Uncontrollable Dendrite Growth Research Articles

Hierarchical Nanosheet Arrays of Metal Oxides Guide Uniform Deposition for Lithium Anodes

Lithium metal, regarded as the “Holy Grail” of lithium battery anodes, has been considered as the most promising material for high-energy density rechargeable batteries. However, its practical application has been hindered by the uncontrolled dendrite growth of the lithium metal during charge–discharge cycles. Guiding uniform deposition of lithium during cycling is an effective route to solve the problem. In this contribution, nanosheet arrays of lithiophilic metal oxides with a hierarchical structure, that is, primary vertical thin arrays coupled with secondary grid-like ones, were constructed on a Cu current collector to regulate lithium nucleation and growth. It was found that the primary vertical thin nanosheet arrays could reduce the current density and provide adequate lithiophilic sites with a lower nucleation barrier, while the secondary grid-like nanosheet arrays offered facile Li-ion diffusion and a large volume for lithium deposition. Owing to the uniform deposition behavior and stable electrod...

Conducting and Lithiophilic MXene/Graphene Framework for High-Capacity, Dendrite-Free Lithium–Metal Anodes

Li-metalanode is widely acknowledged as the ideal anode for high-energy-density batteries, but seriously hindered by the uncontrollable dendrite growth and infinite volume change. Toward this goal, suitable stable scaffolds for dendrite-free Li anodes with large current density (>5 mA cm-2) and high Li loading (>90%) are highly in demand. Herein, a conductive and lithiophilic three-dimensional (3D) MXene/graphene (MG) framework is demonstrated for a dendrite-free Li-metal anode. Benefiting from its high surface area (259 m2 g-1) and lightweight nature with uniformly dispersed lithiophilic MXene nanosheets as Li nucleation sites, the as-formed 3D MG scaffold showcases an ultrahigh Li content (∼92% of the theoretical capacity), as well as strong capabilities in suppressing the Li-dendrite formation and accommodating the volume changes. Consequently, the MG-based electrode exhibits high Coulombic efficiencies (∼99%) with a record lifespan up to 2700 h and is stable for 230 cycles at an ultrahigh current density of 20 mA cm-2. When coupled with Li4Ti5O12 or sulfur, the MG-Li/Li4Ti5O12 full-cell offers an enhanced capacity of 142 mAh g-1 after 450 cycles, while the MG-Li/sulfur cell delivers an improved rate performance, implying the great potential of this 3D MG framework for building long-lifetime, high-energy-density batteries.

Copper decorated ultralight 3D carbon skeleton derived from soybean oil for dendrite-free Li metal anode

Abstract Lithium metal has been regarded as the most promising anode material for next-generation lithium batteries due to its high theoretical capacity and low potential. However, uncontrolled dendrite growth during cycling has remained a big challenge, resulting in poor capacity retention and safety issue. Herein, an ultralight hollow 3D carbon skeleton was fabricated from soybean oil through a facile chemical vapor deposition method, which was subsequently coated with copper oxide layer to improving Li wettability. Molten Li can be infused into the 3D carbon host rapidly due to the interaction between copper oxide and liquid Li. The in situ formed Cu nanograins highly dispersing on the carbon skeleton play a key role in homogenizing Li nucleation. The hollow 3D structure of carbon skeleton can accommodate the volume variations of the electrode and regulate Li stripping/plating behavior, thus suppress the dendrite growth and dead Li formation effectively. As a result, the Li composite electrode presents high areal capacity and cycle stability in both symmetric cell and Li-S cell. This work provides an alternative strategy to develop high loading Li composite anodes.

3D Lithiophilic "Hairy" Si Nanowire Arrays @ Carbon Scaffold Favor a Flexible and Stable Lithium Composite Anode.

Lithium metal anode is considered to be a promising candidate for high-energy-density lithium-based batteries. However, the safety issue induced by uncontrollable dendrite growth hinders the commercialization of a Li anode. Herein, self-supported three-dimensional flexible carbon cloth covered with a lithiophilic silicon nanowire array is constructed as the host for loading of molten Li to achieve the C/SiNW/Li composite anode. The electrode component of the carbon cloth provides the flexible and conductive substrate to accommodate the volume change during the stripping/plating of Li and facilitate more efficient electron transport, while silicon nanowires improve the wettability of the carbon host to liquefied Li and render uniform Li deposition on the surface of the composite electrode. The as-prepared C/SiNW/Li composite anode exhibits enhanced cycling stability with a low hysteresis of 40 mV for more than 200 h and a better rate tolerance even at a current density of up to 5 mA cm-2. When coupling with the LiNi0.5Mn1.5O4 cathode, the full cells using the C/SiNW/Li composite anode demonstrate a remarkable electrochemical performance with an exceptional rate performance of up to 10 C and stable long-term cycling (the capacity retention of 62% at a 5 C rate over 2000 cycles), which is much higher than the cells with pure Li anode. This work provides a universal strategy to fabricate the flexible and stable carbon-based Li metal anode toward high-energy-density batteries.

Lithiophilic montmorillonite serves as lithium ion reservoir to facilitate uniform lithium deposition

The growing demand for lithium batteries with higher energy densities requires new electrode chemistries. Lithium metal is a promising candidate as the anode material due to its high theoretical specific capacity, negative electrochemical potential and favorable density. However, during cycling, low and uneven lithium ion concentration on the surface of anode usually results in uncontrolled dendrite growth, especially at high current densities. Here we tackle this issue by using lithiophilic montmorillonite as an additive in the ether-based electrolyte to regulate the lithium ion concentration on the anode surface and thus facilitate the uniform lithium deposition. The lithiophilic montmorillonite demonstrates a pumping feature that improves the self-concentrating kinetics of the lithium ion and thus accelerates the lithium ion transfer at the deposition/electrolyte interface. The signal intensity of TFSI− shows negligible changes via in situ Raman tracking of the ion flux at the electrochemical interface, indicating homogeneous ion distribution, which can lead to a stable and uniform lithium deposition on the anode surface. Our study indicates that the interfacial engineering induced by the lithiophilic montmorillonite could be a promising strategy to optimize the lithium deposition for next-generation lithium metal batteries.

Formation of hollow nanofiber rolls through controllable carbon diffusion for Li metal host

Abstract Lithium metal has long been seen as a promising battery anode due to its high specific capacity and low anode potential. However, serious safety hazards and poor electrochemical performance caused by uncontrollable dendritic growth hinder its practical application. Here, a stable lithium@nanofiber roll composite electrode is developed by utilizing the carbon diffusion effect. By combining carbon with different metallic elements, a hollow structure with inner lithiophilic surface has been successfully obtained through an orderly chemical potential gradient. The as-prepared nanofiber rolls are demonstrated as the host to accommodate lithium metal and impressively, superior electrochemical performance can be achieved by the resulting composite electrode with high coulombic efficiency of ∼99.6% for over 1400 cycles at 0.5 mA cm−2, 1 mA h cm−2. This study presents new insights in understanding the carbon diffusion and may open up new avenues for preparing fiber-based Li-metal host.

Highly stable lithium metal anode with near-zero volume change enabled by capped 3D lithophilic framework

Uncontrolled dendrite growth, infinite volume-change and unstable solid-electrolyte interface in lithium metal anode have seriously hampered the further applications of Li-based batteries. Despite considerable efforts, challenges still remain in obtaining dendrite-free lithium metal anode with low volume change, especially at high current density with high areal capacity. Herein, we firstly design and fabricate a capped 3D framework, comprising a lithiphilic matrix with polyacrylic acid (PAA) coating, to construct stable artificial SEI on 3D high-lithium-reservoir host. In this way, the in-situ formed high-ion conductive LiPAA can facilitate Li+ transfer inside the skeleton rather than depositing on the surface, leading to dendrite-free lithium anode. Based on the rational structure design, PAA@Li matrix exhibits near-zero volume change upon the cycling, which is tracked by in-situ swelling tester. Therefore, PAA@Li matrix undoubtedly demonstrates enhanced battery performance with excellent cycling stability for 350 h at both high areal capacity (5 mA h/cm2) and high current density (5 mA/cm2). The corresponding LiCoO2|PAA@Li matrix full cell also presents improved long-term stability of 81% retention after 1000 cycles. The novel capped 3D framework may open up a new horizon to achieve highly stable lithium anode with zero volume change.

RuO2 Particles Anchored on Brush-Like 3D Carbon Cloth Guide Homogenous Li/Na Nucleation Framework for Stable Li/Na Anode.

Lithium (sodium)-metal batteries are the most promising batteries for next-generation electrical energy storage due to their high volumetric energy density and gravimetric energy density. However, their applications have been prevented by uncontrollable dendrite growth and large volume expansion during the stripping/plating process. To address this issue, the key strategy is to realize uniform lithium (sodium) deposition during the stripping/plating process. Herein, a thin lithiophilic layer consisting of RuO2 particles anchored on brush-like 3D carbon cloth (RuO2 @CC) is prepared by a simple solution-based method. After infusion of Li, the RuO2 @CC transfers to Li-Ru@CC. Ru nanoparticles not only play a role in leading Li+ (Na+ ) to plate on the 3D carbon framework, but also lower local current density because of the good electrical conductivity. Furthermore, density functional theory calculations demonstrate that Ru metal, the reaction product of alkali metal and Ru, can lead Li+ to plate evenly around carbon fiber owing to the strong binding energy with Li+ . The Li-Ru@CC anode shows ultralong cycle life (1500 h at 5 mA cm-2 ). The full cell of Li-Ru@CC|LiFePO4 exhibits lower polarization (90% capacity retention after 650 cycles). In addition, sodium metal batteries based on Na-Ru@CC anodes can achieve similar improvement.

Controlling Li Ion Flux through Materials Innovation for Dendrite‐Free Lithium Metal Anodes

AbstractLithium (Li) metal with high theoretical capacity and the lowest electrochemical potential has been proposed as the ideal anode for high‐energy‐density rechargeable battery systems. However, the practical commercialization of Li metal anodes is precluded by a short lifespan and safety problems caused by their intrinsically high reductivity, infinite volume change, and uncontrollable dendrite growth during deposition and dissolution processes. Plenty of strategies have been introduced to solve the above‐mentioned problems. Among these, controlling Li+ flux plays a vital role to directly influence the plating and stripping process. In this work, the fundamental effect of Li+ flux distribution on Li nucleation and early dendrite growth is discussed. Then, recent strategies of controlling Li+ flux to suppress dendrite formation and growth through materials design are summarized, including homogenizing Li+ flux, localizing Li+ flux, and guiding gradient Li+ distribution. Finally, underexplored materials are proposed and explored to control Li+ flux and further directions for dendrite‐free Li anodes. It is expected that this progress report will help to deepen the understanding of Li+ flow tuning and morphology control of Li anodes and eventually facilitate the practical application of Li metal batteries.

Marginal Magnesium Doping for High‐Performance Lithium Metal Batteries

AbstractDue to unparalleled theoretical capacity and operation voltage, metallic Li is considered as the most attractive candidate for lithium‐ion battery anodes. However, Li metal electrodes suffer from uncontrolled dendrite growth and consequent interfacial instability, which result in an unacceptable level of performance in cycling stability and safety. Herein, it is reported that a marginal amount (1.5 at%) of magnesium (Mg) doping alters the surface properties of Li metal foil drastically in such a way that upon Li plating, a highly dense Li whisker layer is induced, instead of sharp dendrites, with enhanced interfacial stability and cycling performance. The effect of Mg doping is explained in terms of increased surface energy, which facilitates plating of Li onto the main surface over the existing whiskers. The present study offers a useful guideline for Li metal batteries, as it largely resolves the longstanding shortcoming of Li metal electrodes without significantly sacrificing their main advantages.

In Situ Coupling of Colloidal Silica and Li Salt Anion toward Stable Li Anode for Long-Cycle-Life Li-O2 Batteries

Summary Lithium-oxygen (Li-O2) batteries are promising next-generation batteries owing to their ultrahigh theoretical energy density. However, Li metal anodes in Li-O2 batteries are still plagued by uncontrollable dendrite growth and serious parasitic reactions. Herein, we report an electrolyte regulation strategy via in situ coupling of CF3SO3− and hydrophobic silica colloidal nanoparticle through electrostatic interaction. With the assistance of the seed crystal effect and the solid-like rheological properties, 10 wt % hydrophobic silica colloid electrolyte (HSCE) enables the dendrite-free morphology of Li deposition and helps form a stable solid-electrolyte interface, which can reduce the impedance by about 45-fold after long-term cycling. Moreover, 10 wt % HSCE with a lower diffusion coefficient can achieve a 980-fold better anticorrosion effect than 0 wt % HSCE. Consequently, the 10 wt % HSCE batteries exhibit a stable plating/stripping process (30 mV in overpotential up to 700 h) and a good anodic cycle life in Li-O2 batteries (550 cycles).

Three-dimensional carbon felt host for stable sodium metal anode

Metallic Na possesses high specific capacity and lowest electrochemical potential of all possible candidates, and therefore being regarded as one of the most promising anode materials for Na batteries. Nevertheless, unstable solid electrolyte interface, infinite volume change and uncontrollable dendritic Na growth upon repeated Na plating/stripping processes lead to low Coulombic efficiency, poor cyclability and safety concerns of Na metal anode. Herein, a three-dimensional carbon felt host was employed to suppress Na dendrite growth, thus achieving highly reversible Na plating/stripping process. The interstitial space inside the carbon felt framework accommodates Na deposition, and the plentiful active sites guide homogenous Na nucleation and growth without dendrite formation. As a result, the carbon felt exhibits stable cycling lifetime for 1100 h and 350 h at 1 mA cm−2 and 2 mA cm−2 respectively, which are 5.6 and 3.9 times longer than that of Al foil. Moreover, the carbon felt possesses high average Coulombic efficiency of ∼99.3% for 500 cycles at 0.5 mA cm−2. When paired with Na2/3Ni1/3Mn2/3O2 cathode, the full cell delivers a high capacity retention of 95.1% over 150 cycles.

Biofilm Nanofiber-Coated Separators for Dendrite-Free Lithium Metal Anode and Ultrahigh-Rate Lithium Batteries.

Rechargeable batteries that combine high energy density with high power density are highly demanded. However, the wide utilization of lithium metal anode is limited by the uncontrollable dendrite growth, and the conventional lithium-ion batteries (LIBs) commonly suffer from low rate capability. Here, we for the first time develop a biofilm-coated separator for high-energy and high-power batteries. It reveals that the coating of Escherichia coli protein nanofibers can improve electrolyte wettability and lithium transference number and enhance adhesion between separators and electrodes. Thus, lithium dendrite growth is impeded because of the uniform distribution of the Li-ion flux. The modified separator also enables the stable cycling of high-voltage Li|Li1.2Mn0.6Ni0.2O2 (LNMO) cells at an extremely high rate of 20 C, delivering a high specific capacity of 83.1 mA h g-1, which exceeds the conventional counterpart. In addition, the modified separator in the Li4Ti5O12|LNMO full cell also exhibits a larger capacity of 68.2 mA h g-1 at 10 C than the uncoated separator of 37.4 mA h g-1. Such remarkable performances of the modified separators arise from the conformal, adhesive, and endurable coating of biofilm nanofibers. Our work opens up a new opportunity for protein-based biomaterials in practical application of high-energy and high-power batteries.

Electrolyte additive maintains high performance for dendrite-free lithium metal anode

Because of their high capacity and low potential, lithium metal anodes are considered to be promising candidates for next generation electrode materials. However, the safety concerns and limited cycling life associated with uncontrollable dendrite growth hamper practical applications. In this work, the acidified cellulose ester, which is a mixed fiber microporous membrane film, was used as a novel electrolyte additive that effectively improves the cycle stability of the lithium metal anode and inhibits dendrite growth. The focus of this paper is on inhibiting the formation and growth of lithium dendrites. The coulombic efficiency of a Li|Cu battery with this acidified cellulose ester additive remains stable at 99% after 500 cycles under a current density of 1mA/cm2. Symmetric batteries also remain stable after 500 cycles (1000 h) under a current density of 1 mA/cm2. These superior properties can be ascribed to the induced nucleation and the uniform distribution of lithium ion flux. This study uncovers an approach for effectively enabling stable cycling of dendrite-free lithium metal anodes.

Superlithiophilic Amorphous SiO2-TiO2 Distributed into Porous Carbon Skeleton Enabling Uniform Lithium Deposition for Stable Lithium Metal Batteries.

Lithium (Li) metal anodes have garnered increasing interest in recent years as its high theoretical capacity and low electrochemical potential promises a myriad of opportunities for various applications. However, one critical issue to overcome is the inhomogeneous deposition of Li+ during the plating and stripping process. This inhomogeneous deposition could result in uncontrollable dendrite growth, further leading to poor coulombic efficiency, shorter lifecycles, and safety concerns due to internal short circuit and thermal runaways. To address these issues, a 3D porous core–shell fiber scaffold is presented, comprising of well‐dispersed SiO2, TiO2, and carbon, as superlithiophilic host materials for lithium anodes. The amorphous SiO2 and TiO2 allow for controllable nucleation and deposition of metal Li inside the porous core–shell fiber even at ultrahigh current densities of 10 mA cm−2. In addition, the interconnected conductive fiber with high porosity enables good electrical conductivity with fast ion transport and excellent mechanical strength to withstand massive Li loading during repeated cycles of stripping and plating. As a result, excellent cycling performance and high rate capability are observed in both symmetric cells and full cells, highlighting the feasibility of the proposed Li anode composite.

The Marriage of Solid-State Electrolyte and Safe Lithium Metal Anodes in a Working Battery

Li metal is extensively focused due to its ultrahigh theoretical capacity (3860 mAh g−1, 10 times higher than that of graphite) and the most negative electrochemical potential (−3.040 V versus standard hydrogen electrode). Solid-state electrolyte exhibits enhanced safety relative to non-aqueous electrolyte. Therefore, the marriage of Li metal and solid-state electrolyte is expected to inherit the merits of both. However, the competitive solid-state lithium metal batteries encounter formidable challenges, including dendrite issues and poor solid-solid contact. Investigating the interdisciplinary issues of solid-state electrolyte and Li metal in integrated cells is necessary to realize the efficient and safe solid-state lithium metal batteries. This talk focuses on the energy chemistry issues generated from the marriage of Li metal and solid-state electrolyte, instead of their respective problems. Firstly, the issues generated from the marriage of lithium metal anode and solid-state electrolyte. Specific attentions are paid to the large interfacial resistance, uncontrolled dendrite growth, and low operation current/capacity. The primarily understanding the ionic channels in the composite electrolyte and space charge layers in the interfacial region are also included. Based on these dilemmas and working principles, emerging strategies to render solid-state lithium metal batteries are introduced. Finally, the general conclusion and perspective on the current limitations and recommended research of solid-state lithium metal batteries are presented.

Composite Lithium Metal Anode Via a Simple Rolling-Cutting Method

Lithium metal–based batteries are attractive energy storage devices because of high energy density. However, uncontrolled dendrite growth and virtually infinite volume change, which cause performance fading and safety concerns, have limited their applications. Here, we demonstrate that a composite lithium metal electrode with an ion-conducting mesoscale skeleton can improve electrochemical performance by locally reducing the current density. In addition, the potential for short-circuiting is largely alleviated due to side deposition of mossy lithium on the three-dimensional electroactive surface of the composite electrode. Moreover, the electrode volume only slightly changes with the support of a rigid and stable scaffold. Therefore, this mesoscale composite electrode can cycle stably for 200 cycles with low polarization under a high areal current density up to 5 mA/cm2. Most attractively, the proposed fabrication process, which only involves simple mechanical deformation, is scalable and cost effective, providing a new strategy for developing high performance and long lifespan lithium anodes. It is worth noting that this composite electrode design holds great promise for metal electrodes coupled with solid electrolyte. Figure 1

Lithium Metal Protection through Flexible Composite Electrolyte with Immobilized Anions

Li metal electrode is regarded as a “Holy Grail” anode for next-generation batteries due to its extremely high theoretical capacity and lowest reduction potential. Unfortunately, uncontrolled dendrite growth leads to serious safety issues. This work realizes a dendrite-free Li metal anode by introducing anion-immobilized composite solid electrolyte, where anions are tethered to polymer chains and ceramic particles. Immobilized anions contribute to uniform distribution of Li ions and dendrite-free Li deposition. The flexible electrolyte can be applied in all-solid-state Li metal batteries with excellent specific capacities. This work demonstrates a concept to adjust ion distribution based on solid-state electrolytes for safe dendrite-free Li anodes, paving the way to practical Li metal batteries.

In-Plane Highly Dispersed Cu2O Nanoparticles for Seeded Lithium Deposition.

Uncontrollable dendrite growth is one of the major problems that hinders the application of lithium (Li) metal anode in rechargeable Li batteries. Achieving uniform Li deposition is the key to tackle this intractable problem. Herein, we report the highly dispersed Cu2O nanoparticles (NPs) in situ anchored on partially reduced graphene oxide via a low-temperature pyrolysis process could serve as seeds for the Li metal deposition. The lithiophilic nature of Cu2O NPs reduces the overpotential of Li nucleation and relieves the electrode polarization, enabling uniform Li nucleation and smooth plating, thus effectively eliminating dendritic and dead Li. As a result, the resulted Li metal electrodes deliver a high Coulombic efficiency of 95.6% after 140 cycles at a current density of 2 mA cm-2 and a prolonged lifespan (800 h at 1 mA cm-2) for the symmetrical cell.

Dendrite-Free Epitaxial Growth of Lithium for Efficient Charging of Li–O2 Batteries with Improved Cycle Life

Realization of rechargeable Li-metal batteries with high energy density is hindered by uneven Li deposition leading to dendrite formation during repeated cycles. Uncontrolled dendrite growth induces internal short-circuits which limit the cell lifetime and generate ohmic heat leading to catastrophic failure when a volatile electrolyte is used. Several strategies have been conceived by the researchers to suppress dendritic growth and delay the premature death of the cell. These efforts include using electrolyte additives to form a porous ion-conducting solid electrolyte interphase (SEI) layer on metal preventing further reaction,1 implementing solid electrolytes with optimum mechanical properties,2 designing a Li matrix,3 reducing local space charge on the Li surface,4 and so on. Although considerable improvements have been achieved from these earlier studies, microscopically smooth Li surface covered with thin and uniform SEI layers is yet to be realized. Alternatively, here we show an unprecedented dendrite-free epitaxial electrodeposition of Li in the presence of LiBr–LiNO3/glyme ether electrolyte under O2 atmosphere. Stripping and plating of Li metal was investigated by using a symmetrical Li│Li cell and it has been found that in 1 M LiNO3+0.05 M LiBr/tetraglyme electrolyte the plating of Li metal shows dendrite-free epitaxial growth up to a thickness of >20 μm which is clearly observed by the scanning electron microscopic (SEM) images and electron backscatter diffraction (EBSD) signal in Figure 1. The epitaxial growth of Li metal seems to be benefited from the synergistic effect of the anions Br− and NO3 − forming a thin and homogeneous Li2O–rich solid electrolyte interphase (SEI) layer which is formed during the very first discharge (stripping) process, where the corrosive nature of Br− removes the original thick passivation layer on Li surface which is then again oxidized (passivated) by the NO3 − to prevent further reactions with the electrolyte. Because of this, the SEI layer remains thin and facilitates the electropolishing effect and gets ready for the epitaxial electroplating of Li in the following charge process. Similar epitaxial growths of Li have been observed for both symmetrical Li│Li cell and Li–O2 full cell resulting in a much improved performance with longer cycle life.5,6 However, in contrast, LiNO3 alone or other lithium salts, such as Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), Lithium trifluoromethanesulfonate (LiTf), do not exhibit any epitaxial Li deposition. This demonstrates the bi-functional activity of the dual anion electrolyte LiNO3–LiBr towards dendrite-free epitaxial growth of Li. The role of deposition rate, effect of electrolyte solvent and a detailed mechanism of epitaxial growth will be discussed in the presentation.