Lithium Anode Research Articles

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.

In situ designing an implanted hetero-interface of high adsorption energy in composite lithium anode towards high−rate lithium metal batteries

Lithium metal is considered as the ultimate anode material for next-generation Li based battery chemistries. The constituted lithium metal batteries (LMBs) specialize in high energy density, but the inherent dendritic lithium growth as well as the serious proliferation of native solid electrolyte interphase (SEI) have been impeding their practical application, in particular under the high-rate conditions of a more concentrated Li+ flux. Herein, we report a composite anode design, in which LiF/LiC as the products of the in situ spontaneous reductive defluorination between Li and poly(tetrafluoroethylene) (PTFE) are uniformly implanted in bulk metallic Li via facile mechanical kneading. The macroscopical composite anode creates a dispersion of lithiophilic nanodomains microscopically in bulk. The built-in LiF/LiC doping of high Li adsorption energy improves the affinity towards Li+ flux and avoids the Li+-adhesion-induced Li aggregation. The construction facilitates a dense while large granular plating as well as the generation of a thin, inorganic-rich SEI to synergistically ensure a dendrite-free Li deposition behavior. The improved plating reversibility and cycling stability are verified in forms of both symmetric cell under harsh conditions up to 30 mA cm−2@30 mAh cm−2 and high-areal-capacity Li||LiFeO4 full cell for 500 cycles at 3 C. This not only expands the state-of-the-art LMBs under high-loading and power-intensive scenarios, but also preliminarily evidences its scalable and industry-adaptable potential.

Self‐smoothing lithium metal anode based on screen‐printed Cu‐mesh current collector for long‐term safety of lithium metal batteries

AbstractLithium metal is an attractive anode candidate to enable high‐energy lithium battery systems. However, nonideal dendrite growth at the anode/separator interface hinders the safe application of lithium metal batteries (LMBs). Three‐dimensional (3D) current collectors (CCs) with high specific surface area could afford a crucial effect on suppressing dendrites, yet still subject to large thickness/weight and limited scalability for large‐area fabrication. Here, we show an industry‐compatible screen‐printing technique to prepare ultrathin (∼1.5 μm) and ultralight (∼0.54 mg cm−2) Cu mesh on commercial Cu foil to realize a long‐term safety of LMBs. In contrast to conventional laboratory level techniques, the screen‐printed Cu‐mesh CCs (∼8.3 mg cm−2), which are even lighter than the original Cu foil (∼8.84 mg cm−2), show a high compatibility for large‐area fabrication. Meanwhile, the periodic Cu mesh can be also used to regulate the homogeneous distribution of Li‐ion flux and thus, be in favor of realizing self‐smoothing anodes at even deep and fast plating/stripping of lithium. The resulting lithium anodes demonstrate a long‐term cyclic life of ∼840 h at 1 mA cm−2 with a high Coulombic efficiency of 97.5%. LMBs with Cu‐mesh CCs exhibit outstanding capacity retentions of ∼87% after 350 cycles at 1 C and ∼80% after 200 cycles at 5 C, suggesting a significant step of printable 3D CCs toward practical application of high‐energy LMBs.

Reasonable design a high-entropy garnet-type solid electrolyte for all-solid-state lithium batteries

Traditional garnet solid electrolyte (Li7La3Zr2O12) suffers from low room temperature ionic conductivity, poor air stability, high sintering temperature and energy consumption. Considering the development prospects of high-entropy materials with high structural disorder and strong component controllability in the field of electrochemical energy storage, herein, a novel high-entropy garnet-type oxide solid electrolyte, Li5.75Ga0.25La3Zr0.5Ti0.5Sn0.5Nb0.5O12 (LGLZTSNO) was constructed by partially replacing the Li and Zr sites in Li7La3Zr2O12 with Ga and Ti/Sn/Nb elements, respectively. The experimental and density functional theory (DFT) calculation results show that the high-entropy LGLZTSNO electrolyte has preferable room temperature ion conductivity, air stability, interface contact performance with lithium anode, and the ability to suppress lithium dendrites. Thanks to the improvement of electrolyte performance, the critical current density of Li/Ag@LGLZTSNO/Li symmetric cell was increased from 0.42 to 1.57 mA cm−2, and the interface area specific impedance (IASR) was reduced from 765.2 to 42.3 Ω cm2. Meanwhile, the Li/Ag@LGLZTSNO/LFP full cell also exhibits excellent rate performance and cycling performance (148 mA h g−1 at 0.1 C and 124 mA h g−1 at 0.5 C, capacity retention up to 84.8% after 100 cycles at 0.1 C), showing the application prospects of high-entropy LGLZTSNO solid electrolyte in high-performance all solid state lithium batteries.

Lithium‐Metal‐Free Sulfur Batteries with Biochar and Steam‐Activated Biochar‐Based Anodes from Spent Common Ivy

Lithium‐sulfur batteries are emerging as sustainable replacements for current lithium‐ion batteries. The commercial viability of this novel type of battery is still under debate due to the extensive use of highly reactive lithium‐metal anodes and the complex electrochemistry of the sulfur cathode. In this research, a novel sulfur‐based battery has been proposed that eliminates the need for metallic lithium anodes and other critical raw materials like cobalt and graphite, replacing them with biomass‐derived materials. This approach presents numerous benefits, encompassing ample availability, cost‐effectiveness, safety, and environmental friendliness. In particular, two types of biochar‐based anode electrodes (non‐activated and activated biochar) derived from spent common ivy have been investigated as alternatives to metallic lithium. We compared their structural and electrochemical properties, both of which exhibited good compatibility with the typical electrolytes used in sulfur batteries. Surprisingly, while steam activation results in an increased specific surface area, the non‐activated ivy biochar demonstrates better performance than the activated biochar, achieving a stable capacity of 400 mA h g−1 at 0.1 A g−1 and a long lifespan (>400 cycles at 0.5 A g−1). Our results demonstrate that the presence of heteroatoms, such as oxygen and nitrogen positively affects the capacity and cycling performance of the electrodes. This led to increased d‐spacing in the graphitic layer, a strong interaction with the solid electrolyte interphase layer, and improved ion transportation. Finally, the non‐activated biochar was successfully coupled with a sulfur cathode to fabricate lithium‐metal‐free sulfur batteries, delivering a specific energy density of ~600 Wh kg−1.

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.

Structure and particle surface analysis of Li2S–P2S5–LiI-type solid electrolytes synthesized by liquid-phase shaking

Li2S–P2S5–LiI-type solid electrolytes, such as Li4PS4I, Li7P2S8I, and Li10P3S12I, are promising candidates for anode layers in all-solid-state batteries because of their high ionic conductivity and stability toward Li anodes. However, few studies have been conducted on their detailed local structure and particle surface state. In this study, Li7P2S8I (Li2S: P2S5:LiI = 3:1:1) solid electrolytes as the chemical composition were synthesized by mechanical milling and liquid-phase shaking, and their local structures were analyzed by transmission electron microscopy. The particle surface states were analyzed by X-ray photoelectron spectroscopy, high-energy X-ray scattering measurements, and neutron total scattering experiments. The results showed that Li7P2S8I solid electrolytes are composed of nanocrystals, such as Li4PS4I, LiI, Li10P3S12I and an amorphous area as the main region, indicating that the crystalline components alone do not form ionic conductive pathways, with both the amorphous and crystalline regions contributing to the high ionic conductivity. Moreover, the ionic conductivity of the crystalline/amorphous interface of the glass-ceramic was higher than that of the Li2S–P2S5–LiI glass. Finally, an organic-solvent-derived stable surface layer, which was detected in the liquid-phase shaking sample, served as one of the factors that contributed to its high stability (which surpassed that of the mechanically milled sample) toward lithium anodes. We expect these findings to enable the effective harnessing of particle surface states to develop enhanced sulfide solid electrolytes.

Insight of transport properties of glassy solid electrolytes for energy storage applications

The goal of developing battery systems has attracted researchers' attention for about 30 years, almost since the development of primary electrochemical systems with a lithium anode. To realize the benefits of lithium ion batteries (LIBs) and lithium metal anode batteries, several important issues need to be addressed. The use of liquid non-aqueous electrolytes based on aprotic solvents in lithium battery systems certainly offers advantages over traditional battery systems. However, due to the relatively low evaporation temperatures and high flammability of solvents, liquid electrolytes significantly limit the operating range of battery systems in the high-temperature range. Special measures are required to ensure the safe operation of a lithium-ion battery system. The use of inorganic solid electrolytes (SEs) is one of the most promising directions for improving lithium-ion and solid-state battery systems. The use of SEs will enable the safe cycling of battery systems with both lithium electrodes and intercalation anodes, significantly extend the temperature range of battery operation towards high temperatures and enable the creation of battery systems of new sizes and designs. The development of new solid oxide salt materials and technologies to produce battery systems with electrolytes based on them is an urgent task to solve the above problems.

Identifying Current Collectors that Enable Light-Battery Interactions.

In recent years, there has been an increased focus on studying light-battery interactions in the context of operando optical studies and integrated photoelectrochemical energy harvesting. However, there has been little insight into identifying suitable "light-accepting" current collectors for this class of batteries. In this study, fluorine-doped tin oxide, indium-tin oxide, and silver nanowire-graphene films are analyzed along with carbon paper, carbon nanotube paper, and stainless-steel mesh as current collectors for optical batteries. They are categorized into two classes - transmissive and non-transmissive, based on the orientation of the light-electrode interaction. Various methods to prepare the electrode are highlighted, including drop casting and the fabrication of free-standing electrodes. The optical and electrical properties of these current collectors as well as their electrochemical stability are measured using linear sweep voltammetry against zinc and lithium anodes. Finally, the rate performance and long-term cycling stability of lithium manganese oxide (LiMn2O4) cathodes are measured against lithium anodes with these current collectors and their performance is compared. These results show which current collector to choose depends on the application and cell chemistry. These guidelines will assist in the design of future optical cells for in-situ measurements and photoelectrochemical energy storage.

In situ high‐quality LiF/Li3N inorganic and phenyl‐based organic solid electrolyte interphases for advanced lithium–oxygen batteries

AbstractLithium metal shows a great advantage as the most promising anode for its unparalleled theoretical specific capacity and extremely low electrochemical potential. However, uncontrolled lithium dendrite growth and severe side reactions of the reactive intermediates and organic electrolytes still limit the broad application of lithium metal batteries. Herein, we propose 4‐nitrobenzenesulfonyl fluoride (NBSF) as an electrolyte additive for forming a stable organic–inorganic hybrid solid electrolyte interphase (SEI) layer on the lithium surface. The abundance of lithium fluoride and lithium nitride can guarantee the SEI layer's toughness and high ionic conductivity, achieving dendrite‐free lithium deposition. Meanwhile, the phenyl group of NBSF significantly contributes to both the chemical stability of the SEI layer and the good adaptation to volume changes of the lithium anode. The lithium–oxygen batteries with NBSF exhibit prolonged cycle lives and excellent cycling stability. This simple approach is hoped to improve the development of the organic–inorganic SEI layer to stabilize the lithium anodes for lithium–oxygen batteries.

Perspective of material evolution Induced by sinusoidal reflex charging in lithium-ion batteries

BackgroundLithium-ion batteries are globally prominent and extensively employed alternative energy sources with decisive applications. In depth understanding of influences of various charging and discharging cycles on electrode materials and life span of these batteries is critical as cycle-life and safety of lithium-ion batteries are closely related crystallinity of electrode materials. This study is a detailed investigation endeavor in observing the degree of damage to electrode materials under multiple charging and discharging cycles. Methodology: A constant current-sinusoidal reflex charging method (CC-Sinusoidal) was implemented to charge commercial cathode Lithium cobalt oxide (LiCoO2) electrodes and anode graphite electrodes in comparison to the conventional charging method of constant current-constant voltage (CC-CV). After 100, 300, and 500 cycles of charging and discharging, EIS, SEM, XRD, and Raman spectroscopies were used to compare the degree of electrode damage caused by different charging methods. Significant outcomesThe structure of positive LiCoO2 electrode of the battery was observed to be stable, with no significant change in both the charging methods after 500 cycles. The use of CC-CV charging method had caused severe damages to graphite electrode with generation of solid electrolyte interface (SEI) films. The CC-Sinusoidal charging method had maintained the electrode material in a relatively ideal state.

Constructing lithiophilic sites–rich artificial solid electrolyte interphase to enable dendrite−free and corrosion−free lithium–sulfur batteries

An artificial solid electrolyte interphase (SEI) with lithiophilic sites and chemical bonds anchoring lithium polysulfides (LiPSs) has been developed as a potential solution to protect the lithium (Li) metal anode of Lithium−sulfur (Li–S) batteries. This strategy aims to guide consistent Li deposition and relieve lithium corrosion. Herein, the evolution process of lithiophilic sites based on aluminum fluoride (AlF3) in an artificial SEI is disclosed in Li–S batteries with metal−based lithiophilic sites. The polyester polymer (PMMA and PPC)/AlF3 artificial SEI (MPAF−SEI) was homogeneously anchored on Li anode by in−situ polymerization. The conversion of AlF3 into Li–Al and LiF lithiophilic sites effectively reduce the Li nucleation overpotential and prevents the formation of Li dendrites. At the same time, the polymer can anchor LiPSs by chemical bonds and prevents Li corrosion. The optimized MPAF−SEI protected Li demonstrates excellent stability for over 3000 h at a capacity of 1 mAh cm−2 in Li || Li symmetric cells. The Li–S battery with low N/P (4) exhibits a capacity of 532.6 mAh g −1 over 300 cycles lifespan at 0.5C.

The Effect of Decalin and Perfluorodecalin on Dendrite Formation at Metallic Lithium Anodes during Their Operation

The Effect of Decalin and Perfluorodecalin on Dendrite Formation at Metallic Lithium Anodes during Their Operation

Life cycle assessment of lithium-sulfur batteries with carbon nanotube hosts: Insights from lab experiments

Lithium‑sulfur (Li-S) batteries are candidates for next-generation batteries. It can be produced sustainably using sulfur instead of controversial cathode minerals like cobalt. However, Li-S batteries must improve their energy density and cycle life at their current state of development. Hosting the sulfur on carbon nanotubes (CNT) is a potential solution. This study investigated the environmental performance of a CNT-based Li-S battery based on original experiment data. The CNT in the batteries functioned as binders, conductive fillers, and current collectors, reducing auxiliary materials and simplifying manufacturing processes. We conducted a cradle-to-gate life cycle assessment (LCA) to clarify the environmental performance. We showed that the global warming potential (GWP) of the Li-S battery pack in a conventional battery structure was 105 kg CO2e/kWh. By partially substituting current collectors, increasing lithium anode efficiency, and reducing solvent usage, we could achieve 87, 82, and 78 kg CO2e, respectively. The lowest GWP of Li-S battery was 20 % lower when compared to a graphite‑nickel manganese cobalt oxides (NMC) battery. In addition, the other environmental indicators, including human toxicity, ecotoxicity, and acidification, were 26 % to 79 % lower, showing no major environmental burden shift. One exception was the mineral resource depletion, which was 2 % higher because lithium metal, instead of synthetic graphite, was used as a high-capacity anode pair. This study also found that modifying the cathode production process by using a less energy-intensive filtration before evaporating the remaining solvent could significantly reduce the energy required, thus mitigating the previously identified environmental hotspot. Our finding highlighted that a prospective LCA collaborating with battery experimentalists could lead to novel discoveries for environmentally sustainable battery production. Overall, we showed that Li-S batteries are environmentally preferred at the production stage, as supported by advanced experiments. Further research into improving the cycle life of Li-S batteries is crucial when considering the use stage to reduce the environmental impact per functional unit of energy delivered over the battery lifetime.

Functionalized interfacial cover design toward pure silicon anode for high power density lithium–ion capacitor

A lithium–ion capacitor, comprising a capacitor–type cathode and battery–type anode, exhibits high power and energy density; however, the integration of different charge storage mechanisms in one cell naturally leads to a kinetic mismatch between the two electrodes, reducing the power density and cycle stability. To solve this problem, high–capacity anode materials with thinner electrodes are required. Silicon, with its high specific capacity, is considered a promising anode material with high energy and power density; however, pure Si anodes undergo rapid capacity fading and exhibit increased internal resistance owing to volume changes during cycling. In this study, both sides of the electrode are covered with functional layers consisting of functionalized herringbone–type carbon nanofibers to protect the Si electrode from degradation. The polar functional groups on the nanofibers weakly interact with the native oxide layer of the Si surface and the carboxyl groups of the binder, ensuring stable contact between electrode materials over repeated cycles. Moreover, the conductive functional cover promotes uniform lithium ion fluxes, aiding the formation of a stable solid electrolyte interphase layer. This study investigates the effects of this strategy on pure Si electrodes by surface morphology analysis, assessment of chemical interactions, and electrochemical testing. This approach has the potential to overcome the degradation of Si electrodes and significantly improve the power and energy density of lithium–ion capacitors.

Ultrasonic assessment of aging in lithium metal pouch cells

Lithium metal anodes are prone to non-uniform lithium plating that can lead to dendrite formation, internal short circuits, and catastrophic ignition. This type of structural defect is not captured by battery management systems, prompting the need to advance nondestructive evaluation (NDE) techniques that are suitable for periodic monitoring of the internal structure. An ultrasonic inspection technique is evaluated here as a means of identifying flaws and irregular lithium plating that can be a precursor to dendrite formation and, ultimately, battery failure.Lithium metal pouch cell batteries were aged through electrochemical cycling at a range of moderate constant-current charging and discharging rates. They were inspected intermittently using a tailored local ultrasonic resonance spectroscopy (LURS) approach that measures the local through-thickness resonances of the battery as an indicator of the underlying structure. LURS results showed clear structural resonances in cells in the range of 3–7 MHz, which shifted significantly to lower frequencies as batteries aged. In addition to point measurements, scanning LURS measurements were implemented to map resonance frequencies over the electrode surface. These resonance maps revealed spatial variations in structure that developed during aging and showed better contrast to structural variation than achieved using conventional amplitude-based c-scans of the specimens.NDE results from pouch cell measurements were compared to a destructive physical analysis of the electrode structures using scanning electron microscopy (SEM). The SEM results showed differences in the end-of-life lithium anode structure at different charge rates. The results of this study show the capability of LURS as a means for identifying changes in battery structures during aging and establish resonance trends that may be applied in future work for prognostic modeling of batteries in service.

Li5.5PS4.5Cl1.5-Based All-Solid-State Battery with a Silver Nanoparticle-Modified Graphite Anode for Improved Resistance to Overcharging and Increased Energy Density.

All-solid-state lithium batteries (ASSLBs) are attracting tremendous attention due to their improved safety and higher energy density. However, the use of a metallic lithium anode poses a major challenge due to its low stability and processability. Instead, the graphite anode exhibits high reversibility for the insertion/deinsertion of lithium ions, giving ASSLBs excellent cyclic stability but a lower energy density. To increase the energy density of ASSLBs with the graphite anode, it is necessary to lower the negative/positive (N/P) capacity ratio and to increase the charging voltage. These strategies bring new challenges to lithium metal plating and dendrite growth. Here, a nano-Ag-modified graphite composite electrode (Ag@Gr) is developed to overcome these shortcomings for Li5.5PS4.5Cl1.5-based ASSLBs. The Ag@Gr composite exhibits a strong ability to inhibit lithium metal plating and fast lithium-ion transport kinetics. Ag nanoparticles can accommodate excess Li, and the as-obtained Li-Ag alloy enhances the kinetics of the composite electrode. The ASSLB with the Li(Ni0.8Co0.1Mn0.1)O2 cathode and Ag@Gr anode achieves an energy density of 349 W h kg-1. The full cell using Ag@Gr with an N/P ratio of 0.6 also highlights the rate performance. This work provides a simple and effective method to regulate the charge transport kinetics of graphite anodes and improve the cyclic performance and energy density of ASSLBs.

Self-Catalyzed Growth of Co4N and N-Doped Carbon Nanotubes toward Bifunctional Cathode for Highly Safe and Flexible Li-Air Batteries.

The practical application of high-energy density lithium-oxygen (Li-O2) batteries is severely impeded by the notorious cycling stability and safety, which mainly comes from slow kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) at cathodes, causing inferior redox overpotentials and reactive lithium metal in flammable liquid electrolyte. Herein, a bifunctional electrode, a safe gel polymer electrolyte (GPE), and a robust lithium anode are proposed to alleviate above problems. The bifunctional electrode is composed of N-doped carbon nanotubes (N-CNTs) and Co4N by in situ chemical vapor deposition self-catalyzed growth on carbon cloth (N-CNTs@Co4N@CC). The self-supporting, binder-free N-CNTs@Co4N@CC electrode has a strong and stable three-dimensional (3D) interconnected conductive structure, which provides interconnectivity between the active sites and the electrode to promote the transfer of electrons. Furthermore, the N-CNT-intertwined Co4N ensures efficient catalytic activity. Hence, the electrode demonstrates improved electrochemical properties even under a large current density (2000 mA g-1) and long cycling operation (250 cycles). Moreover, a highly safe and flexible rechargeable cell using the 3D N-CNTs@Co4N@CC electrode, GPE, and robust lithium anode design has been explored. The open circuit voltage is stable at ∼3.0 V even after 9800 cycles, which proves the mechanical durability of the integrated GPE cell. The stable cable-type Li-air battery was demonstrated to stably drive the light-emitting diodes (LEDs), highlighting the reliability for practical use.

High-Energy SiO-Sulfur Battery with Preloaded Li3N in a Cathode as a Lithiation Reagent.

The practical use of lithium-sulfur batteries faces the "shuttle effect" and lithium dendrite growth. Employing SiO instead of Li metal can fundamentally solve the above problems. Nevertheless, selecting a convenient prelithiation method is essential for normal operation of the battery system. Hence, this work proposed a novel SiO-sulfur battery with preloaded Li3N in a cathode as a prelithiation reagent, which can thoroughly solve the dendrite problem and the side reaction with polysulfides of lithium anode. The S@KB-Li3N vs SiO full cell can obtain a high specific capacity of 790 mAh g-1 after the activation process and be maintained at 478 mAh g-1 after 100 cycles. Our design will provide a new prelithiation strategy for a high-specific-energy SiO-sulfur battery system.

The interface modification with polyethyleneimine enhances both ionic conductivity and interfacial compatibility of composite solid electrolyte

The composite solid electrolyte (CSE), polyethylene oxide (PEO)-Li6.4La3Zr1.4Ta0.6O12 (LLZTO), is deemed a promising candidate for all-solid-state batteries. Nevertheless, due to the poor interfacial compatibility between LLZTO nanoparticles and PEO, achieving a homogeneous dispersion of LLZTO nanoparticles within PEO is not readily attainable. The aggregation of LLZTO within PEO leads to a decline in the ionic conductivity of the CSE and poor interface stability with the electrode, ultimately resulting in deteriorated battery cyclic performance. In this work, the interface between LLZTO and PEO is designed and comprehensively investigated. Initially, dopamine self-polymerization is employed to form a uniform coating layer on the surface of LLZTO nanoparticles. Subsequently, by utilizing the amino groups present in polyethyleneimine (PEI), which can react with the phenolic hydroxyl groups of dopamine and the ether linkages in PEO, PEI serves as a bridging agent, enhancing the interfacial compatibility between LLZTO and PEO. Here it is shown that, the ionic conductivity of the LLZTO-PEO CSE containing 40 wt% modified LLZTO increases from 6.14✕10−5 S cm−1 to 1.89✕10−4 S cm−1. Furthermore, this CSE exhibits improved thermal stability, an enlarged electrochemical window of 4.8 V, a lithium-ion transference number of 0.45, and excellent interface stability with the lithium anode. The assembled LiFePO4 | 40 wt% LLZTO@PDA@PEI-PEO CSE | Li all-solid-state battery demonstrates an initial discharge specific capacity of 151.8 mA h g−1 at 0.2 C, with a capacity retention of 85.8% after 200 cycles. This work provides a novel strategy for interface-modified polymer- inorganic composite solid electrolytes, which will advance the development of high-energy-density all-solid-state lithium batteries.