All solid-state lithium batteries are constructed by using highly conducting Ta-doped Li7La3Zr2O12 (LLZTO) as the solid electrolytes as well as the supports, coated with composite cathodes consisting ...of poly(vinylidene fluoride) (PVdF):LiTFSI, Ketjen Black, and carbon-coated LiFePO4 on one side and attached with Li anode on the other side. At 60 °C, the batteries show the first discharge capacity of 150 mAh g−1 at 0.05 C and 93% capacity retention after 100 cycles. As the current density increases from 0.05 C to 1 C, the specific capacity decreases from 150 mAh g−1 to 100 mAh g−1. Further elevated temperature up to 100 °C leads to further improved performance, i.e. 126 mAh g−1 at 1 C and 99% capacity retention after 100 cycles. This good performance can be attributed to the highly conducting ceramic electrolytes, the optimum electronic and ionic conducting networks in the composite cathodes, and closely contacted cathode/LLZTO interface. These results indicate that the present strategy is promising for development of high-performance solid-state Li-ion batteries operated at medium temperature.
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•All solid state batteries were constructed with a mild and convenient approach.•Dense and highly conducting garnet electrolytes were used as supports of the cells.•Composite cathodes with highly conducting ionic and electronic networks were built.•The solid state batteries showed good performance at 60 °C.•Further elevated temperature like 100 °C led to greatly improved cell performance.
Introduction of inorganic solid electrolytes is believed to be an ultimate strategy to dismiss dendritic Li in high-energy Li-metal batteries (LMBs), and garnet-type Li7La3Zr2O12 (LLZO) electrolytes ...are impressive candidates. However, the current density for stable Li plating/stripping in LLZO is still quite limited. Here, we create in situ formed Li-deficient shields by the high-temperature calcination at 900 °C. By this novel process, the formation of Li2CO3 on LLZO is restrained, and then we successfully obtain Li2CO3-free LLZO after removing the Li-deficient compounds. Without any surface modification, Li2CO3-free LLZO shows an intrinsic “lithiophilicity” characteristic. The contact angles of metallic Li on LLZO garnets are assessed by the first-principle calculation to confirm the lithiophilicity characteristic of LLZO electrolytes. The wetting of metallic Li on the Li2CO3-free LLZO surface leads to a continuous and tight Li/LLZO interface, resulting in an ultralow interfacial resistance of 49 Ω cm2 and a homogeneous current distribution in the charge/discharge processes of LMBs. Consequently, the current density for the stable Li plating/stripping in LLZO increases to 900 μA cm–2 at 60 °C, one of the highest current density for LMBs based on garnet-type LLZO electrolytes. Our findings not only offer insight into the lithiophilicity characteristics of LLZO electrolytes to suppress dendritic Li at high current densities but also expand the avenue toward high-performance, safe, and long-life energy-storage systems.
Paramount attention has been paid on solid polymer electrolytes due to their potential in enhancement of energy density as well as improvement of safety. Herein, the composite electrolytes consisting ...of Li-salt-free polyethylene oxides and 200 nm-sized Li6.4La3Zr1.4Ta0.6O12 particles interfacially wetted by BMIMTF2N of 1.8 μL cm−2 have been prepared. Such wetted ionic liquid remains the solid state of membrane electrolytes and decreases the interface impedance between the electrodes and the electrolytes. There is no release of the liquid phase from the PEO matrix when the pressure of 5.0 × 104 Pa being applied for 24 h. The interfacially wetted membrane electrolytes show the conductivity of 2.2 × 10−4 S cm−1 at 20 °C, which is one order of magnitude greater than that of the membranes without the wetted ionic liquids. The conduction mechanism is related to a large number of lithium ions releasing from Li6.4La3Zr1.4Ta0.6O12 particles and the improved conductive paths along the ion-liquid-wetted interfaces between the polymer matrix and ceramic grains. When the membranes being used in the solid-state LiFePO4/Li and LiFe0.15Mn0.85PO4/Li cells at 25 °C, the excellent rate capability and superior cycle stability has been shown. The results provide a new prospect for solid polymer electrolytes used for room-temperature solid-state lithium batteries.
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•The ionic liquid was used to wet the interfaces between PEO and LLZTO.•The ionic liquid of 1.8 μL cm−2 remained the solid state of membrane electrolytes.•The improved conductive paths along the interfaces were studied.•LiFePO4/Li and LiFe0.15Mn0.85PO4/Li batteries were tested at room temperature.
High density (~96%) garnet-type Al-contained Li sub(6.75)La sub(3)Zr sub(1.75)Ta sub(0.25)O sub(12) (LLZTO-Al) solid electrolytes are prepared by conventional solid-state reaction and the following ...flowing oxygen sintering process. An overall ionic conductivity as high as 7.4 x 10 super(-4) S cm super(-1) at 25 degreesC is achievable, remarkably higher than that obtained by sintering in other atmospheres. The dependence of density and conductivity of solid electrolytes on sintering under different oxygen partial pressures is discussed. Atmosphere sintering is proved to be an effective method to improve the relative density of lithium oxide ceramics.
•W Substitution for Zr stabilizes the cubic phase of LLZO grains.•W dopant improves the density of LLZO ceramics.•The LLZWO ceramics are chemically and electrochemically stable against Li.•The ...Li/LLZWO/Electrolyte-soaked separator/NMC batteries show good rechargeable performance.
W-doped Li7La3Zr2O12 electrolytes with composition of Li7-2xLa3Zr2-xWxO12 (LLZWO, x=0-0.55) were prepared by conventional solid state reaction. The incorporation of W proves beneficial to stabilization of cubic phase and densification of the ceramic, resulting in relative density of 96% and ionic conductivity of 6.6×10−4Scm−1 at 25°C. Further analysis indicates that the LLZWO is not only chemically but also electrochemically (at least up to 4.5V) stable against Li metal anodes. The batteries consisting of Li/LLZWO/Electrolyte-soaked separator/LiNi0.33Mn0.33Co0.33O2 at 25°C exhibit the capacity of 142mAhg−1 at a constant current of 15mAg−1 at the first discharge, which could run for 20 cycles with capacity retention of 94%. These results indicate that the W-doped LLZO ceramics are promising electrolytes for solid state lithium ion batteries.
A lot of researches have been focused on the evolution and function of MYB transcription factors (TFs). For revealing the formation of petunia flower color diversity, MYB gene family in petunia was ...identified and analyzed. In this study, a total of 155 MYB genes, including 40 1R-MYBs, 106 R2R3-MYBs, 7 R1R2R3-MYBs and 2 4R-MYBs, have been identified in the Petunia axillaris genome. Most R2R3 genes contain three exons and two introns, whereas the number of PaMYB introns varies from 0 to 12. The R2R3-MYB members could be divided into 28 subgroups. Analysis of gene structure and protein motifs revealed that members within the same subgroup presented similar exon/intron and motif organization, further supporting the results of phylogenetic analysis. Genes in subgroup 10, 11 and 21 were mainly expressed in petal, not in vegetative tissues. Genes in subgroup 9, 19, 25 and 27 expressed in all tissues, but the expression patterns of each gene were different. According to the promoter analysis, five R2R3-MYB and two MYB-related genes contained MBSI cis-element, which was involved in flavonoid biosynthetic regulation. PaMYB100/DPL has been reported to positively regulate to pigmentation. However, although PaMYB82, PaMYB68 and Pa1RMYB36 contained MBSI cis-element, their function in flavonoid biosynthesis has not been revealed. Consistent with existing knowledge, PaMYBs in subgroup 11 had similar function to AtMYBs in subgroup 6, genes in which played an important role in anthocyanin biosynthesis. In addition, PaMYB1 and PaMYB40 belonged to P9 (S7) and were potentially involved in regulation of flavonoid synthesis in petunia vegetative organs. This work provides a comprehensive understanding of the MYB gene family in petunia and lays a significant foundation for future studies on the function and evolution of MYB genes in petunia.
In the context of revealing interfacial effects on ion conduction, thin films are extremely worthwhile due to defined geometry. Of particular interest are heterostructures as they offer symmetric ...boundary conditions and a high density of hetero‐interfaces. The recent progress in this field is reviewed. Materials classes under concern include halides and oxides, and refer to various degrees of disorder and different mobilities. Even though in its infancy, the field of ionic heterostructures is already characterized by a variety of results of fundamental importance and of technological relevance.
Ionically conducting two‐dimensional heterostructures advantageously allow investigation of interfacial effects on ionic conductivity, storage and reactivity. As the interface spacing continuously decreases from micrometer‐ down to nanometer‐scale, not only observation of size effects but also generation of a new artificial crystalline material can be achieved.
Composite electrolytes consisting of polymers and three-dimensional (3D) fillers are considered to be promising electrolytes for solid lithium batteries owing to their virtues of continuous ...lithium-ion pathways and good mechanical properties. In the present study, an electrolyte with polyethylene oxide–lithium (bis trifluoromethyl) sulfate–succinonitrile (PLS) and frameworks of three-dimensional SiO2 nanofibers (3D SiO2 NFs) was prepared. Taking advantage of the highly conductive interfaces between 3D SiO2 NFs and PLS, the total conductivity of the electrolyte at 30 °C was approximately 9.32 × 10−5 S cm−1. With a thickness of 27 μm and a tensile strength of 7.4 MPa, the electrolyte achieved an area specific resistance of 29.0 Ω cm2. Moreover, such a 3D configuration could homogenize the electrical field, which was beneficial for suppressing dendrite growth. Consequently, Li/LiFePO4 cells assembled with PLS and 3D SiO2 NFs (PLS/3D SiO2 NFs), which delivered an original specific capacity of 167.9 mAh g−1, only suffered 3.28% capacity degradation after 100 cycles. In particular, these cells automatically shut down when PLS was decomposed above 400 °C, and the electrodes were separated by the solid framework of 3D SiO2 NFs. Therefore, the solid lithium batteries based on composite electrolytes reported here offer high safety at elevated temperatures.
Study of formation and decomposition of Li2O2 during operations of Li–O2 cells is essential for understanding the reaction mechanism and finding solutions to improve the cell performance. Using ...vertically aligned carbon nanotubes (VACNTs) directly grown on stainless steel meshes as the cathodes in the Li–O2 cells with dimethoxyethane (DME) electrolytes, nucleation, growth, and decomposition processes of the Li2O2 in the first cycle are clearly visualized. Through cycles with the controlled discharge and charge capacities, the abacus-ball-shaped Li2O2 and the rust-like carbonates simultaneously formed around the VACNTs are further identified. It is indicated that the increasing coverage of carbonates on the cathode surface suppresses the formation of Li2O2, which maintains the shape of abacus ball. When the VACNT surfaces are predominantly covered by the carbonates, the cells tend to terminate.
Garnet-type solid-state electrolytes (SSEs) are considered to be a good choice for solid-state batteries, yet the interfacial issues with metallic Li limit their applications. Herein, we propose an ...ultrasimple and effective strategy to enhance the interfacial connection between garnet SSEs and Li metal just by drawing a graphite-based soft interface with a pencil. Both experimental analysis and theoretical calculations confirm that the reaction between the graphite-based interfacial layer and metallic lithium forms a lithiated connection interface with good lithium-ionic and electronic conductivity. Compared to the reported interfacial materials, the graphite provides a soft interface with better ductility and compressibility. With improvement by this soft interface, the impedance of symmetric Li cells significantly decreases and the cell cycle is stable for over 1000 h. Moreover, a solid-state battery with Li-metal anode, ternary NCM523 cathode, and treated-garnet SSEs is fabricated and displays excellent rate capability and long cycling performance.
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