Solid electrolytes are crucial for the development of solid state batteries. Among different types of solid electrolytes, poly(ethylene oxide) (PEO)-based polymer electrolytes have attracted extensive attention owing to their excellent flexibility and easiness for processing. However, their relatively low ionic conductivities and electrochemical instability above 4 V limit their applications in batteries with high energy density. Herein, we prepared poly(vinylidene fluoride) (PVDF) polymer electrolytes with an organic plasticizer, which possesses compatibility with 4 V cathode and high ionic conductivity (1.2 × 10 S/cm) at room temperature. We also revealed the importance of plasticizer content to the ionic conductivity. To address weak mechanical strength of the PVDF electrolyte with plasticizer, we introduced palygorskite ((Mg,Al)SiO(OH)) nanowires as a new ceramic filler to form composite solid electrolytes (CPE), which greatly enhances both stiffness and toughness of PVDF-based polymer electrolyte. With 5 wt % of palygorskite nanowires, not only does the elastic modulus of PVDF CPE increase from 9.0 to 96 MPa but also its yield stress is enhanced by 200%. Moreover, numerical modeling uncovers that the strong nanowire-polymer interaction and cross-linking network of nanowires are responsible for such significant enhancement in mechanically robustness. The addition of 5% palygorskite nanowires also enhances transference number of Li from 0.21 to 0.54 due to interaction between palygorskite and ClO ions. We further demonstrate full cells based on Li(NiMnCo)O (NMC111) cathode, PVDF/palygorskite CPE, and lithium anode, which can be cycled over 200 times at 0.3 C, with 97% capacity retention. Moreover, the PVDF matrix is much less flammable than PEO electrolytes. Our work illustrates that the PVDF/palygorskite CPE is a promising electrolyte for solid state batteries.
Continuously spinnable conductive silk fibers (CSFs) were constructed by a facile dip-coating strategy. The resultant CSFs integrate the mechanical and functional merits of both silk and carbon nanotubes and can be directly woven into smart textiles using automated equipment. These CSF-based e-textiles show promising applications in wearable devices, human augmentation, healthcare monitoring, and human-machine interfaces.
Solid-state lithium metal batteries with solid electrolytes are promising for next-generation energy-storage devices. However, it remains challenging to develop solid electrolytes that are both mechanically robust and strong against external mechanical load, due to the brittleness of ceramic electrolytes and the softness of polymer electrolytes. Herein, we propose a nacre-inspired design of ceramic/polymer solid composite electrolytes with the "brick-and-mortar" microstructure. The nacre-like ceramic/polymer electrolyte (NCPE) simultaneously possesses a much higher fracture strain (1.1%) than pure ceramic electrolytes (0.13%) and a much larger ultimate flexural strength (7.8 GPa) than pure polymer electrolytes (20 MPa). The electrochemical performance of NCPE is also much better than pure ceramic or polymer electrolytes, especially under mechanical load. A 5 × 5 cm 2 pouch cell with LAGP/poly(ether−acrylate) (PEA) NCPE exhibits stable cycling with a capacity retention of 95.6% over 100 cycles at room temperature, even undergoes a large This article is protected by copyright. All rights reserved. point load of 10 N. In contrast, cells based on pure ceramic and pure polymer electrolyte show poor cycle life. The NCPE provides a new design for solid composite electrolyte and opens up new possibilities for future solid-state lithium metal batteries and structural energy storage. The rapid-growing demands for portable electronics and electric vehicles have bolstered needs for next-generation lithium batteries with high energy density [1-4]. However, lithium batteries become more thermally vulnerable as energy density increases. Thermal runaway and explosion are prone to be triggered by failures such as mechanical damage and lithium dendrite growth inside batteries [5, 6]. Nonflammable solid-state ceramic electrolytes (SSEs) provide alternatives to conventional flammable liquid electrolytes [7-9]. Various ceramic electrolytes with attractive ionic conductivities have been developed in the past two decades, including NASICON-type Li 1.5 Al 0.5 Ge 1.5 (PO 4) 3 (LAGP) [10] , Li 1.3 Al 0.3 Ti 1.7 (PO 4) 3 (LATP) [11, 12] , garnet Li 7 La 3 Zr 2 O 12 (LLZO) [13, 14] , and sulfides, such as This article is protected by copyright. All rights reserved. NCPEs, polymer electrolytes and ceramic electrolytes were cut with a thickness of 500 μm and a size of 1.5 cm. A loading rate of 0.5 mm min-1 and a support span of 1.5 cm were used in all tests. The results were averaged from those in five similar specimens. The flexural stress is and The flexural strain is , where F, L, w, h, and D are the applied point force, span length, sample width, thickness, and flexural deflection, respectively. Vickers indentation was carried out on SANS-UTM 6000 using a Vickers indenter. Finite Element Mechanical Simulation: 2D nonlinear finite element simulations were conducted using the software ABAQUS v6.14. In these simulations, the stress/strain distributions and crack propagation in a regular brick-mortar structure and a ceramic film are calculate...
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