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• Polyimide fibers introducing ion transport channels in PEO solid electrolyte. • Composite electrolyte shows enhanced Li+ conductivity and tensile strength. • Electrolyte/electrode interface steadied by high performance electrolyte. • Lithium dendrites were inhibited owing to stable electrolyte/electrode interface. • All-solid-state battery with PI fiber complex electrolyte delivers long cycling life. The widespread deployment of lithium metal battery is limited by inhomogeneous electrodeposition of lithium metal (the growth of lithium dendrite), leading to pulverization, "dead" lithium and the unrestricted volume expansion of lithium metal anode. Owing to the high elastic modulus, thermal stability and electrochemical stability of polyimide, we design a novel composite solid polymer electrolyte blending with polyimide fibers framework paper. Polyimide fibers scaffold improves elastic modulus and tensile strength of composite electrolyte film. Effective ion transport network layers in electrolyte system are formed by adding polyimide fibers due to strong interaction between electron-withdrawing atoms and groups in the lithium salt for accelerating the dissociation of the lithium salt. Thus, polyimide composite electrolyte shows higher Li+ transfer number (∼2 times) than pure polyethylene oxide electrolyte, which is beneficial to regulate Li deposition for lithium dendrites inhibition. The electrochemical window of polyimide composite electrolyte is widened to 4.87 V after introducing stable physicochemical fibers framework, leading to high compatibility and stability with lithium metal anode. Therefore, the Li symmetrical battery with polyimide fibers framework composite electrolyte delivers low overpotential and long cycling life at different current densities. And the all-solid-state Li/LiFePO 4 battery using this composite electrolyte reveals long cycling life (418 cycles), high Coulomb efficiency (99.97%), high capacity retention of 89.5% at 0.3 C, and good rate performance at 60 °C. [ABSTRACT FROM AUTHOR]

Potassium-ions batteries (KIBs) are regarded as an alternative to lithium-ion batteries (LIBs) owing to their affordable cost, abundance and high working voltage. Transition metal sulfides (TMSs) are considered to be attractive anode materials for KIBs, but the practical development is hampered by their inferior conductivity and large volume expansion upon potassiation/depotassiation process. Herein, we report a dual-amorphous confined structure composing of amorphous CoS 1.4 ultrathin nanosheets confined in amorphous N-doped carbon nanobox (a-CoS NS/NCB) as an anode material for KIBs. The isotropic nature of amorphous CoS 1.4 ultrathin nanosheets (about four atomic layers in thickness) can effectively accommodate volume strain as well as decrease the resistance of the carrier to phase transition due to their high level of disorder. Besides, the amorphous N-doped carbon nanobox has the advantages of enhancing electronic conductivity, avoiding the direct contact of active material and electrolyte and restraining the excessive growth of solid electrolyte interphase film. As a result, the a-CoS NS/NCB anode delivers a capacity of 235.3 mAh g−1 at 100 mA g−1 after 800 cycles. While the results prove the new anode is a promising candidate for KIBs, it also opens the door for broader application of amorphous composite in metal-ions batteries. [Display omitted] • Amorphous CoS 1.4 nanosheets confined in amorphous carbon nanobox are designed. • Short ions transmission path and volume expansion buffering ability are obtained. • The isotropic nature decreases the resistance of the carrier to phase transition. [ABSTRACT FROM AUTHOR]

• The poly(ionic liquid)-PEO solid electrolyte was prepared by copolymerization. • Poly(ionic liquid) interpenetrating network was formed in electrolyte film. • Electrolyte membrane shows high thermal stability and ionic conductivity. • All solid polymer-Li metal battery exhibits good electrochemical performance. Solid-state polymer electrolyte with high ionic conductivity and electrochemical stability is desirable for lithium metal batteries. A poly(ionic liquid)-polyethylene oxide semi-interpenetrating polymer network composite solid electrolyte for safe lithium metal batteries is designed to satisfy the demand of ionic conductivity, safety and electrochemical stability. This composite solid electrolyte is fabricated via polymerizing 1-vinyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (ionic liquid monomer) in polyethylene oxide matrix by one-step method. Differential scanning calorimetry results reveal that the crystallinity of composite solid electrolyte reduce to 15.5% comparing with polyethylene oxide solid electrolyte owing to the confinement of poly(ionic liquid) interpenetrating network. The semi-interpenetrating polymer network structure simultaneously endow the composite solid electrolyte with high ionic conductivity (6.12 × 10−4 S cm−1 at 55 °C) and wide electrochemical window (5.44 V vs. Li/Li+) and thermal decomposition temperature (280 °C). In order to verify the favorable electrochemical performance of composite solid electrolyte, we assemble the cells with LiFePO 4 /Li using the electrolyte. The reversible capacity of LiFePO 4 is 147 mAh g−1 with high Coulombic efficiency (up to 99%) at the 0.2 C rate and 55 °C. [ABSTRACT FROM AUTHOR]