Dendrite-free Lithium Research Articles

In situ co-growth LiF-Li3N rich dual-protective layers enable high interface stability for solid-state lithium-metal batteries

Lithium metal anodes hold promise for next-generation high-energy-density batteries. However, serious dendrite formation and unstable solid electrolyte interphase (SEI) impede their practical implementation. Herein, a novel gel polymer electrolyte (GPE) integrated design is exploited to in situ co-growth Li3N and LiF rich SEI by improving electron transfer kinetics and enhancing mechanical properties. Specifically, a polyethylene glycol diacrylate is used as GPE matrix to form a robust crosslinked network. Meanwhile, the high electron transport capacity of acrylonitrile promotes the generation of Li3N. The polyfluorinated polymer introduction boosts electron transfer kinetics, facilitating C-F bond cleavage to form LiF. Finally, the in situ co-growth Li3N and LiF rich dual-protective SEI is constructed, which regulates the ion flux and achieves dendrite-free lithium deposition. Impressively, the SEI treated symmetrical cell demonstrates excellent plating/stripping cycling for 1000 h at 0.5 mA cm−2 with notably reduced overpotentials (50 mV). Moreover, the obtained GEL@F matched with LiFePO4 displays good cycling stability over 400 cycles with 91.8 % capacity retention at 1 C. Concurrently, paired with LiCoO2 drives a good capacity retention of over 82.8 % after 200 cycles. This study introduces a rational SEI design from the structural composition of GPE to optimize the chemical activity/physical properties of lithium metal interfaces.

In situ polymerized polydioxolane interlayer enabled dendrite-free argyrodite-based solid-state batteries

Solid-state batteries (SSBs) involving argyrodite-type sulfide electrolytes are considered as promising candidates for the state-of-art lithium-ion batteries (LIBs) due to their superior safety, energy and power density. However, the incompatibility between the argyrodite-type sulfide and lithium anode has plagued the development of the sulfide-based SSBs. Herein, we introduced a poly-dioxolane-based (PDOL) interlayer at the lithium anode, which is ring-opening polymerized via poly(acrylamide-2-methyl-1-propane-sulfonate) (PAMPS) loaded on the separator. The in-situ polymerized PDOL interlayer could match with the solvent-sensitive lithium argyrodite while enabling a stable and tight lithium interface. The symmetric lithium cell with the PDOL interlayer exhibits over-1200-hour dendrite-free lithium deposition and stripping at 0.5 mA cm-2, and the critical current density reaches 2.7 mA cm-2. The as-cycled lithium interface is further investigated via the depth-profiling X-ray photoelectron spectroscopy, and solid electrolyte interphase (SEI) is determined to be composed of ether polymer as well as inorganic compounds like LiC, Li2O, LiF, and Li2S. The Li|LiCoO2 SSB with PDOL interlayer presents a high discharge capacity of 120.7 mAh g-1 at 0.1 C and a capacity retention rate of 95.4% after 200 cycles. The rational design of the PDOL interlayer at the lithium anode opens a new alternative for high-performance SSBs.

Dynamic physical network constructed by tripartite H-bonds in artificial SEI to shape ultra-long life dendrite-free lithium-metal anodes

Constructing artificial solid electrolyte interfaces (SEIs) to shape dendrite-free lithium (Li)-metal anodes remains challenges. Herein, we designed dynamic physical network (DPN) with abundant lithiophilic/anionphilic groups through tripartite hydrogen bonds (H-bonds), serving as artificial SEIs in high-loading NCM811-Li metal batteries. The formation and dissociation of DPN endowed by tripartite H-bonds under tension release during Li plating/stripping cycling skillfully balance the contradiction between mechanical robustness and deformability. LiO bonds between lithiophilic sites and Li ions, and extra H-bonds between hydroxyl and electrolyte anions, endow DPN with functions of homogenizing Li-ion flux and accelerating its desolvation, synergistically achieving the uniform Li-ion deposition and weakening the charge shielding. The artificial SEI enhanced Li-anode (DPN@Li) withstood repeated Li ions plating/stripping processes for over 1000 h, which is 5 times longer than pure Li-anodes, and maintained low overpotential at a high current density of 10 mA cm−2. DPN@Li-based NCM811 full cells deliver high specific capacities and outstanding cycle life over 3000 cycles. Further, DPN@Li possesses excellent electrochemical performance in the high active material loading (7.84 mg cm−2) and foldable pouch cells. This work provides a conceptual framework of DPN constructed by multiple weak intermolecular interaction for artificial SEI to shape anode performance, and achieves the idea with a facile manner and simple chemical substances to promote practical applications of LMBs.

Self-extinguishing polyimide sandwiched separators for high-safety and fast-charging lithium metal batteries

Developing fast-charging lithium metal battery (LMB) with high specific capacity arouses enormous attentions. Unfortunately, during the operation of fast-charging LMB, substantial amount of Joule heat generated within battery often induces inhomogeneous heat accumulation that concomitantly deteriorates the lithium dendrite growth issues, resulting in rapid capacity fading and potentially fatal thermal runaway. It is critically essential to develop advanced separator that possesses high ionic conductivity, effective dendrite inhibition and self-extinguishing property for fast-charging LMB with high-safety. Here, we report a facile approach to fabricate polyimide composite separator (denoted as PIFAP), where the polyimide fiber (PIF) membrane is sandwiched by aerogel layers of polyimide/ammonium polyphosphate composite. Notably, compared with PIF, the PIFAP features significant enhancement in flame retardance, electrolyte affinity, electrolyte adsorption and ionic conductivity. Moreover, beneficiating from the aerogel layers with uniform nanopores of ∼100 nm, the optimized PIFAP separator can enable homogeneous lithium deposition, achieving a dendrite-free lithium deposition on the surface of anode for over 1600 h, superior to the PIF and Celgard separators. The resulting “LiFePO4/PIFAP/Li” cell can exhibit a remarkably high cycling stability with 99.1 % of capacity retention after long-term cycling at a current density of 10 C.

Two-dimensional MXene/MOFs heterojunction nanosheets as confinement hosts for dendrite-free lithium metal anodes

Although metallic lithium is regarded as the most potential anode candidate for next-generation batteries, its applications are greatly restricted by the uncontrollable growth of lithium dendrites and unstable anode/electrolyte interface. Herein, MXene/MOFs heterojunction nanosheets are developed through a convenient self-assembly process by harnessing the chemical interactions between MXene and Ni-MOFs monolayers. In this heterojunction, not only the MXene interlayer induces uniform lithium nucleation, but also MOFs monolayers act as stable interfaces to promote Li ion transport and homogenize the subsequent lithium deposition. Moreover, the MXene/MOFs substrate mitigates the volume change of lithium anodes. Consequently, 2D MXene/MOFs heterojunction nanosheets as confinement hosts effectively suppress lithium dendrites and exhibit enhanced electrochemical performances including a coulombic efficiency of 99 % over 300 cycles at 0.5 mA cm−2 and 1 mAh cm−2, and a long cycling life up to 500 h at 1 mA cm−2 and 1 mAh cm−2. The MXene/MOFs-Li||LiFePO4 cells exhibit a stable cycling performance with a capacity retention of 91 % after 600 cycles.

High-Performance Dendrite-Free Lithium Metal Anode Based on Metal-Organic Framework Glass.

The performance of lithium metal batteries is severely hampered by uncontrollable dendrite growth and volume change within the anode. This work addresses these obstacles by introducing a novel strategy: applying an isotropic and internal grain-boundary-free layer, specifically, a metal-organic framework (MOF) glass layer with nano-porosity onto the electrochemically plated lithium metal anode. Both ab initio and classical molecular dynamics simulations indicate that the MOF glass layer makes the lithium transport smooth and uniform via its internal monolithic and interfacial advantages. This MOF glass layer with the fast and more uniform lithium diffusion in the monolithic interior and its interface enables dendrite-free lithium plating and stripping through surface confinement effect and interfacial effect. When employed in symmetric batteries, the achieved Li metal anode can operate over 300h at 1mAcm-2. The full batteries matched with LiFePO4 exhibit high capacity (148mAhg-1), excellent rate performance (61mAhg-1 at 5C), and outstanding cycling stability (with capacity retention of ≈90% after 1000 cycles). The full batteries matched with high-voltage LiCoO2 also show superior performances. Therefore, the strategy of utilizing a MOF glass layer enables the development of high-performance lithium metal anodes.

One-stone, two birds: One step regeneration of discarded copper foil in zinc battery for dendrite-free lithium deposition current collector

The ever-growing requirement for electrochemical energy storage has exacerbated the production of spent batteries, and the recycling of valuable battery components has recently received a remarkable attention. Among all battery components, copper foil is widely utilized as a current collector for stable zinc platting and stripping in zinc metal batteries (ZMBs) due to the perfect lattice matching of between metal copper and zinc, which is accompanied by the formation of multiple copper-zinc alloy components during the cycling process. Herein, a novel “two birds with one-stone” strategy through a one simple heat treatment step to revive the discarded copper foil in zinc metal battery is reported to further obtain a lithiophilic current collector (CuxZny-Cu) with multiple copper-zinc alloy components on the surface of the discarded copper foil. Such revived CuxZny-Cu current collector greatly reduces the lithium nucleation overpotential and realizes uniform lithium deposition and further inhibits lithium dendrites growth. The formed multiple CuxZny alloy phases on the surface of discarded copper foil exhibit a low Li nucleation overpotential of only 15 mV at 0.5 mA cm−2 for the first cycle. Moreover, such a CuxZny-Cu current collector could achieve stable cycle for 220 cycles at 0.5 mA cm−2 and 110 cycles at 1 mA cm−2 with a Li plating capacity of 1 mAh cm−2. Theoretical calculations indicate that, compared with pure Cu foil, the formed multiple alloy components of CuZn5, CuZn8, Cu0.61Zn0.39 and CuZn have low adsorption energy of −2.17, −2.55, −2.16 and −2.35 eV with lithium atoms, respectively, which result in reduced lithium nucleation overpotential. The full cell composed of CuxZny alloy current collector with deposition of 5 mAh cm−2 metal Li anode coupled with LiFePO4 (LFP) cathode exhibits a reversible capacity of 125.6 mAh/g after 110 cycles at a current of 0.5 C with capacity retention of 85.1 %. This work proposed a promising strategy to regenerate the discarded copper foil in rechargeable batteries.

Li3N/SiO2 modified 3D collectors to extend the cycle life of lithium anode

Despite the many benefits of lithium-metal anodes in next-generation lithium-metal batteries, they are limited by their infinite volume expansion and lithium dendrite growth. In this study, we propose a novel method for producing stable lithium-metal anodes by first coating a Cu current collector with a thin insulating silica layer, then laser etching to create holes where lithium deposition can take place. Additionally, an artificial solid electrolyte interphase layer of Li3N, which is generated in situ on the deposited lithium metal surface can reduced electrolyte consumption and promote uniform lithium deposition, and the confined space within the holes prevent dendrite formation. The above design realizes the use of limited lithium and improves the utilization of lithium metal while increasing the safety of the cells. The 3D Cu supported Li anode exhibited stable average coulombic efficiency of 99.8 % for 300 cycles at a current density of 1 Ma cm−2. Specifically, full cells made of such a 3D Cu anode coupled with a LiFePO4 cathode exhibited a capacity of 125 mA h g−1 after 250 cycles (low N/P capacity ratio of 2.38), providing a dendrite-free lithium metal anode.

Improved plating/stripping in anode-free lithium metal batteries through electrodeposition of lithiophilic zinc thin films

The new concept of anode-free Li batteries (AFLBs) with no excess lithium, while retaining numerous strengths, does come with certain challenges, such as high capacity loss and low coulombic efficiency. These challenges can be addressed through the utilization of modified lithiophilic current collectors to enhance the electrochemical performances. Herein, we investigated the surface modification of the Cu current collector by zinc electrodeposition to provide a lithiophilic thin layer. This process aims to facilitate a smoother plating/stripping process, leading to a uniform and dendrite-free lithium deposition on the LixZny phase formed at the first stages of plating. The zinc-modified current collectors improved cell's performances, including smooth and dense lithium deposition, reduced overpotential at various applied current densities (44.5 mV to 16.8 mV @0.25 mA cm−2), prolonged cycling stability for about 300 cycles and provided high coulombic efficiency of 95 % when compared to bare Cu electrodes. These improvements are attributed to a favorable lithium alloying reaction on the Zn-coated surface. Galvanostatic Intermittent Titration Technique (GITT) and Electrochemical Impedance Spectroscopy (EIS) revealed high diffusion coefficients for lithium (ranging from 10−9 to 10−6 cm² s-1), despite of the solid-state Li diffusion in the Zn film coating. We anticipate that implementing this modified current collector in a half-cell configuration could lead to the realization of a high-performance, anode-free lithium battery. This holistic approach proposes a scalable and cost-effective technique for boosting the performance of AFLBs.

Regulating lithium nucleation and deposition on carbon cloth decorated with vertically aligned Ag-doped MnO2 nanosheet arrays for dendrite-free lithium metal anode

Metallic Li with high specific capacity and low electrode potential is considered as the most promising anode material. The main obstacles to its application are uncontrollable Li dendrites growth and infinite volume changes. Herein, we design a modified carbon cloth (CC) by vertically aligned MnO2 nanosheet arrays embedded with tiny Ag (Ag/MnO2@CC) through hydrothermal approach. Density functional theory (DFT) calculations indicate that MnO2 and Ag show a more negative adsorption energy (−4.31 and −2.34 eV) than C (−1.65 eV), implying their better lithiophilicity. Finite element simulations demonstrate that the Ag-doped MnO2 nanosheet arrays reduce local current density and redistribute Li-ion flux. Moreover, the channels assembled by vertical-aligned MnO2 nanosheets and 3D CC can offer sufficient spaces to buffer volume fluctuation during cycling. Accordingly, the Ag/MnO2@CC is employed as a lithiophilic host to supervise homogenous Li nucleation and deposition. The Ag/MnO2@CC electrodeposited with Li exhibits dendrite-free feature and a high Coulombic efficiency of 99.9% during 300 cycles. The symmetric cell shows an ultra-low polarization voltage of 14 mV over 1300 h at 1 mA cm−2 with the capacity of 1 mAh cm−1. The full cell paired with LiFePO4 exhibits excellent capacity of 105.5 mAh g−1 after 400 cycles at 1 C.

Excellent Polymerized Ionic-Liquid-Based Gel Polymer Electrolytes Enabled by Molecular Structure Design and Anion-Derived Interfacial Layer.

Polymerized ionic liquid (PIL)-based gel polymer electrolytes (GPEs) are well known as highly safe and stable electrolytes but with low ambient ionic conductivity. Herein, we first designed and synthesized an IL monomer with a long and flexible side chain and then mixed it with LiTFSI and MEMPTFSI to construct a PIL-based GPE (denoted as GM-GPE). The special molecular structure of the monomer greatly improves the ionic transport through the PIL chain, and the introduction of MEMPTFSI plasticizer further improves the ionic conductivity, promoting a TFSI--anion-derived SEI formation to suppress Li dendrite growth and forming an electrostatic shielding effect of MEMP+ cations to promote the uniform deposition of Li+. Consequently, the as-prepared GM-GPE exhibits high ambient ionic conductivity (4.3 × 10-4 S cm-1, 30 °C), robust electrochemical stability, excellent thermal stability, nonflammability, and superior ability to inhibit Li dendrite growth. The resultant LiFePO4|GM-GPE|Li cell exhibits a high discharge capacity of 150 mA h g-1 at 0.2 C along with a good cycling stability and rate capability. This work brings about new guidance for the development of high-quality GPEs with high ionic conductivity, high stability, and safety for long cycling and dendrite-free lithium metal batteries.

A dicarbonate solvent electrolyte for high performance 5 V-Class Lithium-based batteries

Rechargeable lithium batteries using 5 V positive electrode materials can deliver considerably higher energy density as compared to state-of-the-art lithium-ion batteries. However, their development remains plagued by the lack of electrolytes with concurrent anodic stability and Li metal compatibility. Here we report a new electrolyte based on dimethyl 2,5-dioxahexanedioate solvent for 5 V-class batteries. Benefiting from the particular chemical structure, weak interaction with lithium cation and resultant peculiar solvation structure, the resulting electrolyte not only enables stable, dendrite-free lithium plating-stripping, but also displays anodic stability up to 5.2 V (vs. Li/Li+), in additive or co-solvent-free formulation, and at low salt concentration of 1 M. Consequently, the Li | |LiNi0.5Mn1.5O4 cells using the 1 M LiPF6 in 2,5-dioxahexanedioate based electrolyte retain >97% of the initial capacity after 250 cycles, outperforming the conventional carbonate-based electrolyte formulations, making this, and potentially other dicarbonate solvents promising for future Lithium-based battery practical explorations.

Compressible and Elastic Reduced Graphene Oxide Sponge for Stable and Dendrite-Free Lithium Metal Anodes.

Dendritic Li deposition, an unstable solid-electrolyte interphase (SEI), and a nearly infinite relative volume change during cycling are three major obstacles to the practical application of Li metal batteries. Herein, we introduce a compressible and elastic reduced graphene oxide sponge (rGO-S) to simultaneously eliminate Li dendrite growth, stabilize the SEI, and accommodate the volume change. The volume change is contained by compressing and expanding the rGO-S anode, which effectively releases the Li plating-induced stress during cycling. The smooth and dense Li metal is deposited on rGO-S without dendrites, which preserves the SEI, reduces consumption of the electrolyte, and prevents the formation of Li debris. The half-cells employing rGO-S show a steady and high Coulombic efficiency. The Li@rGO-S symmetric cells demonstrate excellent cycling stability over 1200 cycles with a low overpotential. When paired with LiFePO4 (LFP), the Li@rGO-S||LFP full cells exhibit a high specific capacity (150.3 mAh g-1 at 1C), superior rate performance, and good capacity retention.

In situ synthesis of lithiophilic Ag sites in 3D MOF-derived nitrogen-doped porous carbon composites towards dendrite-free lithium metal anodes

Synergistic modulation of Li nucleation/growth achieved by MOF-derived nitrogen-doped porous carbon framework and lithiophilic Ag nanoparticles.

Refining grains and optimizing grain boundaries by Al2Yb to enable a dendrite-free lithium anode

The stripping/plating behavior of the lithium metal anode was successfully improved, resulting in the improvement of the electrochemical cycling stability and rate performance.

Flexible self-supporting inorganic nanofiber membrane-reinforced solid-state electrolyte for dendrite-free lithium metal batteries.

Compounding of suitable fillers with PEO-based polymers is the key to forming high-performance electrolytes with robust network structures and homogeneous Li+-transport channels. In this work, we innovatively and efficiently prepared Al2O3 nanofibers and deposited an aqueous dispersion of Al2O3 into a membrane via vacuum filtration to construct a nanofiber membrane with a three-dimensional (3D) network structure as the backbone of a PEO-based solid-state electrolyte. The supporting effect of the nanofiber network structure improved the mechanical properties of the reinforced composite solid-state electrolyte and its ability to inhibit the growth of Li dendrites. Meanwhile, interconnected nanofibers in the PEO-based electrolyte and the strong Lewis acid-base interactions between the chemical groups on the surface of the inorganic filler and the ionic species in the PEO matrix provided facilitated pathways for Li+ transport and regulated the uniform deposition of Li+. Moreover, the interaction between Al2O3 and lithium salts as well as the PEO polymer increased free Li+ concentration and maintained its stable electrochemical properties. Hence, assembled Li/Li symmetric cells achieved a cycle life of more than 2000 h. LFP/Li and NMC811/Li cells provided high discharge specific capacities of up to 146.9 mA h g-1 (0.5C and 50 °C) and 166.9 mA h g-1 (0.25C and 50 °C), respectively. The prepared flexible self-supporting 3D nanofiber network structure construction can provide a simple and efficient new strategy for the exploitation of high-performance solid-state electrolytes.

Synergistic regulation of Li deposition on F-doped hollow carbon spheres toward dendrite-free lithium metal anodes.

The notorious issues of lithium (Li) dendrite growth and volume change hinder the practical applications of Li metal anodes. LiF as a key component of the solid electrolyte interface (SEI) governs Li+ transport and deposition, yet the formation of LiF consumes the anions (PF6-/TFSI-) in the electrolyte, preventing the stable cycling of Li anodes. Herein, fluorine (F)-doped hollow carbon (FHC) was synthesized and used to construct a composite current collector with FHC as an F-rich buffer layer for modifying the Cu foil. The F content provided by FHC not only mitigates the anion (PF6-/TFSI-) consumption but also enhances the stability of SEI. The hollow structure of FHC with abundant internal space can accommodate deposited Li to relieve the volume change during cycling. Besides, the significantly improved specific surface area of the electrode effectively reduces the local current density to achieve a homogeneous Li deposition. Due to the above cooperation, the symmetrical cell of Cu@FHC-Li||Cu@FHC-Li maintains stable cycling for more than 1800 h with a hysteresis voltage of 19 mV. In addition, full cell coupling with LiFePO4 cathode delivers excellent long-term cycling and rate performance. This work provides an effective route for developing stable Li metal anodes.

Magnesium fluoride-engineered UiO-66 artificial protection layers for dendrite-free lithium metal batteries

The MgF2 and F-terminated groups effectively infiltrated the ion transport channels within UiO-66, thereby regulating the desolvation process and facilitating rapid Li+ transport kinetics.

Attaining improved cycling durability and engineering a dendrite-free lithium metal anode

Schematic diagram of Li plating/stripping behavior with Li metal and Li metal powder electrode.

Ultralight Ag-grid current collector enabled by screen printing Ag ink on Cu foil as efficient deposition-inducing layer for dendrite-free lithium metal batteries

An ultralight deposition-inducing layer consisting of a grid-like Ag pattern on Cu foil was designed and fabricated by using a scalable screen-printing technique to guide a uniform lithium-plating behavior.