Lithium Metal Deposition Research Articles

Magnetic field enable lithium ions to penetrate lithophilic 3D collectors and enhance electrochemical performance

Abstract Lithium metal batteries, celebrated for their exceptional energy density, are promising for advanced energy storage. Nevertheless, the dynamic deformation of lithium metal during cycling often leads to the unchecked proliferation of lithium dendrites, compromising the solid electrolyte interface. This not only deteriorates cycle stability but also poses significant safety risks. In our approach, we develop a three-dimensional lithium-affinitive composite current collector, utilizing an external magnetic field. The lithiophilic nature of V2O5, coupled with the deformability support provided by nickel foam and the depth-enhancing influence of the magnetic field on lithium metal deposition, collectively contribute to a more controlled and stable lithium environment. Our findings indicate that this novel setup allows for a lithium metal deposition depth of up to 310 μm, markedly curtailing the growth of dendrites in successive cycles. Remarkably, batteries reassembled with this magnetically-enhanced, lithium pre-deposited current collector exhibits a coulombic efficiency of 98.3% after 320 cycles at 1 mA cm-2. Moreover, a full cell, equipped with LiFePO4, delivers an initial capacity of 158.4 mAh g-1 at 1 C.

Anion-Tuned Fluorinated Solvation Sheath Enables Stable Lithium Metal Batteries.

Continuous side reactions between conventional carbonate-based electrolytes and electrodes lead to electrolyte consumption and the growth of lithium dendrites, which always lead to serious capacity fading or safety issues, hindering the development of lithium metal batteries. Here, a nonflammable all-fluorinated electrolyte with the anion-participating Li+ solvation sheath is developed and the corresponding electrochemical properties are studied. Combining theoretical calculations and X-ray photoelectron spectroscopy analysis, ethyl 2,2,2-trifluoroethyl carbonate (ETFEC) and methyl difluoroacetate (MDFA) as cosolvents in the all-fluorinated electrolyte, PF6- anions accumulate on the lithium metal anode and preferentially reduced to obtain a LiF-rich solid electrolyte layer, inducing uniform lithium metal deposition. Additionally, the anions located in the solvation structure improve the reduction stability of the solvent, which avoids the rapid decline in battery capacity caused by the continued decomposition of the solvent. Consequently, The Li||NCM811 battery achieved initial capacity retention of 71.48% after 430 cycles at a voltage of 4.3 V, and the capacity retention reached 64.52% after 225 cycles even at a high voltage of 4.5 V. This nonflammable electrolyte can alleviate the rapid decline in battery capacity caused by solvent decomposition.

Laser‐Structured Graphite Paper Hybrid Anode with Selective Lithiophilic Grooves for Controlled Lithium Metal Deposition

Laser‐Structured Graphite Paper Hybrid Anode with Selective Lithiophilic Grooves for Controlled Lithium Metal Deposition

Direct contact pre-lithiation for practical lithium ion batteries: Focus review

Pre-lithiation methods address the challenges of low initial coulombic efficiency (ICE) and reduced energy density in lithium-ion batteries (LIBs) by adding additional lithium sources to compensate for initial irreversible Li+ losses. The direct contact pre-lithiation (DC-Pr) method has garnered extensive attention due to its simplicity, convenience as well as significant effects on the improved cycling durability. Considering the most important factors, i.e., effectiveness and uniformity, this review focuses on the anode DC-Pr method for LIBs with the lithium sources from Li foil, stabilized lithium metal powder (SLMP), lithium-rich alloys, and physical vapor deposition of lithium metal. After summarizations and discussions, the review overviews the challenges and prospects for DC-Pr methods, aiming to provide guidance for the construction and developments of practical LIBs.

Janus-Architectured Lithium Replenishment Separators Boosting Longevity of Anode-Free Lithium Metal Batteries.

Addressing the issue of inactive dead lithium deposition on the anode side remains a significant challenge for anode-free lithium metal batteries. While lithium compensation techniques can mitigate lithium depletion, directly introducing lithium compounds into the cathode material may degrade the electrode structure. Here the design and fabrication of a novel lithium replenishment separator (LRS) using a lithium compensation agent of Li2C4O4 is reported. The electrospun LRS demonstrates excellent ionic conductivity of 1.82 mS cm-1 and a high Li+ transference number of 0.51. Such a functionalized LRS not only provides additional active lithium for anode-free lithium metal batteries but also promotes uniform deposition of lithium metal. Compared with conventional polyolefin-based separators, the LRS effectively boosts LiFePO4||Cu anode-free batteries with enhanced cyclability. These results suggest this LRS strategy can find promising applications in next-generation anode-free batteries with high energy densities.

Tailoring the Electrode-Electrolyte Interface for Reliable Operation of All-Climate 4.8 V Li||NCM811 Batteries.

Combining high-voltage nickel-rich cathodes with lithium metal anodes is among the most promising approaches for achieving high-energy-density lithium batteries. However, most current electrolytes fail to simultaneously satisfy the compatibility requirements for the lithium metal anode and the tolerance for the ultra-high voltage NCM811 cathode. Here, we have designed an ultra-oxidation-resistant electrolyte by meticulously adjusting the composition of fluorinated carbonates. Our study reveals that a solid-electrolyte interphase (SEI) rich in LiF and Li2O is constructed on the lithium anode through the synergistic decomposition of the fluorinated solvents and PF6 - anion, facilitating smooth lithium metal deposition. The superior oxidation resistance of our electrolyte enables the Li||NCM811 cell to deliver a capacity retention of 80 % after 300 cycles at an ultrahigh cut-off voltage of 4.8 V. Additionally, a pioneering 4.8 V-class lithium metal pouch cell with an energy density of 462.2 Wh kg-1 stably cycles for 110 cycles under harsh conditions of high cathode loading (30 mg cm-2), low N/P ratio (1.18), and lean electrolytes (2.3 g Ah-1).

Tailoring the Electrode‐Electrolyte Interface for Reliable Operation of All‐Climate 4.8 V Li||NCM811 Batteries

AbstractCombining high‐voltage nickel‐rich cathodes with lithium metal anodes is among the most promising approaches for achieving high‐energy‐density lithium batteries. However, most current electrolytes fail to simultaneously satisfy the compatibility requirements for the lithium metal anode and the tolerance for the ultra‐high voltage NCM811 cathode. Here, we have designed an ultra‐oxidation‐resistant electrolyte by meticulously adjusting the composition of fluorinated carbonates. Our study reveals that a solid‐electrolyte interphase (SEI) rich in LiF and Li2O is constructed on the lithium anode through the synergistic decomposition of the fluorinated solvents and PF6− anion, facilitating smooth lithium metal deposition. The superior oxidation resistance of our electrolyte enables the Li||NCM811 cell to deliver a capacity retention of 80 % after 300 cycles at an ultrahigh cut–off voltage of 4.8 V. Additionally, a pioneering 4.8 V‐class lithium metal pouch cell with an energy density of 462.2 Wh kg−1 stably cycles for 110 cycles under harsh conditions of high cathode loading (30 mg cm−2), low N/P ratio (1.18), and lean electrolytes (2.3 g Ah−1).

Quantum-Sized Co Nanoparticles with Rich Vacancies Enabled the Uniform Deposition of Lithium Metal and Fast Polysulfide Conversion.

The notorious polysulfide shuttling and uncontrollable Li-dendrite growth are the main obstacles to the marketization of Li-S batteries. Herein, a dual-functional material consisting of vacancy-rich quantum-sized Co nanodots anchored on a mesoporous carbon layer (v-Co/meso-C) is proposed. This material exposes more active sites to improve its reaction performance and simultaneously realizes excellent lithiophilicity and sulfiphilicity characteristics in Li-S electrochemistry. As Li metal deposition hosts, v-Co/meso-C shows small nucleation overpotential, low polarization, and ultra-long cycling stability in both half and symmetric cells, as confirmed by experimental studies. On the S cathode side, experimental and theoretical calculations demonstrate that v-Co/meso-C enhances the adsorption of polysulfides and boosts their catalytic conversion rate. This, in turn, suppresses the shuttle effect of polysulfides and improves sulfur utilization efficiency. Finally, a shuttle-free and dendrite-free v-Co/meso-C@Li//v-Co/meso-C@S full cell is fabricated, exhibiting excellent rate performance (739 mAhg-1 at 5.0 C) and good cyclability (capacity decay rate is 0.033% and 0.035% per cycle at 2.0 and 5.0 C, respectively). Even a pouch cell with high sulfur loading (5.5mgcm-2) and lean electrolyte/sulfur (4.8µLmg-1) can still work 50 cycles with 80% capacity retention rate. This study shows far-reaching implications in the design of dendrite-free, shuttle-free Li-S batteries.

(Invited) The Role of Carbon in Enabling Stable Solid State Batteries

Carbonaceous materials are widely used as the anode materials in rechargeable lithium-ion batteries. In that context, they serve as the host for lithium ions. Their structural stability and limited volume changes underpin the long-term stability of the batteries. In solid-state batteries, however, their roles have evolved. With the focus on raising cell energy density and the promise of stable operation of lithium metal due to the absence of organic solvent, carbon has not been widely studied as an anode material. Unfortunately, the promise of lithium metal has encountered significant challenges: it chemical reacts with virtually all known solid state electrolytes; lithium also grows dendrites which can eventually lead to shorting; the stripping of lithium is also often inhomogeneous which had led to void formation at the interface. To address these challenges, carbonaceous materials have been reintroduced.In this talk, we overview several applications of carbonaceous materials in solid state batteries. We have shown that graphite can be engineered as a 3D host for lithium deposition. Lithiated graphite becomes lithiophilic with low nucleation barrier for lithium metal deposition. The voids between the graphite particles can accomodate lithium metal. As a result, the critical current density and cycling stability of both full cells and symmetric cells have greatly improved. We note that in this context, the anode is essentially a graphite electrode that experiences intentional overlithiation.In a second application, we show that carbon can serve as an effective interlayer between lithium and the solid electrolyte. This interlayer reduces the side reaction between lithium and the electrolyte, thus greatly improving the cycle life and coulombic efficiency. It is rather surprising that upon lithiation, the interlayer enables lithium transport and preferential lithium deposition at the carbon/lithium interface, rather than the carbon/electrolyte interface. This desirable outcome is observed despite the fact that the interlayer itself is electrically conducting. We studied a wide variety of carbon materials in terms of surface area, crystal structure, and defect density. With the optimized carbon material, critical current densities of over 30 mA/cm2 have been observed. The mechanism of lithium transport will be discussed along with the design criteria for using carbon as an effective mixed electron and ion conductor.

Regulating the horizontal confined deposition of lithium metal by Co-Nx modified honeycomb-like carbon nanosheets

The uncontrollable Li dendrite growth as well as the severe volume expansion of Li metal anodes during cycling significantly impedes the practical applications of high-energy-density Li metal batteries. In this work, an innovative modulation strategy has been developed by constructing honeycomb-like nitrogen-doped carbon nanosheets with uniformly anchored cobalt nanoparticles (denoted as Co@HNC) for regulating the Li deposition behavior and meanwhile alleviating volume change during cycling. On one hand, the lithiophilic Co-Nx sites can largely reduce the energy barrier of Li nucleation and subsequently guide horizontal confined Li deposition in the honeycomb-like holes of Co@HNC, which is verified by the density functional theory calculations and in-situ optical microscopy observations. On the other hand, the honeycomb-like carbon framework with good structural integrity can endure the huge volume change during repeated Li plating/stripping processes. Consequently, the optimized Co@HNC electrode delivered a promoted cycling life for over 600 times with high Coulombic efficiency of 98.5 % at 1 mA cm−2. When matched with the high-mass-loading LiFePO4 (20 mg cm−2) or high-voltage LiNi0.8Mn0.1Co0.1O2 cathode, the Li@Co@HNC anode exhibited outstanding cycling stability and rate capability under low negative/positive capacity ratio, demonstrating its great potential in practical applications of high-energy-density lithium metal batteries.

Effects of solid electrolyte particle size and silver-carbon interlayer on lithium deposition in all-solid-state lithium-metal batteries

All-solid-state batteries with lithium-metal anodes are expected to exhibit high performance. For practical application, the growth of lithium dendrites must be suppressed. One method to suppress dendrite growth is to insert a carbon interlayer at the interface between the anode and solid electrolyte (SE). Dendrite growth is related to the anode interface properties and depends on the SE particle size used in the SE layer. Appropriate control of the SE particle size used at the anode interface can improve battery performance. In this study, the effects of SE particle size and carbon interlayer type on lithium-metal deposition morphology are investigated by X-ray CT measurement. The results show that dendrite growth is suppressed when the small-particle SE is used owing to the smaller pores between the SE layer and carbon interlayer. In addition, by controlling the SE particle size distribution using a double SE layer, both high ionic conductivity and dendrite suppression can be achieved. Furthermore, dendrite growth can be suppressed using a silver particle-added carbon interlayer, even with the large-particle SE where dendrites are prone to grow more easily.

Current density alters the mechanical stresses during electrodeposition of lithium metal anodes

“Lithium metal” batteries operate via electroplating/stripping of Li metal and promise vast theoretical capacities. However, significant technical barriers must be addressed prior to commercialization. The primary challenges include the generation of mechanical stresses and strains due to "infinite volume expansion,” as well as non-uniform deposition of lithium metal, which often leads to dendrite formation and growth. Lithium dendrite formation is particularly critical, as dendrites can penetrate solid-state electrolytes, eventually shorting to the cathode, thereby diminishing the capacity of the battery and inducing severe safety hazards. These primary issues are intrinsically linked to the mechanical behavior of lithium; as such, this study focuses on the mechanical response of lithium electrodeposition under various electrochemical conditions. Experimental tests herein reveal that larger applied current densities induce significantly larger mechanical stresses during electroplating of Li metal. This manuscript concludes by detailing practical implications of these experimental observations, particularly regarding dendrite growth through solid-state electrolytes of solid-state batteries.

Dendrite-Free All-Solid-State Lithium Metal Batteries by In Situ Phase Transformation of the Soft Carbon-Li3N Interface Layer.

The accelerated formation of lithium dendrites has considerably impeded the advancement and practical deployment of all-solid-state lithium metal batteries (ASSLMBs). In this study, a soft carbon (SC)-Li3N interface layer was developed with both ionic and electronic conductivity, for which the in situ lithiation reaction not only lithiated SC into LiC6 with good electronic/ionic conductivity but also successfully transformed the mixed-phase Li3N into pure-phase β-Li3N with a high ionic conductivity/ion diffusion coefficient and stability to lithium metal. The mixed conductive interface layer facilitates fast Li+ transport at the interface and induces the homogeneous deposition of lithium metal inside it. This effectively inhibits the formation of lithium dendrites and greatly improves the performance of the ASSLMB. The ASSLMB assembled with the SC-Li3N interface layer exhibits high areal capacity (15 mA h cm-2), high current density (7.5 mA cm-2), and long cycle life (6000 cycles). These results indicate that this interface layer has great potential for practical applications in high-energy-density ASSLMBs.

Interfacial Layers with Desolvation Function Induced Stable Deposition of Lithium Metal for Long-Cycling Lithium Metal Batteries.

The unstable solid electrolyte interface (SEI) formed by uncontrollable electrolyte degradation, which leads to dendrite growth and Coulombic efficiency decay, hinders the development of Li metal anodes. A controllable desolvation process is essential for the formation of stable SEI and improved lithium metal deposition behavior. Here, we show a functional artificial interface protective layer comprised of chondroitin sulfate-reduced graphene oxide (CrG), on which polar functional groups are distributed to effectively reduce the energy barrier for desolvation of Li+ and effectively alienate solvent molecules to avoid solvent involvement in SEI formation, thus promoting the formation of a LiF-rich SEI. Consequently, stable Coulombic efficiencies of 98.4% were achieved after 500 cycles in a Li//Cu cell. Moreover, the LiFePO4 full cells achieve steady circulation (470 cycles at 80%, 1 C) with a negative/positive electrode capacity ratio of 2.87. Our multifunctional artificial interface protective layer provides a new way to advance Li metal batteries.

Boosted Li+ transport ensured by high-entropy Prussian blue analogues with tuned PF6− adsorption for stable Li metal anode

The inhomogeneous lithium metal (Li) deposition and low lithium ion (Li+) mobility lead to the formation and growth of Li dendrites, which impede the desirable performance of Li metal batteries (LMBs) with high energy density in widely practical applications. Herein, a high-entropy MnCoNiCuZn-Prussian blue analogue (HE-PBA) is utilized to modify the commercial polypropylene separator (PP@HE-PBA), which will form an artificial protective layer on the surface of Li. The polar –CN groups of HE-PBA can enhance the wettability of PP to the electrolyte, while the movement of PF6− anions are flexibly tuned by the appropriate absorption ability and synergistic effect of multiple metal ions in HE-PBA. A high Li+ transference number of 0.69 is achieved, which can relieve the Li+ concentration polarization, regulate the Li+ flow, and realize the uniform Li deposition. With PP@HE-PBA, the Li||Li symmetric cells display durability up to 600 h in the ester-based electrolyte at 1 mA cm−2 for 1 mAh cm−2. Also, the PP@HE-PBA exhibits great potential in LMBs, where the Li4Ti5O12 (LTO) ||Li and sulfated polyacrylonitrile (S-PAN) ||Li batteries deliver superior cycling performance to those without PP@HE-PBA.

Fluorine-Doped Li7La3Zr2O12 Fiber-Based Composite Electrolyte for Solid-State Lithium Batteries with Enhanced Electrochemical Performance.

Garnet-based electrolytes with high ionic conductivity and excellent stability against lithium metal anodes are promising for commercial applications in solid-state lithium batteries (SSLBs). However, the further development of SSLBs is inhibited by issues such as low ionic conductivity and uncontrolled lithium dendrite growth. Herein, we report the synthesis of fluorine-doped Li7La3Zr2O12 (LLZO-F0.2) fibers by electrospinning and the subsequent calcination at high temperatures. The solid composite electrolyte with LLZO-F0.2 exhibits an ionic conductivity of 5.37 × 10-4 S cm-1 and a high lithium-ion transference number of 0.61 at room temperature. Meanwhile, it exhibits lower resistance and more uniform lithium metal stripping and deposition in symmetric cells. The full cell with LiFePO4 cathode exhibits excellent rate capability and cycling stability for 800 cycles at 0.5 C with a discharge specific capacity retention of 97.7%. This fluorine-doped fibrous garnet-type electrolyte provides a viable option for preparing high-performance SSLBs.

Dendrite/Volume Expansion-Free Lithium Deposition Inside the Enclosed Nanoscale Space of Electrochemically Modified Graphite

Though over-lithiation of graphite can increase the initial specific capacity of the anodes, the cycling stability is unsatisfactory as metallic lithium depositing on the surface of graphite has poor reversibility. In this work, we utilize electrochemical co-intercalation of Li+ and diethylene glycol dimethyl ether (DEGDME) to prepare [Li-DEGDME]+-graphite co-intercalation compounds ([Li-DEGDME]-Gr) from pristine graphite. The expanded d-spacing and abundant cross-layer voids in the interlayer structure of [Li-DEGDME]-Gr owing to the co-intercalation of [Li-DEGDME]+ complex ions and parasitic chemical reactions between solvent molecules and graphene layers promotes the migration of bare Li+ and provides sufficient interior space for extra lithium-storage. As a result, a much higher lithium-storage capacity of 810 mAh g−1 can be successfully achieved. The extra lithium-storage is proved to originate from the deposition of lithium metal inside the enclosed nanoscale space of the as modified graphite, which inhibits the formation of lithium dendrites, isolates lithium metal from electrolytes and avoids volumetric expansion, enabling the [Li-DEGDME]-Gr electrodes to exhibit better cycling stability with high specific capacity. This work proposes a new strategy to enhance the reversibility of lithium metal plating/stripping by accommodating lithium deposition inside modified carbon materials, thus effectively increasing the reversible capacity of graphite-based anode materials.

A Stable Lithium Metal Anode Enabled by the Site-Directed Lithium Deposition of ZnO-Nanosheet-Modified Carbon Cloth.

Uneven lithium (Li) metal deposition typically results in uncontrollable dendrite growth, which renders an unsatisfactory cycling stability and coulombic efficiency (CE) of Li metal batteries (LMBs), preventing their practical application. Herein, a novel carbon cloth with the modification of ZnO nanosheets (ZnO@CC) is fabricated for LMBs. The as-prepared ZnO@CC with a cross-linked network significantly reduces the local current density, and the design of ZnO nanosheets can promote the uniform deposition of Li metal as lithiophilic sites. As a result, the Li metal anodes (LMAs) based on ZnO@CC (ZnO@CC@Li) enables a long cycle life over 640 hours with a low overpotential of 65 mV at a current density of 4 mA cm-2 with a capacity of 1 mAh cm-2 in the symmetric cell. Moreover, when coupling the ZnO@CC@Li with a LiFePO4 cathode, the assembled full cell exhibits excellent long cycle and rate performance, highlighting its promising practical application prospect.

Operando Optical Microscopy of Dead Lithium Growth in Anode‐Less Configuration

AbstractThere is an increasing demand to improve battery safety and performance as part of the global push to convert the small electronics and transportation sector to infrastructures based on electricity. This work follows the deposition of lithium metal in anode‐less conditions by an operando optical microscope using a transparent indium tin oxide‐polyethylene terephthalate (ITO‐PET) window as the current collector in a readily‐available electrochemical set‐up. The mechanism of Li metal nucleation strongly depends on the selected current densities (C/40 and 2C). After the deposition of the solid electrolyte interface (SEI), Li nucleates from mossy to needle morphology. Moreover, layer‐by‐layer growth of dead Li in voids is monitored by following its accumulation upon cycling. Dead Li deposits in residual hollow structures, especially when high current densities are applied. These optical observations are coupled with computer vision analyses to evaluate the average size of the Li deposits: smaller Li nuclei plate when high C‐rate is applied. The results here described provide insights into a new electrochemical cell concept that enables to elucidate the influence of spatial inhomogeneities of the lithophilic ITO‐PET surface on the mechanism of Li nucleation and plating.

High‐Areal‐Capacity and Long‐Cycle‐Life All‐Solid‐State Lithium‐Metal Battery by Mixed‐Conduction Interface Layer

AbstractThe rapid growth of lithium dendrites has seriously hindered the development and practical application of high‐energy‐density all‐solid‐state lithium metal batteries (ASSLMBs). Herein, a soft carbon (SC)‐nano Li6.4La3Zr1.4Ta0.6O12 (LLZTO) (with high ionic conductivity and diffusion coefficient) mixed ionic and electronic conducting interface layer is designed to promote the rapid migration of Li+ at the interfacial layer, induce the uniform deposition of lithium metal on nanoscale (nano) LLZTO ion‐conducting network inside the interface layer, effectively suppress the growth of lithium dendrites, and significantly improve the electrochemical performance of ASSLMBs. LiZrO2@LiCoO2(LZO@LCO)/Li6PS5Cl(LPSCl)‐nano LLZTO/Li ASSLMB achieves high current density (12.5 mA cm−2), ultra‐high areal capacity (15 mAh cm−2, corresponding to LZO@LCO mass loadings of 111.11 mg cm−2), and ultra‐long cycle life (20 000 cycles). Therefore, the introduction of SC‐nano LLZTO mixed conducting interface layer can greatly improve the interfacial stability between solid‐state electrolyte (SSE) and lithium metal anode to enable dendrite‐free ASSLMBs.