ABSTRACT
Composite polymer electrolytes (CPEs) utilizing fillers as the promoting component bridge the gap between solid polymer electrolytes and inorganic solid electrolytes. The integration of fillers into the polymer matrices is demonstrated as a prevailing strategy to enhance Li-ion transport and assist in constructing Li+ -conducting electrode-electrolyte interface layer, which addresses the two key barriers of solid-state lithium batteries (SSLBs): low ionic conductivity of electrolyte and high interfacial impedance. Recent review articles have largely focused on the performance of a broad spectrum of CPEs and the general effects of fillers on SSLBs device. Recognizing this, in this review, after briefly presenting the categories of fillers (traditional and emerged) and the promoted ionic conducting mechanisms in CPEs, the progress in the interfacial structure design principle, with the emphasis on the crucial influence of filler size, concentration, and hybridization strategies on filler-polymer interface that is the most critical to Li-ion transport is assessed. The latest exciting advances on filler-enabled in situ generation of a Li+ -conductive layer at the electrode-electrolyte interface to greatly reduce the interfacial impedance are further elaborated. Finally, this review discusses the challenges to be addressed, outlines research directions, and provides a future vision for developing advanced CPEs for high-performing SSLBs.
ABSTRACT
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.
ABSTRACT
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 (1.24×10-4 â S cm-1 ) and construct a model integrated TiO2 /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 (3.7â V) and volumetric energy density comparable to many commercial thin-film batteries.
ABSTRACT
MnO2 is one of the most studied cathodes for aqueous neutral zinc-ion batteries. However, the diverse reported crystal structures of MnO2 compared to δ-MnO2 inevitably suffer a structural phase transition from tunneled to layered Zn-buserite during the initial cycles, which is not as kinetically direct as the conventional intercalation electrochemistry in layered materials and thus poses great challenges to the performance and multifunctionality of devices. Here, a binder-free δ-MnO2 cathode is designed and a favorable "layered to layered" Zn2+ storage mechanism is revealed systematically using such a "noninterferencing" electrode platform in combination with ab initio calculation. A flexible quasi-solid-state Zn-Mn battery with an electrodeposited flexible Zn anode is further assembled, exhibiting high energy density (35.11 mWh cm-3; 432.05 Wh kg-1), high power density (676.92 mW cm-3; 8.33 kW kg-1), extremely low self-discharge rate, and ultralong stability up to 10 000 cycles. Even with a relatively high δ-MnO2 mass loading of 5 mg cm-2, significant energy and power densities are still achieved. The device also works well over a broad temperature range (0-40 °C) and can efficiently power different types of small electronics. This work provides an opportunity to develop high-performance multivalent-ion batteries via the design of a kinetically favorable host structure.
ABSTRACT
A V2O5 porous nanodisk thin film is synthesized through a simple hydrothermal and subsequent VO2 template oxidation strategy. For the first time, V2O5 is employed as a cathode rather than an anode to construct lithium-ion hybrid capacitors. This design effectively utilizes the intrinsic layered structure of V2O5 for facile Li+ intercalation and facilitates the charge balance with the capacitive electrode, enabling superior performance of the device.
