Solid-state Lithium Research Articles

Solvation-Tailored PVDF-Based Solid-State Electrolyte for High-Voltage Lithium Metal Batteries.

Poly(vinylidene fluoride) (PVDF)-based polymer electro-lytes are attracting increasing attention for high-voltage solid-state lithium metal batteries because of their high room temperature ionic conductivity, adequate mechanical strength and good thermal stability. However, the presence of highly reactive residual solvents, such as N, N-dimethylformamide (DMF), severely jeopardizes the long-term cycling stability. Herein, we propose a solvation-tailoring strategy to confine residual solvent molecules by introducing low-cost 3 Å zeolite molecular sieves as fillers. The strong interaction between DMF and the molecular sieve weakens the ability of DMF to participate in the solvation of Li+, leading to more anions being involved in solvation. Benefiting from the tailored anion-rich coordination environment, the interfacial side reactions with the lithium anode and high-voltage NCM811 cathode are effectively suppressed. As a result, the solid-state Li||Li symmetrical cells demonstrates ultra-stable cycling over 5100 h at 0.1 mA cm-2, and the Li||NCM811 full cells achieve excellent cycling stability for more than 1130 and 250 cycles under the charging cut-off voltages of 4.3 V and 4.5 V, respectively. Our work is an innovative exploration to address the negative effects of residual DMF in PVDF-based solid-state electrolytes and highlights the importance of modulating the solvation structures in solid-state polymer electrolytes.

Solid-state synthesis and ion transport characteristics of the β-KSbF4 for all-solid-state fluoride-ion batteries

All-solid-state fluoride ion batteries (FIBs) have been recently considered as a post-lithium-ion battery system due to their high safety and high energy density. Just like all solid-state lithium batteries, the key to the development of FIBs lies in room-temperature electrolytes with high ionic conductivity. β-KSbF4 is a kind of promising solid-state electrolyte for FIBs owing to its rational ionic conductivity and relatively wide electrochemical stability window at room temperature. However, the previous synthesis routes of β-KSbF4 required the use of highly toxic hydrofluoric acid and the ionic conductivity of as-prepared product needs to be further improved. Herein, the β-KSbF4 sample with an ionic conductivity of 1.04 × 10−4 S cm−1 (30 °C) is synthesized through the simple solid-state route. In order to account for the high ionic conductivity of the as-synthesized β-KSbF4, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS) are used to characterize the physicochemical properties. The results show that the as-synthesized β-KSbF4 exhibits higher carrier concentration of 1.0 × 10−6 S cm−1 Hz−1 K and hopping frequency of 1.31 × 106 Hz at 30 °C due to the formation of the fluorine vacancies. Meanwhile, the hopping frequency shows the same trend as the changes of ionic conductivity with the changes of temperature, while the carrier concentration is found to be almost constant. The two different trends indicate the hopping frequency is mainly responsible for the ionic conduction behavior within β-KSbF4. Furthermore, the all-solid-state FIBs, in which Ag and Pb + PbF2 are adopted as cathode and anode, and β-KSbF4 as fluoride ion conductor, are capable of reversible charge and discharge. The assembled FIBs show a discharge capacity of 108.4 mA h g−1 at 1st cycle and 74.2 mA h g−1 at 50th cycle. Based on an examination of the capacity decay mechanism, it has been found that deterioration of the electrolyte/electrode interface is an important reason for hindering the commercial application of FIBs. Hence, the in-depth comprehension of the ion transport characteristics in β-KSbF4 and the interpretation of the capacity fading mechanism will be conducive to promoting development of high-performance FIBs.

Lithiophilic Li-Si alloy-solid electrolyte interface enabled by high-concentration dual salt-reinforced quasi-solid-state electrolyte

Solid polymer electrolytes (SPEs) are urgently required to achieve practical solid-state lithium metal batteries (LMBs) and lithium-ion batteries (LIBs). Herein, we proposed a mechanism for modulating interfacial conduction and anode interfaces in high-concentration SPEs by LiDFBOP. Optimized electrolyte exhibits superior ionic conductivity and remarkable interface compatibility with salt-rich clusters: (1) polymer-plastic crystal electrolyte (P-PCE, TPU-SN matrix) dissociates ion pairs to facilitate Li+ transport in the electrolyte and regulates Li+ diffusion in the SEI. The crosslinking structure of the matrix compensates for the loss of mechanical strength at high-salt concentrations; (2) dual-anion TFSI–n-DFBOP–m in the Li+ solvation sheath facilitates facile Li+ desolvation and formation of salt-rich clusters and is conducive to the formation of Li conductive segments of TPU-SN matrix; (3) theoretical calculations indicate that the decomposition products of LiDFBOP form SEI with lower binding energy with LiF in the SN system, thereby enhancing the interfacial electrochemical redox kinetics of SPE and creating a solid interface SEI layer rich in LiF. As a result, the optimized electrolyte exhibits an excellent ionic conductivity of 9.31 × 10−4 S cm−1 at 30 °C and a broadened electrochemical stability up to 4.73 V. The designed electrolyte effectively prevents the formation of Li dendrites in Li symmetric cells for over 6500 h at 0.1 mA cm−2. The specific Li-Si alloy-solid state half-cell capacity shows 711.6 mAh g−1 after 60 cycles at 0.3 A g−1. Excellent rate performance and cycling stability are achieved for these solid-state batteries with Li-Si alloy anodes and NCM 811 cathodes. NCM 811|| Prelithiated silicon-based anode solid-state cell delivers a discharge capacity of 195.55 mAh g−1 and a capacity retention of 97.8% after 120 cycles. NCM 811||Li solid-state cell also delivers capacity retention of 84.2% after 450 cycles.

Composition regulation of polyacrylonitrile-based polymer electrolytes enabling dual-interfacially stable solid-state lithium batteries

The polyacrylonitrile (PAN) is an attractive matrix of polymer electrolytes owing to its wide electrochemical window and strong coordination with Li salts. However, the PAN-based electrolytes undergo severe interfacial problems from both cathode and anode sides, including uneven ionic transfer induced by high rigidity of dry PAN-based polymer, as well as inferior stability against Li-metal anode. Herein, the composition regulation of PAN-based electrolytes is proposed by introducing succinonitrile (SN) plastic crystal and LiNO3 salt for the construction of interfacially stable solid-state lithium batteries. The plastic nature of SN enables the rapid ionic transfer in electrolytes, along with the establishment of conformally interfacial contacts. Meanwhile, a stable solid-electrolyte-interface (SEI) layer consisting of Li3N and LiNO2 is in-situ formed at Li/electrolyte interface, contributing to the inhibition of uncontrol reactions between PAN and Li-metal. Consequently, the resultant Li symmetric cell delivers an extended critical current density of 1.7 mA cm−2 and an outstanding cycling lifespan of 700 h at 0.1 mA cm−2. Moreover, the corresponding solid-state LiNi0.6Co0.2Mn0.2O2/Li full cell shows an initial discharge capacity of 161 mAh/g followed by an outstanding capacity retention of 88.7 % after 100 cycles at 0.1C. This work paves the way for application of PAN-based electrolytes in the field of solid-state batteries by facile composition regulation.

Solid-State Electrolytes by Electrospinning Techniques for Lithium Batteries.

Solid-state lithium batteries (SSLBs) are regarded as next-generation energy storage devices because of their advantages in terms of safety and energy density. However, the poor interfacial compatibility and low ionic conductivity seriously hinder their development. Electrospinning is considered as a promising method for fabricating solid-state electrolytes (SSEs) with controllable nanofiber structures, scalability, and cost-effectiveness. Numerous efforts are dedicated to electrospinning SSEs with high ionic conductivity and strong interfacial compatibility, but a comprehensive summary is lacking. Here, the history of electrospinning SSEs is overeviewed and introduce the electrospinning mechanism, followed by the manipulation of electrospun nanofibers and their utilization in SSEs, as well as various methods to improve the ionic conductivity of SSEs. Finally, new perspectives aimed at enhancing the performance of SSEs membranes and facilitating their industrialization are proposed. This review aims to provide a comprehensive overview and future perspective on electrospinning technology in SSEs, with the goal of guiding the further development of SSLBs.

Facile in situ polymerization synthesis of poly(ionic liquid)-based polymer electrolyte for high-performance solid-state batteries

The rational one-step design of poly(ionic liquid) solid polymer electrolyte (PIL-SPE) with outstanding ionic conductivity and inferior interfacial resistance with Li-electrode to preclude the Li-dendrite growth and interfacial instability of solid-state lithium metal batteries (ASLMBs) remains a grand challenge. Herein, we provide a s facile, one-step, and productive approach for the synthesis of PIL-SPE via the in situ polymerization of 1-vinyl-3-butylimidazolium bis(trifluoromethanesulfony)imide ([VBIm][TFSI]) in the presence of bis(trifluoromethane) sulfonamide lithium salt (LiTFSI) using azodiisobutyronitrile (AIBN) as initiator. This approach endows a compact and compatible interface between Li-electrode and PIL-SPE with an excellent ionic conductivity that depends on the Li-salt concentration. Thereby, in situ polymerization of monomer with 40 wt% LiTFSI (PIL-SPE-LiTFSI-40) revealed the highest ionic conductivity of 1.35 × 10-3 S cm−1 at 303 K and 6.16 × 10-3 S cm−1 at 353 K, besides excellent lithium transference number (0.54), oxidative stability up to 5.3 V, and constant current plating/stripping cycles for 1000 h at 0.15 mA cm−2. Meanwhile, ASLMBs composed of PIL-SPE with LiFePO4 and LiNi0.8Co0.1Mn0.1O2 cathodes delivered discharge capacities of 164.3 mA h g−1 and 155.3 mA h g−1 at 0.1 C, respectively, along with 92 % capacity retention after 100 cycles. This study may revolutionize the synthesis of PIL-SPE electrolytes for the next generation of efficient and durable ASLMBs.

Long‐cycling and High‐voltage Solid State Lithium Metal Batteries Enabled by Fluorinated and Crosslinked Polyether Electrolytes

AbstractSolid‐state lithium metal batteries (LMBs), constructed through the in situ fabrication of polymer electrolytes, are considered a critical strategy for the next‐generation battery systems with high energy density and enhanced safety. However, the constrained oxidation stability of polymers, such as the extensively utilized polyethers, limits their applications in high‐voltage batteries and further energy density improvements. Herein, an in situ fabricated fluorinated and crosslinked polyether‐based gel polymer electrolyte, FGPE, is presented, exhibiting a high oxidation potential (5.1 V). The fluorinated polyether significantly improves compatibility with both lithium metal and high‐voltage cathode, attributed to the electron‐withdrawing −CF3 group and the generated LiF‐rich electrolyte/electrode interphase. Consequently, the solid‐state Li||LiNi0.6Co0.2Mn0.2O2 batteries employing FGPE demonstrate exceptional cycling performances of 1000 cycles with 78 % retention, representing one of the best results ever reported for polymer electrolytes. Moreover, FGPE enables batteries to operate at 4.7 V, realizing the highest operating voltage of polyether‐based batteries to date. Notably, our designed in situ FGPE provides the solid‐state batteries with exceptional cycling stability even at practical conditions, including high cathode loading (21 mg cm−2) and industry‐level 18650‐type cylindrical cells (1.3 Ah, 500 cycles). This work provides critical insights into the development of oxidation‐stable polymer electrolytes and the advancement of practical high‐voltage LMBs.

Long-cycling and High-voltage Solid State Lithium Metal Batteries Enabled by Fluorinated and Crosslinked Polyether Electrolytes.

Solid-state lithium metal batteries (LMBs), constructed through the in situ fabrication of polymer electrolytes, are considered a critical strategy for the next-generation battery systems with high energy density and enhanced safety. However, the constrained oxidation stability of polymers, such as the extensively utilized polyethers, limits their applications in high-voltage batteries and further energy density improvements. Herein, an in situ fabricated fluorinated and crosslinked polyether-based gel polymer electrolyte, FGPE, is presented, exhibiting a high oxidation potential (5.1 V). The fluorinated polyether significantly improves compatibility with both lithium metal and high-voltage cathode, attributed to the electron-withdrawing -CF3 group and the generated LiF-rich electrolyte/electrode interphase. Consequently, the solid-state Li||LiNi0.6Co0.2Mn0.2O2 batteries employing FGPE demonstrate exceptional cycling performances of 1000 cycles with 78 % retention, representing one of the best results ever reported for polymer electrolytes. Moreover, FGPE enables batteries to operate at 4.7 V, realizing the highest operating voltage of polyether-based batteries to date. Notably, our designed in situ FGPE provides the solid-state batteries with exceptional cycling stability even at practical conditions, including high cathode loading (21 mg cm-2) and industry-level 18650-type cylindrical cells (1.3 Ah, 500 cycles). This work provides critical insights into the development of oxidation-stable polymer electrolytes and the advancement of practical high-voltage LMBs.

Enhancing room temperature performance of solid-state lithium cell via a facile solid electrolyte-cathode interface design

Herein, we report the enhanced electrochemical performance of a solid-state cell realized through an engineered solid electrolyte-cathode interface via a simple casting technique. The ceramic-in-polymer solid electrolyte sample with 15 wt% NASICON-type Li1·2Sn0·9Zr0·9Al0·2(PO4)3 ceramic filler in a P(VDF-HFP) matrix (CPSE15) showed the highest room temperature conductivity of ∼1.1 × 10−4 S cm−1 and lithium-ion transference number of ∼0.60. The symmetric Li|CPSE15|Li cell showed a consistent voltage profile with an over-potential of ∼45 mV for 750 h at a current density of 0.1 mA cm−2. CPSE15 slurry was directly cast onto the LiFePO4 (LFP) cathode layer using a doctor-blade coating method to obtain a cathode-electrolyte assembly. Subsequently, a full cell fabricated using this assembly and lithium metal delivered an initial discharge capacity of ∼157 mAh g−1 at 0.2C. Further, the cell exhibited ∼90 mAh g−1 discharge capacity at 1C and sustained 500 charge-discharge cycles at room temperature. The engineered interface in cathode-electrolyte assembly enabled this cell to outperform its conventionally fabricated counterpart with a stacked LFP cathode sheet and freestanding CPSE15 electrolyte membrane, which was attributed to a lower interfacial resistance (∼51%) of the former.

Interfacial self-healing polymer electrolytes for Long-Cycle silicon anodes in High-Performance solid-state lithium batteries

For all-solid-state lithium-ion batteries (ASSLIBs), silicon (Si) stands out as an appealing anodes material due to its high energy density and improved safety compared to lithium metal. However, the substantial volume changes during cycling result in poor solid-state physical contact and electrolyte–electrode interface issues, leading to unsatisfactory electrochemical performance. In this study, we employed in-situ polymerization to construct an integrated Si anodes/self-healing polymer electrolyte for ASSLIBs. The polymer chain reorganization stems from numerous dynamic bonds in the constructed self-healing dynamic supermolecular elastomer electrolyte (SHDSE) molecular structure. Notably, SHDSE also serves as a Si anodes binder with enhanced adhesive capability. As a result, the well-structured Li|SHDSE|Si-SHDSE cell generates subtle electrolyte–electrode interface contacts at the molecular level, which can offer a continuous and stable Li+ transport pathway, reduce Si particle displacement, and mitigate electrode volume expansion. This further enhances cyclic stability (>500 cycles with 68.1 % capacity retention and >99.8 % Coulombic efficiency). More practically, the 2.0 Ah wave-shaped Si||LiCoO2 soft-pack battery with in-situ cured SHDSE exhibits strongly stabilized electrochemical performance (1.68 Ah after 700 cycles, 86.2 % capacity retention) in spite of a high operating temperatures up to 100 °C and in various bending tests. This represents a groundbreaking report in flexible solid-state soft-pack batteries containing Si anodes.

A three-dimensional co-continuous network structure polymer electrolyte with efficient ion transport channels enabling ultralong-life all solid-state lithium metal batteries

Solid polymer electrolytes (SPEs) have emerged as one of the most promising candidates for the construction of solid-state lithium batteries due to their excellent flexibility, scalability, and interface compatibility with electrodes. Herein, a novel all-solid polymer electrolyte (PPLCE) was fabricated by the copolymer network of liquid crystalline monomers and poly(ethylene glycol) dimethacrylate (PEGDMA) acts as a structural frame, combined with poly(ethylene glycol) diglycidyl ether short chain interspersed serving as mobile ion transport entities. The preparaed PPLCEs exhibit excellent mechanical property and outstanding electrochemical performances, which is attributed to their unique three-dimensional co-continuous structure, characterized by a cross-linked semi-interpenetrating network and an ionic liquid phase, resulting in a distinctive nanostructure with short-range order and long-range disorder. Remarkably, the addition of PEGDMA is proved to be critical to the comprehensive performance of the PPLCEs, which effectively modulates the microscopic morphology of polymer networks and improves the mechanical properties as well as cycling stability of the solid electrolyte. When used in a lithium-ion symmetrical battery configuration, the 6 wt%-PPLCE exhibites super stability, sustaining operation for over 2000 h at 30 °C, with minimal and consistent overpotential of 50 mV. The resulting Li|PPLCE|LFP solid-state battery demonstrates high discharge specific capacities of 160.9 and 120.1 mA h g−1 at current densities of 0.2 and 1 C, respectively. Even after more than 300 cycles at a current density of 0.2 C, it retaines an impressive 73.5% capacity. Moreover, it displayes stable cycling for over 180 cycles at a high current density of 0.5 C. The super cycle stability may promote the application for ultralong-life all solid-state lithium metal batteries.

In-situ curing poly(N,N'-Methylenebisacrylamide)-based composite electrolyte reinforced with high-strength glass fiber skeleton for solid state lithium ion batteries

Polymer solid-state electrolytes have been extensively studied for their favorable flexibility, ease of processing, and good interfacial contact. However, the low ionic conductivity, narrow electrochemical window and poor mechanical properties restrict their practical application. Here, a novel poly(N,N'-Methylenebisacrylamide) (PMBA)-based composite electrolyte reinforced with high-strength glass fiber (GF) skeleton is fabricated via in-situ polymerization. Due to the high electrolyte uptake of PMBA network and the strong interaction between the amide units and other components in the electrolyte, it displays high ionic conductivity (1.53 mS cm−1) and lithium-ion transference number (0.74) at ambient temperature, respectively. The synergistic effect of the polymer network and GF skeleton endows the electrolyte with excellent mechanical properties (2.05 GPa), thermal stability, and flame-retardant characteristics. Furthermore, the electrolyte exhibits favorable interface compatibility with the anode and cathode. The Li||Li symmetrical cell exhibits excellent Li plating/stripping reversibility for over 1200 h at 0.1 mA cm−2. The LFP||Li exhibit high discharge capacity of 138.5 mAh/g at 1C. Noteworthy, the LFP|DEE@PMBA-GF|Li cell demonstrates outstanding cycling stability with 83.7 % capacity retention after 600 cycles at 1C and 99.89 % average Coulombic efficiency. Additionally, the LFP|DEE@PMBA-GF|graphite pouch cell with high cathode mass loading (∼12 mg cm−2) demonstrates satisfactory safety and electrochemical performance.

Mof-derived ionic conductor enhancing the performance of polymer electrolyte for solid-state lithium batteries

The solid-state electrolyte is an important component of solid-state batteries and significantly influences the performance of batteries. However, pure solid-state polymer electrolyte has challenges such as low ionic conductivity, weak mechanical strength and poor ability to inhibit lithium dendrites. Therefore, a unique nano porous structural material based on a metal–organic framework (MOF) was proposed as a filler to enhance the polymer electrolyte, which is lithium ionic liquid (Li-IL) immersed into the MIL-125 framework to transform MIL-125 from an inert conductor to an efficient ionic conductor to obtain MIL-125-Li. MIL-125-Li not only has Lewis acid nature, but also provides a more definite and continuous transport pathway for the rapid migration of Li+. The composite polymer electrolytes (CPEs), containing 15 wt% of MIL-125-Li, exhibit an ionic conductivity of 3.9 × 10-4 S cm−1 at 28 °C. Furthermore, the CPEs demonstrate excellent interfacial stability with the lithium metal electrode, effectively inhibiting the growth of lithium dendrites. The assembled symmetric Li/PL-15 % MIL-125/Li battery can be stably cycled for more than 700 h at 0.1 mA cm−2 at 28 °C. Applying the composite polymer electrolyte to LiFePO4/Li batteries, the discharge specific capacity achieves ∼130 mAh g-l with a capacity retention rate of 83.9 % after cycling for 500 cycles at 0.5C. This simple modification method provides a novel design idea for all solid-state lithium batteries with excellent electrochemical performance.

Research Progress on the Composite Methods of Composite Electrolytes for Solid-State Lithium Batteries.

In the current challenging energy storage and conversion landscape, solid-state lithium metal batteries with high energy conversion efficiency, high energy density, and high safety stand out. Due to the limitations of material properties, it is difficult to achieve the ideal requirements of solid electrolytes with a single-phase electrolyte. A composite solid electrolyte is composed of two or more different materials. Composite electrolytes can simultaneously offer the advantages of multiple materials. Through different composite methods, the merits of various materials can be incorporated into the most essential part of the battery in a specific form. Currently, more and more researchers are focusing on composite methods for combining components in composite electrolytes. The ion transport capacity, interface stability, machinability, and safety of electrolytes can be significantly improved by selecting appropriate composite methods. This review summarizes the composite methods used for the components of composite electrolytes, such as filler blending, embedded framework, and multilayer bonding. It also discusses the future development trends of all-solid-state lithium batteries (ASSLBs).

Built-in garnet-rich composite solid electrolyte towards fast ion transport and dendrite-free for high-energy lithium batteries

Composite solid-state electrolytes (CSEs), which could provide greater flexibility to harness the advantages of single-phase electrolytes, are promising candidates for solid-state lithium (Li) batteries. However, the agglomeration of inorganic phase obstructs the efficient ion-conduction channel and accelerates dendrite growth, limiting the practical application of CSEs. Herein, a flexible garnet-rich composite skeleton is prepared by incorporating well-dispersed Li6.4La3Zr1.4Ta0.6O12 (LLZTO) with robust polyimide scaffold through a simple method. Subsequently, a compact composite bi-phase electrolyte with abundant and well-dispersed built-in LLZTO could be attained via in-situ curing of a poly(ethylene glycol)diacrylate-based polymer electrolyte within this skeleton. Capitalizing on the rapid Li+ pathways contributed by the high fraction and well-distributed ceramic phase, this electrolyte demonstrates remarkably ionic conductivity and Li+ transference number of 0.95 mS cm−1 and 0.81, respectively. The deigned bi-phase composite enables a stable and uniform Li stripping/plating in symmetrical Li||Li batteries over 1000 h at 0.2 mA cm−2 and a high critical current density of 1.9 mA cm−2, facilitated by enhanced Li+ conduction dynamics and homogenous Li+ flux. LiNi0.8Co0.1Mn0.1O2||Li cells using this electrolyte exhibit favorable battery performances (159.8 mAh g−1, 96.4%@180 cycles, 0.5C). Furthermore, this scalable fabrication process for this composite electrolyte holds great potential in grid-scale production for safe and high-energy Li batteries.

Progress of Polymer Electrolytes Worked in Solid-State Lithium Batteries for Wide-Temperature Application.

Solid-state Li-ion batteries have emerged as the most promising next-generation energy storage systems, offering theoretical advantages such as superior safety and higher energy density. However, polymer-based solid-state Li-ion batteries face challenges across wide temperature ranges. The primary issue lies in the fact that most polymer electrolytes exhibit relatively low ionic conductivity at or below room temperature. This sensitivity to temperature variations poses challenges in operating solid-state lithium batteries at sub-zero temperatures. Moreover, elevated working temperatures lead to polymer shrinkage and deformation, ultimately resulting in battery failure. To address this challenge of polymer-based solid-state batteries, this review presents an overview of various promising polymer electrolyte systems. The review provides insights into the temperature-dependent physical and electrochemical properties of polymers, aiming to expand the temperature range of operation. The review also further summarizes modification strategies for polymer electrolytes suited to diverse temperatures. The final section summarizes the performance of various polymer-based solid-state batteries at different temperatures. Valuable insights and potential future research directions for designing wide-temperature polymer electrolytes are presented based on the differences in battery performance. This information is intended to inspire practical applications of wide-temperature polymer-based solid-state batteries.

Improvement of the Interface Contact between Solid Polymer Electrolytes and Electrodes via Ultrasonic-Press Fusion

All solid-state lithium batteries have high energy density, good safety, and broad prospects. However, the poor compatibility of the electrolyte/electrode interface limits its development. To improve the interface contact performance of batteries, this study proposes an ultrasonic-press fusion method. The electrolyte/electrode structure was pressed by an ultrasonic sonotrode, and fused tightly via thermal and mechanical effects produced by ultrasonic-press fusion. The results showed that the charge transfer impedance at the battery interface was reduced by 80.3% in AC impedance testing, and the battery interface impedance performance was significantly improved. By observing the surface and interface morphology of the electrolyte, it was found that ultrasonic-press fusion improved the electrolyte interface contact. The electrolyte melted and produced microscale rheological behavior under the action of ultrasonic-press fusion, ultimately filling the capillary structure of anode in the battery, improving contact performance of the interface. Furthermore, a molecular dynamics model of the interface was constructed to calculate the contact performance. It was found that ultrasonic-press fusion generates thermal and mechanical effects. The thermal effect facilitates the electrolyte melts, and the mechanical effect causes the melt to vibrate, which coordinate and act on the electrolyte and cause the electrolyte to solder to the anode.

Highly liquid retentive, ordered ion transport quasi-solid polymer electrolytes for lithium metal batteries

Solid-state lithium metal batteries (SSLMB) offer a compelling solution to address the low energy density issue present in current liquid lithium-ion batteries (LIB). Nevertheless, SSLMB electrolytes continue to face specific challenges that impede their commercial viability. These challenges encompass low ionic conductivity, high production cost, instability of interfacial contact, and other hurdles. In this context, a cost-effective quasi-solid polymer electrolyte (QPE) based on Polyvinylidene fluoride (PVDF) was developed to reshape the transport of lithium-ion (Li+) within the electrolyte, resulting in accelerated Li+ transport, with an achieved ionic conductivity of 0.71 mS cm−1 at 25 °C. The assembled LiFePO4|PVDF-OH|Li cell demonstrates exceptional battery performance, boasting an initial capacity of 145.9 mAh/g at 30 °C and maintaining an impressive capacity retention of 85.4 % even after 1000 cycles. The experimental findings underscore the critical role played by the immobilized solvent within the innovative PVDF-based QPE in facilitating the migration of Li+, consequently enhancing electrochemical performance. This study showcases a pioneering approach aimed at enhancing ionic conductivity, representing a significant stride towards the development of low-cost, high-performance, and easily processable solid polymer electrolytes, with potential implications for broader research in the field of energy storage systems.

A bipolar organic molecule towards the anion/cation-hosting cathode compatible with polymer electrolytes for quasi-solid-state dual-ion batteries

Ion concentration and mobility are tightly associated with the ionic conductance of polymer electrolytes in solid-state lithium batteries. However, the anions involved in the movement are irrelevant to energy generation and cause uncontrolled dendritic growth and concentration polarization. In the current study, we proposed the strategy of using a bipolar organic molecule as the anion/cation-hosting cathode to expand the active charge carriers of polymer electrolytes. As a proof-of-concept demonstration of the novel strategy, a bipolar phthalocyanine derivative (2,3,9,10,16,17,23,24-octamethoxyphthalocyaninato) Ni(II) (NiPc-(OH)8) that could successively store anions and cations was used as the cathode hosting material in quasi-solid-state dual-ion batteries (QSSDIBs). Interestingly, peripheral polyhydroxyl substituents could build a compatible interface with poly(vinylidene fluoride-hexafluoro propylene-based gel polymer electrolytes (PVDF-HFP). As expected, NiPc-(OH)8 displays a high specific capacity of 248.2 mAh/g (at 50 mA g−1) and improved cyclic stability compared with that in liquid electrolyte. This study provides a solution to the issue of anion migration and could open another way to build high-performance QSSDIBs.

In Situ Construction of Elastic Solid-State Polymer Electrolyte with Fast Ionic Transport for Dendrite-Free Solid-State Lithium Metal Batteries.

Solid-state lithium metal batteries (LMBs) have been extensively investigated owing to their safer and higher energy density. In this work, we prepared a novel elastic solid-state polymer electrolyte based on an in situ-formed elastomer polymer matrix with ion-conductive plasticizer crystal embedded with Li6.5La3Zr1.5Ta0.5O12 (LLZTO) nanoparticles, denoted as LZT/SN-SPE. The unique structure of LZT/SN-SPE shows excellent elasticity and flexibility, good electrochemical oxidation tolerance, high ionic conductivity, and high Li+ transference number. The role of LLZTO filler in suppressing the side reactions between succinonitrile (SN) and the lithium metal anode and propelling the Li+ diffusion kinetics can be affirmed. The Li symmetric cells with LZT/SN-SPE cycled stably over 1100 h under a current density of 5 mA cm-2, and Li||LiFePO4 cells realized an excellent rate (92.40 mAh g-1 at 5 C) and long-term cycling performance (98.6% retention after 420 cycles at 1 C). Hence, it can provide a promising strategy for achieving high energy density solid-state LMBs.