Poly ethylene oxide (PEO) composite polymer electrolytes (CPEs) are one of the most promising candidates for all-solid-state batteries with high energy density, flexibility and safety. However, the applications of PEO with practicability have been refrained from its poor tensile strength, limited Li-ion migration and ionic conductivity. In this work, the compact and stable flexible CPEs are prepared by PEO matrix with dual-fillers of LiBH4 and Al2O3, where Al2O3 with Lewis acid sites can weaken the complexation of Li+ and PEO as well as enhance the dissociation of Li salts. Meanwhile LiBH4 acts as fast ion conductor to provide free Li+ at the interfaces between fillers and PEO. Benefiting from their synergistic effects, both ionic conductivity and interface stability between electrolyte and anode of CPEs are improved greatly while the lithium dendrites is also inhibited. As a result, the PEO/Lithium bis(trifluoromethanesulfonyl)imide(LiTFSI)/(4%LiBH4/4%γ-Al2O3) CPEs exhibit a high ionic conductivity of 0.3 mS cm−1 and the Li-Li symmetrical battery can cycle for 800 h at 60 °C.
Despite the high energy density of lithium metal batteries (LMBs), their application in rechargeable batteries is still hampered due to insufficient safety. Here, we present a novel flame-retardant solid-state electrolyte based on polyvinylidene fluoridehexafluoropropylene (PVDF-HFP) with nano SiO 2 aerogel as an inert filler but Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 (LLZTO) as an auxiliary component to enhance the ion conductivity. The introduction of SiO 2 aerogels imparts the polymer electrolyte with exceptional thermal stability and flame retardancy. Simultaneously, the interaction between hydroxyl groups of SiO 2 particles and PVDF-HFP creates a strong cross-linking structure, enhancing the mechanical strength and stability of the electrolyte. Furthermore, the presence of SiO 2 aerogel and LLZTO facilitates the dissociation of lithium salts through Lewis acid-base interactions, resulting in a high ionic conductivity of 1.01 × 10 − 3 S·cm − 1 and a wide electrochemical window of ∼ 5.0 V at room temperature for the prepared electrolytes. Remarkably, the assembled Li|Li cell demonstrates the excellent resistance to lithium dendrite and runs stablly for over 1500 h at a current density of 0.25 mA·cm −2 . Thus, we prepare a pouch cell with high safety, which can work normally after short-circuiting under the external folding and cutting.
Xin Wang,Fu-Lin Gao,Hao-Yu Zhao,Lin Tian,Shumiao Li,Shuaiyuan Wang,Zhong-Zhen Yu,Xiaofeng Li
The drive toward miniaturization, integration, and extreme environmental adaptability in electronic devices imposes stringent demands on the energy density and thermal conductivity of polymer dielectric materials. Here, the long-standing challenge of simultaneously improving dielectric constant and thermal conductivity through a “heterogeneous interface enhancement-dual filler synergy” strategy is addressed. Hydroxylated boron nitride nanosheets (BNNS) and reduced graphene oxide (rGO) are codispersed within a polyimide (PI) matrix, forming continuous networks that facilitate efficient dielectric and thermal transport. Robust hydrogen bonding among hydroxylated BNNS, rGO, and PI establishes stable interfaces, while the permittivity mismatch between BNNS and rGO induces interfacial polarization, yielding a dielectric constant of 12.6 at 1 kHz. The interpenetrating BNNS/rGO network facilitates efficient phonon transport, resulting in a thermal conductivity of 13.6 W (m K) −1 . Furthermore, the large lateral size of ultrathin BNNS suppresses breakdown channel propagation, maintaining a high breakdown strength of 440 kV mm −1 . Notably, the composite exhibits a discharge energy density of 4.6 J cm − 3 with charge–discharge efficiency over 90% at 150 °C, surpassing most advanced polymer dielectrics. This work overcomes the trade-off between dielectric and thermal properties of polymer-inorganic nanocomposites, offering a compelling strategy for developing high-performance dielectric films for advanced electronics.
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