Li Deposition Research Articles

Sustainable Release of LiNO3 from a Fluorine‐Decorated Metal–Organic Framework Separator to Enable High‐Performance Li‐Metal Batteries in Carbonate Electrolytes

AbstractHigh‐voltage Li‐metal batteries hold great prospects for boosting energy density, while the Li‐metal anodes show poor compatibility with high‐voltage tolerant carbonate electrolytes, leading to unstable solid‐electrolyte interphase (SEI) and uncontrolled Li dendrites growth. Herein, a F‐decorated UIO‐66/polyimide (PI) functional separator encapsulated with LiNO3 (LNO@UIO‐66F/PI) is rationally designed to regulate the interfacial chemistry and Li deposition behavior. Specifically, the UIO‐66F nanoparticles in situ grown on the PI fibers form continuous electronegative nanochannels, which promote rapid and uniform Li+ flux while repelling the anion migration. Furthermore, the LiNO3 encapsulated in the UIO‐66F nanopores sustainably releases to form a thin and conductive Li3N‐rich SEI. This synergy effect induces a dense and spherical Li deposition behavior, effectively inhibiting the growth of Li dendrites. Consequently, this LNO@UIO‐66F/PI separator demonstrates highly reversible Li plating/stripping over 1000 h at an extremely high current density of 10 mA cm−2 in carbonate electrolytes, and also enables the stable cycling of Li||LiNi0.8Co0.1Mn0.1O2 cell over 1000 cycles under a high cut‐off voltage of 4.5 V, paving the way for practical application of high‐energy‐density Li‐metal batteries.

Anion-Rich Interface via a Self-Assembled Monolayer toward a Long-Lifespan Li Metal Battery.

Due to the extremely high energy density of Li metal, Li metal batteries are regarded as one of the most promising candidates for next-generation energy storage systems. However, interfacial issues, particularly the unstable solid electrolyte interphase (SEI) and lithium dendritic growth, hinder practical application. Herein, we induce an anion-rich interface near the Li metal by introducing positively charged self-assembled monolayers (SAMs) on ceramic-coated separators to simultaneously stabilize the SEI and homogenize the Li deposition. The anion-rich interface, originating from the electrostatic attraction of SAMs, promotes the preferential decomposition of salt anions over organic solvent molecules, leading to the formation of a stable anion-derived inorganic component, notably LiF. Furthermore, the positively charged SAMs immobilize anions, significantly mitigating dendritic Li by improving the Li+ transference number (∼0.73) and thereby mitigating dendritic Li growth. Hence, we present SAMs on ceramic-coated separators as an innovative way to improve the long-term cycling performance of Li metal batteries.

Monofluorinated acetal electrolyte for high-performance lithium metal batteries

High degree of fluorination for ether electrolytes has resulted in improved cycling stability of lithium metal batteries due to stable solid electrolyte interphase (SEI) formation and good oxidative stability. However, the sluggish ion transport and environmental concerns of high fluorination degree drive the need to develop less fluorinated structures. Here, we depart from the traditional ether backbone and introduce bis(2-fluoroethoxy)methane (F2DEM), featuring monofluorination of the acetal backbone. High coulombic efficiency and stable long-term cycling in Li||Cu half cells can be achieved with F2DEM even under fast Li metal plating conditions. The performance of F2DEM is further compared with diethoxymethane (DEM) and 2-[2-(2,2-difluoroethoxy)ethoxy]-1,1,1-trifluoroethane (F5DEE). A significantly lower overpotential is observed with F2DEM, which improves energy efficiency and enables its application in high-rate conditions. Comparative studies of F2DEM with DEM and F5DEE in anode-free lithium iron phosphate (LiFePO4) LFP pouch cells and high-loading LFP coin cells further show improved capacity retention of F2DEM electrolyte, demonstrating its practical applicability. More importantly, we also extensively investigate the underlying mechanism for the superior performance of F2DEM through various techniques, including X-ray photoelectron spectroscopy, scanning electron microscopy, cryogenic electron microscopy, focused ion beam, electrochemical impedance spectroscopy, and titration gas chromatography. Overall, F2DEM facilitates improved Li deposition morphology with reduced amount of dead Li. This enables F2DEM to show superior performance, especially under higher charging and slower discharging rate conditions.

Anchoring Sn Nanoparticles in Necklace-Like B,N,F-Doped Carbon Fibers Enables Anode-Less 5V-Class Li-Metal Batteries.

Li metal batteries (LMBs), particularly with a limited Li metal anode and a 5V-class cathode, offer significantly higher energy density compared to the state-of-the-art Li-ion batteries. However, the limited Li anode poses severe challenges to cycling stability due to low efficiency and large volume expansion issues associated with Li. Herein, we design a lightweight and functionalized host composed of Sn nanoparticles embedded into necklace-like B,N,F-doped carbon macroporous fibers (Sn@B/N/F-CMFs) toward anode-less 5V-class LMBs. The macroporous framework can decrease the local current density to homogenize Li deposition and release structural stress to realize high areal capacity of over 40 mAh cm-2. The lithiophilic B,N,F-doped carbon and Sn nanoparticles can function as high-affinity Li binding sites to uniformize Li nucleus growth on the internal and external surface of hollow fibers. Accordingly, the Sn@B/N/F-CMFs enable stable dendrite-free Li plating/stripping behaviors for 1700 h even in the carbonate-based electrolyte. When coupled with a 5V-class LiNi0.5Mn1.5O4cathode, the assembled anode-less pouch cell also displays stable cycling performance even under harsh conditions.

A lithiophilic interphase enabled by thiophenol additive for stable lithium metal anode

Lithium metal is regarded as a highly promising anode material owing to its ultrahigh theoretical capacity and low electrode potential. Unfortunately, significant concerns including poor Coulombic efficiency (CE) and uncontrolled Li dendritic growth severely hinder its development. Constructing a stable solid electrolyte interphase (SEI) on the electrode surface has been considered a practical and effective approach to settle the previous issues. In this study, 4-(trifluoromethyl)thiophenol (TFTP), an organic thiophenol, is introduced as an electrolyte additive to generate a lithiophilic organosulfur interphase with lithiophilic S sites through in situ reaction, guiding uniform Li nucleation and Li plating. Additionally, the generation of LiF/Li3N-rich layer during the cycling further facilitates homogeneous Li deposition. Therefore, the reliable SEI results in a uniform Li morphology and rapid kinetic of Li deposition. Benefiting from the TFTP electrolyte, the Li–Li symmetric cell exhibits a long-lasting lifespan of 1200 hours, and the full cell coupling with sulfur cathode shows a remarkable discharge capacity of 733.6 mAh g−1 after 200 cycles.

Lithium directed growth triggered by vertical interface activity gradient framework enabling long-life Li metal anode

Three-dimension (3D) current collector with interior porous structure and large specific surface area can suppress the volume change of lithium (Li) metal anode and reduce the local current density, which is beneficial for uniform deposition of Li. However, the low Li affinity and instability of Li+ transport allow Li metal to easily deposit on the top of the 3D current collector, accelerating the growth of Li dendrites. Herein, a 3D current collector with a stable Li+ transport channel and a vertical interfacial activity gradient is proposed, realizing a long-life Li metal battery. The density functional theory (DFT) and experimental results demonstrate that the vertically Cu nanoarray has a low Li+ migration barrier, while the ZnO nanocrystalline at the bottom of the 3D current collector has a high Li affinity. The synergistic action of the vertically Cu nanoarray and ZnO nanocrystalline results in the directed Li metal homogeneous deposition. Furthermore, the Li2O artificial protective layer formed by the interaction of ZnO with Li metal also promotes the transport of Li+ into the inner current collector. Hence, the Li directed homogeneous deposition realizes a long cycle life Li metal anode for more than 4000 h of the symmetrical cell at 2.0 mA cm−2 current density and 1.0 mA h cm−2 plating/stripping capacity, as well as more than 500 cycles with 98.8 % coulombic efficiency of the half cell at 1.0 mA cm−2 current density and 1.0 mA h cm−2 capacity. This work provides a feasible vertical activity gradient directionally guided Li deposition strategy for realizing long cycle life Li metal batteries.

Stable low-temperature lithium metal batteries with dendrite-free ability enabled by electrolytes with cooperative Li+-solvation

In subzero environments, sluggish electrochemical kinetics and unstable electrode/electrolyte interphases hinder progress in lithium metal batteries (LMBs), emphasizing the need for advanced electrolytes to ensure stability in harsh environments. Herein, we proposed a balanced “cocktail optimized” electrolyte by manipulating solvated and anionic species. The dual salt/dual solvent electrolyte simultaneously achieves low bulk impedance and low interfacial impedance, while also demonstrating improved Li reversibility and oxidation stability. The tailored solvation structure encourages the breakdown of anions, leading to the formation of inorganic-rich interphases at both the cathode and Li-anode, which enables a uniform plating-stripping of Li while maintaining exceptional voltage resilience on the cathode. Moreover, NO3– ions preferentially adsorb onto the cathode surface within the inner Helmholtz plane, shielding the easily-oxidized non-solvating solvent molecules, a phenomenon referred to as the “shielding effect”, thus inhibiting side oxidation reactions. Consequently, the anion-derived interface chemistry contributes to the dendrite-free Li deposition with a high CE of 99.45%, a stable cycling of Li||NCM523 battery with 85% capacity retention after 150 cycles, and a superior low-temperature discharge performance at −30 ℃ with a capacity retention of 68.2%. This work sheds light on an encouraging electrolyte strategy for stable LMBs in a wide-temperature range.

Stabilizing the Interface of Li1.3Al0.3Ti1.7(PO4)3 and Lithium Electrodes via Interlayers Strategy in Solid-State Batteries

The polyvinylidene carbonate:BN layer was constructed between Li1.3Al0.3Ti1.7(PO4)3 (LATP) and the lithium (Li) electrode, improving interfacial compatibility and thermal stability. The Li3N-rich solid electrolyte interphase regulates Li deposition behaviors. The...

Decoupling Interfacial Stability and Ion Transport in Solid Polymer Electrolyte by Tailored Ligand Chemistry for Lithium Metal Battery

AbstractAchieving fast ion transport kinetics and high interfacial stability simultaneously is challenging for polymer electrolytes in solid‐state lithium batteries, as the coordination environment optimal for Li+ conduction struggles to generate desirable interphase chemistry. Herein, the adjustable property of organic ligands is exploited in metal–organic frameworks (MOFs) to develop a hierarchical composite electrolyte, incorporating heterogeneous and spatially confined MOF nanofillers into a poly‐1,3‐dioxolane matrix. The defect‐engineered University of Oslo‐66 MOFs (UiO‐66d) with tailored Lewis acidity can separate ion pairs and optimize Li+ migration through weakened solvation effects, thereby enhancing ion conductivity by over sixfold (0.85 mS cm−1@25 °C). At the lithium anode side, a densified University of Oslo‐67 MOFs (UiO‐67) layer with conjugated π electrons facilitates anion participation in the solvation sheath, promoting anion reduction and thereby forming LiF/Li3N‐dominated solid electrolyte interphase for isotropic Li deposition. The as‐assembled Li||LiFePO4 full cell delivers superior cycling stability with 92.7% of capacity retained over 2000 cycles at 2 C. Notably, the developed electrolyte demonstrates excellent compatibility with high‐voltage cathodes, achieving 80% capacity retention with LiNi0.5Co0.2Mn0.3O2 over 630 cycles. This work provides valuable insights into decoupling transport and interfacial challenges in solid‐state lithium batteries, paving the way for advanced battery technologies.

Electrochemically Tailored Host Design with Gradient Seeds for Dendrite-Free Li Metal Batteries.

Dendritic challenges in Li metal batteries are commonly resolved using porous three-dimensional (3D) current collectors, which have a significant issue in that Li is deposited from the top (top growth) of the structure rather than from the bottom (bottom growth), failing to effectively suppress dendrite growth and volumetric expansion. We propose the structure incorporating a gradient lithiophilic seed within a 3D framework by pulse electroplating Mg, specifically targeting the near bottom to promote bottom growth and achieve dense Li deposition. This method achieves precise control over the catalytic seed size and distribution. Optimal conditions for maximizing the catalytic effect are identified. The resulting Mg-gradient porous-Cu structure exhibits superior Li-plating behavior with bottom growth, significantly reducing dendrite formation and improving cycle life. The mechanistic origin of bottom-guided Li growth is supported by DFT and 3D simulation results. This method presents a significant step forward in developing high-performance Li-metal batteries.

From the Passivation Layer on Aluminum to Lithium Anode in Batteries

Many low-density metals are also reactive. This article draws inspiration from the passivation oxide layer formed on aluminum to the design of electrochemically stable surface layers on lithium metal electrodes in batteries. First, reactive molecular dynamics simulations are used to compare the oxide layer formation on lithium and aluminum metal surfaces. While a uniform dense aluminum oxide layer forms on aluminum, vertical cracks in the lithium oxide layer lead to a deformed lithium oxide layer. These observations are consistent with the empirical Pilling–Bedworth Ratio (PBR) that uses the molar volume ratio of oxide to metal to determine whether a metal is likely to passivate in dry air by creating a protective oxide layer. A passivation layer needs to form on the lithium metal surface in the presence of electrolytes. The PBR concept is thus extended to the multiple compounds found in the spontaneously formed solid electrolyte interphase (SEI). It is suggested that a mixture of LiF/Li2CO3 or LiF/Li2O or replacing Li2O with Li2S can effectively create a PBR that is in the 1 to 1.3 range for better passivation. While these analyses are consistent with some experimental evidence, a seeding layer concept is proposed to further prevent dendrite growth and simplify the battery manufacturing process. The role of metallic nanoparticles in the metal–carbon nanocomposite seeding layer to control lithium nucleation and growth is investigated by an atomically informed phase field model (AI-PFM). The model predicts the formation of a Li-rich phase with Ag nanoparticles but non-uniform lithium metal nucleation on Au nanoparticles, showing the AI-PFM model to be a desired design tool to evaluate which metallic nanoparticles can be used to control the Li deposition morphology. These results collectively emphasize the need for highly coupled electrochemical–mechanical modeling to solve the challenges of designing a multifunctional passivation layer for metal electrodes in batteries.

Visualizing Lithium Deposition and Identifying Two Types of Dendrites in Extreme-Fast-Charging Full Cells across the Entire Lifespan by Operando EPR and EPR Imaging.

Metallic lithium deposition processes in NCM811∥graphite full cells during extreme-fast charging of 4 C (fully charged within 15 min) are detected via operando electron paramagnetic resonance (EPR) and EPR imaging over hundreds of cycles to quantify lithium deposits and visualize their spatial distribution. EPR imaging shows that constant-voltage charge generates loose Li dendrites with divergent growth whereas overcharge leads to long dendrites with vertical growth, and these Li deposits accumulate at the anode edges, which could deplete the Li resource at the cathode edges. Moreover, quantitative EPR indicates that the stripping current correlates to the deposit surface areas, while the reintercalation current depends on the contact areas between plated Li and graphite. Overall, the results of EPR and EPR imaging suggest that the introduction of a relaxation period after extreme-fast charge for Li reintercalation into graphite is important to mitigate the accumulation of dead Li.

Constructing a Li2O/LiZn Mixed Ionic Electron Conductive Layer by Ultrasonic Spraying to Enhance Li/Garnet Solid Electrolyte Interface Stability for Solid-State Batteries.

Garnet-type Li6.25Ga0.25La3Zr2O12(LGLZO) is believed to be a promising solid electrolyte for solid-state batteries due to its high ionic conductivity, safety, and good stability toward Li. However, one of the most challenges in practical application of LGLZO is the poor contact between Li and LGLZO. Herein, a ZnO layer is prepared on the surface of LGLZO pellet by ultrasonic spraying. Then, a Li2O/LiZn mixed ionic and electron conductive (MIEC) layer is formed at the Li/LGLZO interface via the conversion reaction between ZnO and molten Li. Experiments and theoretical calculations reveal that this MIEC layer can simultaneously improve interface contact, optimize interfacial kinetics, and guide homogeneous Li deposition. As a result, the interface impedance decreases significantly to 36 Ω cm2, the critical current density (CCD) can reach as high as 2.15 mA cm-2, and the Li/ZnO@LGLZO/LiFePO4 all-solid-state cells stably cycle 100 times at 0.5 C. This simple and effective approach may provide a viable strategy for improving the cycle performance of solid lithium metal batteries.

Mesoscopic Modelling of Li Deposition in Sulfide-Based Solid Electrolyte Using Two-Dimensional Artificial Polycrystal Structure

Abstract Understanding Li nucleation and growth mechanism during charging in solid electrolytes (SEs) is essential in development of all-solid-state batteries with metallic Li, because the Li dendrite could cause internal short-circuit by penetration of SE. However, it is still under debate how the factors including degradation of SE layer, the stacking pressure, and the microstructure affect the Li nucleation and growth in SE. In this study, the coupled current-deposition-stress models using the two-dimensional artificial SE structures have been developed by combination of finite element method and Monte Carlo simulations. The model assumed that Li flux on the SE grain induces an eigen strain in the deposited Li region, and Li grows into the SE layer by breaking grain boundary (GB). Degradation of SE was modelled as the decrease of fracture strength of GB using a coefficient. The effects of these microstructure and operation factors on GB fracture and Li deposition have been evaluated and discussed.

Advanced Hierarchical Lithiophilic Scaffold Design to Facilitate Synchronous Deposition for Dendrite‐Free Lithium Metal Batteries

AbstractLocalized deposition behavior tends to induce the growth of lithium dendrite and hinder the the full utilization of lithium storage space, significantly impeding the practical application of 3D conductive hosts. Here, a novel synchronous deposition mode is proposed for the first time through hierarchical structure design of 3D Li host. The top‐down gradually enhanced lithiophilicity and conductivity of 3D scaffold provide sufficient driving force for Li+ to migrate downward, promoting synchronous Li deposition within the entire space of the host. Notably, the novel deposition mode has been theoretically and experimentally validated through finite element simulation and in situ optical microscopy, respectively. The meticulously designed strategy not only maximizes the utilization of the entire 3D scaffold space but also prevents the formation of Li dendrites under high current rate. Consequently, the symmetric Li//Li cell exhibits a long‐term cycling lifespan over 3700 h with a low overpotential of 15.6 mV, together with a Coulombic efficiency as high as 99.5% over 300 cycles at 3 mA cm−2. The full cell paired with LiFePO4 cathode demonstrates a cycling lifespan of 1000 cycles with a capacity retention rate of 91.6%. The proposed synchronous deposition strategy opens up a new paradigm for the design and construction of 3D hosts for dendrite‐free Li metal anode.

Highly crystalline nanorods pyrene-based covalent organic framework artificial solid electrolyte interface accelerated interface Li+ regulation on lithium anode

The detrimental effects of heterogeneous Li deposition and aeolotropic Li dendrite propagation critically hamper its serviceability of Li metal batteries. The exploitation of neutral multifunctional porous polymer artificial SEI is imperative to modulate interfacial ionic transfer behavior. Herein, we propose a strategy based on dual-functional nanorod-shaped covalent organic frameworks (COF) to accelerate Li+ diffusion and mitigate lithium dendrite growth by creating an artificial solid electrolyte interface (SEI) layer. As anticipated, the immobilized high-polarity –OH and −CN- groups, along with the porous channel facilitates, facilitate uniform Li+ flux distribution and rapid Li+ migration. Additionally, the highly conjugated nature of the pyrene moiety not only enhances the plane π-π stacking crystallinity of TFDH-COF, but contributes positively to Li+ and repelling TFSI−. The combination of comprehensive ex-situ/in-situ characterizations and DFT calculations have unraveled the underlying mechanisms on the reductive Li mitigation energy barrier and enhancive Li+ transfer ability. In contrast with bare Li, the resultant TFDH-COF@Li electrode demonstrates the elevated reversibility of Li+ utilization, slight polarization, dendrite-free interface and prolonged cyclic performance in Li|Cu, Li|Li, and Li-based full cells operated at rigorous current densities. Those unswerving evidences enlighten the feasibility of engineering the neutrality COF layer to get rid of adverse disordered Li proliferation.

Boosting Li‐Metal Anode Performance with Lithiophilic Li–Zn Seeds in a 2D Reduced Graphene Oxide Scaffold

AbstractThe substitution of conventional graphite with Li metal as an anode material has garnered significant interest due to its exceptionally high theoretical energy density. However, the direct application of Li metal as an anode in batteries faces formidable challenges, including dendrite growth and interphase instability. Herein, a high‐performance composite anode (LZ‐rGO) that integrates a reduced graphene oxide (rGO) scaffold with lithiophilic Li–Zn alloy nanoparticles is presented. The Li–Zn seeds embedded in the structure lower the initial nucleation barrier and facilitate uniform Li deposition. Furthermore, the rGO scaffold, possessing a large specific surface area, enables the LZ‐rGO anode to significantly reduce voltage hysteresis and prevents the deactivation of metallic Li during the plating/stripping processes. As a result, the symmetric cell demonstrates stability over 1200 h at a current density of 1 mA cm−2, with negligible voltage fluctuation. When paired with a LiFePO4 cathode, the full cell achieves stable cycling for 1000 cycles with a high‐capacity retention, demonstrating exceptional interface stability and cycling efficiency.

Ordered and Expanded Li Ion Channels for Dendrite‐Free and Fast Kinetics Lithium–Sulfur Battery

AbstractThe uncontrolled polysulfide shuttling and lithium dendrite growth greatly impede the practical implementation of Li–S batteries. These issues can be alleviated by constructing an artificial layer that immobilizes soluble polysulfides and regulates Li+ flux. Here, a layer‐expanded lithium montmorillonite is fabricated through molecular intercalation to serve as a dual regulator for Li–S batteries. The lithiophilic montmorillonite, with its ordered and expanded Li+ diffusion channels, exhibits a high transference number, and promotes homogeneous Li deposition. Additionally, its moderate adsorption of polysulfides, combined with favorable Li diffusion behavior, enhanced the redox kinetics of sulfur species. This unique structure enables a prolonged lifespan of 1000 cycles at 0.5C with a low capacity decay of 0.04% per cycle for practical Li–S batteries.

Investigating the Effects of Electrolytes on Li Deposition By Electrochemical Quartz Crystal Microbalance

Batteries for EVs and grid-scale energy storage are necessary to meet the increasing energy demands in modern society and support the creation of a net-zero emission world. Among various kinds of batteries, lithium metal batteries (LMBs) using lithium metal anodes (LMAs) are one of the most promising candidates. They provide high theoretical specific capacity (3,860 mAh g-1) and high specific energy (>500 Wh kg-1), improving performance beyond what is possible with lithium-ion batteries1,2. However, the high reactivity of LMAs brings problems like low Coulombic efficiency and poor cycling stability to the LMBs. Electrolyte engineering is one approach to solve these problems since it can enable smooth, compact, and uniform Li deposition with large particles. Considering the strong size effect on mechanical properties of Li, desired Li deposits exhibit different mechanical properties, such as shear modulus, compared with smaller Li particles3. Therefore, studying mechanical properties of Li at micrometer scale is also important for forming desired Li deposition and can guide the design of next-generation electrolytes. To investigate the mechanical properties of favored Li deposits, an in situ characterization technology of electrochemical quartz crystal microbalance (EQCM) is employed.In this presentation, we will discuss the mechanisms of Li deposition in LMBs studied by EQCM. This technique allows the in situ monitoring of mass changes, as well as the measurements of mechanical properties detected by EQCM-dissipation (EQCM-D) mode4. We used it to investigate the Li film formed by different electrolytes, especially focusing on localized high concentration electrolytes (LHCEs), which are the state-of-the-art electrolytes in LMBs5. The effects of different diluents including 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropylether (TTE), tris(2,2,2-trifluoroethyl)orthoformate (TFEO), and bis(2,2,2-trifluoroethyl) ether (BTFE) were studied. The measurements of mass change and modulus of Li film can give new insights into the mechanisms of Li deposition, supporting the other characterization techniques such as SEM. Ultimately, this study provides new insights into the subtle mechanical differences of Li metal deposited in different electrolytes. This will guide the next-generation electrolyte design for achieving high Coulombic efficiency, excellent cycling stability, and practical application for LMBs.

Resilient and Confined Polymer Microlattices for Low-Swelling, Pressure-Free Lithium Metal Pouch Cells

Automotive and consumer applications require batteries that last longer, recharge faster, and readily integrate into mass-manufactured battery packs. Of the available cell packaging designs, pouch cells with lithium (Li) metal anodes are attractive because they can achieve ~95% packaging efficiency, allow size and shape flexibility, and have high theoretical specific energy. Li metal anodes, however, suffer from dramatic thickness increases as they are cycled, which leads to pouch cell swelling of up to 220% by volume. Although current Li metal pouch cells incorporate alternative electrolytes, protective layers, and current collectors to prevent Li dendrite growth and stabilize the solid-electrolyte interphase (SEI), high initial external pressures of 54 to 1,000 kPa are required to suppress cell swelling and maintain stable Li deposition. Maintaining a high pressure is impractical in most applications, requires considerable extra mass and volume not accounted for in reported battery metrics, and increases the complexity of cooling. Despite these applied pressures, Li pouch cells still swell at least 39%, which is far from commercial requirements of less than 10%, causes serious safety issues, and makes integration incompatible with most electric devices. In a cell with 39% swelling, the Li anode swells up to 300% so that the final anode volume is four times the initial volume and the volumetric capacity is 33% of Li’s 2093 mAh cm-3 theoretical capacity, which is lower than the volumetric capacity of lithiated graphite (790 mAh cm-3). Additionally, these challenges are escalated in high-capacity and high-rate Li metal pouch cells. New Li electrode designs that provide control over interfacial chemistry while accommodating the extreme mechanics of Li plating and etching are required to break current technical bottlenecks for practical Li metal batteries.This talk will report the use of architected polymer microlattices that combine chemical and mechanical functions to enable high-rate, swelling-free, and pressure-free Li anodes and anode-less pouch cells. The 3D printed gyroidal polymer contains Li+ affinitive sites that accelerate Li+ transport and the gyroidal microgeometry is highly resilient and confines Li growth. Unlike prior Li anodes and porous Li scaffolds that need an SEI layer across large surface areas, 89% of the Li surface in the gyroid is covered by the polymer and the microgeometry is optimized so the remaining Li-electrolyte interface is protected by a LiF-rich SEI layer generated by F donating groups on the polymer. We study the LiF generated at the polymer and show that it moves up to 100 micrometers across the Li surface to enhance the anode stability. We also show how the combined chemical, mechanical, and geometric control allows dense and void-free Li metal to grow into complex 3D shapes. In a 5 mAh cm-2 pouch cell with zero external pressure, we demonstrate swelling-free Li deposition at 5-30 mA cm-2, or 1–6 C-rates, for over 100 cycles. Li deposition efficiency was 99.86% in a carbonate electrolyte with an areal capacity of 10 mAh cm-2 and 10 mA cm-2 current density. The Li anode achieved a 1,580 mAh cm-3 volumetric capacity. A 366 Wh kg-1 anode-less Li metal pouch cell (15.4 Ah) incorporating polymer microlattices on copper as the anode and a LiNi0.8Mn0.1Co0.1O2 (NMC) cathode achieved over 333 cycles with 80% capacity retention. The final cell swelling was below 2%. Insights into the excellent performance of these batteries can provide new paths towards achieving high rate and long life Li metal pouch cells with zero swelling.Figure Caption: Polymer microlattice enabling pressure-free and swelling-free Li metal pouch cells. a, During Li deposition, the growth and merging of Li particles generate voids even under a pressure of 54-1,000 kPa, causing cell swelling of 39-220%. b, Polymer microlattices confine Li deposition in the gyroidal channels through chemical interactions and mechanical resilience. The polymer contains -NH2 or CH2CH2O- groups to accelerate Li+ transport and -SO2F to generate LiF to protect the remaining Li surface. The crosslinked polymer is highly resilient and restrains Li for dense deposition. c,d,Cycling stability (a) and voltage profiles (b) of an anode-less Li metal pouch cell, presenting a cell-level energy density of 366 Wh kg-1. NMC was used as the cathode. e, The measurement of cell thickness upon cycling. 6 sampling points were collected. Figure 1