Solid-state lithium batteries (SSLBs) are promising owing to enhanced safety and high energy density but plagued by the relatively low ionic conductivity of solid-state electrolytes and large electrolyte-electrode interfacial resistance. Herein, we design a poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)-based polymer-in-salt solid electrolyte (PISSE) with high room-temperature ionic conductivity (1.24 10 À4 S cm À1 ) and construct a model integrated TiO 2 /Li SSLB with 3D fully infiltration of solid electrolyte. With forming aggregated ion clusters, unique ionic channels are generated in the PISSE, providing much faster Li + transport than common polymer electrolytes. The integrated device achieves maximized interfacial contact and electrochemical and mechanical stability, with performance close to liquid electrolyte. A pouch cell made of 2 SSLB units in series shows high voltage plateau (3.7 V) and volumetric energy density comparable to many commercial thin-film batteries.

Figure 6. a) Schematic illustration of the electron transport pathway in a SEI-wrapped 3D CNT NAs-sulfur cathode. Reproduced with permission. [99] Copyright 2017, Wiley-VCH. b) SEM images of CC@ZnO anode after cycling test without (b 1 ) and with (b 2 ) 3D CF NAs. Reproduced with permission. [103] Copyright 2016, Wiley-VCH. c) The local current density and electric field distribution of Zn anode on a planar current collector (c 1 ) and a 3D current collector (c 2 ). d) Regulated growth of SEI on 3D titanate NAs with ether electrolyte. e) Discharge/charge profiles of the Na 2 Ti 2 O 5 anode with ether electrolyte (inset: HRTEM image of the fully discharged Na 2 Ti 2 O 5 NSs). d,e) Reproduced with permission. [112] Copyright 2019, Wiley-VCH.

Vanadium-based cathodes have attracted great interest in aqueous zinc ion batteries (AZIBs) due to their large capacities, good rate performance and facile synthesis in large scale. However, their practical application is greatly hampered by vanadium dissolution issue in conventional dilute electrolytes. Herein, taking a new potassium vanadate K0.486V2O5 (KVO) cathode with large interlayer spacing (~ 0.95 nm) and high capacity as an example, we propose that the cycle life of vanadates can be greatly upgraded in AZIBs by regulating the concentration of ZnCl2 electrolyte, but with no need to approach “water-in-salt” threshold. With the optimized moderate concentration of 15 m ZnCl2 electrolyte, the KVO exhibits the best cycling stability with ~ 95.02% capacity retention after 1400 cycles. We further design a novel sodium carboxymethyl cellulose (CMC)-moderate concentration ZnCl2 gel electrolyte with high ionic conductivity of 10.08 mS cm−1 for the first time and assemble a quasi-solid-state AZIB. This device is bendable with remarkable energy density (268.2 Wh kg−1), excellent stability (97.35% after 2800 cycles), low self-discharge rate, and good environmental (temperature, pressure) suitability, and is capable of powering small electronics. The device also exhibits good electrochemical performance with high KVO mass loading (5 and 10 mg cm−2). Our work sheds light on the feasibility of using moderately concentrated electrolyte to address the stability issue of aqueous soluble electrode materials.

Solid-state lithium batteries (SSLBs) are promising owing to enhanced safety and high energy density but plagued by the relatively low ionic conductivity of solid-state electrolytes and large electrolyte-electrode interfacial resistance. Herein, we design a poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)-based polymer-in-salt solid electrolyte (PISSE) with high room-temperature ionic conductivity (1.24 10 À4 S cm À1 ) and construct a model integrated TiO 2 /Li SSLB with 3D fully infiltration of solid electrolyte. With forming aggregated ion clusters, unique ionic channels are generated in the PISSE, providing much faster Li + transport than common polymer electrolytes. The integrated device achieves maximized interfacial contact and electrochemical and mechanical stability, with performance close to liquid electrolyte. A pouch cell made of 2 SSLB units in series shows high voltage plateau (3.7 V) and volumetric energy density comparable to many commercial thin-film batteries.

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