RESUMEN
"Polymer-in-ceramic" (PIC) electrolytes are widely investigated for all-solid-state batteries (ASSBs) due to their good thermal stability and mechanical performance. However, achieving fast and diversified lithium-ion transport inside the PIC electrolyte and uniform Li+ deposition at the electrolyte/Li anode interface simultaneously remains a challenge. Besides, the effect of ceramic particle size on Li+ transport and Li anodic compatibility is still unclear, which is essential for revealing the enhanced mechanism of the performance for PIC electrolytes. Herein, PIC with moderate ceramic size and contents are prepared and studied to strike a balance between ionic conductivity and anodic compatibility. Through moderate filler-filler interfacial impedance and appropriate surface roughness, a particle size of 17 µm is optimized to facilitate homogeneous Li+ flux on anode and enhance Li+ conductivity of the electrolyte. The PIC electrolyte with ceramic particle size of 17 µm achieves a high lithium ion transference number (0.74) and an ionic conductivity of 4.11 × 10-4 S cm-1 at 60 °C. The Li/PIC/Li symmetric cell can stably cycle for 2800 h at 0.2 mA cm-2 with 0.2 mAh cm-2. Additionally, the Li/PIC/LiFePO4 cell also delivers a superior cycling performance at 0.5C, a high capacity retention of 93.28% after 100 cycles and 83.17% after 200 cycles, respectively.
RESUMEN
Composite solid electrolytes combining the advantages of inorganic and polymer electrolytes are considered as one of the promising candidates for solid-state lithium metal batteries. Compared with ceramic-in-polymer electrolyte, polymer-in-ceramic electrolyte displays excellent mechanical strength to inhibit lithium dendrite. However, polymer-in-ceramic electrolyte faces the challenges of lack of flexibility and severely blocked Li+transport. In this study, we prepared polymer-in-ceramic film utilizing ultra-high molecular weight polymers and ceramic particles to combine flexibility and mechanical strength. Meanwhile, the ionic conductivity of polymer-in-ceramic electrolytes was improved by adding excess lithium salt in polymer matrix to form polymer-in-salt structure. The obtained film shows high stiffness (10.5 MPa), acceptable ionic conductivity (0.18 mS cm-1) and high flexibility. As a result, the corresponding lithium symmetric cell stably cycles over 800 h and the corresponding LiFePO4cell provides a discharge capacity of 147.7 mAh g-1at 0.1 C without obvious capacity decay after 145 cycles.
RESUMEN
Composite polymer-ceramic electrolytes have shown considerable potential for high-energy-density Li-metal batteries as they combine the benefits of both polymers and ceramics. However, low ionic conductivity and poor contact with electrodes limit their practical usage. In this study, a highly conductive and stable composite electrolyte with a high ceramic loading is developed for high-energy-density Li-metal batteries. The electrolyte, produced through in situ polymerization and composed of a polymer called poly-1,3-dioxolane in a poly(vinylidene fluoride)/ceramic matrix, exhibits excellent room-temperature ionic conductivity of 1.2 mS cm-1 and high stability with Li metal over 1500 h. When tested in a Li|electrolyte|LiFePO4 battery, the electrolyte delivers excellent cycling performance and rate capability at room temperature, with a discharge capacity of 137 mAh g-1 over 500 cycles at 1 C. Furthermore, the electrolyte not only exhibits a high Li+ transference number of 0.76 but also significantly lowers contact resistance (from 157.8 to 2.1 Ω) relative to electrodes. When used in a battery with a high-voltage LiNi0.8 Mn0.1 Co0.1 O2 cathode, a discharge capacity of 140 mAh g-1 is achieved. These results show the potential of composite polymer-ceramic electrolytes in room-temperature solid-state Li-metal batteries and provide a strategy for designing highly conductive polymer-in-ceramic electrolytes with electrode-compatible interfaces.
RESUMEN
Composite solid-state electrolytes (CSEs) are regarded as a promising alternative for the next-generation lithium-ion batteries because they integrate the advantages of inorganic electrolytes and organic electrolytes. However, there are two issues faced by current CSEs: 1) a green and feasible approach to prepare CSEs in large scales is desired; and 2) the trace solvents, remaining from the preparation processes, lead to some serious concerns, such as safety hazard issues, electrolyte-electrode interfacial issues, and reduced durability of batteries. Here, a continuous thermal-extrusion process is presented to realize the large-scale fabrication of solvent-free CSE. A 38.7-meter CSE membrane was prepared as a demonstration in this study. Thanks to the elimination of residual solvents, the electrolyte membrane exhibited a high tensile strength of 3.85 MPa, satisfactory lithium transference number (0.495), and excellent electrochemical stability (5.15 V). Excellent long-term stability was demonstrated by operating the symmetric lithium cell at a stable current density of 0.1 mA cm-2 for over 3700 h. Solvent-free CSE lithium metal batteries showed a discharge capacity of 155.7 - 25.17 mAh g-1 at 0.1 - 2.0C, and the discharge capacity remained 78.1% after testing for 380cycles.
RESUMEN
The fast Li+ transportation of "polymer-in-ceramic" electrolytes is highly dependent on the long-range Li+ migration pathways, which are determined by the structure and chemistry of the electrolytes. Besides, Li dendrite growth may be promoted in the soft polymer region due to the inhomogeneous electric field caused by the commonly low Li+ transference number of the polymer. Herein, a single-ion-conducting polymer electrolyte is infiltrated into intertwined Li1.3Al0.3Ti1.7(PO4)3 (LATP) nanofibers to construct free-standing electrolyte membranes. The composite electrolyte possesses a large electrochemical window exceeding 5 V, a high ionic conductivity of 0.31 mS cm-1 at ambient temperature, and an extraordinary Li+ transference number of 0.94. The hybrid electrolyte in the lithium symmetric cell shows stable Li plating/stripping up to 2000 h under 0.1 mA cm-2 without dendrite formation. The Li|hybrid electrolyte|LiFePO4 battery exhibits enhanced rate capability up to 1 C and a stable cycling performance with an initial discharge capacity of 131.8 mA h g-1 and a retention capacity of 122.7 mA h g-1 after 500 cycles at 0.5 C at ambient temperature. The improved electrochemical performance is attributed to the synergistic effects of the LATP nanofibers and the single-ion-conducting polymer. The fibrous fast ion conductors provide continuous ion transport channels, and the polymer improves the interfacial contact with the electrodes and helps to suppress the Li dendrites.
RESUMEN
Solid polymer electrolytes can be used to construct solid-state lithium batteries (SSLBs) using lithium metals as the anode. However, the lifespan and safety problems of SSLBs caused by lithium dendrite growth have hindered their practical application. Here, we have designed and prepared a rigid-flexible asymmetric solid electrolyte (ASE) that is used in building SSLBs. The ASE can inhibit efficiently the growth of lithium dendrites and lead to a long cycle life of SSLBs due to the hierarchical structure of a combination of "polymer-in-ceramic" (i.e., rigid ceramic layer of Li6.4La3Zr1.4Ta0.6O12) and "LiBOB-in-polymer" (i.e., soft polymer-layer of polyethylene oxide and LiBOB components). The results demonstrated that a symmetrical battery with ASE (Li|ASE|Li) can be steadily cycled for more than 2000 h and yielded a flat plating/stripping voltage profile under a current density of 0.1 mA cm-2. As a consequence, the SSLB of LiFePO4|ASE|Li delivered a specific capacity of 155.1 mA h g-1 with a capacity retention rate up to 90.2% after 200 cycles with the Coulombic efficiency over 99.6% per cycle. This asymmetric structure combines the advantages of ceramics and polymers, providing an ingenious solution for building rigid and flexible solid electrolytes.