Low-Temperature Fabrication of Bulk-Type All-Solid-State Lithium-Ion Battery Utilizing Nanosized Garnet Solid Electrolytes.

Garnet-type Li7 La3 Zr2 O12 (LLZ) materials are attracting attention as solid electrolytes (SEs) in oxide-based all-solid-state batteries (ASSBs) owing to their high ionic conductivity. Although the electrochemical stability of LLZ against Li metal is demonstrated with possible high energy density, high-temperature sintering above 1000 °C, which is required to achieve high Li-ion conductivity, results in the formation of insulating impurities at the electrode-electrolyte interfaces. Here, nanosized fine-particle samples of Ta-substituted Li6.5 La3 Zr1.5 Ta0.5 O12 (LLZT) are successfully prepared at a remarkably low temperature of 400 °C utilizing an amorphous precursor oxide. The dense LLZT SE sintered by hot pressing at 500 °C shows room-temperature Li-ion conductivity of 1.03 × 10-4 S cm-1 without any additives. In addition, the bulk-type NCM-graphite full battery cell fabricated with the LLZT fine particles through a hot-pressing sintering method at 550 °C exhibits a good charge-discharge performance at room temperature with the bulk-type areal discharge capacity of 0.831 mAh cm-2 . The nanosized garnet SE strategy demonstrated in this study paves the way for the formation of oxide-based ASSBs by low-temperature sintering.

Design of a Self-Powered System by Wind-Driven Triboelectric Nanogenerator Based on 0.94(Bi0.5 Na0.5 )TiO3 -0.06Ba(Zr0.25 Ti0.75 )O3 /Polyvinylidene Fluoride (BNT-BZT/PVDF) Composites.

The portable power bank as an energy storage device has received tremendous attention while the limited capacity and periodical charging are critical issues. Here, a self-charging power system (SCPS) consisting of a 0.94(Bi0.5 Na0.5 )TiO3 -0.06Ba(Zr0.25 Ti0.75 )O3 /polyvinylidenefluoride (BNT-BZT/PVDF) composite film-based triboelectric nanogenerator (TENG) is designed as a wind energy harvester and an all-solid-state lithium-ion battery (ASSLIB) as the energy storage device. The optimized TENG can provide an output voltage of ≈400 V, a current of ≈45 µA, and a maximum power of ≈10.65 mW, respectively. The ASSLIB assembled by LiNiCoMnO2 as the cathode, NiCo2 S4 as the anode, and Li7 La3 Zr2 O12 as the solid electrolyte can maintain a discharge capacity of 51.3 µAh after 200 cycles with a Coulombic efficiency of 98.5%. Particularly, an ASSLIB can be easily charged up to 3.8 V in 58 min using the wind-driven TENG, which can continuously drive 12 parallel-connected white light-emitting diodes (LEDs) or a pH meter. This work demonstrates the development of low-cost, high-performance and high-safety SCPSs and their large-scale practical application in self-powered microelectronic devices.

Implementation of Bismuth Chalcogenides as an Efficient Anode: A Journey from Conventional Liquid Electrolyte to an All-Solid-State Li-Ion Battery.

Bismuth chalcogenide (Bi2X3; X = sulfur (S), selenium (Se), and tellurium (Te)) materials are considered as promising materials for diverse applications due to their unique properties. Their narrow bandgap, good thermal conductivity, and environmental friendliness make them suitable candidates for thermoelectric applications, photodetector, sensors along with a wide array of energy storage applications. More specifically, their unique layered structure allows them to intercalate Li+ ions and further provide conducting channels for transport. This property makes these suitable anodes for Li-ion batteries. However, low conductivity and high-volume expansion cause the poor electrochemical cyclability, thus creating a bottleneck to the implementation of these for practical use. Tremendous endeavors have been devoted towards the enhancement of cyclability of these materials, including nanostructuring and the incorporation of a carbon framework matrix to immobilize the nanostructures to prevent agglomeration. Apart from all these techniques to improve the anode properties of Bi2X3 materials, a step towards all-solid-state lithium-ion batteries using Bi2X3-based anodes has also been proven as a key approach for next-generation batteries. This review article highlights the main issues and recent advances associated with Bi2X3 anodes using both solid and liquid electrolytes.

Synergistic Enhancement of Biaxial Stretching and Multilayer Composites in All-Solid-State Polymer Electrolytes.

As an important component of lithium-ion batteries, all-solid-state electrolytes should possess high ionic conductivity, excellent flexibility, and relatively high mechanical strength. All-solid-state polymer electrolytes (ASSPEs) based on polymers seem to be able to meet these requirements. However, pure ASSPEs have relatively low ionic conductivity, and the addition of inorganic fillers such as lithium salts will reduce their flexibility and mechanical strength. To address the above issues, in this paper, the solvent-free method was used to prepare a poly(vinylidenefluoride-co-hexafluoropropylene)/lithium bis(trifluoromethanesulfonyl) imide/poly(ethylene oxide) all-solid-state polymer electrolyte, which was then subjected to 4 × 4 magnification synchronous bidirectional stretching. Subsequently, it was multilayered with PEO-based composite polymer electrolytes to obtain multilayered composite polymer electrolytes (MCPEs). Bidirectional stretching provides superior in-plane and out-of-plane mechanical properties to MCPEs by inducing molecular chain orientation, which suppresses the growth of lithium dendrites. Concurrently, it facilitates the formation of the ß-crystal form of PVDF-HFP, thereby weakening the ion solvation effect and reducing the lithium-ion migration energy barrier. Multilayered compounding improves the interfacial contact between MCPEs and electrodes, thereby reducing the interfacial impedance. Experiments have demonstrated that the MCPEs prepared in this paper exhibit high ionic conductivity at room temperature (1.83 × 10-4 S cm-1), low interfacial resistance (547 Ω cm-2), excellent mechanical properties (26 MPa), and excellent cycling rate performance (a capacity retention rate of 90% after 110 cycles at 0.1 C), which can meet the performance requirements of lithium-ion batteries for ASSPEs.

The Effect of Conductive Additive Morphology and Crystallinity on the Electrochemical Performance of Ni-Rich Cathodes for Sulfide All-Solid-State Lithium-Ion Batteries.

Sulfide electrolyte all-solid-state lithium-ion batteries (ASSLBs) that have inherently nonflammable properties have improved greatly over the past decade. However, determining both the stable and functional electrode components to pair with these solid electrolytes requires significant investigation. Solid electrolyte comprises 20-40% of the composite cathode electrode, which improves the ionic conductivity. However, this results in thick electrolyte that blocks the electron pathways in the electrode, significantly lowering the electrochemical performance. The application of conductive carbon material is required to overcome this issue, and, hence, determining the carbon properties that result in the most stable performance in the sulfide solid electrolyte is vital. This study analyzes the effect of the cathode conductive additive's morphology on the electrochemical performance of sulfide electrolyte-based ASSLBs. Carbon black (CB) and carbon nanotubes (CNTs), which provide electron pathways at the nanoscale and sub-micron scale, and carbon nanofiber (CNF), which provides electron pathways at the tens-of-microns scale, are all tested individually as potential conductive additives. When the CNF, with its high crystallinity, is used as a conductive material, the electrochemical performance shows an excellent initial discharge capacity of 191.78 mAh/g and a 50-cycle capacity retention of 83.9%. Conversely, the CB and the CNTs, with their shorter pathways and significantly increased surface area, show a relatively low electrochemical performance. By using the CNF to provide excellent electrical conductivity to the electrode, the polarization is suppressed. Furthermore, the interfacial impedance across the charge transfer region is also reduced over 50 cycles compared with the CB and CNT composite cells. These findings stringently analyze and emphasize the importance of the morphology of the carbon conductive additives in the ASSLB cathode electrodes, with improvements in the electrochemical performance being realized through the application of long-form two-dimensional crystalline CNFs.

Review of the Developments and Difficulties in Inorganic Solid-State Electrolytes.

All-solid-state lithium-ion batteries (ASSLIBs), with their exceptional attributes, have captured the attention of researchers. They offer a viable solution to the inherent flaws of traditional lithium-ion batteries. The crux of an ASSLB lies in its solid-state electrolyte (SSE) which shows higher stability and safety compared to liquid electrolyte. Additionally, it holds the promise of being compatible with Li metal anode, thereby realizing higher capacity. Inorganic SSEs have undergone tremendous developments in the last few decades; however, their practical applications still face difficulties such as the electrode-electrolyte interface, air stability, and so on. The structural composition of inorganic electrolytes is inherently linked to the advantages and difficulties they present. This article provides a comprehensive explanation of the development, structure, and Li-ion transport mechanism of representative inorganic SSEs. Moreover, corresponding difficulties such as interface issues and air stability as well as possible solutions are also discussed.

Improving Cyclability of All-Solid-State Batteries via Stabilized Electrolyte-Electrode Interface with Additive in Poly(propylene carbonate) Based Solid Electrolyte.

In this study, tetraethylene glycol dimethyl ether (TEGDME) is demonstrated as an effective additive in poly(propylene carbonate) (PPC) polymers for the enhancement of ionic conductivity and interfacial stability and a tissue membrane is used as a backbone to maintain the mechanical strength of the solid polymer electrolytes (SPEs). TEGDME in the PPC allows the uniform distribution of conductive LiF species throughout the cathode electrolyte interface (CEI) layer which plays a critically important role in the formation of a stable and efficient CEI. In addition, the high modulus of SPEs suppresses the formation of a protrusion-type CEI on the cathode. The SPE with the optimized TEGDME content exhibits a high ionic conductivity of 0.89 mS cm-1 , an adequate potential stability of up to 4.89 V, and a high Li-ion transference number of 0.81 at 60 °C. Moreover, the Li/SPE/Li cell demonstrates excellent cycling stability for 1650 h, and the Li/SPE/LFP full cell exhibits an initial reversible capacity of 103 mAh g-1 and improved stability over 500 cycles at a rate of 1 C. The TEGDME additive improves the electrochemical properties of the SPEs and promotes the creation of a stable interface, which is crucial for ASSLIBs.

Towards Recycling of LLZO Solid Electrolyte Exemplarily Performed on LFP/LLZO/LTO Cells.

All-solid-state lithium ion batteries (ASS-LIBs) are promising due to their safety and higher energy density as compared to that of conventional LIBs. Over the next few decades, tremendous amounts of spent ASS-LIBs will reach the end of their cycle life and would require recycling in order to address the waste management issue along with reduced exploitation of rare elements. So far, only very limited studies have been conducted on recycling of ASS-LIBS. Herein, we investigate the recycling of the Li7 La3 Zr2 O12 (LLZO) solid-state electrolyte in a LiFePO4 /LLZO/Li4 Ti5 O12 system using a hydrometallurgical approach. Our results show that different concentration of the leaching solutions can significantly influence the final product of the recycling process. However, it was possible to recover relatively pure La2 O3 and ZrO2 to re-synthesize the cubic LLZO phase, whose high purity was confirmed by XRD measurements.

Foldable nano-Li2MnO3 integrated composite polymer solid electrolyte for all-solid-state Li metal batteries with stable interface.

All-solid-state lithium-ion batteries (ASSLBs) are considered as the most promising next-generation energy storage devices. In this work, a low-cost foldable nano-Li2MnO3 integrated Poly (ethylene oxide) (PEO) based composite polymer solid electrolyte (CPSE) is prepared by simply solid-phase method. Density functional theory calculations indicate that the LMO could provide faster ion transfer channels for the migration of lithium ions between PEO chains and segments. As such, the CPSE obtained has a high ionic conductivity of 5.1 × 10-4 S cm-1 at 60 °C with a high lithium ions transference number of 0.5. The CPSE remains stable even at high temperature with no heat escaping. This could improve the safety performance of the batteries. As a result, the lithium metal battery assembled with CPSE works stably after over 200 cycles at a high rate of 0.5C, and its specific capacity is as high as 125 mAh g-1. Also, it is confirmed that this CPSE adapts to three cathode materials. The Li metal pouch battery assembled with the CPSE is foldable and has excellent mechanical properties. All these results indicate that the CPSE obtained has excellent electrochemical and outstanding safety performances, which can make it have broad commercial applications in ASSLBs.

All-Solid-State Lithium-Ion Batteries with Oxide/Sulfide Composite Electrolytes.

Li6.3La3Zr1.65W0.35O12 (LLZO)-Li6PS5Cl (LPSC) composite electrolytes and all-solid-state cells containing LLZO-LPSC were fabricated by cold pressing at room temperature. The LPSC:LLZO ratio was varied, and the microstructure, ionic conductivity, and electrochemical performance of the corresponding composite electrolytes were investigated; the ionic conductivity of the composite electrolytes was three or four orders of magnitude higher than that of LLZO. The high conductivity of the composite electrolytes was attributed to the enhanced relative density and the rule of mixture for soft LPSC particles with high lithium-ion conductivity (~10-4 S·cm-1). The specific capacities of all-solid-state cells (ASSCs) consisting of a LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode and the composite electrolytes of LLZO:LPSC = 7:3 and 6:4 were 163 and 167 mAh·g-1, respectively, at 0.1 C and room temperature. Moreover, the charge-discharge curves of the ASSCs with the composite electrolytes revealed that a good interfacial contact was successfully formed between the NCM811 cathode and the LLZO-LPSC composite electrolyte.

Enhanced Cyclability of Cr8O21 Cathode for PEO-Based All-Solid-State Lithium-Ion Batteries by Atomic Layer Deposition of Al2O3.

Cr8O21 can be used as the cathode material in all-solid-state batteries with high energy density due to its high reversible specific capacity and high potential plateau. However, the strong oxidation of Cr8O21 leads to poor compatibility with polymer-based solid electrolytes. Herein, to improve the cycle performance of the battery, Al2O3 atomic layer deposition (ALD) coating is applied on Cr8O21 cathodes to modify the interface between the electrode and the electrolyte. X-ray photoelectron spectroscopy, scanning electron microscope, transmission electron microscope, and Fourier transform infrared spectroscopy, etc., are used to estimate the morphology of the ALD coating and the interface reaction mechanism. The electrochemical properties of the Cr8O21 cathodes are investigated. The results show that the uniform and dense Al2O3 layer not only prevents the polyethylene oxide from oxidization but also enhances the lithium-ion transport. The 12-ALD-cycle-coated electrode with approximately 4 nm Al2O3 layer displays the optimal cycling performance, which delivers a high capacity of 260 mAh g-1 for the 125th cycle at 0.1C with a discharge-specific energy of 630 Wh kg-1.

Impact of Li3BO3 Addition on Solid Electrode-Solid Electrolyte Interface in All-Solid-State Batteries.

All-solid-state lithium-ion batteries raise the issue of high resistance at the interface between solid electrolyte and electrode materials that needs to be addressed. The article investigates the effect of a low-melting Li3BO3 additive introduced into LiCoO2- and Li4Ti5O12-based composite electrodes on the interface resistance with a Li7La3Zr2O12 solid electrolyte. According to DSC analysis, interaction in the studied mixtures with Li3BO3 begins at 768 and 725 °C for LiCoO2 and Li4Ti5O12, respectively. The resistance of half-cells with different contents of Li3BO3 additive after heating at 700 and 720 °C was studied by impedance spectroscopy in the temperature range of 25-340 °C. It was established that the introduction of 5 wt% Li3BO3 into LiCoO2 and heat treatment at 720 °C led to the greatest decrease in the interface resistance from 260 to 40 Ω cm2 at 300 °C in comparison with pure LiCoO2. An SEM study demonstrated that the addition of the low-melting component to electrode mass gave better contact with ceramics. It was shown that an increase in the annealing temperature of unmodified cells with Li4Ti5O12 led to a decrease in the interface resistance. It was found that the interface resistance between composite anodes and solid electrolyte had lower values compared to Li4Ti5O12|Li7La3Zr2O12 half-cells. It was established that the resistance of cells with the Li4Ti5O12/Li3BO3 composite anode annealed at 720 °C decreased from 97.2 (x = 0) to 7.0 kΩ cm2 (x = 5 wt% Li3BO3) at 150 °C.

Constructing Li-Rich Artificial SEI Layer in Alloy-Polymer Composite Electrolyte to Achieve High Ionic Conductivity for All-Solid-State Lithium Metal Batteries.

To achieve high ionic conductivity for solid electrolyte, an artificial Li-rich interface layer of about 60 nm thick has been constructed in polymer-based poly(ethylene oxide)-lithium bis(trifluoromethanesulfonyl)imide composite solid electrolyte (briefly noted as PEOm ) by adding Li-based alloys. As revealed by high-resolution transmission electron microscopy and electron energy loss spectroscopy, an artificial interface layer of amorphous feature is created around the Li-based alloy particles with the gradient distribution of Li across it. Electrochemical analysis and theoretical modeling demonstrate that the interface layer provides fast ion transport path and plays a key role in achieving high and stable ionic conductivity for PEOm -Li21 Si5 composite solid electrolyte. The PEOm -5%Li21 Si5 composite electrolyte exhibits an ionic conductivity of 3.9 × 10-5  S cm-1 at 30 °C and 5.6 × 10-4  S cm-1 at 45 °C. The LiFePO4 | PEOm -5%Li21 Si5 | Li all-solid-state batteries could maintain a stable capacity of 129.2 mA h g-1 at 0.2 C and 30 °C after 100 cycles, and 111.3 mA h g-1 after 200 cycles at 0.5 C and 45 °C, demonstrating excellent cycling stability and high-rate capability.

Revealing the Role of Liquid Metals at the Anode-Electrolyte Interface for All Solid-State Lithium-Ion Batteries.

All-solid-state lithium-ion batteries (ASSLIBs) are receiving tremendous attention for safety concerns over liquid system. However, current ASSLIBs still suffer from poor cycling and rate performance because of unfavorable interfacial contact between solid electrolyte and electrodes, especially in the alloy-based anode. To wet the solid electrode/electrolyte interface, accommodate volume change, and further boost kinetics, liquid metal Ga is introduced into the representative Sb anode, and its corresponding role is comprehensively revealed by experimental results and theoretical calculations for the first time. In addition to interface contact and strain accommodation, with the aid of in situ generation of liquid metal Ga, the lithiation/de-lithiation activity of Sb is stimulated, showing outstanding rate and cycling performance in half cells. Furthermore, benefited from the in situ chemical reaction, TiS2 powder can be directly used to construct a novel "Li-free" TiS2|LiBH4|GaSb full cell, which exhibits an outstanding capacity retention of 226 mA h g-1 after 1000 cycles at a current density of 0.5 A g-1. This work provides guidance for implementing future rational design of alloy anodes within ASSLIBs.

Superior Blends Solid Polymer Electrolyte with Integrated Hierarchical Architectures for All-Solid-State Lithium-Ion Batteries.

Exploration of advanced solid electrolytes with good interfacial stability toward electrodes is a highly relevant research topic for all-solid-state batteries. Here, we report PCL/SN blends integrating with PAN-skeleton as solid polymer electrolyte prepared by a facile method. This polymer electrolyte with hierarchical architectures exhibits high ionic conductivity, large electrochemical windows, high degree flexibility, good flame-retardance ability, and thermal stability (workable at 80 °C). Additionally, it demonstrates superior compatibility and electrochemical stability toward metallic Li as well as LiFePO4 cathode. The electrolyte/electrode interfaces are very stable even subjected to 4.5 V at charging state for long time. The LiFePO4/Li all-solid-state cells based on this electrolyte deliver high capacity, outstanding cycling stability, and superior rate capability better than those based on liquid electrolyte. This solid polymer electrolyte is eligible for next generation high energy density all-solid-state batteries.