separator is an essential component of sodium‐ion batteries (SIBs) to determine their electrochemical performances. However, the separator with high mechanical strength, good electrolyte wettability and excellent electrochemical performance remains an open challenge. Herein, a new separator consisting of amphoteric nanofibers with abundant functional groups was fabricated through supramolecular assembly of natural polymers for SIB. The uniform nanoporous structure, remarkable mechanical properties and abundant functional groups (e.g. −COOH, −NH2 and −OH) endow the separator with lower dissolution activation energy and higher ion migration numbers. These metrics enable the separator to lower the barrier for desolvation of Na+, accelerate the migration of Na+, and generate more stable solid electrolyte interphase (SEI) and cathode electrolyte interphase (CEI). The battery assembled with the amphoteric nanofiber separator shows higher specific capacity and better stability than that assembled with glass fiber (GF) separator.

LiF-Rich Solid Electrolyte Interphase Formation by Establishing Sacrificial Layer on the Separator.

The formation of a stable solid electrolyte interphase (SEI) layer is crucial for enhancing the safety and lifespan of Li metal batteries. Fundamentally, a homogeneous Li+ behavior by controlling the chemical reaction at the anode/electrolyte interface is the key to establishing a stable SEI layer. However, due to the highly reactive nature of Li metal anodes (LMAs), controlling the movement of Li+ at the anode/electrolyte interface remains challenging. Here, an advanced approach is proposed for coating a sacrificial layer called fluorinated self-assembled monolayer (FSL) on a boehmite-coated polyethylene (BPE) separator to form a stable SEI layer. By leveraging the strong affinity between the fluorine functional group and Li+, the rapid formation of a LiF-rich SEI layer in the cell production and early cycling stage is facilitated. This initial stable SEI formation promotes the subsequent homogeneous Li+ flux, thereby improving the LMA stability and yielding an enhanced battery lifespan. Further, the mechanism behind the stable SEI layer generation by controlling the Li+ dynamics through the FSL-treated BPE separator is comprehensively verified. Overall, this research offers significant contributions to the energy storage field by addressing challenges associated with LMAs, thus highlighting the importance of interfacial control in achieving a stable SEI layer.

Restructuring Electrolyte Solvation by a Partially and Weakly Solvating Cosolvent toward High-Performance Potassium-Ion Batteries.

Ether-based electrolytes are among the most important electrolytes for potassium-ion batteries (PIBs) due to their low polarization voltage and notable compatibility with potassium metal. However, their development is hindered by the strong binding between K+ and ether solvents, leading to [K+-solvent] cointercalation on graphite anodes. Herein, we propose a partially and weakly solvating electrolyte (PWSE) wherein the local solvation environment of the conventional 1,2-dimethoxyethane (DME)-based electrolyte is efficiently reconfigured by a partially and weakly solvating diethoxy methane (DEM) cosolvent. For the PWSE in particular, DEM partially participates in the solvation shell and weakens the chelation between K+ and DME, facilitating desolvation and suppressing cointercalation behavior. Notably, the solvation structure of the DME-based electrolyte is transformed into a more cation-anion-cluster-dominated structure, consequently promoting thin and stable solid-electrolyte interphase (SEI) generation. Benefiting from optimized solvation and SEI generation, the PWSE enables a graphite electrode with reversible K+ (de)intercalation (for over 1000 cycles) and K with reversible plating/stripping (the K||Cu cell with an average Coulombic efficiency of 98.72% over 400 cycles) and dendrite-free properties (the K||K cell operates over 1800 h). We demonstrate that rational PWSE design provides an approach to tailoring electrolytes toward stable PIBs.

1,3,6-Hexanetricarbonitrile as electrolyte additive to inhibit sodium dendrites in sodium-metal batteries

Sodium-metal batteries (SMBs) offer substantial competitiveness owing to their wide elemental distribution and high specific capacity. However, SMBs face safety issues such as unstable properties of the Solid Electrolyte Interphase (SEI) layer due to irregular sodium dendrites. In this paper, we constructed a stable and uniform SEI layer by introducing the 1,3,6-Hexanetricarbonitrile (HTCN) electrolyte additive, replacing the conventional, insoluble nitrate. HTCN facilitates the generation of substances like Na3N with high electrical conductivity on the Na anode surface. This accelerates Na+ shuttling and provides high-flux nucleation sites. Molecular dynamics simulations were employed to elucidate the solvated structure of electrolyte and radial distribution of Na+ after HTCN addition. Moreover, in-situ optical microscopy revealed a stable and robust SEI layer, effectively inhibiting the disorderly growth of sodium dendrites. The superior cycling performance of the Na3V2(PO4)3 (NVP)/Na full cell further demonstrates the addition of HTCN.

Coordination polymer-reinforced composite polymer electrolyte for all-solid-state Li-metal batteries

Composite polymer electrolytes (CPEs) have garnered significant interest due to their lightweight, flexible, and suitability for large-scale processing. However, current CPEs still face challenges such as unsatisfactory ionic conductivity (σ), low Li+ transference number (t+), and poor interfacial stability. This study presents the synthesis of a coordination polymer by coordinating Co2+ with terpyridine-end-capped polyethylene glycol (Co(tpy)-PEG). The resulting Co(tpy)-PEG-reinforced PEO-based CPE exhibits exceptional properties, including a high σ of 0.22 mS cm−1, large t+ of 0.75, and superior durability in both Li|Li (1400 h at 0.2 mA cm−2) and Li|LiFePO4 cells (70 % capacity retention after 1000 cycles at 1C) at 60 °C, comparable to the best available CPEs. The incorporation of Co(tpy)-PEG filler plays a vital role in enhancing the σ by disrupting the PEO crystallinity and creating additional Li+ conducting pathways. Additionally, it can free Li+ to increase t+ through Lewis acid-base interactions between Co2+ and TFSI−/O atoms, as well as NO3− and Li+. Furthermore, Co(tpy)-PEG facilitates the formation of a stable multicomponent solid electrolyte interphase containing beneficial Li2Sx, LiF, and Li3N. This work introduces a promising strategy for designing and preparing multifunctional fillers capable of simultaneously reinforcing the σ, t+, and interfacial stability of CPEs.

Designing high-chaos mixed-salt electrolytes for enhancing graphite-electrolyte interfacial stability in lithium-ion batteries

The interfacial stability between graphite anodes and electrolytes is crucial for the electrochemical performance of lithium-ion batteries, particularly at low temperatures. This study investigates the effect of incorporating four common Solid-Electrolyte Interphase (SEI) components—LiF, LiNO3, Li2O, and Li2CO3—directly into two types of commercial electrolytes: carbonate-based (1.0 M LiPF6-EC/DMC, LP30) and ether-based (1 M LiTFSI-DOL/DME+2 % LiNO3, LDD) both with 5 % FEC (v/v) to create high-chaos mixed-salt electrolytes (LP30-FEC-4S and LDD-FEC-4S). Our findings show that Li/graphite cells exhibit significantly enhanced rate performance in both LP30-FEC-4S and LDD-FEC-4S electrolytes, compared to commercial LP30 and LP57 electrolytes. LiFePO4/graphite full cells using LP30-FEC-4S and LDD-FEC-4S electrolytes also showed excellent electrochemical performance (124.73 mAh g−1 and 119.21 mAh g−1 specific capacities at 0.5C). Remarkably, stable SEIs form rapidly on the graphite anode surfaces in the designed electrolytes even at low temperatures of −10 °C. Moreover, we demonstrate that the Li+ solvation structure is fundamental in determining the overall electrochemical performance. This study suggests that enhancing the mixing entropy of the system by adding multiple lithium salts to a commercial electrolyte is an effective and cost-efficient strategy for improving graphite-electrolyte compatibility.

Design of dual carbon encapsulated porous micron silicon composite with compact surface for enhanced reaction kinetics of lithium-ion battery anodes

Developing high-performance composites with fast charging and superior cycle life is paramount for lithium-ion batteries (LIBs). Herein, we synthesized a double-shell carbon-coated porous structure composite with a compact surface (P-Si@rGO@C) using low-cost commercial micron-sized silicon (Si) instead of nanoscale silicon. Results reveal that the unique P-Si@rGO@C features high adaptability to volume expansion, accelerates electron/ion transmission rate, and forms a stable solid electrolyte interphase (SEI) film. This phenomenon arises from the synergistic effect of abundant internal voids and an external double-layer carbon shell with a dense surface. Specifically, the P-Si@rGO@C anode exhibits a high initial coulombic efficiency (ICE) (88.0 %), impressive rate-capability (612.1 mAh/g at 2C), and exceptional long-term cyclability (972.2 mAh/g over 500 cycles at 0.5C). Further kinetic studies elucidate the diffusion-capacitance hybrid energy storage mechanism and reveal an improved Li+ diffusion coefficient (from 3.47 × 10-11 to 2.85 × 10-9 cm2 s-1). Ex-situ characterization confirms the crystal phase change of micron-sized Si and the formation of a stable LiF-rich SEI. Theoretical calculations support these findings by demonstrating an enhancement in the adsorption ability of Si to Li+ (from -0.89 to -0.97 eV) and a reduction in the energy migration barrier (from 0.35 to 0.18 eV). Additionally, practical LixSi powder is shown to increase the ICE of full cells from 67.4 % to 87.9 %. Furthermore, a pouch cell utilizing the prelithiated P-Si@rGO@C anode paired with LiNi1/3Co1/3Mn1/3O2 (NCM111) cathode delivers a high initial reversible capacity of 7.2 mAh and 76.8 % capacity retention after 100 cycles. This work provides insights into the application of commercial silicon-aluminum alloy powder in the anode of high-energy LIBs.

Functionalized interfacial cover design toward pure silicon anode for high power density lithium–ion capacitor

A lithium–ion capacitor, comprising a capacitor–type cathode and battery–type anode, exhibits high power and energy density; however, the integration of different charge storage mechanisms in one cell naturally leads to a kinetic mismatch between the two electrodes, reducing the power density and cycle stability. To solve this problem, high–capacity anode materials with thinner electrodes are required. Silicon, with its high specific capacity, is considered a promising anode material with high energy and power density; however, pure Si anodes undergo rapid capacity fading and exhibit increased internal resistance owing to volume changes during cycling. In this study, both sides of the electrode are covered with functional layers consisting of functionalized herringbone–type carbon nanofibers to protect the Si electrode from degradation. The polar functional groups on the nanofibers weakly interact with the native oxide layer of the Si surface and the carboxyl groups of the binder, ensuring stable contact between electrode materials over repeated cycles. Moreover, the conductive functional cover promotes uniform lithium ion fluxes, aiding the formation of a stable solid electrolyte interphase layer. This study investigates the effects of this strategy on pure Si electrodes by surface morphology analysis, assessment of chemical interactions, and electrochemical testing. This approach has the potential to overcome the degradation of Si electrodes and significantly improve the power and energy density of lithium–ion capacitors.

In Situ Polymerized Quasi-Solid Electrolytes Compounded with Ionic Liquid Empowering Long-Life Cycling of 4.45 V Lithium-Metal Battery.

High-voltage resistant quasi-solid-state polymer electrolytes (QSPEs) are promising for enhancing the energy density of lithium-metal batteries in practice. However, side reactions occurring at the interfaces between the anodes or cathodes and QSPEs considerably reduce the lifespan of high-voltage LMBs. In this study, a copolymer of vinyl ethylene carbonate (VEC) and poly(ethylene glycol) diacrylate (PEGDA) was used as the framework, with a cellulose membrane (CE) as the supporting layer. Based on density functional theory calculations, 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (Pyr14TFSI), an ionic liquid, was screened because of its lowest unoccupied molecular orbital energy level as a modifying agent for the in situ P(VECx-EGy)/Pyrz/LiTFSI@CE QSPEs synthesis. Pyr14+, with a lithiophobic alkyl chain, forms a dense positive ion shielding layer on the protruding tips of deposited lithium, facilitating uniform and smooth lithium deposition. Pyr14TFSI assists in constructing a stable solid electrolyte interphase (SEI) layer on the Li surface enriched with LiF, Li3N, and RCOOLi. The modulation of lithium deposition behavior on the anode by Pyr14TFSI ensures stable Li plating/stripping for >1500 h. A Li-Cu cell exhibits stable cycling for >200 cycles at a current density of 0.05 mA cm-2, with an average Coulombic efficiency of 92.7%. In situ polymerization ensures that P(VECx-EGy)/Pyrz/LiTFSI@CE QSPEs exhibit excellent interface compatibility with the anode and the cathode. The CR2032 button cell Li|P(VEC1-EG0.06)/Pyr0.4/LiTFSI@CE|LiCoO2 demonstrates stable cycling with a negligible capacity decay of 0.083% per cycle for >390 cycles at 25 °C and 0.2 C when using a high-voltage LiCoO2 (4.45 V) cathode. Furthermore, a 7.1 mAh pouch cell achieves stable charge-discharge cycles, confirming the pronounced stability of the as-fabricated QSPE at the interfaces of the high-voltage LiCoO2 cathode and Li anode.

High-Rate Performance of a Designed Si Nanoparticle–Graphite Nanosheet Composite as the Anode for Lithium-Ion Batteries

A silicon nanoparticle–graphite nanosheet composite was prepared via a facile ball milling process for use as the anode for high-rate lithium-ion batteries. The size effect of Si nanoparticles on the structure and on the lithium-ion battery performance of the composite is evaluated. SEM and TEM analyses show a structural alteration of the composites from Si nanoparticle-surrounded graphite nanosheets to Si nanoparticle-embedded graphite nanosheets by decreasing the size of Si nanoparticles from 250 nm to 40 nm. The composites with finer Si nanoparticles provide an effective nanostructure containing encapsulated Si and free space. This structure facilitates the indirect exposure of Si to electrolyte and Si expansion during cycling, which leads to a stable solid–electrolyte interphase and elevated conductivity. An enhanced rate capability was obtained for the 40 nm Si nanoparticle–graphite nanosheet composite, delivering a specific capacity of 276 mAh g−1 at a current density of 1 C after 1000 cycles and a rate capacity of 205 mAh g−1 at 8 C.

Rational Lithium Salt Molecule Tuning for Fast Charging/Discharging Lithium Metal Battery.

The electrolytes for lithium metal batteries (LMBs) are plagued by a low Li+ transference number (T+) of conventional lithium salts and inability to form a stable solid electrolyte interphase (SEI). Here, we synthesized a self-folded lithium salt, lithium 2-[2-(2-methoxy ethoxy)ethoxy]ethanesulfonyl(trifluoromethanesulfonyl) imide (LiETFSI), and comparatively studied with its structure analogue, lithium 1,1,1-trifluoro-N-[2-[2-(2-methoxyethoxy)ethoxy)]ethyl]methanesulfonamide (LiFEA). The special anion chemistry imparts the following new characteristics: i) In both LiFEA and LiETFSI, the ethylene oxide moiety efficiently captures Li+, resulting in a self-folded structure and high T+ around 0.8. ii) For LiFEA, a Li-N bond (2.069 Å) is revealed by single crystal X-ray diffraction, indicating that the FEA anion possesses a high donor number (DN) and thus an intensive interphase "self-cleaning" function for an ultra-thin and compact SEI. iii) Starting from LiFEA, an electron-withdrawing sulfone group is introduced near the N atom. The distance of Li-N is tuned from 2.069 Å in LiFEA to 4.367 Å in LiETFSI. This alteration enhances ionic separation, achieves a more balanced DN, and tunes the self-cleaning intensity for a reinforced SEI. Consequently, the fast charging/discharging capability of LMBs is progressively improved. This rationally tuned anion chemistry reshapes the interactions among Li+, anions, and solvents, presenting new prospects for advanced LMBs.

Rational Lithium Salt Molecule Tuning for Fast Charging/Discharging Lithium Metal Battery

AbstractThe electrolytes for lithium metal batteries (LMBs) are plagued by a low Li+ transference number (T+) of conventional lithium salts and inability to form a stable solid electrolyte interphase (SEI). Here, we synthesized a self‐folded lithium salt, lithium 2‐[2‐(2‐methoxy ethoxy)ethoxy]ethanesulfonyl(trifluoromethanesulfonyl) imide (LiETFSI), and comparatively studied with its structure analogue, lithium 1,1,1‐trifluoro‐N‐[2‐[2‐(2‐methoxyethoxy)ethoxy)]ethyl]methanesulfonamide (LiFEA). The special anion chemistry imparts the following new characteristics: i) In both LiFEA and LiETFSI, the ethylene oxide moiety efficiently captures Li+, resulting in a self‐folded structure and high T+ around 0.8. ii) For LiFEA, a Li−N bond (2.069 Å) is revealed by single crystal X‐ray diffraction, indicating that the FEA anion possesses a high donor number (DN) and thus an intensive interphase “self‐cleaning” function for an ultra‐thin and compact SEI. iii) Starting from LiFEA, an electron‐withdrawing sulfone group is introduced near the N atom. The distance of Li−N is tuned from 2.069 Å in LiFEA to 4.367 Å in LiETFSI. This alteration enhances ionic separation, achieves a more balanced DN, and tunes the self‐cleaning intensity for a reinforced SEI. Consequently, the fast charging/discharging capability of LMBs is progressively improved. This rationally tuned anion chemistry reshapes the interactions among Li+, anions, and solvents, presenting new prospects for advanced LMBs.

Thermodynamic Understanding of Formation and Evolution of Solid Electrolyte Interface in Li‐ion Batteries

Formation is an essential process in the manufacturing of lithium‐ion batteries and determines the performance of batteries, including life time, rate capability and so forth. The core of formation is to form a stable solid electrolyte interphase (SEI), which profoundly influences interfacial reactions and ion transport within Li‐ion batteries, on the surface of electrode. It is crucial to fully and deeply understand the intricate structure and evolution of SEI, which remains largely uncharted. This paper aims to systematically analyze SEI thermodynamics, encompassing energy distribution, entropy dynamics during SEI formation, and enthalpy changes. SEI evolves towards an equilibrium state, maximizing entropy. The intricate relationship between SEI thermodynamics and battery performance is established by dissecting the impacts of temperature and current density on SEI thermodynamic parameters and battery characteristics. Elevated temperatures and higher current densities foster the development of a more porous and high‐entropy outer SEI layer, rendering organic SEI constituents prone to decompose into high‐energy gases and low‐energy inorganic compounds. Notably, a fast formation strategy within a high state‐of‐charge range offers a potential solution to high quality SEI. This review strives to bridge the divide between fundamental thermodynamics and practical battery performance, ultimately contributing to the advancement of battery manufacturing.

Suppressing the damage of deposited Mn(II) ions to graphite anode in lithium‐ion batteries by electrolyte additive agent and positive material coating

AbstractSEM and EDS techniques are carried out to demonstrate the variation of morphology and chemical compound on the surface of graphite anode, which suggest a well‐accepted concept that the manganese ions have serious influence on the reversible capacity fade of graphite anode in lithium ion batteries. Based the main chemical compounds of the inorganic layer on the graphite surface, the evolution steps of graphite structure damaged by Mn ions are derived. Although the amount of deposited manganese ions is small, these play an important role in the catalytic decomposition of the electrolyte. Moreover, Raman analysis shows that the structure of the graphite anode becomes irregular at initial SEI formation cycles and tends to be stable at subsequent cycles. This structure variation is probably generated from the manganese ion deposition and the solid electrolyte interphase (SEI) film formation. According to the capacity tests, the cycling performance of NCM811/graphite lithium‐ion batteries could be improved 50% by FEC additive and B2O3 surface coating. FEC additive maybe benefit graphite forming a stable SEI film in the early stages of cycling to suppress the damage of Mn2+ ions, then improving the cycling performance.

Constructing the Polymer Molecules to Regulate the Electrode/Electrolyte Interface to Enhance Lithium-Metal Battery Performance.

Lithium-ion batteries, with high energy density and long cycle life, have become the battery of choice for most vehicles and portable electronic devices; however, energy density, safety and cycle life require further improvements. Single-functional group electrolyte additives are very limited in practical applications, a ternary polymer bifunctional electrolyte additive copolymer (acrylonitrile-butyl hexafluoro methacrylate- poly (ethylene glycol) methacrylate- methyl ether) (PMANHF) was synthesized by free radical polymerization of acrylonitrile, 2, 2, 3, 4, 4, 4-hexafluorobutyl methacrylate and poly (ethylene glycol) methyl ether methacrylate. A series of characterizations show that in Li metal anodes, the preferential reduction of PMANHF is conducive to the formation of a uniform and stable solid electrolyte interphase layer, and Li deposition is uniform and dense. At the NCM811 cathode, a film composed of LiF- and Li3N-rich is formed at the cathode-electrolyte interface, mitigating the side reaction at the interface. At 1.0 mA cm-2, the Li/Li cell can be stabilized for 1000 cycles. In addition, the Li/NCM811 cell can stabilize 200 cycles with a cathode capacity of 153.7 mAh g-1, with the capacity retention of 89.93 %, at a negative/positive capacity ratio of 2.5. This study brings to light essential ideas for the fabrication of additives for lithium-metal batteries.

Investigating the failure mechanism of solid electrolyte interphase in silicon particles from an electrochemical-mechanical coupling perspective

Silicon is considered one of the most promising anode materials owing to its high theoretical energy density, however, the volume expansion/contraction during electrochemical lithiation/delithiation cycles leads to instability of the solid electrolyte interphase (SEI), which ultimately results in capacity degradation. Herein, the local stress and deformation evolution status of an SEI layer on an anode particle are investigated through a quantitative electrochemical-mechanical model. The impacts of structural uniformity, mechanical strength, and operating conditions on the stability of the SEI layer are investigated in detail. The simulation results demonstrate that when the silicon particle radius decreases from 800 ​nm to 600 and 400 ​nm, the failure time increases by 29% and 65%, respectively, of the original failure time; When the structural defect depth ratio is reduced from 0.6 to 0.4 and 0.2, the failure time increases by 72% and 132%, respectively; For the discharge rate, the condition at 0.1 C has 34% and 139% longer time to failure than that at 0.2 C and 0.3 C, respectively. This work provides insight into the rational design of stable SEI layers and sheds light on possible methods for constructing silicon-based lithium-ion batteries with longer cycling lives.

Lignin‐derived carbon with pyridine N‐B doping and a nanosandwich structure for high and stable lithium storage

AbstractBiomass‐derived carbon is a promising electrode material in energy storage devices. However, how to improve its low capacity and stability, and slow diffusion kinetics during lithium storage remains a challenge. In this research, we propose a “self‐assembly‐template” method to prepare B, N codoped porous carbon (BN‐C) with a nanosandwich structure and abundant pyridinic N‐B species. The nanosandwich structure can increase powder density and cycle stability by constructing a stable solid electrolyte interphase film, shortening the Li+ diffusion pathway, and accommodating volume expansion during repeated charging/discharging. The abundant pyridinic N‐B species can simultaneously promote the adsorption/desorption of Li+/PF6− and reduce the diffusion barrier. The BN‐C electrode showed a high lithium‐ion storage capacity of above 1140 mAh g−1 at 0.05 A g−1 and superior stability (96.5% retained after 2000 cycles). Moreover, owing to the synergistic effect of the nanosandwich structure and pyridinic N‐B species, the assembled symmetrical BN‐C//BN‐C full cell shows a high energy density of 234.7 W h kg−1, high power density of 39.38 kW kg−1, and excellent cycling stability, superior to most of the other cells reported in the literature. As the density functional theory simulation demonstrated, pyridinic N‐B shows enhanced adsorption activity for Li+ and PF6−, which promotes an increase in the capacity of the anode and cathode, respectively. Meanwhile, the relatively lower diffusion barrier of pyridinic N‐B promotes Li+ migration, resulting in good rate performance. Therefore, this study provides a new approach for the synergistic modulation of a nanostructure and an active site simultaneously to fabricate the carbon electrode material in energy storage devices.

Anchoring Active Li Metal in Oriented Channel by In Situ Formed Nucleation Sites Enabling Durable Lithium-Metal Batteries.

Lithium metal is the ultimate anode material for pursuing the increased energy density of rechargeable batteries. However, fatal dendrites growth and huge volume change seriously hinder the practical application of lithium metal batteries (LMBs). In this work, a lithium host that preinstalled CoSe nanoparticles on vertical carbon vascular tissues (VCVT/CoSe) is designed and fabricated to resolve these issues, which provides sufficient Li plating space with a robust framework, enabling dendrite-free Li deposition. Their inherent N sites coupled with the in situ formed lithiophilic Co sites loaded at the interface of VCVT not only anchor the initial Li nucleation seeds but also accelerate the Li+ transport kinetics. Meanwhile, the Li2 Se originated from the CoSe conversion contributes to constructing a stable solid-electrolyte interphase with high ionic conductivity. This optimized Li/VCVT/CoSe composite anode exhibits a prominent long-term cycling stability over 3000h with a high areal capacity of 10 mAh cm-2 . When paired with a commercial nickel-rich LiNi0.83 Co0.12 Mn0.05 O2 cathode, the full-cell presents substantially enhanced cycling performance with 81.7% capacity retention after 300 cycles at 0.2 C. Thus, this work reveals the critical role of guiding Li deposition behavior to maintain homogeneous Li morphology and pave the way to stable LMBs.

Stable operation of highly loaded pure Si-Fe anode under ambient pressure via carboxy silane-directed robust solid electrolyte interphase

Incorporation of higher content Si anode material beyond 5 wt% to Li-ion batteries (LIBs) is challenging, owing to large volume change, swelling, and solid electrolyte interphase (SEI) instability issues. Herein, a strategy of diacetoxydimethylsilane (DAMS) additive-directed SEI stabilization is proposed for a stable operation of Si-0.33FeSi2 (named as Si-Fe) anode without graphite, which provides siloxane inorganics and organics enrichment that compensate insufficient passivation of fluoroethylene carbonate (FEC) additive and reduce a dependence on FEC. Unprecedented stable cycling performance of highly loaded (3.5 mA h cm−2) pure Si-Fe anode is achieved with 2 wt% DAMS combined with 9 wt% FEC additives under ambient pressure, yielding high capacity 1270 mA h g−1 at 0.5 C and significantly improved capacity retention of 81% after 100 cycles, whereas short circuit and rapid capacity fade occur with FEC only additive. DAMS-directed robust SEI layer dramatically suppresses swelling and particles crossover through separator, and therefore prevents short circuit, demonstrating a possible operation of pure Si or Si-dominant anodes in the next-generation high-energy-density and safe LIBs.