Li0.35La0.55TiO3 Research Articles

Oriented Crystal Growth of Li0.33La0.557TiO3 Nanowire Induced by One-Dimensional Polymer Sheath toward Rapid Lithium-Ion Transfer.

Superionic conductor-based solid-state electrolytes with preferred crystal structures hold great promise for realizing ultrafast lithium-ion (Li+) transfer, which is urgently desired for all-solid-state lithium batteries. However, the precise control of crystal growth of superionic conductors is still challenging since the crystals always spontaneously grow to disordered structures with the lowest internal energy to ensure thermodynamic stability. Herein, a coaxial nanowire with a polyvinylpyrrolidone (PVP) sheath and a Li0.33La0.557TiO3 (LLTO) precursor core (PVP/LLTO-caNW) is prepared through coaxial electrospinning, followed by sintering into LLTO nanowire with an oriented crystal structure (LLTO-caNW). We demonstrate that the one-dimensional PVP sheath as a sacrificial layer generates uniform and the strongest adsorption ability on the (110) phase among different LLTO crystal planes, which induces the crystal to preferentially grow along the c-axis (the fastest Li+ transfer direction) during the nucleation and growth processes. As a result, the prepared LLTO-caNW displays an ultrahigh bulk ionic conductivity of 3.13 × 10-3 S cm-1, exceeding most LLTO crystals and approaching the theoretical conductivity. Meanwhile, the oriented crystal growth imparts to LLTO-caNW significantly reduced grain boundary resistance, and the grain-boundary conductivity reaches up to 1.09 × 10-3 S cm-1. This endows the composite solid electrolyte with high ionic conduction performance and superior cycle stability in the assembled all-solid-state lithium battery.

Electrospun Perovskite Nanofiber/Poly(vinylidene fluoride-cohexafluoropropylene) Quasi-Solid-State for Lithium-Metal Batteries

Solid-state lithium-metal batteries (SSLMBs) with a composite solid electrolyte (CSE) have great potential for achieving both high energy density and high safety and are thus promising next-generation energy storage devices. Nevertheless, the key bottleneck issues are a high electrode/electrolyte interface resistance and the limited Li+ conductivity of the solid electrolyte. A free-standing CSE consisting of Li0.33La0.557TiO3 (LLTO) nanofibers, poly(vinylidene fluoride-co-hexafluoropropylene (PVDF-HFP), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) is developed for room-temperature SSLMB applications. First, the calcination temperature for the electrospun LLTO precursor is optimized. The effects of the LLTO filler fraction and the morphology (spherical vs. fibrous) on CSE conductivity are examined. Furthermore, a succinonitrile interlayer (SNI), which is composed of succinonitrile, fluoroethylene carbonate, and LiTFSI, is developed to lower the high interfacial impedance. Compared to a conventional ester-based interlayer (EBI), SNI effectively decreases the Li//CSE interfacial resistance and suppresses unfavorable interfacial side reactions. The derived LiF- and CF x -rich protective layer on the Li electrode surface prevents the accumulation of dead Li and the excessive formation of SEI. Importantly, the dehydrofluorination reactions of PVDF-HFP are adequately mitigated, and a highly conductive and stable Li//CSE interface is achieved owing to SNI. Accordingly, both Li//CSE@SNI//Li and Li//CSE@SNI//LiFePO4 cells exhibit superior charge-discharge properties and cyclability to those of an EBI counterpart. A simple and low-cost interface modification strategy to enhance the performance of SSLMBs is proposed in this paper.

In-situ interfacial passivation and self-adaptability synergistically stabilizing all-solid-state lithium metal batteries

The function of solid electrolytes and the composition of solid electrolyte interphase (SEI) are highly significant for inhibiting the growth of Li dendrites. Herein, we report an in-situ interfacial passivation combined with self-adaptability strategy to reinforce Li0.33La0.557TiO3 (LLTO)-based solid-state batteries. Specifically, a functional SEI enriched with LiF/Li3PO4 is formed by in-situ electrochemical conversion, which is greatly beneficial to improving interface compatibility and enhancing ion transport. While the polarized dielectric BaTiO3-polyamic acid (BTO-PAA, BP) film greatly improves the Li-ion transport kinetics and homogenizes the Li deposition. As expected, the resulting electrolyte offers considerable ionic conductivity at room temperature (4.3 × 10−4 S cm−1) and appreciable electrochemical decomposition voltage (5.23 V) after electrochemical passivation. For Li-LiFePO4 batteries, it shows a high specific capacity of 153 mA h g−1 at 0.2 C after 100 cycles and a long-term durability of 115 mA h g−1 at 1.0 C after 800 cycles. Additionally, a stable Li plating/stripping can be achieved for more than 900 h at 0.5 mA cm−2. The stabilization mechanisms are elucidated by ex-situ XRD, ex-situ XPS, and ex-situ FTIR techniques, and the corresponding results reveal that the interfacial passivation combined with polarization effect is an effective strategy for improving the electrochemical performance. The present study provides a deeper insight into the dynamic adjustment of electrode-electrolyte interfacial for solid-state lithium batteries.

Suppression of Dehydrofluorination Reactions of a Li0.33La0.557TiO3-Nanofiber-Dispersed Poly(vinylidene fluoride-co-hexafluoropropylene) Electrolyte for Quasi-Solid-State Lithium-Metal Batteries by a Fluorine-Rich Succinonitrile Interlayer.

Solid-state lithium-metal batteries have great potential to simultaneously achieve high safety and high energy density for energy storage. However, the low ionic conductivity of the solid electrolyte and large electrode/electrolyte interfacial impedance are bottlenecks. A composite solid electrolyte (CSE) that integrates electrospun Li0.33La0.557TiO3 (LLTO) nanofibers, poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) is fabricated in this work. The effects of the LLTO filler fraction and morphology (spherical vs fibrous) on CSE conductivity are examined. Additionally, a fluorine-rich interlayer based on succinonitrile, fluoroethylene carbonate, and LiTFSI, denoted as succinonitrile interlayer (SNI), is developed to reduce the large interfacial impedance. The use of SNI rather than a conventional ester-based interlayer (EBI) effectively decreases the Li//CSE interfacial resistance and suppresses unfavorable interfacial side reactions. The LiF- and CFx-rich solid electrolyte interphase (SEI), derived from SNI, on the Li metal electrode, mitigates the accumulation of dead Li and excessive SEI. Importantly, dehydrofluorination reactions of PVDF-HFP are significantly reduced by the introduction of SNI. A symmetric Li//CSE//Li cell with SNI exhibits a much longer cycle life than that of an EBI counterpart. A Li//CSE@SNI//LiFePO4 cell shows specific capacities of 150 and 112 mAh g-1 at 0.1 and 2 C (based on LiFePO4), respectively. After 100 charge-discharge cycles, 98% of the initial capacity is retained.

Multi-component solid PVDF-HFP/PPC/LLTO-nanorods composite electrolyte enabling advanced solid-state lithium metal batteries

Substituting flammable and leaky liquid electrolytes with advanced solid composite electrolytes considered as one of the most hopeful strategy to develop solid-state lithium metal batteries with high security and high energy density. However, it is still an arduous task to develop a solid electrolyte with high ionic conductivity and wide electrochemical window. To this end, we designed three-component solid poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)/poly(propylene carbonate) (PPC)/Li0.33La0.557TiO3 (LLTO) nanorods composite electrolyte. Oxidation-resistant PVDF-HFP can stabilize the cathode of lithium metal batteries and widen the electrochemical window. The controlled degradation of PPC can wet and stabilize the interface between the electrolyte and the lithium metal anode to a certain extent. The introduction of LLTO nanorods not only decreases the crystallinity of the composite solid electrolyte, but also provides an additional path for the transmission of lithium ions, and improves the ionic conductivity of the electrolyte membrane (2.18×10−4 S·cm−1 at room temperature). The Li/PPLSE3/Li symmetric cell assembled with this electrolyte has a long cycling life of 2000 h at a current density of 0.1 mA·cm−2 at room temperature. The assembled NCM622/PPLSE3/Li full battery has a specific discharge capacity of 142 mAh·g−1 and a capacity retention rate of 84.6% after 100 cycles at room temperature.

A Janus-faced, perovskite nanofiber framework reinforced composite electrolyte for high-voltage solid lithium-metal batteries

High-voltage solid lithium-metal batteries (HVSLMBs) are not only energy denser but also safer than state-of-the-art lithium-ion batteries. However, the narrow electrochemical stability windows and low ionic conductivities of polymer solid electrolytes severely hinder the practical application of this type of battery. To simultaneously address these issues, we propose and fabricate a thin yet mechanically strong composite solid electrolyte by forming a layer of a reduction-tolerant polyethylene glycol diacrylate (PEGDA) and oxidation-resistant poly(vinylidene fluoride) (PVDF) within the perovskite nanofiber framework. The unique Janus-faced design enables stable and intimate contact with the lithium metal anode and high-voltage cathode, while the perovskite inorganic electrolyte Li0.33La0.557TiO3 (LLTO) nanofiber framework endows the membrane with a high ionic conductivity of 0.1 mS cm−1 at room temperature (25 °C) and excellent mechanical strength with the thickness of as low as 24 μm. When paired with a high-voltage LiNi0.8Co0.1Mn0.1O2 cathode, the solid lithium battery can deliver a reversible discharge capacity of as high as 176 mAh g−1 at 0.2C at room temperature. This work offers a novel, effective strategy to develop high-performance solid electrolytes for next-generation high-voltage lithium batteries.

High Performance Single-Crystal Ni-Rich Cathode Modification via Crystalline LLTO Nanocoating for All-Solid-State Lithium Batteries.

Sulfide-based all-solid-state lithium batteries (ASSLBs) assembled with Ni-rich layered cathodes are currently promising candidates for achieving high-energy-density and high-safety energy storage systems. However, the interfacial challenges between sulfide electrolyte and Ni-rich layered cathode, such as space charge layer, side reaction, and poor physical contact, greatly limit the practicality of all-solid-state batteries. In this work, an optimal crystalline Li0.35La0.55TiO3 (LLTO) surface coating with a thickness of roughly 6 nm and a high Li ion conductivity of 0.3 mS cm-1 was adopted to enhance the structural stability of the single-crystal LiNi0.6Co0.2Mn0.2O2 (S-NCM622) cathode in ASSLBs. Furthermore, due to the high ionic conductivity and chemical stability of the LLTO coating layer, the interfacial problems, involving interfacial reaction and a space charge layer, in sulfide-based all-solid-state batteries have been effectively solved. As a result, the assembled ASSLBs with the S-NCM622@LLTO cathode exhibit high initial capacity (179.7 mAh g-1) at 0.05 C and excellent cycling performance with 84.5% capacity retention after 100 cycles at 0.1 C at room temperature. This work proposes an effective strategy to enhance the performance of Ni-rich layered cathodes for next-generation high-energy-density sulfide-based lithium batteries.

Preparing Two-Dimensional Ordered Li0.33 La0.557 TiO3 Crystal in Interlayer Channel of Thin Laminar Inorganic Solid-State Electrolyte towards Ultrafast Li+ Transfer.

Inorganic superionic conductor holds great promise for high-performance all-solid-state lithium batteries. However, the ionic conductivity of traditional inorganic solid electrolytes (ISEs) is always unsatisfactory owing to the grain boundary resistance and large thickness. Here, a 13 μm-thick laminar framework with ≈1.3 nm interlayer channels is fabricated by self-assembling rigid, hydrophilic vermiculite (Vr) nanosheets. Then, Li0.33 La0.557 TiO3 (LLTO) precursors are impregnated in interlayer channels and afterwards in situ sintered to large-size, oriented, and defect-free LLTO crystal. We demonstrate that the confinement effect permits ordered arrangement of LLTO crystal along the c-axis (the fastest Li+ transfer direction), permitting the resultant 15 μm-thick Vr-LLTO electrolyte an ionic conductivity of 8.22×10-5 S cm-1 and conductance of 87.2 mS at 30 °C. These values are several times' higher than that of traditional LLTO-based electrolytes. Moreover, Vr-LLTO electrolyte has a compressive modulus of 1.24 GPa. Excellent cycling performance is demonstrated with all-solid-state Li/LiFePO4 battery.

Preparing Two‐Dimensional Ordered Li0.33La0.557TiO3 Crystal in Interlayer Channel of Thin Laminar Inorganic Solid‐State Electrolyte towards Ultrafast Li+ Transfer

AbstractInorganic superionic conductor holds great promise for high‐performance all‐solid‐state lithium batteries. However, the ionic conductivity of traditional inorganic solid electrolytes (ISEs) is always unsatisfactory owing to the grain boundary resistance and large thickness. Here, a 13 μm‐thick laminar framework with ≈1.3 nm interlayer channels is fabricated by self‐assembling rigid, hydrophilic vermiculite (Vr) nanosheets. Then, Li0.33La0.557TiO3 (LLTO) precursors are impregnated in interlayer channels and afterwards in situ sintered to large‐size, oriented, and defect‐free LLTO crystal. We demonstrate that the confinement effect permits ordered arrangement of LLTO crystal along the c‐axis (the fastest Li+ transfer direction), permitting the resultant 15 μm‐thick Vr‐LLTO electrolyte an ionic conductivity of 8.22×10−5 S cm−1 and conductance of 87.2 mS at 30 °C. These values are several times’ higher than that of traditional LLTO‐based electrolytes. Moreover, Vr‐LLTO electrolyte has a compressive modulus of 1.24 GPa. Excellent cycling performance is demonstrated with all‐solid‐state Li/LiFePO4 battery.

Synthesizing Superior Flexible Oxide Perovskite Ceramic Nanofibers by Precisely Controlling Crystal Nucleation and Growth.

Oxide perovskite ceramics are cornerstone materials of electronic devices, but they easily break under bending. Such brittle failure phenomenon limits their applications in emerging flexible electronics. Here, the authors propose a scalable approach of sol-gel electrospinning to synthesize flexible perovskite Li0.35 La0.55 TiO3 (LLTO) nanofibers (NFs) by reducing grain sizes and pore defects in the NFs. The strategy is to precisely control crystal nucleation and growth by forming homogeneous nuclei in the sol before electrospinning and to construct soft twin and amorphous grain boundaries by controlling calcination temperatures. Ball-milling the sol promotes the formation of numerous LLTO nuclei and thus effectively refines grains, while using gradient calcination temperatures from 200 to 900°C creates intricate soft grain boundaries. The individual LLTO NF shows ceramic toughness with an elastic modulus of ≈40GPa and the NF film demonstrates silk-like softness with a large elastic strain of 1.51%. Moreover, the LLTO film shows superior fatigue resistance and it maintains structure well after repeated tensile-buckling cycles at 40% strain. The proposed strategy facilitates to develop flexible oxide perovskite ceramic films with appealing applications.

Significant Reduction in Interface Resistance and Super-Enhanced Performance of Lithium-Metal Battery by In Situ Construction of Poly(vinylidene fluoride)-Based Solid-State Membrane with Dual Ceramic Fillers

Due to the degradation of lithium-metal anode, lithium dendritic growth and other challenging problems like interface resistance among electrolyte and electrode may damage the actual performance of lithium-metal batteries (LMB). Recently, ceramic nanofillers Li1.3Al0.3Ti1.7P(O4)3 (LATP) and Li0.33La0.557TiO3 (LLTO) seem to be suitable solid-state electrolytes for lithium metallic solid-state batteries with outstanding energy densities and highly safer energy storage devices. Herein, the solid-state electrolytic materials are composed of a fast ion-conducting solid-state LATP, LLTO, and optimized amount of adequate polarized poly(vinylidene fluoride) (PVDF) electrolyte with lithium salt (LiClO4) to fabricate the dual semi-solid-state polymer electrolyte (DSPE) membrane. The prepared membrane provides a promising solution for battery safety and the most challenging problems of interface resistance. The proposed DSPE membrane is investigated via analytical techniques; testing results showed that the DSPE membrane possesses excellent electrochemical performance, including suitable Li-transference numbers and improved ionic conductivities with enhanced stability. Furthermore, the DSPE membrane is beneficial to resist the growth of Li dendrites effectively. The symmetrical cell Li//DSPE//Li exhibits excellent stability at a high current density of 1 mA/cm2 over 1000 h, and the membrane sustains long-cycle performance with a high retention of 95% after 100 cycles. The designed DSPE membrane opens a path of fabricating a safe electrolyte membrane for elevated temperature metal-ion battery applications.

Li0.35La0.55TiO3 nanofibers filled poly (ethylene carbonate) composite electrolyte with enhanced ion conduction and electrochemical stability

A solid electrolyte with flexible and high ion conductivity is of great concern in high-performance all-solid-state lithium batteries. Using flexible polymer matrix combining with conductive ceramics filler is a convenient and effective strategy to integrate high ion conductivity into flexibility. Here, flexible solid electrolytes with continuous Li-ion transfer pathways were constructed by combining the Li0.33La0.557TiO3 (LLTO) nanofibers with poly (ethylene carbonate) (PEC) matrix. The effect of the content and diameter of the LLTO nanofibers on the ionic conductivity, electrochemical stability, and glass transition temperature of the composite electrolyte was investigated. The results are demonstrated that adding LLTO nanofibers into the PEC improves ionic conductivity and electrochemical stability of the electrolytes. The composite electrolyte containing 5 wt.% of LLTO nanofibers shows the maximum ionic conductivity of 3.48 × 10−3 S cm−1 at 85 °C with the electrochemical stability window of 5.1 V when the diameter of nanofiber is 250 nm. In addition, the composite electrolyte is flexible with elongation at breaking up to 362%.

Fabrication of LiFePO<sub>4</sub>-Based Composite Cathode Deposited on LLTO Li-Ion Conducting Solid Electrolyte via Slurry Coating and Hot-Pressing

LiFePO4 (LFPO)-based composite cathode was deposited on Li0.35La0.55TiO3 (LLTO) solid electrolyte via slurry coating method. A composite cathode comprising of LiFePO4, LLTO, and carbon black (CB) were mixed together in a slurry and deposited on a dense LLTO pellet substrate. The effects of heat treatment temperature and hot-pressing in the structure and densification of the deposited composite cathode were investigated. Cathode component precursors were analyzed for its particle size distribution using particle size analyzer and revealed a bimodal particle size distribution for each component materials. Structural characterization using X-ray powder diffraction (XRD) analysis revealed that distinct XRD peaks were observed which can be attributed to LFPO and LLTO for the deposited as-dried and heat treated (450 °C ) composite cathodes. Surface and cross-sectional SEM images revealed that hot-pressing provided denser morphology with smaller thickness as compared to the just as-dried and heat treated samples without the application of temperature with pressure.

Asymmetry-structure electrolyte with rapid Li+ transfer pathway towards high-performance all-solid-state lithium–sulfur battery

All-solid-state lithium–sulfur (Li–S) battery, with solid state electrolyte (SSE) replacing liquid electrolyte, is considered as promising candidate for next-generation energy storage devices due to the high capacity and safety. However, the fabrication of SSE with high ion conduction and efficient dendrite suppression remains a daunting challenge. Herein, an asymmetric Li0.33La0.557TiO3 (LLTO) framework with porous layer and dense layer is designed and fabricated, followed by impregnating poly (ethylene oxide) (PEO) to prepare SSE. The continuous LLTO framework serves as rapid lithium ion (Li+) transfer pathway, imparting an excellent ionic conductivity of 1.49 × 10−4 S cm−1 at 30 °C, over 40 times higher than that of blank PEO. The presence of dense layer remarkably improves the compression strength of composite electrolyte and facilitates the Li+ uniform deposition, thus effectively suppressing the lithium dendrite growth. As a result, the assembled Li–S battery exhibits extraordinary cycling stability, which preserves a capacity of 907.6 mAh g−1 after 100 cycles with a Coulombic efficiency of ~ 99%. Meanwhile, the continuous PEO phase that rooted in the porous layer of framework also imparts composite electrolyte favorable flexibility and processability.

Open-Structured Nanotubes with Three-Dimensional Ion-Accessible Pathways for Enhanced Li+ Conductivity in Composite Solid Electrolytes.

Composite solid electrolytes (CSEs) hold great promise toward safe lithium metal batteries with high energy density, due to integration of the merits of polymer matrixes and fillers. Rational design of filler nanostructures has attracted increasing attention for improving the ionic transport of CSEs in solid batteries. In this work, we fabricated open-structured Li0.33La0.557TiO3 (LLTO) nanotubes (NTs) as ion-conductive fillers in CSEs by a gradient electrospinning method for the first time. Different from nanoparticles (NPs) and nanowires (NWs), our nanotubes are composed of connected small NPs, which offer three-dimensional (3D) Li+-accessible pathways, large polymer/filler interfacial ionic conduction regions, and enhanced wettability against the polymer matrix. As a result, the solid electrolytes based on LLTO NTs and polyacrylonitrile (PAN) can display a high ionic conductivity of up to 3.6 × 10-4 S cm-1 and a wide electrochemical window of 5 V at room temperature (RT). Furthermore, Li-Li symmetric cells using the LLTO NTs/PAN CSE can work stably over 1000 h with a polarization of 20 mV. LiFePO4-Li full cells exhibit a high capacity of 142.5 mAh g-1 with a capacity retention of 90% at 0.5 C after 100 cycles. All of these results demonstrate that the design of open-structured nanotubes as fillers is a promising strategy for high-performance solid electrolytes.

Approaching high performancePVDF‐HFPbased solid composite electrolytes withLLTOnanorods for solid‐state lithium‐ion batteries

Solid polymer electrolytes have the merits of high safety and energy density and lightweight. Therefore, they gradually become the key for commercial applications of solid batteries. In this study, a new type of solid composite electrolyte (SCE) is prepared by adding Li0.33La0.557TiO3 (LLTO) nanorods into poly(vinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) matrix. This SCE displays excellent thermal stability and mechanical properties. Moreover, it has been proven to sufficiently suppress the growth of lithium dendrites. When the content of the LLTO nanorods reaches 10 wt%, the SCE delivers a high ionic conductivity of 1.21 × 10−4 S cm−1 at 25°C and the electrochemical stability window of 4.7 V (vs Li+/Li). The NCM622/SCE/Li solid-state lithium-ion battery delivers a discharge specific capacity of 129.1 mAh g−1 at 0.5 C after 100 cycles, and the coulombic efficiency reaches 99%. These results demonstrate that the SCE is expected to become one of the most hopeful candidates for the coming generation of solid-state lithium-ion batteries.

A novel ceramic/polyurethane composite solid polymer electrolyte for high lithium batteries

Compared with the organic electrolyte, the solid electrolyte is more stable and non-volatile at high potential, which solves the decomposition problem of organic electrolyte and the potential safety hazard of flammability and explosion. Based on the advantages of inorganic solid electrolyte and polymer solid electrolyte, a ceramic/polyurethane composite polymer electrolyte (CPPE) based on Li0.35La0.55TiO3 (LLTO) and polyurethane (LPU) was prepared in this work. First, a linear polyurethane (LPU) was synthesized via 2,4-toluene diisocyanate (TDI) and poly(propylene oxide) (PPO), owing to the high ionic conductivity of LLTO and good mechanical property of LPU. The CPPE has a satisfactory lithium ion conductivity (3.8 × 10−4 S cm−1) at room temperature. Furthermore, the assembled LiFePO4|CPPE|Li battery exhibit excellent cycle performance at room temperature, the discharge capacity was still 149.8 mAh g−1 after 200 cycles and with a superior capacity retention of 97.8% at 0.5 °C. Additionally, the LiNi0.8Co0.1Mn0.1O2|CPPE|Li exhibited remarkable rate capacity that the initial capacity reached to 216.4 mAh g−1 at 0.1 °C and maintains the excellent specific capacity of 138 mAh g−1 at 1 °C. These findings suggest that CPPE provides a viable idea for the development of high-performance lithium batteries.

Biomimetic PVDF/LLTO composite polymer electrolyte enables excellent interface contact and enhanced ionic conductivity

Composite polymer electrolyte (CPE) with enhanced ionic conductivity, excellent flexibility and strong strength are urgently required for all-solid-state lithium metal batteries (LMBs). Inspired by the dragonfly wings that are super-lightweight and ultrathin but have excellent stability when subject to bending and twisting during flapping, we have constructed Li0.35La0.55TiO3 (LLTO) nanowires-filled polyvinylidene fluoride (PVDF). In our design, the PVDF is used to construct the ultrathin membrane, the 1D LLTO nanowires are acted as the veins to give rise to a high mechanical strength of 10 Mpa. The special design creates cellular surface of PVDF/LLTO-CPE, which guarantees the excellent flexibility as well as a good interface contact between CPE and Li anode. When evaluated as electrolyte for LiFePO4|Li battery, the PVDF/LLTO-CPEs can suppress Li dendrites growth, and thus presents an excellent cycling stability of 140 mAh g−1 after 200 cycles. Moreover, the flexible LiFePO4|PVDF/LLTO-CPE|Li4Ti5O12 pouch cell delivers a satisfactory rate performance and cycle stability under folding and bending states. The excellent performances are attributed to the unique cellular structure and super mechanical strength of biomimetic PVDF/LLTO-CPE. All results show the PVDF/LLTO-CPE is a promising solid-state electrolyte for flexible electronic devices.

Polydopamine Coated Lithium Lanthanum Titanate in Bilayer Membrane Electrolytes for Solid Lithium Batteries.

The demand for solid lithium batteries with high energy density and safety boosts the development of solid-state electrolytes in which composite membrane electrolytes consisting of polymers and ceramic fillers are attractive. As the common ceramic filler, perovskite-structured Li0.33La0.557TiO3 (LLTO) has great advantage on cost and environmental friendliness by using earth-abundant raw materials in the production. Nevertheless, the chemical instability of LLTO against Li-metal hinders its application. Herein, LLTO particles are coated by biodegradable polydopamine (PDA) layers and united with poly(vinylidene fluoride) (PVDF) to prepare composite electrolytes which perform superior stability against Li-metal. Besides, PVDF:LLTO membranes are assembled at cathode sides and show high voltage tolerance. The Li/Ni0.6Mn0.2Co0.2O2 cells with bilayer membrane electrolytes can deliver the specific capacity of 158.2 mAh g-1 and maintain 83% capacity after 100 cycles at 0.1 C. Furthermore, based on the bilayer membranes with outstanding flexibility and stretchability, the cells can even survive under several extreme conditions, such as bending, twisting, crimping, and stretching. This study offers an environmentally friendly strategy to improve the stability of LLTO against Li and sheds light on the development of cost-effective solid electrolytes.

A flexible, ion-conducting solid electrolyte with vertically bicontinuous transfer channels toward high performance all-solid-state lithium batteries

All-solid-state lithium batteries, featuring high security and volume energy density, hold great potential as next-generation energy storage device. However, their development needs the fabrication of ionic conductive and structural stable solid electrolyte. Herein, Li0.33La0.557TiO3 (LLTO) framework with interlocked porous structure is synthesized by sintering the gel permeated nylon. Then, poly(ethylene oxide) (PEO) is incorporated in the pores to produce PEO-LLTO framework solid electrolyte (PLLF electrolyte) with vertically bicontinuous phase. We demonstrate that LLTO framework fast transports Li+ through the intrinsic vacancy; meanwhile the confined PEO with low crystallization displays fast Li+ transfer ability, thus synergistically realizing efficient Li+ conduction. This novel PLLF electrolyte exhibits a remarkable ionic conductivity of 2.04 × 10−4 S cm−1, which is ~72 times higher than that of traditional PEO-based electrolytes and superior to most reported solid electrolytes. Moreover, the interconnected networks endow PLLF electrolyte with excellent structural stability. Thus, the LiFePO4 (LFP)/Li cell exhibits extraordinary cycling stability: the discharge capacity of 154.7 mAh g−1 at 1 C after 150 cycles with capacity decay of only 0.03% per cycle. Briefly, such a vertically bicontinuous phase structure maximizes the cooperation between the conduction function of ceramic framework and the stability of polymer, offering a promising approach for all-solid-state batteries.