Tin-based materials with high specific capacity have been studied as high-performance anodes for energy storage devices. Herein, a SnO x (x = 0, 1, 2) quantum dots@carbon hybrid is designed and prepared by a binary oxide-induced surface-targeted coating of ZIF-8 followed by pyrolysis approach, in which SnO x quantum dots (under 5 nm) are dispersed uniformly throughout the nitrogen-containing carbon nanocage. Each nanocage is cross-linked to form a highly conductive framework. The resulting SnO x @C hybrid exhibits a large BET surface area of 598 m2 g–1, high electrical conductivity, and excellent ion diffusion rate. When applied to LIBs, the SnO x @C reveals an ultrahigh reversible capacity of 1824 mAh g–1 at a current density of 0.2 A g–1, and superior capacities of 1408 and 850 mAh g–1 even at high rates of 2 and 5 A g–1, respectively. The full cell assembled using LiFePO4 as cathode exhibits the high energy density and power density of 335 Wh kg–1 and 575 W kg–1 at 1 C based on the total active mass of cathode and anode. Combined with in situ XRD analysis, the superior electrochemical performance can be attributed to the SnO x -ZnO-C asynchronous and united lithium storage mechanism, which is formed by the well-designed multifeatured construction composed of SnO x quantum dots, interconnected carbon network, and uniformly dispersed ZnO nanoparticles. Importantly, this designed synthesis can be extended for the fabrication of other electrode materials by simply changing the binary oxide precursor to obtain the desired active component or modulating the type of MOFs coating to achieve high-performance LIBs.

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Optimization of the cathode structure and exploration of a novel electrolyte system are important approaches for achieving high-performance zinc-ion batteries (ZIBs) and zinc dendrite suppression. Herein, a quasi-solid-state ZIB combining a sandwich-like MnO 2 @rGO cathode, a laponite (Lap)-modified polyacrylamide (PAM) hydrogel electrolyte, and an electrodeposited zinc anode is designed and constructed by a synergistic optimization strategy. The MnO 2 composite prepared through the intercalation of rGO shows developed mesopores, providing accessible ion transport channels and exhibiting a high electrical conductivity. Thanks to the high dispersion of Lap nanoplates in the hydrogel and good charge-averaging effect, the Zn//PAM-5% Lap//Zn symmetrical battery exhibits a consistent low-voltage polarization of less than 60 mV within 2000 h without a short-circuit phenomenon or any over-potential rise, indicating a stable zinc peeling/plating process. The optimized quasi-solid-state ZIB delivers a high reversible capacity of 291 mA h g −1 at a current density of 0.2 A g −1 due to the synergistic effect of each component of ZIB. Even at a high rate of 2 A g −1 , it still maintains a high reversible capacity of 97 mA h g −1 after 2000 cycles, indicating its excellent electrochemical performance. Furthermore, the assembled flexible battery performs excellently in terms of damage and bending resistance.

High-energy rechargeable Li-metal batteries require safer and more reliable electrolyte systems because of the dendrite growth caused by the organic liquid electrolytes. Polymer electrolytes with both high electrochemical and mechanical properties are expected, although they are challenging to prepare. Herein, a novel gel polymer electrolyte (GPE) based on poly(vinylidene fluoride) (PVDF) has been fabricated by introducing laponite nanoplates via a facile solution-casting method. The composite GPE shows a high ion conductivity and mechanical strength. When applied to LIBs with LiFePO 4 as cathode, the battery exhibits a high capacity of 157 mA h g −1 at 0.2 C with an excellent initial Coulombic efficiency of 95%. After 1000 cycles, the capacity retention is as high as 97%. Remarkably, a superior capacity of 111 mA h g −1 is still maintained at a high rate of 10 C. This result provides a way to design a high-performance electrolyte and flexible devices.

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