Novel porous ZnO/ZnFe2O4/C octahedra with hollow interiors are fabricated by a facile self-sacrificing template method involving the refluxing synthesis of hollow, metal-organic framework octahedra in solution and subsequent thermal annealing in N2 . When evaluated as an anode material for lithium-ion batteries, these porous hollow ZnO/ZnFe2O4/C octahedra exhibit significantly enhanced electrochemical performances with high rate capability, high capacity, and excellent cycling stability.

S‐doped carbon is investigated as a high‐performance anode material for sodium‐ion batteries. Due to the introduction of a high‐content of S atoms, the as‐obtained S‐doped carbon shows an enlarged interlayer distance. As an anode, a high specific capacity of up to 303 mAh g−1 is achieved, even after 700 cycles at 0.5 A g−1.

A flexible asymmetric supercapacitor (ASC) with high energy density is designed and fabricated using flower‐like Bi2O3 and MnO2 grown on carbon nanofiber (CNF) paper as the negative and positive electrodes, respectively. The lightweight (1.6 mg cm−2), porous, conductive, and flexible features make the CNF paper an ideal support for guest active materials, which permit a large areal mass of 9 mg cm−2 for Bi2O3 (≈85 wt% of the entire electrode). Thus, the optimal device with an operation voltage of 1.8 V can deliver a high energy density of 43.4 μWh cm−2 (11.3 W h kg−1, based on the total electrodes) and a maximum power density of 12.9 mW cm−2 (3370 W kg−1). This work provides an example of large areal mass and flexible electrode for ASCs with high areal capacitance and high energy density, holding great promise for future flexible electronic devices.

cathodes, [10][11][12] silicon-based anodes, [13][14][15][16] and optimizing organic liquid electrolytes. [17,18] However, the safety challenges related to the electrolyte are serious because operation of LIBs is exothermic and organic liquid electrolytes mostly with ester carbonates are highly flammable, generating massive heat. [19,20] Dendritic lithium in LIB represents a further challenge considering internal short circuit would occur if the dendrite punctures the separator. [21,22] Therefore, solutions for safety of LIBs are urgently required.Inorganic ceramic solid-state electrolyte (SSE) provides an ideal alternative to liquid flammable electrolytes for the design of safe ASSBs, since ceramic SSE is nonflammable and it has adequate fracture toughness to prevent internal short circuit from lithium dendrite. [23][24][25] Furthermore, lithium metal anode, the ultimate anode with the highest specific capacity and lowest electrochemical potential has been demonstrated in ASSBs, which exhibited intrinsic safety under rigorous conditions. [26][27][28][29][30] In the search for SSEs, while most of the superionic conductors with conductivity >1 mS cm −1 are based on sulfides, such as Li 10 GeP 2 S 12 , [31,32] Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 , [33] and Li 9.6 P 3 S 12 , [34] it has shown that garnet-type oxides are the most stable SSEs with lithium metal anode. [35][36][37][38][39] However, the lithium/garnet interface appeared to have a remarkably large impedance due to the poor interfacial contact. [40] This motivates a variety of studies to turn garnet from lithiophobic to lithiophilic by coating garnet with metal, [41][42][43][44] metal oxides, [45,46] semi-conductors, [47,48] polymer interlayers, [49,50] and graphite. [51] Although these approaches have shown great progress, they mainly addressed the interface issue from garnet side. As a result, ample opportunities remain on lithium metal side.Here we introduce a new strategy to synthesize a ceramic compatible lithium anode by using graphite additives. Our scheme to implement a lithium/garnet interface experiment is sketched in Figure 1. We find that pure lithium is not compatible with garnet, which is consistent with that expected for lithiophobic garnet surface and previous reports (Figure 1a). [52] On the other side, lithium-graphite (Li-C) composite presents lower fluidity and higher viscosity compared to pure Li. So the Li-C composite, like a paste, can be casted onto garnet and exhibits an intimate contact (Figure 1b). As expected, All-solid-state batteries (ASSBs) with ceramic-based solid-state electrolytes (SSEs) enable high safety that is inaccessible with conventional lithium-ion batteries. Lithium metal, the ultimate anode with the highest specific capacity, also becomes available with nonflammable SSEs in ASSBs, which offers promising energy density. The rapid development of ASSBs, however, is significantly hampered by the large interfacial resistance as a matched lithium/ ceramic interface that is not easy to pursue. Here, a lithium-graphite...

Solid‐state Li metal batteries (SSLMBs) have attracted considerable interests due to their promising energy density as well as high safety. However, the realization of a well‐matched Li metal/solid‐state electrolyte (SSE) interface remains challenging. Herein, we report g‐C3N4 as a new interface enabler. We discover that introducing g‐C3N4 into Li metal can not only convert the Li metal/garnet‐type SSE interface from point contact to intimate contact but also greatly enhance the capability to suppress the dendritic Li formation because of the greatly enhanced viscosity, decreased surface tension of molten Li, and the in situ formation of Li3N at the interface. Thus, the resulting Li‐C3N4|SSE|Li‐C3N4 symmetric cell gives a significantly low interfacial resistance of 11 Ω cm2 and a high critical current density (CCD) of 1500 μA cm−2. In contrast, the same symmetric cell configuration with pristine Li metal electrodes has a much larger interfacial resistance (428 Ω cm2) and a much lower CCD (50 μA cm−2).