Dendritic Generation Research Articles

Reaction Current Heterogeneity at the Interface between a Lithium Electrode and Polymer/Ceramic Composite Electrolytes

Although lithium metal anodes are expected to increase the energy density of next-generation batteries, dendrite growth during charge remains a major bottleneck preventing widespread implementation. Composite solid electrolytes with ceramic particles embedded in a polymer matrix have the potential to prevent dendrites owing to the higher mechanical stiffness while also possessing the flexibility to maintain contact with the electrode. However, microscopically, the different mechanical and electrochemical properties of the polymer and ceramic domains can cause inhomogeneous charge transfer at the Li/electrolyte interface, which can lead to nonuniform Li deposition and propagation of dendrites. Here, we computationally examine the coupled electrochemical, transport, and mechanical processes at the interface to determine the propensity for dendrite formation and possible approaches to mitigate this issue. Predictions of two possible microstructures at the interface, namely, (i) where both the polymer and ceramic come in contact with Li metal and (ii) when only the polymer comes in contact with Li metal, suggest that the former has a greater tendency for nonuniform plating. In addition, predictions suggest that minimizing the interfacial resistance between polymers and ceramics and incorporating interlayers between the electrode and electrolyte help mitigate current heterogeneity. These predictions provide guidance for experimental approaches to prevent dendrites in composite electrolytes.

Catalytically Induced Robust Inorganic‐Rich Cathode Electrolyte Interphase for 4.5 V Li||NCM622 Batteries

AbstractTailoring inorganic components of cathode electrolyte interphase (CEI) and solid electrolyte interphase (SEI) is critical to improving the cycling performance of lithium metal batteries. However, it is challenging due to complicated electrolyte reactions on cathode/anode surfaces. Herein, the species and inorganic component content of the CEI/SEI is enriched with an objectively gradient distribution through employing pentafluorophenyl 4‐nitrobenzenesulfonate (PFBNBS) as electrolyte additive guided by engineering bond order with functional groups. In addition, a catalytic effect of LiNi0.6Mn0.2Co0.2O2 (NCM622) cathode is proposed on the decomposition of PFBNBS. PFBNBS with lower highest occupied molecular orbital can be preferentially oxidized on the NCM622 surface with the help of the catalytic effect to induce an inorganic‐rich CEI for superior electrochemical performance at high voltage. Moreover, PFBNBS can be reduced on the Li surface due to its lower lowest unoccupied molecular orbital , increasing inorganic moieties in SEI for inhibiting Li dendrite generation. Thus, 4.5 V Li||NCM622 batteries with such electrolyte can retain 70.4% of initial capacity after 500 cycles at 0.2 C, which is attributed to the protective effect of the excellent CEI on NCM622 and the inhibitory effect of its derived CEI/SEI on continuous electrolyte decomposition.

Surface engineering of inorganic solid-state electrolytes via interlayers strategy for developing long-cycling quasi-all-solid-state lithium batteries

Lithium metal batteries (LMBs) with inorganic solid-state electrolytes are considered promising secondary battery systems because of their higher energy content than their Li-ion counterpart. However, the LMB performance remains unsatisfactory for commercialization, primarily owing to the inability of the inorganic solid-state electrolytes to hinder lithium dendrite propagation. Here, using an Ag-coated Li6.4La3Zr1.7Ta0.3O12 (LLZTO) inorganic solid electrolyte in combination with a silver-carbon interlayer, we demonstrate the production of stable interfacially engineered lab-scale LMBs. Via experimental measurements and computational modelling, we prove that the interlayers strategy effectively regulates lithium stripping/plating and prevents dendrite penetration in the solid-state electrolyte pellet. By coupling the surface-engineered LLZTO with a lithium metal negative electrode, a high-voltage positive electrode with an ionic liquid-based liquid electrolyte solution in pouch cell configuration, we report 800 cycles at 1.6 mA/cm2 and 25 °C without applying external pressure. This cell enables an initial discharge capacity of about 3 mAh/cm2 and a discharge capacity retention of about 85%.

Impaired dendritic spike generation in the Fragile X prefrontal cortex is due to loss of dendritic sodium channels.

Patients with Fragile X syndrome, the leading monogenetic cause of autism, suffer from impairments related to the prefrontal cortex, including working memory and attention. Synaptic inputs to the distal dendrites of layer 5 pyramidal neurons in the prefrontal cortex have a weak influence on the somatic membrane potential. To overcome this filtering, distal inputs are transformed into local dendritic Na+ spikes, which propagate to the soma and trigger action potential output. Layer 5 extratelencephalic (ET) prefrontal cortex (PFC) neurons project to the brainstem and various thalamic nuclei and are therefore well positioned to integrate task-relevant sensory signals and guide motor actions. We used current clamp and outside-out patch clamp recording to investigate dendritic spike generation in ET neurons from male wild-type and Fmr1 knockout (FX) mice. The threshold for dendritic spikes was more depolarized in FX neurons compared to wild-type. Analysis of voltage responses to simulated in vivo 'noisy' current injections showed that a larger dendritic input stimulus was required to elicit dendritic spikes in FX ET dendrites compared to wild-type. Patch clamp recordings revealed that the dendritic Na+ conductance was significantly smaller in FX ET dendrites. Taken together, our results suggest that the generation of Na+ -dependent dendritic spikes is impaired in ET neurons of the PFC in FX mice. Considering our prior findings that somatic D-type K+ and dendritic hyperpolarization-activated cyclic nucleotide-gated-channel function is reduced in ET neurons, we suggest that dendritic integration by PFC circuits is fundamentally altered in Fragile X syndrome. KEY POINTS: Dendritic spike threshold is depolarized in layer 5 prefrontal cortex neurons in Fmr1 knockout (FX) mice. Simultaneous somatic and dendritic recording with white noise current injections revealed that larger dendritic stimuli were required to elicit dendritic spikes in FX extratelencephalic (ET) neurons. Outside-out patch clamp recording revealed that dendritic sodium conductance density was lower in FX ET neurons.

Performance improvement of aqueous zinc batteries by zinc oxide and Ketjen black co-modified glass fiber separators.

Rechargeable aqueous zinc-based batteries (AZBs) are intriguing candidates for next-generation energy storage batteries. However, the dendrites generated plagued their development during charging. To inhibit the dendrite generation, a novel modification method based on the separators was proposed in this study. The separators were co-modified by spraying sonicated Ketjen black (KB) and zinc oxide nanoparticles (ZnO) uniformly. The highly conductive KB homogenizes the anode interface's electric field. The deposited ions are deposited on ZnO preferentially rather than on the anode electrode, and the deposited particles can be refined. The ZnO in the uniform KB conductive network can provide sites for zinc deposition, and the by-products of the zinc anode electrode reduced. The Zn-symmetric cell with the modified separator (Zn//ZnO-KB//Zn) can cycle for 2218 h at 1 mA cm-2 stably (the unmodified Zn-symmetric cell (Zn//Zn) only can cycle for 206 h). With the modified separator, the impedance and polarization of Zn//MnO2 reduced, and the cell can charge/discharge 995 times at 0.3 A g-1. In conclusion, the electrochemical performance of AZBs can be improved effectively after separator modification by the synergistic effect of ZnO and KB.

Recent advances in lithiophilic materials: material design and prospects for lithium metal anode application

The rapid development of electronic technology and energy industry promotes the increasing desire for energy storage systems with high energy density, thus calling for the exploration of lithium metal anode. However, the enormous challenges, such as uncontrollable lithium deposition, side reaction, infinite volume change and dendrite generation, hinders its application. To address these problems, the deposition behavior of lithium must be exactly controlled and the anode/electrolyte interface must be stabilized. The deposition of lithium is a multi-step process influenced by multi-physical fields, where nucleation is the key to final morphology. Hence, increasing investigations have focused on the employment of lithiophilic materials that can regulate lithium nucleation in recent years. The lithiophilic materials introduced into the deposition hosts or solid electrolyte interphases can regulate the nucleation overpotential and facilitate uniform deposition. However, the concept of lithiophilicity is still undefined and the mechanism is still unrevealed. In this review, the recent advances in the regulation mechanisms of lithiophilicity are discussed, and the applications of lithiophilic materials in hosts and protective interphases are summarized. The in-depth exploration of lithiophilic materials can enhance our understanding of the deposition behavior of lithium and pave the way for practical lithium metal batteries.

C60 and ZIF-67 synergistically modified gelatin-based nanofibrous separators for Li-S batteries

The lithium-sulfur (Li-S) battery has been attracting much more attention in recent years due to its high theoretical capacity and low cost, although various issues, such as the “shuttle effect” and the low use ratio of active materials, have been hindering the development and application of Li-S batteries. The separator is an important part of Li-S batteries, and its modification is a simple and effective strategy to improve the electrochemical performance of Li-S batteries. In this work, we explore separators with different functions on their two sides that have been produced by a step-by-step electrospinning method. The multifunctional separator on one side is pure gelatin, and the other side is zeolitic imidazolate framework-67 (ZIF-67)-C60-gelatin. The ZIF-67-C60-gelatin layer on the cathode side is of great importance. The chemisorption sites on it are provided by ZIF-67, and the transformation sites of lithium polysulfide are provided by C60. Gelatin, which is on the anode side, as an admirable separator material, makes the lithium flux uniform and thus prevents the generation of lithium dendrites. This type of multifunctional nanofiber separator based on double gelatin layers plays an important role in the adsorption and conversion of polysulfides, and it improves the overall performance of the Li-S battery. As a result, the Li-S batteries assembled with the prepared separator can still maintain the capacity of 888 mAh g-1 after 100 cycles at 0.2 C, and the capacity retention rate of the Li-S batteries is 72.9% after 400 cycles at 2 C. This simple preparation method and high-performance bilayer membrane structure provide a new route for commercial application.

Rapid sintering of Li6.5La3Zr1Nb0.5Ce0.25Ti0.25O12 for high density lithium garnet electrolytes with current induced in situ interfacial resistance reduction

In this paper, a high-entropy type lithium garnet is presented that rapidly sinters/densifies from the precursors, with favourable electrochemical properties in terms of both conductivity and limiting dendrite propagation.

Rectifying interphases for preventing Li dendrite propagation in solid-state electrolytes

The concept of asymmetric electronic conductance is explored in solid-state batteries and realised by a p–n junction interphase, enabling dynamic dendrite-free operation via slow reductive generation and rapid oxidative elimination.

A poly(ether block amide) based solid polymer electrolyte for solid-state lithium metal batteries.

Solid-state lithium (Li) metal batteries (SSLMBs) with high-energy density and high-security are promising for energy storage application and electronic device development. However, Li dendrite generation is still one of the most important factors hindering the application of SSLMBs since interface contact degradation, dead Li accumulation, and continuous solid-electrolyte interphase (SEI) growth are always caused by Li dendrite growth, making the performances of SSLMBs deteriorate rapidly. In this study, a poly(ether block amide) (PEBA) based polymer electrolyte with lithium bis-(trifluoromethanesulfonyl)imide (LiTFSI) as the Li salt is developed. It is found that the PEBA 2533-20% LiTFSI electrolyte possesses an ion conductivity of 3.0×10-5 S cm-1 at 25 °C. Especially, the Li dendrite suppression ability of SEI is greatly enhanced since it provides abundant amide groups to activate TFSI- anions and further enriches lithium fluoride (LiF) content in the SEI layer, which endows the full-cell with enhanced cyclability. As a result, the fabricated solid-state Li/PEBA 2533-20% LiTFSI/LiFePO4 (areal capacity: 0.15 mAh cm-2) battery remains 94% of its maximum capacity (127.5 mAh g-1) at a rate of 0.5C and 60 °C after 200 cycles. In particular, the full cell can cycle for almost 1000 times without short circuit. Therefore, the PEBA based electrolyte could promote the LiF enriched SEI layer into a platform to suppress the growth of Li dendrite toward SSLMBs with a long-life span.

Customizing Component Regulated Dense Heterointerfaces for Crafting Robust Lithium‐Sulfur Batteries

AbstractLithium–sulfur (Li–S) batteries hold great promise for the next‐generation energy storage system. However, their commercial applications are severely hindered by myriads of drawbacks such as poor electrical conductivity of sulfur, sluggish redox reaction kinetics of sulfur species, “shuttling effect” of soluble lithium polysulfides (LiPSs) and uncontrollable dendritic Li growth. Herein, it is conceptually demonstrated that sluggish conversion kinetics of LiPSs is markedly stimulated by exquisite heterointerface modulation at nanoscale level over transition metal carbides and nitrides. In this scenario, N‐doped carbon coupled with molybdenum nitride/carbide (Mo2N‐MoC/NC) hybrid nanocomposites are designed through a one‐step carbonization‐nitridation process, wherein component regulation induced dense heterointerfaces are in situ produced. Benefiting from high electrical conductivity, strong chemical adsorption, and superior catalytic activity afforded by dense heterointerfaces, the Mo2N‐MoC/NC modified separators significantly restrict the soluble LiPSs shuttling and simultaneously suppress the Li dendrite generation. The assembled Li–S batteries with Mo2N‐MoC/NC modified separators exhibit remarkable electrochemical performance. Integrated experimental and theoretical results substantiate the boosted chemisorption and catalytic conversion of LiPSs endowed by such dense heterointerfaces. The work will open a new vista for rationally constructing multifarious heterostructured materials for the communities of Li‐S batteries.

Highly Stable Zn Anodes Modulated by Selenizing In Situ Grown Metal–Organic Frameworks

The unsatisfactory cycling stability of Zn anode stemming from dendritic growth and side reactions has slowed the rapid development of aqueous Zn-ion batteries (AZIBs). Constructing a three-dimensional (3D) artificial interphase layer is an appealing solution since it could dictate Zn deposition at the interface. Here, the in situ growth of a Cu-based metal–organic framework (Cu-MOF) over commercial Zn foil followed by subsequent selenization endows selenized Cu-MOF (SCM) with a stabilized Zn anode. The 3D SCM coating could homogenize the electric field and function as a reservoir to tolerate the deposited Zn. As a result, both rampant dendritic propagation and the notorious side reactions are concurrently inhibited. The SCM@Zn symmetric cell displays an elongated cyclic life for over 500 h at 2.0 mA cm–2. The assembled AZIB full cell readily realizes high electrochemical reversibility under different current densities. Our investigation offers insights into the design of a protective layer for high-performance Zn anodes.

High-donor electrolyte endows graphite with anion-derived interphase to achieve stable K-storage

Graphite anodes are expected to be applied in potassium-ion batteries, but it is limited by uncontrolled volume fluctuation and dendrite growth during cycles. Herein, an anion-derived interphase with high mechanical strength and ionic conductivity is constructed to address the aforementioned issues using an amide-based electrolyte. The high-donor number for an amide molecule can strengthen the solvation with K+, ensuring more anions enter the primary solvation sheath. The shortened distance is in favor of the electron transfer from the solvated K+ to the anion and subsequently motivates the anion reduction. The obtained inorganic-rich interphase buffers volume change, suppresses K dendrite propagation, and facilitates ion diffusion. Based on these, symmetric K//K cells could operate stable plating and stripping with a small polarization of 0.15 V for over 2800 h. The graphite electrode achieves a highly reversible phase transition of C↔KC60↔KC48↔KC36↔KC24↔KC8. A high discharge capacity of 217.6 mA h g−1 with retention of 86.9% is obtained after 100 cycles. The assembled full battery also exhibits a high energy density of 52.5 W h kg−1. This work highlights the importance of the interfacial structure and provides a brand-new strategy for designing high-performance electrolytes.

Controlling dendrite propagation in solid-state batteries with engineered stress

<h2>Summary</h2> Metal-dendrite penetration is a mode of electrolyte failure that threatens the viability of metal-anode-based solid-state batteries. Whether dendrites are driven by mechanical failure or electrochemical degradation of solid electrolytes remains an open question. If internal mechanical forces drive failure, superimposing a compressive load that counters internal stress may mitigate dendrite penetration. Here, we investigate this hypothesis by dynamically applying mechanical loads to growing dendrites in Li_6.₆La₃Zr_1.₆Ta_0.₄O₁₂ solid electrolytes. <i>Operando</i> microscopy reveals marked deflection in the dendrite growth trajectory at the onset of compressive loading. For sufficient loading, this deflection averts cell failure. Using fracture mechanics, we quantify the impact of stack pressure and in-plane stresses on dendrite trajectory, chart the residual stresses required to prevent short-circuit failure, and propose design approaches to achieve such stresses. For the materials studied here, we show that dendrite propagation is dictated by electrolyte fracture, with electronic leakage playing a negligible role.

“Polymer-in-ceramic” PEO/2D heterojunction composite electrolytes for solid-state batteries

The ferroelectric spontaneous polarizability of the piezoelectric TBA+CNO− also has an enhanced effect on ion transport and electrode interface modification, and its ferroelectric spontaneous polarization field also helps to reduce the generation and growth of anode dendrites. The structural instability of LRAP electrolyte Li2.99Ba0.005OCl are maintained by forming a heterojunction structure with two-dimensional nanosheets TBA+CNO−, and the fast conduction channels of lithium ions (Li+) are established. Composite electrolytes possess Li+ conductivity σi > 10−4 S/cm at 25°C. The composite materials composed of “polymer-in-ceramic” with flexibility and mechanical strength are fabricated by the casting method. PEO-Li2.99Ba0.005OCl/TBA+CNO− shows good compatibility with lithium metal, forming a stable solid electrolyte interface. The plastic crystal electrolyte dripped on the cathode side avoids the direct contact between high-voltage cathode and electrolyte and protects PEO from being oxidized and decomposed. NCM811|Li batteries show 70.9 mAh•g−1 with capacity retention of 97.88% after 100 cycles.

A Carboranyl Electrolyte Enabling Highly Reversible Sodium Metal Anodes via a "Fluorine-Free" SEI.

Realization of practical sodium metal batteries (SMBs) is hindered due to lack of compatible electrolyte components, dendrite propagation, and poor understanding of anodic interphasial chemistries. Chemically robust liquid electrolytes that facilitate both favorable sodium metal deposition and a stable solid-electrolyte interphase (SEI) are ideal to enable sodium metal and anode-free cells. Herein we present advanced characterization of a novel fluorine-free electrolyte utilizing the [HCB11 H11 ]1- anion. Symmetrical Na cells operated with this electrolyte exhibit a remarkably low overpotential of 0.032 V at a current density of 2.0 mA cm-2 and a high coulombic efficiency of 99.5 % in half-cell configurations. Surface characterization of electrodes post-operation reveals the absence of dendritic sodium nucleation and a surprisingly stable fluorine-free SEI. Furthermore, weak ion-pairing is identified as key towards the successful development of fluorine-free sodium electrolytes.

A Carboranyl Electrolyte Enabling Highly Reversible Sodium Metal Anodes via a “Fluorine‐Free” SEI

AbstractRealization of practical sodium metal batteries (SMBs) is hindered due to lack of compatible electrolyte components, dendrite propagation, and poor understanding of anodic interphasial chemistries. Chemically robust liquid electrolytes that facilitate both favorable sodium metal deposition and a stable solid‐electrolyte interphase (SEI) are ideal to enable sodium metal and anode‐free cells. Herein we present advanced characterization of a novel fluorine‐free electrolyte utilizing the [HCB11H11]1− anion. Symmetrical Na cells operated with this electrolyte exhibit a remarkably low overpotential of 0.032 V at a current density of 2.0 mA cm−2 and a high coulombic efficiency of 99.5 % in half‐cell configurations. Surface characterization of electrodes post‐operation reveals the absence of dendritic sodium nucleation and a surprisingly stable fluorine‐free SEI. Furthermore, weak ion‐pairing is identified as key towards the successful development of fluorine‐free sodium electrolytes.

Intracellular simulated biophoton stimulation and transsynaptic signal transmission

The traditional theory holds that the information transmission between nerve cells includes electrical and chemical transmission; however, these known functional features do face some difficulties to explain the fast and efficient information processing and cognitive processes in the brain due to the existing functional limitations of neuronal networks, such as the dendritic and axonal propagation delays as well as the chemical synaptic transmission time delay that have been debated for a long time. We generated three kinds of ultraweak lasers, called as simulated biophotons, with different spectra and intensities to implement intracellular stimulation in a single nerve cell of the hippocampal areas in mouse brain slices combined with intracellular membrane potential recording and biophoton imaging techniques. We found that the simulated biophoton stimulation can lead to transsynaptic biophotonic activities and transmission in the ipsilateral and contralateral projection circuits in the hippocampus. The activity and transmission characteristics were related to the spectra and intensities of the simulated biophotons but not to the levels of membrane potentials before stimulation. These findings present specific characteristics of neural biophoton signal transmission, which may be involved in the mechanisms of processing, encoding, and storage of neural signals.

Sodium–gallium alloy layer for fast and reversible sodium deposition

AbstractSodium metal has been regarded as the potential alternative for metal batteries owing to its advantages of high theoretical capacity and abundant reserves. Nevertheless, propagation of Na dendrites can boost the interfacial instability of Na metal, retarding its practical implementation. Thus, the Na–Ga alloy layer is designed and fabricated by in situ rolling of metal Ga on the surface of Na metal. This alloy layer possesses good sodiophilicity, which can effectively protect Na metal and favor the uniform Na+ deposition, obtaining the inhibition of Na dendrites growth. Consequently, the symmetric cells assembled by the alloy‐layer protected Na metal electrodes (NGAL‐Na||NGAL‐Na) have a long lifetime (468 h) even under a high plating/stripping capacity of 6 mAh cm−2 in carbonate electrolyte. The full battery of NGAL‐Na||Na3V2(PO4)3 is able to sustain an excellent rate capability of 100 mAh g−1 after 500 cycles at 10 C under ambient temperature. This work provides a new route to prevent metal anodes from severe dendrite growth, and paves the way toward safer and stable‐performing metal‐based rechargeable batteries.

Li2Se: A High Ionic Conductivity Interface to Inhibit the Growth of Lithium Dendrites in Garnet Solid Electrolytes.

All-solid-state Li metal batteries (ASSLBs) are currently regarded as one of the most promising next-generation energy storage technologies because of their great potential in realizing both high energy density and safety. However, the development of high performance ASSLBs is still restricted by the large interfacial resistance and Li dendrite propagation within solid electrolytes. Herein, a simple and efficient interfacial modification strategy is proposed to improve the interfacial contact between Li and Li6.4La3Zr1.4Ta0.6O12 (LLZTO) by introducing a uniform and thin Li2Se buffer layer. The Li2Se buffer layer formed by an in situ conversion reaction can not only enhance the wettability of lithium metal toward LLZTO electrolyte but also facilitate uniform lithium plating/stripping. As a result, the interfacial resistance of Li/LLZTO decreased from 270.5 to 5.1 Ω cm2, and the lithium symmetric cell can cycle stably for 350 h at a current density of 0.5 mA cm-2. Meanwhile, the Li|LLZTO-Li2Se|LiNi0.8Co0.1Mn0.1O2 full cells exhibit a high initial capacity of 162.3 mAh g-1 and good cycling stability with a capacity retention of 84.3% after 100 cycles at 0.2 C. These results prove the effectiveness of this modification method and provide new design strategies for the development of high performance ASSLBs.