in LIBs are mostly organic and harmful, which inevitably enhance the difficulty and the cost of battery fabrication and also bring about some environmental impact. [3] As an alternative, rechargeable aqueous zinc-ion batteries (ZIBs) have shown great promise because of low toxicity, low cost, and the abundant distribution of zinc resources. [4] More importantly, zinc possesses a low redox potential (−0.762 V vs. standard hydrogen electrode) and a high theoretical capacity (819 mAh g −1 , 5851 mAh mL −1 ). [4d] Furthermore, zinc is stable in water, which can reduce the production cost and improve the safety. [5] Despite these advantages, it is a large challenge to develop a high-performance cathode material for aqueous ZIBs that provides high and stable capacities and keeps the structure integrity in Zn 2+ uptake, which is mainly due to heavy mass and high polarization of divalent Zn 2+ . Among various reported cathode materials (such as α, β, γ, and δ-MnO 2 , [4c,6] Prussian blue analogs, [7] Na 3 V 2 (PO 4 ) 3 , [8] and vanadium-based materials [9] ), vanadium pentoxide (V 2 O 5 ) is of particular interest owing to its high Zn 2+ ion storage capacity (≈590 mAh g −1 according to the two-electron redox center of vanadium) in its layered structure consisting of VO 5 units. [10] Unfortunately, V 2 O 5 cathodes exhibit rapid capacity decline during (de)intercalation of Zn 2+ due to the low ion diffusion coefficient, poor conductivity, elements dissolution, and selfaggregation. [11] To overcome this drawback, it has been reported that intercalation of H 2 O molecules into the interlayers of V 2 O 5 could effectively enlarge and maintain the layered configuration of V 2 O 5 -based materials, which offered high Zn 2+ ion storage capability and stable cycling performance. [5c,12] Also, by inserting other metallic ions such as Ca 2+ , [9a] Zn 2+ , [9e] Na + , [13] or Li + , [14] the formation of metal vanadium oxide bronzes has been demonstrated to enhance Zn 2+ storage performances. The typical structure of these metal vanadates is that the V-O layers expand along the c-axis while the intercalated metal ions and H 2 O molecules stay in the interlayer space. [15] Despite significant progress, further boosting the Zn 2+ storage ability of V 2 O 5 -based cathodes through other strategies is still urgently required, particularly at large rates.As a highly conductive and extremely stable polymer, poly(3,4-ethylenedioxythiophene) (PEDOT) has been reported to not only effectively improve the electronic conductivity of Aqueous zinc-ion batteries (ZIBs) have become research focus because of their cost-effectiveness, high safety, and eco-friendliness. Unfortunately, sluggish Zn 2+ diffusion kinetics and the poor cycling stability in cathode materials impede their large-scale application. Herein, V 2 O 5 @poly(3,4ethylenedioxythiophene) (PEDOT) hybrid nanosheet arrays are uniformly deposited on carbon cloth (CC) as a superior ZIB cathode. The as-fabricated V 2 O 5 @PEDOT/CC electrode displays a maximum capacity of 360 mAh ...

Conducting polyaniline (PANI) exhibits interesting properties, such as high conductivity, reversible convertibility between redox states, and advantageous structural feature. It therefore receives ever‐increasing attention for various applications. This Minireview evaluates recent studies on application of PANI for Li‐ion batteries (LIBs), Li–S batteries (LSBs) and supercapacitors (SCPs). The flexible PANI is crucial for cyclability, especially for buffering the volumetric changes of electrode materials, in addition to enhancing the electron/ion transport. Furthermore, PANI can be directly used as an electroactive component in electrode materials for LIBs or SCPs and can be widely applied in LSBs due to its physically and chemically strong affinity for S and polysulfides. The evaluation of studies herein reveals significant improvements of electrochemical performance by physical/chemical modification and incorporation of PANI.

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Conductive polypyrrole (PPy) coated urchin-like hollow NiCo 2 O 4 (NCO) porous microspheres (NCO@PPy) were synthesized by an easy and cost-effective method. The NCO@PPy shows improved cycling stability and rate capability in comparison with the pure NiCo 2 O 4 when used as anode material for lithium-ion batteries. In order to undersatnd the improvement of electrochemical performance of NCO@PPy, kinetic parameters and the lithium storage mechanism are investigated by EIS spectra and sweep voltammetry measurements. The sweep-rate-dependent CV (cyclic voltammetry) curves demonstrate an ever-increasing redox capacitive-controlled lithium storage originating from both, the hierarchical hollow structure and the effect of the PPy coating layer. The apparent Li + ion diffusion coefficient of NCO@PPy and NCO derived from EIS and CV curves indicates that PPy coating layer reduces the charge-transfer resistances and improves the lithium-ion diffusion coefficient.

Aqueous Zn-based energy-storage devices have aroused much interest in recent years. However, uncontrollable dendrite growth in the Zn anode significantly limits their cycle life. Moreover, the poor low-temperature performance arising from the freezing of aqueous electrolytes at sub-zero temperatures restricts their practical applications in cold regions. Here, we fabricated low-temperature-tolerant and durable Zn-ion hybrid supercapacitors (ZHSCs) via modulating a co-solvent water/ethylene glycol electrolyte. The interaction of intermolecular hydrogen bonds between water and ethylene glycol as well as cation solvation was systematically investigated by tuning the co-solvent composition. The results illustrate that the ZnSO 4 /water/ethylene glycol (65%) electrolyte possesses high ionic conductivity at low temperatures and effectively prevents the dendrite formation of the Zn anode. The as-fabricated ZHSCs exhibit long-term cyclability and are capable of working at sub-zero temperatures as low as −40°C. The present ZHSCs are anti-freezing and cost-effective, which may find new applications in the fields of next-generation electrochemical energy storage devices.