Li Secondary Batteries Research Articles

Improving Cycling Stability of Ni‐Rich Cathode for Lithium‐Metal Batteries via Interphases Tunning

AbstractCombining Li‐metal anodes (LMAs) with high‐voltage Ni‐rich layered‐oxide cathodes is a promising approach to realizing high‐energy‐density Li secondary batteries. However, these systems experience severe capacity decay due to structural degradation of high‐voltage cathodes and side reactions of electrolyte solutions with both electrodes. Herein, the use of multi‐functional additives in fluoroethylene carbonate‐based electrolyte solutions that enable the operation of successfully rechargeable high‐voltage (4.5 V) Li‐metal batteries (LMBs) with high areal capacity (>4 mAh cm−2) are reported. Customized electrolyte solutions are pivotal in passivating the electrodes, minimizing microcrack formation, and ensuring that current is uniformly distributed within cathode particles. The developed electrolyte solution protects the LMA by forming a very stable and effective solid–electrolyte interphase. Together with the Li[Ni0.78Co0.1Mn0.12]O2 cathode material, which is composed of radially aligned rod‐shaped primary particles, the developed high‐voltage LMB containing 20 mg cm−2 of cathode material delivers a high specific capacity of 230 mAh g−1 at 0.1 C and retains >86% of its initial capacity after 200 cycles at 0.5 C. This study highlights the significance of controlling the interfacial structure via electrolyte solution modification and the use of cathode materials with engineered morphologies that enhance mechanical stability.

Insights into charge transfer dynamics of Li batteries through temperature-dependent electrochemical impedance spectroscopy (EIS) utilizing symmetric cell configuration

Studying charge transfer processes in Li batteries poses a challenge due to their complicated nature and the battery's inherent inertness. While electrochemical impedance spectroscopy (EIS) offers a promising approach to investigating these processes, its effectiveness is hindered by the complexity of the data generated and the ambiguity in the analyses. Here, we demonstrate that the assignment process is not straightforward for complex secondary Li batteries, and it necessitates additional measurements and in-depth analysis. We first performed simplification of the impedance data by employing symmetric cell configurations to obtain charge transfer resistance values for each electrode. We second took advantage of altering three parameters during the EIS measurement: electrolyte composition, measurement temperature, and the state of health to extract important parameters related to both the anodic and cathodic charge transfer mechanisms. The analysis enabled the correlation of the observed charge transfer resistances to the corresponding electrochemical process and to obtain the kinetic parameters of the studied process. Our work illustrates how EIS can be used to study and understand the intricate electrochemical charge transfer processes in Li batteries, which are difficult to explore using alternative techniques.

P-Phenylenediamine-Bridged Binder-Electrolyte-Unified Supramolecules for Versatile Lithium Secondary Batteries.

The binder is an essential component in determining the structural integrity and ionic conductivity of Li-ion battery electrodes. However, conventional binders are not sufficiently conductive and durable to be used with solid-state electrolytes. In this study, a novel system is proposed for a Li secondary battery that combines the electrolyte and binder into a unified structure, which is achieved by employing para-phenylenediamine (pPD) moiety to create supramolecular bridges between the parent binders. Due to a partial crosslinking effect and charge-transferring structure of pPD, the proposed strategy improves both the ionic conductivity and mechanical properties by a factor of 6.4 (achieving a conductivity of 3.73 × 10-4 S cm-1 for poly(ethylene oxide)-pPD) and 4.4 (reaching a mechanical strength of 151.4kPa for poly(acrylic acid)-pPD) compared to those of conventional parent binders. As a result, when the supramolecules of pPD are used as a binder in a pouch cell with a lean electrolyte loading of 2µL mAh-1 , a capacity retention of 80.2% is achieved even after 300 cycles. Furthermore, when it is utilized as a solid-state electrolyte, an average Coulombic efficiency of 99.7% and capacity retention of 98.7% are attained under operations at 50°C without external pressure or a pre-aging process.

Molecular Level Origin of Ion Dynamics in Highly Concentrated Electrolytes.

Single-ion conducting liquid electrolytes are key to achieving rapid charge/discharge in Li secondary batteries. The Li+ transference (or transport) numbers are the defining properties of such electrolytes and have been discussed in the framework of concentrated solution theories. However, the connection between macroscopic transference and microscopic ion dynamics remains unclear. Molecular dynamics simulations were performed to obtain direct information regarding the microscopic behaviors in highly concentrated electrolytes, and the relationships between these behaviors and the transference number were determined under anion-blocking conditions. Various solvents with different donor numbers (DNs) were used along with a Li salt of the weakly Lewis basic bis(fluorosulfonyl)amide anion for electrolyte preparation. Favorable ordered Li+ structuring and a continuous Li+ conduction pathway were observed for the fluoroethylene carbonate-based electrolyte due to its low DN. The properties were less pronounced at higher DNs, e.g., for the dimethyl sulfoxide-based electrolyte. The τLi-solventlife/τdipolerelax ratio was introduced as a factor for ion dynamics, and the two mechanisms of ion transport were considered an exchange mechanism (τLi-solventlife/τdipolerelax < 1) and a vehicle mechanism (translational motion of solvated Li+) (τLi-solventlife/τdipolerelax ≥ 1). Vehicle-type transport was dominant with high DNs, while exchangeable transport was preferable at lower DNs. These findings should aid the further selection of solvents and Li salts to prepare single-ion conducting electrolytes.

A stable full cell having high energy density realized by using a three-dimensional current collector of carbon nanotubes and partial prelithiation of silicon monoxide

The prelithiation of SiO-based negative electrodes is essential for stable and high-energy-density Li secondary batteries. In this study, a new partial prelithiation method by two-stack electrodes was developed using lightweight and high-capacity carbon-coated silicon monoxide (SiO/C) films held in a sponge-like matrix of carbon nanotubes (CNTs). The charge-discharge cycles of a full cell with the partially prelithiated SiO/C-CNT negative electrode (p-LixSiO/C-CNT with SiO/C content of 85 mass%) and LiNi0.8Mn0.1Co0.1O2 (NCM811)-CNT positive electrode (NCM content of 97 mass%) reduced the irreversible capacity, achieving high energy densities per the total mass of the negative and positive electrodes of 542 and 420 W h kgelectrode−1 at the 1st and 300th cycle, respectively, with high areal capacities of 4.6 and 3.1 mA h cm−2 for the negative and positive electrodes. The flexible CNT sponge matrix expanded/shrunk reversibly during lithiation/delithiation and retained its structure, whereas the thin Li metal formed Li dendrites and dead Li after cycling, as demonstrated by scanning electron microscopy. The partial prelithiation method of simply stacking the pristine SiO/C-CNT film with a fully prelithiated film enables the careful control of the degree of prelithiation, contributing to full cells of various chemistries.

Li Electrodeposition Modeling for Analyzing the Effect of Li+ Redistribution in Li Metal Secondary Batteries

To meet the high-energy-density requirement of Li secondary batteries for EV applications, Li metal is still being re-examined extensively beyond conventional carbon-based anode active materials. However, unlike intercalation mechanism-based anodes, Li metal anodes (LMAs), suffering from significant surface morphology changes during electroplating and stripping, can accompany several issues such as Li dendrite growth and continuous side reactions, thereby leading to the poor electrochemical performance and cycle stability. Among various reasons of the Li dendrite formation, inhomogeneous and slow Li+ transport to the LMAs are representatively known, accelerating irregular electrodeposition and rapid Li+ depletion on the LMA surface.In this study, we attempted to simulate Li dendrite growth under practical current conditions by developing a 2D Li electrodeposition model. Based on this model, we analyzed the geometric-electrochemical characteristics of Li metal interface depending on Li+ concentration distribution in the electrolyte and SEI. Furthermore, in order to verify a nanomaterial-based micro-convection effect in the electrolyte for improving mass transfer, the Li+ concentration change nearby the interface was calculated while simulating the Li dendritic growth. Also, real 2D morphologies of the Li dendrites were reconstructed and analyzed together in a similar way. As a result, the micro-convection enables relatively uniform Li+ distribution at the LMA interface and enhances the mass transport in the electrolyte, which can suppress the Li dendrite growth even at 5.0 mA cm-2.

Li-Ion Transport and Solution Structure in Sulfolane-Based Localized High-Concentration Electrolytes

Localized high-concentration electrolytes (LHCEs), which are mixtures of highly concentrated electrolytes (HCEs) and non-coordinating diluents, have attracted significant interest as promising liquid electrolytes for next-generation Li secondary batteries, owing to their various beneficial properties both in the bulk and at the electrode/electrolyte interface. We previously reported that the large Li+-ion transference number in sulfolane (SL)-based HCEs, attributed to the unique exchange/hopping-like Li+-ion conduction, decreased upon dilution with the non-coordinating hydrofluoroether (HFE) despite the retention of the local Li+-ion coordination structure. Therefore, in this study, we investigated the effects of HFE dilution on the Li+ transference number and the solution structure of SL-based LHCEs via the analysis of dynamic ion correlations and molecular dynamics simulations. The addition of HFE caused nano-segregation in the SL-based LHCEs to afford polar and nonpolar domains and fragmentation of the polar ion-conducting pathway into smaller clusters with increasing HFE content. Analysis of the dynamic ion correlations revealed that the anti-correlated Li+–Li+ motions were more pronounced upon HFE addition, suggesting that the Li+ exchange/hopping conduction is obstructed by the non-ion-conducting HFE-rich domains. Thus, the HFE addition affects the entire solution structure and ion transport without significantly affecting the local Li+-ion coordination structure. Further studies on ion transport in LHCEs would help obtain a design principle for liquid electrolytes with high ionic conductivity and large Li+-ion transference numbers.

Li-metal anode of fixed volume located behind current collector for safe li storage

Li-metal anodes (LMAs) have been researched as a core technology for high-performance Li secondary batteries, but the problems of dendritic Li growth and unstable changes in the electrode thickness remain to be solved. In this study, a new anode structure is proposed in which Li is plated in a fixed-volume space located behind the current collector, unlike conventional electrodes where Li is stored on the front side facing the counter electrode. The anode is composed of a current collector with hole arrays and a spacer mesh to secure the Li storage space, and subjected to an insulation/Li-philic dual surface treatment to guide Li plating in the area behind the current collector. This new anode structure prevents the growth of Li dendrites into the separator and maintains a constant electrode thickness, thus ensuring stable full-cell operation. The anode structure is expected to serve as a platform in which microscopic material technologies can be installed for the further development of effective LMA technology.

Li-phobicity of polyvinyl alcohol for the control of Li electrodeposition in Li-secondary batteries

As various types of new electrode designs for Li-secondary batteries are researched, development of technologies to control the electrodeposition of Li is required. Herein, the Li affinity of polyvinyl alcohol (PVA) is investigated to examine its applicability as a coating material for the control of Li plating position in battery anodes, via first-principle simulation and experimental studies. The simulation indicates that the oxygen ions in the PVA provide favorable adsorption sites for Li at the initial stage of Li deposition, but the sites are readily passivated because Li is combined with multiple O ions. Therefore, the binding force for the subsequent Li becomes weak and the PVA surface generally exhibits Li-phobic characteristics. The experiment of a patterned PVA coating on the Li-ion battery anode demonstrates the anti-Li-plating function of the PVA. From the investigation results, it is concluded that PVA is Li-phobic, and can be utilized for guiding the Li plating in the future design of Li-secondary battery anodes.

NASICON-Type Li1+xAlxZryTi2−x−y(PO4)3 Solid Electrolytes: Effect of Al, Zr Co-Doping and Synthesis Method

Replacing liquid electrolytes with solid-state conductors is one of the key challenges to increasing the safety and energy density of next-generation Li secondary batteries. In this work, the NASICON-type Li1+xAlxZryTi2−x−y(PO4)3 with 0 ≤ x, y ≤ 0.2 solid electrolytes were synthesized using solid-state and sol-gel techniques at various sintering temperatures (800, 900, and 1000 °C). Their morphology and conducting properties were studied to determine the optimal dopant content and synthesis method. Li1.2Al0.2Zr0.1Ti1.7(PO4)3 and Li1.1Al0.1Zr0.2Ti1.7(PO4)3 prepared at 900 °C using a solid-state reaction exhibit the highest total conductivity at 25 °C (7.9 × 10−4 and 5.4 × 10−4 S cm−1, respectively), which is due to the optimal size of lithium transport channels, as well as the high density of these samples. The potential profile of Li|Li1.2Al0.2Zr0.1Ti1.7(PO4)3|Li cells was retained during cycling at a current density of 0.05 mA cm−2 for 100 h, indicating a high interfacial Li metal/electrolyte stability.

On the concentration polarisation in molten Li salts and borate-based Li ionic liquids.

Electrolytes that transport only Li ions play a crucial role in improving rapid charge and discharge properties in Li secondary batteries. Single Li-ion conduction can be achieved via liquid materials such as Li ionic liquids containing Li+ as the only cations because solvent-free fused Li salts do not polarise in electrochemical cells, owing to the absence of neutral solvents that allow polarisation in the salt concentration and the inevitably homogeneous density in the cells under anion-blocking conditions. However, we found that borate-based Li ionic liquids induce concentration polarisation in a Li/Li symmetric cell, which results in their transference (transport) numbers under anion-blocking conditions (tabcLi) being well below unity. The electrochemical polarisation of the borate-based Li ionic liquids was attributed to an equilibrium shift caused by exchangeable B-O coordination bonds in the anions to generate Li salts and borate-ester solvents at the electrode/electrolyte interface. By comparing borate-based Li ionic liquids containing different ligands, the B-O bond strength and extent of ligand exchange were found to be directly linked to the tabcLi values. This study confirms that the presence of dynamic exchangeable bonds causes electrochemical polarisation and provides a reference for the rational molecular design of Li ionic liquids aimed at achieving single-ion conducting liquid electrolytes.

Organic ionic plastic crystals: flexible solid electrolytes for lithium secondary batteries

This review introduces organic ionic plastic crystals (OIPCs) as Li-ion conductors and recent progress in the development of Li secondary batteries with OIPC-based solid electrolytes.

Performance of Lithium Ion Battery with Graphene Microstructure in Cathode

Lithium-ion battery is a promising energy source with high output voltage, large energy density, low auto discharge, and no memory effect. Graphene, as a dimensional carbon material, has excellent electrical conductivity, strong mechanical properties, a large specific surface area, which has been widely applied in lithium-ion battery for modifying the cathode material of lithium secondary batteries, thus significantly promoting the flow performance, conductivity, and cycling stability of Li secondary batteries. In this review, we discussed the excellent properties of various cathode materials based on graphene with different microstructures including three dimensional network structure, Core/Shell structure, layered structure, porous structure, and sandwich structure, which could provide motivations for improving the performance of the lithium-ion battery.

1-D Modeling of an Electroactive Electrolyte for Advanced Primary and Secondary Li Batteries

In the search for more energy- and power- dense battery materials, the cathode is most often the component that is engineered to boost operating voltage and capacity. However, new approaches to battery design have yielded performance improvements by designing electrolytes with reactive species that increase capacity and energy density of full-cells. These approaches borrow insights from commercial battery technologies such as Pb-H2SO4, Li-SO2, or Li-SOCl2, where the cathodic reaction involves liquid-phase active species1–3, while employing solid-phase cathode materials.To better understand how specific examples of electroactive electrolytes improve rather than impede performance, our work focuses on two battery chemistries: a primary Li-CFx cell with an irreversible electrolyte reaction, and a secondary Li-LMR cell with a reversible electrolyte reaction. For each case, we develop a 1-D COMSOL model to investigate how the reaction of electrolyte species affects cell impedance, impacts Li cation transport, alters the electrolyte conductivity, and finally how each of these mechanistically impact the energy and power density of the cell. Our modeling work is complemented by experimental studies that measure important electrolyte and cathode properties at various states of discharge or cycling.(1) Park, H.; Lim, H.-D.; Lim, H.-K.; Seong, W. M.; Moon, S.; Ko, Y.; Lee, B.; Bae, Y.; Kim, H.; Kang, K. High-Efficiency and High-Power Rechargeable Lithium–Sulfur Dioxide Batteries Exploiting Conventional Carbonate-Based Electrolytes. Nat. Commun. 2017, 8 (1), 14989. https://doi.org/10.1038/ncomms14989.(2) Schlaikjer, C. R.; Goebel, F.; Marincic, N. Discharge Reaction Mechanisms in Li / SOCl2 Cells. J. Electrochem. Soc. 1979, 126 (4), 513–522. https://doi.org/10.1149/1.2129078.(3) Ruetschi, P. Aging Mechanisms and Service Life of Lead–Acid Batteries. J. Power Sources 2004, 127 (1–2), 33–44. https://doi.org/10.1016/j.jpowsour.2003.09.052.

A Fluorine-Based Linear Carbonate Electrolyte Additive for Enhanced High-Voltage Cycle Performance of Li-Metal Secondary Batteries

Due to growing demand for electric vehicles (EVs) and energy storage systems (ESS), it is essential to meet the requirement for high energy density of Li secondary batteries. In this sense, an electrode chemistry matching high-Ni cathode materials and thin Li metal anode has been investigated most actively under high voltage operation. As a result, there are a variety of degradation issues on both electrodes like high-resistance cathode electrolyte interphase (CEI) as well as solid electrolyte interphase (SEI) on the anode, electrolyte depletion, or Li dendritic growth. Thus, advanced electrolytes containing functional additives are extensively being developed to mitigate those stresses occurred in the high-energy-density Li-metal secondary batteries (LMSBs). Especially, to minimize the amount of expensive additives, many research groups have made much effort in discovering new or multi-functional additives for LMSBs.In this work, we report a bis(2-fluoroethyl) carbonate (B-FEC) as a new fluorine-based linear carbonate electrolyte additive to stabilize the SEI even in the high voltage conditions (4.5 V cut-off). To confirm the role of B-FEC on electrochemical properties, we evaluated its electrochemical properties with Li/Li symmetric cells as well as LiNi0.6Co0.2Mn0.2O2 (NCM 622)/Li cells with or without B-FEC. Also, various analysis data were also gathered to check the morphological and compositional changes caused by B-FEC through SEM, XPS, etc.

Synergistic effects between dual salts and Li nitrate additive in ether electrolytes for Li-metal anode protection in Li secondary batteries

The practical applications of Li-metal batteries (LMBs) are limited by dendrite formation. Thus, a synergistic approach for enhancing the cycling performance of LMBs by combining dual salts with lithium nitrate as an additive in an ether-based electrolyte system is presented. The dual salts, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium bis(oxalate)borate (LiBOB), and lithium nitrate (LiNO3), are dissolved in a dual ether-based solvent composed of 1,2-dimethoxyethane and 1,3-dioxane. The electrolyte shows high electrochemical stability of up to ∼ 4.6 V, circumventing the drawback of ether-based solvents, which are known to exhibit an oxidation potential of <4 V. Moreover, dendrite inhibition is enhanced by the formation of a robust and passivating solid-electrolyte interface (SEI). Additionally, the rate capability and cycling performance are enhanced up to 1000 cycles, with a 90.0% discharge capacity retention at 1C for the lithium iron phosphate (LFP)/Li battery. Furthermore, Li/Li symmetric cells exhibit a high stability with >2300 h of repeated stripping and plating at 0.5 mA cm−2, which is an enhancement of approximately 300% compared with the reference electrolyte. This study provides a promising strategy for the practical application of ether-based electrolytes for Li-metal anodes in rechargeable batteries at low salt concentrations.

Bridging 1D Inorganic and Organic Synthesis to Fabricate Ultrathin Bismuth-Based Nanotubes with Controllable Size as Anode Materials for Secondary Li Batteries.

The growth of ultrathin 1D inorganic nanomaterials with controlled diameters remains challenging by current synthetic approaches. A polymer chain templated method is developed to synthesize ultrathin Bi2 O2 CO3 nanotubes. This formation of nanotubes is a consequence of registry between the electrostatic absorption of functional groups on polymer template and the growth habit of Bi2 O2 CO3 . The bulk bismuth precursor is broken into nanoparticles and anchored onto the polymer chain periodically. These nanoparticles react with the functional groups and gradually evolve into Bi2 O2 CO3 nanotubes along the chain. 5.0 and 3.0nm tubes with narrow diameter deviation are synthesized by using branched polyethyleneimine and polyvinylpyrrolidone as the templates, respectively. Such Bi2 O2 CO3 nanotubes show a decent lithium-ion storage capacity of around 600mA h g-1 at 0.1 A g-1 after 500 cycles, higher than other reported bismuth oxide anode materials. More interestingly, the Bi materials developed herein still show decent capacity at very low temperatures, that is, around 330mA h g-1 (-22 °C) and 170mA h g-1 (-35 °C) after 75 cycles at 0.1 A g-1 , demonstrating their promising potential for practical application in extreme conditions.

Synergistic Effect of Dual-Ceramics for Improving the Dispersion Stability and Coating Quality of Aqueous Ceramic Coating Slurries for Polyethylene Separators in Li Secondary Batteries

We demonstrate that dispersion stability and excellent coating quality are achieved in polyethylene (PE) separators by premixing heterogeneous ceramics such as silica (SiO2) and alumina (Al2O3) in an aqueous solution, without the need for functional additives such as dispersing agents and surfactants. Due to the opposite polarities of the zeta potentials of SiO2 and Al2O3, SiO2 forms a sheath around the Al2O3 surface. Electrostatic repulsion occurs between the Al2O3 particles encapsulated in SiO2 to improve the dispersion stability of the slurry. The CCSs fabricated using a dual ceramic (SiO2 and Al2O3)-containing aqueous coating slurry, denoted as DC-CCSs, exhibit improved physical properties, such as a wetting property, electrolyte uptake, and ionic conductivity, compared to bare PE separators and CCSs coated with a single ceramic of Al2O3 (SC-CCSs). Consequently, DC-CCSs exhibit an improved electrochemical performance, in terms of rate capability and cycle performance. The half cells consisting of DC-CCSs retain 93.8% (97.12 mAh g−1) of the initial discharge capacity after 80 cycles, while the bare PE and SC-CCSs exhibit 22.5% and 26.6% capacity retention, respectively. The full cells consisting of DC-CCSs retain 90.9% (102.9 mAh g−1) of the initial discharge capacity after 400 cycles, while the bare PE and SC-CCS exhibit 64.7% and 73.4% capacity retention, respectively.

Upgrading the Properties of Ceramic-Coated Separators for Lithium Secondary Batteries by Changing the Mixing Order of the Water-Based Ceramic Slurry Components

Developing uniform ceramic-coated separators in high-energy Li secondary batteries has been a challenging task because aqueous ceramic coating slurries have poor dispersion stability and coating quality on the hydrophobic surfaces of polyolefin separators. In this study, we develop a simple but effective strategy for improving the dispersion stability of aqueous ceramic coating slurries by changing the mixing order of the ceramic slurry components. The aqueous ceramic coating slurry comprises ceramics (Al2O3), polymeric binders (sodium carboxymethyl cellulose, CMC), surfactants (disodium laureth sulfosuccinate, DLSS), and water. The interaction between the ceramic slurry components is studied by changing the mixing order of the ceramic slurry components and quantitatively evaluating the dispersion stability of the ceramic coating slurry using a Lumisizer. In the optimized mixing sequence, Al2O3 and DLSS premixed in aqueous Al2O3-DLSS micelles through strong surface interactions, and they repel each other due to steric repulsion. The addition of CMC in this state does not compromise the dispersion stability of aqueous ceramic coating slurries and enables uniform ceramic coating on polyethylene (PE) separators. The prepared Al2O3 ceramic-coated separators (Al2O3–CCSs) exhibit improved physical properties, such as high wettability electrolyte uptake and ionic conductivity, compared to the bare PE separators. Furthermore, Al2O3–CCSs exhibit improved electrochemical performance, such as rate capability and cycling performance. The half cells (LiMn2O4/Li metal) comprising Al2O3–CCSs retain 90.4% (88.4 mAh g−1) of initial discharge capacity after 150 cycles, while 27.6% (26.4 mAh g−1) for bare PE. Furthermore, the full cells (LiMn2O4/graphite) consisting of Al2O3–CCSs exhibit 69.8% (72.2 mAh g−1) of the initial discharge capacity and 24.9% (25.0 mAh g−1) for bare PE after 1150 cycles.

Self-Healing Mechanism of Lithium in Lithium Metal.

Li is an ideal anode material for use in state‐of‐the‐art secondary batteries. However, Li‐dendrite growth is a safety concern and results in low coulombic efficiency, which significantly restricts the commercial application of Li secondary batteries. Unfortunately, the Li‐deposition (growth) mechanism is poorly understood on the atomic scale. Here, machine learning is used to construct a Li potential model with quantum‐mechanical computational accuracy. Molecular dynamics simulations in this study with this model reveal two self‐healing mechanisms in a large Li‐metal system, viz. surface self‐healing, and bulk self‐healing. It is concluded that self‐healing occurs rapidly in nanoscale; thus, minimizing the voids between the Li grains using several comprehensive methods can effectively facilitate the formation of dendrite‐free Li.