Lithium Dendrite Growth Research Articles

Effect of Different Surface States of Electrolytic Copper Foils on the Performance of Lithium-Ion Batteries

Currently, the field of lithium-ion batteries faces an urgent challenge, which is how to effectively inhibit the growth of dendrites, thereby improving the coulombic efficiency of plated/stripped lithium on copper foils and enhancing the cycling stability of the batteries. In this paper, the surface of copper foil is roughened by annealing post-treatment, which in turn improves the interfacial adhesion between the copper foil and the active material. This treatment helps the anode current collector to form a flat graphite electrode sheet and a uniform solid electrolyte interphase film, reducing the growth of lithium dendrites as well as extending the cycle life of the batteries. Among them, the annealed electrode exhibits extremely high roughness (0.533 μm) and elongation (9.91%), with the initial discharge capacity of the prepared lithium battery reaching as high as 384.22 mAh g−1. It also maintains good cycling performance at different rates, which confirms the gain effect of surface roughening on battery capacity.

Application of artificial SEI layers for lithium metal battery anodes

Unpredictable lithium dendrite growth on the metal anode and repeated destruction and creation of the solid electrolyte interphase (SEI) layer result in hidden risks and low Coulombic efficiencies (CEs). Researchers have found that designing a high-quality SEI layer can prevent the growth of dendrite. However, designing and forming a high-quality SEI layer is still a problem. Making trade-off between capacity reduction caused by the SEI layer and better cycle stability significantly limits the general performance of lithium metal batteries. In this research, characteristics of SEI layers and some significant advancements made in SEI formation are outlined. Some designs for the SEI layers on the lithium metal anodes include designing hybrid polymer SEI layers, producing synthetic SEI layers. By controlling the behaviours of Li ions throughout the stripping and depositing processes, the capacity and stability of Li metal anodes may be improved. Finally, some case studies of the applying of SEI in lithium metal battery systems are introduced.

Constructing a three-dimensional continuous grain boundary with lithium ion conductivity and electron blocking property in LLZO to suppress lithium dendrites

Li7La3Zr2O12 (LLZO) stands out as a promising material for solid-state batteries due to its superior performance. However, the lithium dendrite growth in LLZO significantly affects battery performance due to high electronic conduction of LLZO. Herein, amorphous Li3BO3 (ALBO) is introduced into LLZO to construct a three-dimensional continuous grain boundary with lithium ion conductivity and electron-blocking property to suppress lithium dendrites. The symmetric cells of ALBO-LLZO achieved a high critical current density (CCD) of 1.1 mA·cm−2 and cycled stably for 2000 h at 0.3 mA·cm−2. The capacity retention of LFP/1 ALBO-LLZO/Li battery retains 84.6 % after 200 cycles at 0.2 C, room temperature. This research offers a potential solution to enhance the performance of the garnet electrolyte for ASSBs.

Polyvinylidene fluoride gel‐polyethylene composite separator optimizing the interface compatibility between the separator and the electrode

AbstractThe interface issue concerning lithium dendrite formation between the separator and electrode remains a significant impediment to the further advancement of lithium‐ion batteries (LIB). Due to the inadequate interface compatibility between the conventional polyolefin separator and the electrode, there is a propensity for lithium dendrite growth. In this work, the surface of the polyethylene (PE) separator is coated with polyvinylidene fluoride (PVDF) gel using a simple phase transformation method, resulting in the preparation of a composite separator consisting of PE and PVDF. The results demonstrate an enhanced interface compatibility following the introduction of the gel layer, with a polarization voltage as low as 0.14 V observed after 250 h of cycling. Additionally, the ionic conductivity of the PE/PVDF composite separator (1.77 mS cm−1) is enhanced, attributed to the incorporation of F functional group in PVDF gel, which could facilitate the formation of a rapid ion transport pathway through the interaction between F functional group and Li+. After the introduction of the gel layer, the discharge capacity of the battery after 250 cycles measures ~1.28 mAh, with a mere 27% decay in capacity. This study presents a novel concept for the design of composite separator in LIB.

Nitrogen-Doped TiO2- x(B)/MXene Heterostructures for Expediting Sulfur Redox Kinetics and Suppressing Lithium Dendrites.

Practical application of lithium-sulfur (Li-S) batteries is severely impeded by the random shuttling of soluble lithium polysulfides (LiPSs), sluggish sulfur redox kinetics, and uncontrollable growth of lithium dendrites, particularly under high sulfur loading and lean electrolyte conditions. Here, nitrogen-doped bronze-phase TiO2(B) nanosheets with oxygen vacancies (OVs) grown in situ on MXenes layers (N-TiO2- x(B)-MXenes) as multifunctional interlayers are designed. The N-TiO2- x(B)-MXenes show reduced bandgap of 1.10eV and high LiPSs adsorption-conversion-nucleation-decomposition efficiency, leading to remarkably enhanced sulfur redox kinetics. Moreover, they also have lithiophilic nature that can effectively suppress dendrites growth. The cell based on the N-TiO2- x(B)-MXenes interlayer under sulfur loading of 2.5mg cm-2 delivers superior cycling performance with a high specific capacity of 690.7 mAh g-1 over 600 cycles at 1.0 C. It still has a notable areal capacity of 6.15 mAh cm-2 after 50 cycles even under a high sulfur loading of 7.2mg cm-2 and a low electrolyte-to-sulfur (E/S) ratio of 6.4 µL mg-1. The Li-symmetrical battery with the N-TiO2- x(B)-MXenes interlayer showcases a low over-potential fluctuation with 21.0mV throughout continuous lithium plating/stripping for 1000h. This work offers valuable insights into the manipulation of defects and heterostructures to achieve high-energy Li-S batteries.

Amorphous High‐Entropy Alloy Interphase for Stable Lithium Metal Batteries

AbstractThe unstable anode/electrolyte interphase induces severe lithium dendrite growth hindering the practical application of lithium metal batteries. The lithium alloy interphase presents a promising strategy for regulating Li+ plating/stripping behavior. However, binary or ternary alloys are insufficient to address various challenges in lithium metal batteries and the high temperature required for alloy preparation hampers their direct applications on lithium metal surfaces. In this study, a high‐entropy alloy (HEA) interphase is developed on lithium metal surfaces via room‐temperature magnetron sputtering, showcasing multifunctional advantages in regulating Li+ plating/stripping behavior. The cocktail effect of the (HEA) facilitated the formation of a homogeneous amorphous interphase with abundant lithiophilic sites and magnetic properties, promoting uniform Li+ nucleation and deposition. Furthermore, the high mechanical strength and corrosion resistance of HEA provided physicochemical stability for the lithium anode interphase, consistently suppressing dendrite growth. Consequently, lithium metal anodes with HEA interphases exhibited robust cycling performance lasting over 4000 h at 2 mA cm−2. The LFP full battery demonstrated high‐capacity retention of 90% with an average Coulombic efficiency of 99.7%. Thus, the HEA interphases on lithium metal surfaces offer controllable regulation of Li+ deposition behavior through high‐entropy manipulation, opening novel strategies for stable lithium metal batteries.

Covalent Organic Framework-Coated Polyimide Ion-Track-Etched Separator with High Thermal Stability for Developing Lithium-Ion Batteries with Long Lifespans.

Separators play a crucial role in inhibiting thermal runaway in lithium-ion batteries (LIBs). In this study, the doctor blade coating method and heavy-ion track etching technology were used to prepare a polyimide-based covalent organic framework (PI_COF) separator with excellent thermal stability and a long cycle life. Specifically, COF300 was simply coated on the surface of a polyimide-based track-etched membrane (PI_TEM) with straight through holes, which provided a rigid framework and high-temperature stability at 300 °C. These features were conducive to inhibiting thermal runaway, while porous COF300 with large holes increased the wettability of the electrolyte, facilitating lithium-ion migration and suppression of lithium dendrite growth; consequently, LIBs with an excellent cycling performance and a high rate capacity were obtained. The cell with the PI_COF separator delivered a high capacity of 90.0 mA h g-1 after 1000 cycles. The PI_COF separator with high thermal stability exhibited a long cycle life in LIBs. These features are beneficial for improving the safety characteristics of LIBs as well as for accelerating the practical application process of the PI_COF separator.

Rationally Designed Li-Ag Alloy with In-Situ-Formed Solid Electrolyte Interphase for All-Solid-State Lithium Batteries.

All-solid-state lithium batteries (ASSLBs) with sulfide-based solid electrolytes have attracted significant attention as promising energy storage devices, owing to their high energy density and enhanced safety. However, the combination of a lithium metal anode and a sulfide solid electrolyte results in performance degradation, owing to lithium dendrite growth and the side reactions of lithium metal with the solid electrolyte. To address these issues, a Ag-based Li alloy with a favorable solid electrolyte interphase (SEI) was prepared using electrodeposition and applied to the ASSLB as an anode. The electrochemically formed SEI layer on the Li-Ag alloy primarily comprised LiF and Li2O with high mechanical strength and Li3N with high ionic conductivity, which suppressed the formation of lithium dendrites and short-circuiting of the cell. The symmetric cell with the Li-Ag alloy achieved a critical current density of 1.6 mA cm-2 and maintained stable cycling for over 2000 h at a current density of 0.6 mA cm-2. Consequently, the all-solid-state lithium cell assembled with the Li-Ag alloy anode with SEI, Li6PS5Cl solid electrolyte, and LiNi0.78Co0.10Mn0.12O2 cathode delivered a high discharge capacity of 185 mAh g-1 and exhibited good cycling performance in terms of cycling stability and rate capability at 25 °C.

Adjusting Ion Diffusion Kinetics of Li Deposition Enabled by an Elastic Porous Melamine Sponge Host for Stable Lithium Metal Anodes.

Lithium (Li) dendritic growth and huge volume expansion seriously hamper Li-metal anode development. Herein, we design a lightweight 3D Li-ion-affinity host enabled by silver (Ag) nanoparticles fully decorating a porous melamine sponge (Ag@PMS) for dendrite-free and high-areal-capacity Li anodes. The compact Ag nanoparticles provide abundant preferred nucleation sites and give the host strong conductivity. Moreover, the high specific surface area and polar groups of the elastic, porous melamine sponge enhance the Li-ion diffusion kinetics, prompting homogeneity of Li deposition and stripping. As expected, the integrated 3D Ag@PMS-Li anode delivered a remarkable electrochemical performance, with a Coulombic efficiency (CE) of 97.14% after 450 cycles at 1 mA cm-2. The symmetric cell showed an ultralong lifespan of 3400 h at 1 mA cm-2 for 1 mAh cm-2. This study provides a facile and cost-effective strategy to design an advanced 3D framework for the preparation of a stable dendrite-free Li metal anode.

Highly Tough Slide-Crosslinked Gel Polymer Electrolyte for Stable Lithium Metal Batteries.

Gel polymer electrolytes (GPEs) hold great promise for the practical application of lithium metal batteries. However, conventional GPEs hardly resists lithium dendrites growth and maintains long-term cycling stability of the battery due to its poor mechanical performance. Inspired by the slide-ring structure of polyrotaxanes (PRs), herein we developed a dynamic slide-crosslinked gel polymer electrolyte (SCGPE) with extraordinary stretchability of 970.93 % and mechanical strength of 1.15 MPa, which is helpful to buffer the volume change of electrodes and maintain mechanical integrity of the battery structure during cycling. Notably, the PRs structures can provide fast ion transport channels to obtain high ionic conductivity of 1.73×10-3 S cm-1 at 30 °C. Additionally, the strong polar groups in SCGPE restrict the free movement of anions to achieve high lithium-ion transference number of 0.71, which is favorable to enhance Li+ transport dynamics and induce uniform Li+ deposition. Benefiting from these features, the constructed Li|SCGPE-3|LFP cells exhibit ultra-long and stable cycle life over 1000 cycles and high-capacity retention (89.6 % after 1000 cycles). Even at a high rate of 16 C, the cells deliver a high capacity of 79.2 mAh g-1. The slide-crosslinking strategy in this work provides a new perspective on the design of advanced GPEs for LMBs.

Interfacial engineering assists dendrite-inhibiting separators for high-safety Li-S batteries

The impediments to the safety and cyclic performance of lithium-sulfur (Li-S) batteries arise from the lithium dendrite growth and “shuttle effect” of polysulfides. Herein, an interfacial engineering was proposed by pre-irradiation grafting acrylic acid (AA) into polypropylene (PP) separator to achieve a dendrite-inhibiting and high stability functional separators. The abundant –COOH groups, introduced to the surface of PP along with AA, effectively modulate lithium dendrite growth by eliminating the local aggregation of Li+ on the surface of the anode and restrain the “shuttle effect” of polysulfides by the physical confinement and electrostatic interaction. Lithium-sulfur batteries with the grafted separator achieved a high initial capacity of 1108.7 mAh g−1 with an ultralow attenuation rate of 0.012 % per cycle at 1C, outperforming the traditional commercial PP separator. Additionally, the grafted separator also appeared a remarkable flexibility owing to the chemical bond between AA and PP-chain. Notably, the pre-irradiation grafting process, characterized by a mild reaction condition and high economic benefit, endowed the grafted separator with outstanding potential for industrialization. Those results showed the practical prospects of the grafted separator, offering a promising new option for high-safety Li-S batteries.

Optimizing the Microenvironment in Solid Polymer Electrolytes by Anion Vacancy Coupled with Carbon Dots.

The practical application of solid polymer electrolyte is hindered by the small transference number of Li+, low ionic conductivity and poor interfacial stability, which are seriously determined by the microenvironment in polymer electrolyte. The introduction of functional fillers is an effective solution to these problems. In this work, based on density functional theory (DFT) calculations, it is demonstrated that the anion vacancy of filler can anchor anions of lithium salt, thereby significantly increasing the transference number of Li+ in the electrolyte. Therefore, flower-like SnS2-based filler with abundant sulfur vacancies is prepared under the regulation of functionalized carbon dots (CDs). It is worth mentioning that the CDs dotted on the surface of SnS2 have rich organic functional groups, which can serve as the bridging agent to enhance the compatibility of filler and polymer, leading to superior mechanical performance and fast ion transport pathway. Additionally, the in situ formed Li2S/Li3N at the interface of Li metal and electrolyte facilitate the fast Li+ diffusion and uniform Li deposition, effectively mitigating the growth of lithium dendrites. As a result, the assembled lithium metal batteries exhibit excellent cycling stability, reflecting the superiority of the carbon dots derived vacancy-rich inorganic filler modification strategy.

Optimizing the Microenvironment in Solid Polymer Electrolytes by Anion Vacancy Coupled with Carbon Dots

The practical application of solid polymer electrolyte is hindered by the small transference number of Li+, low ionic conductivity and poor interfacial stability, which are seriously determined by the microenvironment in polymer electrolyte. The introduction of functional fillers is an effective solution to these problems. In this work, based on density functional theory (DFT) calculations, it is demonstrated that the anion vacancy of filler can anchor anions of lithium salt, thereby significantly increasing the transference number of Li+ in the electrolyte. Therefore, flower‐like SnS2‐based filler with abundant sulfur vacancies is prepared under the regulation of functionalized carbon dots (CDs). It is worth mentioning that the CDs dotted on the surface of SnS2 have rich organic functional groups, which can serve as the bridging agent to enhance the compatibility of filler and polymer, leading to superior mechanical performance and fast ion transport pathway. Additionally, the in‐situ formed Li2S/Li3N at the interface of Li metal and electrolyte facilitate the fast Li+ diffusion and uniform Li deposition, effectively mitigating the growth of lithium dendrites. As a result, the assembled lithium metal batteries exhibit excellent cycling stability, reflecting the superiority of the carbon dots derived vacancy‐rich inorganic filler modification strategy.

"Peapod-like" Fiber Network: A Universal Strategy for Composite Solid Electrolytes to Inhibit Lithium Dendrite Growth in Solid-State Lithium Metal Batteries.

Solid-state lithium metal batteries (SSLMBs) are a promising energy storage technology, but challenges persist including electrolyte thickness and lithium (Li) dendrite puncture. A novel three-dimensional "peapod-like" composite solid electrolyte (CSEs) with low thickness (26.8 μm), high mechanical strength, and dendrite inhibition was designed. Incorporating Li7La3Zr2O12 (LLZO) enhances both mechanical strength and ionic conductivity, stabilizing the CSE/Li interface and enabling Li symmetric batteries to stabilize for 3000 h. With structural advantages, the assembled LFP||Li and NCM811||Li cells exhibit excellent cycling performance. In addition, the constructed NCM811 pouch cell achieves a high gravimetric/volumetric energy density of 307.0 Wh kg-1/677.7 Wh L-1, which can light up LEDs under extreme conditions, demonstrating practicality and high safety. This work offers a generalized strategy for CSE design and insights into high-performance SSLMBs.

Interfacial Catalysis Strategy for High‐Performance Solid‐State Lithium Metal Batteries

AbstractSolid‐state lithium metal batteries (SSLMBs) with polymer electrolytes (SPEs) have attracted tremendous attention owing to their superior safety and high energy density. However, the unstable solid electrolyte interphase (SEI) between Lithium (Li) and SPEs hinders their practical application. Herein, an innovative interfacial catalysis strategy is applied to the in situ construction of a multifunctional inorganic‐rich SEI. The transfer of unpaired electrons adjacent to calcium vacancies (VCa) to the TFSI− anion promotes the breaking of S─N and C─F bonds during the electrochemical decomposition of TFSI−, thus enhancing its decomposition kinetics. The inorganic‐rich SEI derived from TFSI− is super‐stable and kinetically favorable for fast and homogeneous transport of Li ions, thereby hindering the growth of lithium dendrites. Consequently, the interfacial catalysis strategy endows Li||Li symmetric cells, LFP||Li and NCM811||Li full batteries with enhanced cyclability. Thus, this work expands the interfacial catalysis strategy to a platform for designing multifunctional SEI in long‐life SSLMB.

Solid composite electrolyte with a Cs doped fluorapatite-interfacial layer enabling dendrite-free anodes for solid-state lithium batteries

Composite electrolytes have garnered considerable attention owing to ease of processing, flexibility, and cost-effectiveness. Nevertheless, their practical applicability has been hindered by the insufficient ionic conductivity and the formation of dendrites duo to solid–solid interfacial interactions. In this work, an interfacial layer with Cs-doped fluorapatite (Ca5(PO4)3F, FA) as the filler was constructed to enhance the flame-retardant property of the composite electrolyte and inhibit dendrite growth during cycling process. The CSE with the Cs doped FA interfacial layer exhibits significant flame-retardant properties. Furthermore, the self-healing electrostatic shielding (SHES) mechanism of Cs+ effectively inhibits the growth of lithium dendrite and promotes uniform lithium deposition. The solid electrolyte integrated with the Cs doped FA interfacial layer exhibits a broad voltage window of 5.58 V vs. Li+/Li, high ionic conductivity of 5.43 × 10-4 S cm−1, and Li+ transference number of 0.716. Density functional theory (DFT) calculations reveal a competitive interaction between Cs+ and Li+ for TFSI- coordination, leading to reduced binding energy of LiTFSI and thus increasing the availability of free lithium ions, enhancing lithium ions mobility. Additionally, the symmetrical cell with the Cs doped FA interfacial layer demonstrates cyclic stability over 2000 h at 0.2 mA cm−2 due to the lower nucleation overpotential, demonstrating excellent lithium plating/stripping capabilities. The LFP||Li full cell shows a remarkable capacity retention of 99.54 % after 300 cycles at 0.5C, and 95.58 % with a higher Coulombic efficiency (CE) of 99 % after 600 cycles at 1C. In addition, the cell with this CSE and NCM811 cathode exhibits excellent capacity retention of 78 % after 150 cycles at 0.5C. This approach to designing interfacial layers offers new avenues for advancing solid-state lithium-metal batteries.

Bonded Interface Enabled Durable Solid‐state Lithium Metal Batteries with Ultra‐low Interfacial Resistance of 0.25 Ω cm2

AbstractThe solid‐state batteries (SSBs) with Li anode present one of the most promising energy storage systems due to their enhanced energy density and safety. However, interfacial problems between Li anode and solid‐state electrolyte hinder the advancement of SSBs. Among them, insufficient solid‐solid interfacial contact is the main issue, which causes large resistance and hinders Li+ diffusion, leading to current distribution unevenness and lithium dendrites growth. To meet these challenges, a silver/carbon interlayer composed of ultrafine Ag nanoparticles (≈5 nm) grown on COOH‐CNTs (nano‐Ag@COOH‐CNTs) is constructed. In which, nano‐Ag is designed to guide homogeneous Li deposition, while CNTs substrate bonds with Li6.5La3Zr1.5Ta0.5O12 (LLZTO) electrolyte by reactions between ─COOH groups and LLZTO alkaline surface, thus transforming loose physical solid‐solid contact to chemical bonding contact. In addition, nano‐Ag is immobilized by CNTs, avoiding the migration of Li+ implanted nano‐Ag during cycling. Therefore, nano‐Ag@COOH‐CNTs interlayer can boost Li+ transport at LLZTO/Li interface and inhibit Li dendrites, achieving an ultra‐low interfacial resistance of 0.25 Ω cm2, a high critical current density of 1.7 mA cm−2 and a long cycling over 2155 h at 0.5 mA cm−2. The modified SSBs with LiNi0.83Co0.12Mn0.05O2 cathode cycles stably over 500 cycles. Moreover, high‐loading SSBs operate stably for 85 cycles.

A joint diffusion/collision model for crystal growth in pure liquid metals

The kinetics of atomic attachments at the liquid/solid interface is one of the foundations of solidification theory, and to date one of the long-standing questions remains: whether or not the growth is thermal activated in pure liquid metals. Using molecular dynamics simulations and machine learning, I have demonstrated that a considerable fraction of liquid atoms at the interfaces of Al(111), (110) and (100) needs thermal activation for growth to take place while the others attach to the crystal without an energy barrier. My joint diffusion/collision model is proved to be robust in predicting the general growth behaviour of pure metals. Here, I show this model is able to quantitatively describe the temperature dependence of growth kinetics and to properly interpret some important experimental observations, and it significantly advances our understanding of solidification theory and also is useful for modelling solidification, phase change materials and lithium dendrite growth in lithium-ion battery.

Regulating ion transport in lithium metal batteries via metal‐organic frameworks electrolyte modulator

AbstractLow Li+ transference number in liquid electrolytes can lead to uneven lithium deposition and dendrite growth, reducing coulombic efficiency and cycle life of lithium metal batteries. In this study, metal‐organic frameworks (MOFs) are used as electrolyte modulator to regulate Li+ transport. The ‐NH2 group introduced into MOFs can form hydrogen bonds with anions in the electrolyte, immobilizing these anions and thereby facilitating the migration of cations. As a result, a uniform and dense deposition morphology of lithium was achieved. The Li+ transference number is increased from 0.26 to 0.57. The assembled Li||Li symmetrical cell can stably cycle for over for 900 h with an average overpotential below 20 mV. In addition, the rate performance of the battery can be enhanced.

A modified PVDF-HFP/PMMA crosslinked co-polymer for high-performance all-solid-state lithium metal batteries

For all-solid-state lithium batteries (ASSLBs), polymer-blended solid composite electrolytes (SCEs) have drawn wide interest owing to their significance in improving the interfacial solid-solid contacts and inhibiting the growth of lithium dendrites. In this work, SCEs based on PVDF-HFP/PMMA matrix containing MOFs (NH2-MIL-53(Al)) and LiTFSI were designed and synthesized employing an easy solution casting method. The synthesized samples were examined by XRD, SEM, EDS, and electrochemical tests. It was found that MPP-2 SCE not only has excellent ionic conductivity at 60 °C of 5.54 × 10−4 S cm−1, but also exhibits superior interfacial compatibility in Li||Li symmetric batteries, which can constantly cycle for about 800 h at 0.1 mA cm−2 with no short-circuiting. The assembled Li|MPP-2|LiFePO4 cell exhibited a first discharge specific capacity of up to 157.1 mAh g−1 at 60 °C and 0.2 C. This work may help to further advance the progress of ASSLBs in the future.