Search

Summary: A desirable operating temperature range and small temperature gradient is beneficial to the safety and longevity of lithium‐ion (Li‐ion) batteries, and battery thermal management systems (BTMSs) play a critical role in achieving the temperature control. Having the advantages of direct access and low viscosity, air is widely used as a cooling medium in BTMSs. In this paper, an air‐based BTMS is modified by integrating a direct evaporative cooling (DEC) system, which helps reduce the inlet air temperature for enhanced heat dissipation. Experiments are carried out on 18650‐type batteries and a 9‐cell battery pack to study how relative humidity and air flow rate affect the DEC system. The maximum temperatures, temperature differences, and capacity fading of batteries are compared between three cooling conditions, which include the proposed DEC, air cooling, and natural convection cooling. In addition, a DEC tunnel that can produce reciprocating air flow is assembled to further reduce the maximum temperature and temperature difference inside the battery pack. It is demonstrated that the proposed DEC system can expand the usage of Li‐ion batteries in more adverse and intensive operating conditions. [ABSTRACT FROM AUTHOR]

As one of the most promising cathodes for next‐generation lithium ion batteries (LIBs), Li‐rich materials have been extensively investigated for their high energy densities. However, the practical application of Li‐rich cathodes is extremely retarded by the sluggish electrode–electrolyte interface kinetics and structure instability. In this context, piezoelectric LiTaO3 is employed to functionalize the surface of Li1.2Ni0.17Mn0.56Co0.07O2 (LNMCO), aiming to boost the interfacial Li+ transport process in LIBs. The results demonstrate that the 2 wt% LiTaO3‐LNMCO electrode exhibits a stable capacity of 209.2 mAh g−1 at 0.1 C after 200 cycles and 172.4 mAh g−1 at 3 C. Further investigation reveals that such superior electrochemical performances of the LiTaO3 modified electrode results from the additional driving force from the piezoelectric LiTaO3 layer in promoting Li+ diffusion at the interface, as well as the stabilized bulk structure of LNMCO. The supplemented LiTaO3 layer on the LNMCO surface herein, sheds new light on the development of better Li‐rich cathodes toward high energy density applications. [ABSTRACT FROM AUTHOR]

Summary: Battery thermal management (BTM) system is an indispensable component for large‐sized lithium‐ion battery packs used in aerospace and automotive applications. Besides providing a proper temperature range for batteries to operate, thus improving their efficiency, lifespan, and safety, the BTM system also needs to be well designed with considering the cost, weight, and practicability. In this paper, an internal passive BTM system is proposed for the cylindrical Li‐ion batteries. The design embeds a phase change material (PCM) filled mandrel inside the battery to achieve the cooling effect. A thermal test cell is first fabricated and tested in a wind tunnel under different cooling scenarios, and it is also used to verify a numerical thermal model. The proposed BTM system is further examined through the model and found to be able to create a preferable environment for batteries to operate. Specifically, the core BTM system consumes less PCM and achieves lower temperature rises and more uniform temperature distributions than an external BTM system. The proposed design can also exert its full latent heat to manage the heat generated from the battery without having a thermally conductive matrix, which is usually composite with PCM in external BTM systems. In addition, experiments show that the battery equipped with the proposed BTM system is ready for intensive cycling tests. [ABSTRACT FROM AUTHOR]

Organic-inorganic composites show great potential for organic rechargeable lithium-ion batteries. In this work, two-dimensional phthalocyanine molecules were converted into hybrid nanoparticles with a porous structure and bound to a conductive graphene layer to act as a cathode material. The conductivity of this reduced graphene oxide/Fe-phthalocyanine (rGO/FePc) composite is improved through good interfacial connections and internal polymerization. The FePc spheres were shaped with the assistance of Fe3O4 and immobilized between the layers of reduced graphene oxide (rGO). The electrochemical properties of the organic-inorganic composites were investigated by testing in a lithium-ion cell. A high discharge capacity of 186 mAh g−1 was maintained after 100 cycles at 300 mA g−1, which demonstrates a significant improvement in the cycle life compared to previous reports of phthalocyanine-based electrochemical energy storage behaviour. [ABSTRACT FROM AUTHOR]

An effective and compact thermal management system is essential for modern lithium-ion (Li-ion) battery powered vehicles, which involve rigorous constraints on weight and volume. In this paper, a phase change material (PCM) based battery internal cooling system is proposed by replacing the hollow mandrel in cylindrical battery with a PCM-filled mandrel, and it is tested on a fabricated steel cell. With verifying its effectiveness in cooling, as well as the accuracy of the thermal model, numerical studies are carried out on a Li-ion battery submodule consisting of 40 cylindrical batteries. Variables including PCM species ( n -octadecane, n -eicosane, and n -docosane), PCM core size, and PCM core size distribution are used in the simulations to optimize the design by examining the performance indices involving temperature, temperature difference, PCM solidification time, and pack compactness. The numerical results show that the PCM cores can effectively alleviate the temperature rise inside the battery pack, and a uniform temperature distribution can be obtained when thicker PCM cores are embedded in the interior batteries. A pack compactness study indicates that the internal cooling is a space-saving design that facilitates the achievement of the high energy density of the battery pack. [ABSTRACT FROM AUTHOR]

Li-ion batteries are the state-of-the-art power sources for portable electronics, electric vehicles, and aerospace applications. The safety issues regarding Li-ion batteries arouse particular attentions after several accidents reported in recent years. Among various abuse conditions, nail penetration is one of the most dangerous for Li-ion batteries due to the accumulated heat generation, which could give rise to the thermal runaway and could damage entire energy storage system. In this paper, an electrochemical-thermal coupling model is developed to study the nail penetration process of Li-ion batteries. By introducing joule heating at the nail location, the model shows good agreement with the testing results. With this verified model, a comprehensive parametric study is carried out to investigate the effects of battery capacity, internal resistance, and nail diameter on the electrochemical and thermal behaviors of Li-ion batteries during the penetration processes. Furthermore, three possible solutions to prevent the thermal runaway, which includes decreasing the state of charge, improving heat dissipation, and increasing contact resistance, are compared and discussed in detail based on a series of simulations. [ABSTRACT FROM AUTHOR]

The safety of lithium-ion battery (LIB)-powered electric vehicles and stationary energy storage devices relies on a high-efficient state of health (SOH) prediction of the LIB system. In this regard, the health indicators (HIs) play a critical role in determining the SOH prediction performance. Due to the rich kinetic and dynamic information of LIB system measured by electrochemical impedance spectroscopy (EIS), valuable HIs can be extracted from EIS for SOH prediction based on machine learning. The present work is concentrated on how to extract and tune HIs for a high-efficient SOH prediction based on the Gaussian process regression (GPR) model. First, 6-dimension feature x DRT are extracted from 120-dimension impedance x EIS with distribution of relaxation times (DRT) for 4 battery samples; secondly, the extracted x DRT is tuned into x ARD by the GPR with automatic relevance determination (ARD) kernels; thirdly, the SOH prediction results show that the tuned x ARD needs less training time than the raw x EIS does for the ARD-GPR model. Furthermore, x ARD has stronger robustness than x EIS with respect to kernel functions, training sets, and samples. Summarily, the method addressed in the present work to extract HIs may offer a promising solution for battery SOH prediction with a stronger robustness and less training time. [Display omitted] • Extracted health indicators from EIS by DRT method for battery SOH prediction. • Tuned health indicators extracted from EIS by DRT based on ARD-GPR model. • Demonstrated robustness of the tuned health indicators for battery SOH prediction. [ABSTRACT FROM AUTHOR]

[Display omitted] Sodium-ion batteries (SIBs) are expected to replace lithium-ion batteries as the next generation of commercial secondary batteries. However, the large-scale commercial use is hindered by the lack of suitable anode materials. Based on first-principles calculations, we systematically investigate the electrochemical performance of 2D silicether as an anode material for SIBs. It could turn to the metallic state from semiconductor after being intercalated with a low Na concentration of 0.056. Owing to the special groove-like structure of silicether, Na atom crosses a low energy barrier of 0.40 eV along the armchair direction. The theoretical storage capacity (418 mA h/g), the average electron potential (2.22 V), and no significant volume expansion suggest that silicether has a great potential in SIBs. Moreover, bilayer silicether could preserve the performances of silicether monolayer, such as strong Na adsorption capability and fast ionic mobility. The above-mentioned appealing results make silicether a high-performance anode material for SIBs. [ABSTRACT FROM AUTHOR]

Safety is the first priority in lithium ion (Li-ion) battery applications. A large portion of electrical and thermal hazards caused by Li-ion battery is associated with short circuit. In this paper, both external and internal short circuit tests are conducted. Li-ion batteries and battery packs of different capacities are used. The results indicate that external short circuit is worse for smaller size batteries due to their higher internal resistances, and this type of short can be well managed by assembling fuses. In internal short circuit tests, higher chance of failure is found on larger capacity batteries. A modified electrochemical–thermal model is proposed, which incorporates an additional heat source from nail site and proves to be successful in depicting temperature changes in batteries. Specifically, the model is able to estimate the occurrence and approximate start time of thermal runaway. Furthermore, the effectiveness of a hydrogel based thermal management system in suppressing thermal abuse and preventing thermal runaway propagation is verified through the external and internal short tests on batteries and battery packs. [ABSTRACT FROM AUTHOR]

Based on a 1D electrochemical model, a series of galvanostatic charge processes of lithium ion batteries with different initial electrolyte salt concentrations are simulated and investigated. In light of the simulation results, it is found that many electrochemical characters, including charge curve, end-of-charge salt concentration, anode potential, and reaction depth distribution, can all be affected by initial electrolyte salt concentration. Meanwhile, the lithium plating phenomenon commonly occurring during charge is studied with batteries of different salt concentrations during overcharge. A corresponding solution, changing the thickness ratio of anode to cathode, is proposed, which can also be used to extend the charging capacity. Overall, this study gives better understanding of the relevance between electrochemical behaviors of charging battery and initial electrolyte salt concentration, thus emphasizes the important role of electrolyte salt concentration in the performance and health of lithium ion battery. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Lithium ion (Li-ion) battery has emerged as an important power source for portable devices and electric vehicles due to its superiority over other energy storage technologies. A mild temperature variation as well as a proper operating temperature range are essential for a Li-ion battery to perform soundly and have a long service life. In this review paper, the heat generation and dissipation of Li-ion battery are firstly analyzed based on the energy conservation equations, followed by an examination of the hazardous effects of an above normal operating temperature. Then, advanced techniques in respect of electrode modification and systematic battery thermal management are inspected in detail as solutions in terms of reducing internal heat production and accelerating external heat dissipation, respectively. Specifically, variable parameters like electrode thickness and particle size of active material, along with optimization methods such as coating, doping, and adding conductive media are discussed in the electrode modification section, while the current development in air cooling, liquid cooling, heat pipe cooling, and phase change material cooling systems are reviewed in the thermal management part as different ways to improve the thermal performance of Li-ion batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] Porous organic polymers are considered as excellent candidates for the electrode materials in rechargeable battery due to their desirable properties including porosity, customizable structure, and intrinsic chemical stability. Herein a Salen-based porous aromatic framework (Zn/Salen-PAF) is synthesized through a metal directed method and further used as efficient anode material for lithium-ion battery. Attributing to the stable functional skeleton, Zn/Salen-PAF delivers a reversible capacity of 631 mAh·g−1 at 50 mA·g−1, a high-rate capability of 157 mAh·g−1 at 20.0 A·g−1 and a long-term cycling capacity of 218 mAh·g−1 at 5.0 A·g−1 even after 2000 cycles. Compared to the Salen-PAF without metal ions, Zn/Salen-PAF possesses better electrical conductivity and more active sites. X-ray photoelectron spectroscopy (XPS) investigation indicates that the coordination of Zn2+ with N 2 O 2 unit not only improves the conjugation of the framework but also contributes to the in situ cross-sectional oxidation of the ligand during reaction, which results in the electron redistribution of oxygen atom and the formation of C O bonds. [ABSTRACT FROM AUTHOR]

Lithium ion (Li-ion) battery, consisting of multiple electrochemical cells, is a complex system whose high electrochemical and thermal stability is often critical to the well-being and functional capabilities of electric devices. Considering any change in the specifications may significantly affect the overall performance and life of a battery, an investigation on the impacts of electrode thickness on the electrochemical and thermal properties of lithium-ion battery cells based on experiments and a coupling model composed of a 1D electrochemical model and a 3D thermal model is conducted in this work. In-depth analyses on the basis of the experimental and simulated results are carried out for one cell of different depths of discharge as well as for a set of cells with different electrode thicknesses. Pertinent results have demonstrated that the electrode thickness can significantly influence the battery from many key aspects such as energy density, temperature response, capacity fading rate, overall heat generation, distribution and proportion of heat sources. [ABSTRACT FROM AUTHOR]

Abstract: As a typical heat source in the operation of lithium-ion (Li-ion) battery, reversible heat (RH) makes a considerable contribution to the temperature variation of the battery, and the determination of this contribution is of great significance, especially for mission-critical applications. In previous research works, the determination of including or excluding the RH was typically made based on the rate of discharge. This study, however, finds that the importance of RH could be more meaningfully judged based on its contribution to the overall thermal response of Li-ion battery at various conditions. An improved electrochemical–thermal coupling model is developed to incorporate the RH. This model is applied to simulate the operation of batteries with different physical properties (e.g., electrode thickness and active material particle size) under different discharge rates. The simulation results are compared in terms of RH generation rates, battery temperature, as well as several other associated characteristics. It is found that the significance of RH to the overall heat generation varies when different intrinsic and extrinsic parameters are considered. This significance becomes more appreciable for batteries with thinner electrodes and/or finer active material particles. A correction diagram is then proposed to modify the results for thermal analyses without including RH. [Copyright &y& Elsevier]

Abstract: Many portable devices such as soldier carrying devices are powered by low-weight but high-capacity lithium ion (Li-ion) batteries. An effective battery thermal management (BTM) system is required to keep the batteries operating within a desirable temperature range with minimal variations, and thus to guarantee their high efficiency, long lifetime and great safety. However, the rigorous constraints imposed by the budgets in weight and volume for this specific application eliminate the possible consideration of many existing classical cooling approaches and make the development of BTM system very challenging in this field. In this paper, a flexible hydrogel-based BTM system is developed to address this challenge. The proposed BTM system is based on cost-effective sodium polyacrylate and can be arbitrarily shaped and conveniently packed to accommodate any Li-ion stacks. This BTM system is tested through a series of high-intensity discharge and abnormal heat release processes, and its performance is compared with three classical BTM systems. The test results demonstrate that the proposed low-cost, space-saving, and contour-adaptable BTM system is a very economic and efficient approach in handling the thermal surge of Li-ion batteries. [Copyright &y& Elsevier]

Abstract: An appropriate operating temperature range is critical for the overall performance and safety of lithium-ion batteries. Considering the excellent performance of water in heat dissipation in industrial applications, in this paper, a water based PAAS (sodium polyacrylate) hydrogel thermal management system has been proposed to handle the heat surge during the operation of a Li-ion battery pack. A thermal model with constant heat generation rate is employed to simulate the high current discharge process (i.e., 10 A) on a 4S1P battery pack, which shows a good consistence with the corresponding experimental results. Further experiments on 4S1P and 5S1P battery packs validate the effectiveness of the hydrogel thermal management system in lowering the temperature increase rate of battery packs at different discharge rates and minimizing the temperature difference inside battery packs during operation, thereby enhancing the stability and safety in continuous charge and discharge process and decreasing the capacity fading rate during life cycle tests. This novel hydrogel based cooling system also possesses the characteristics of high energy efficiency, easy manufacturing process, compactness, and low cost. [Copyright &y& Elsevier]

Abstract: A series of olivine LiFe1−x Co x PO4 composites were synthesised by a hydrothermal route under reductive atmosphere. The structure of the prepared samples was characterised by X-ray diffraction. Morphology, particle size, and elemental concentration were observed by scanning electron microscopy, high-resolution transmission electron microscopy, and corresponding EDS mapping, respectively. Raman spectroscopy was employed to study the surface information of the carbon-coated LiFe1−x Co x PO4. The electrochemical properties of the samples were studied by AC impedance spectroscopy and charge–discharge instruments at room temperature. The discharge capacity of LiFe3/4Co1/4PO4/C is 170mAh/g at rate of 0.1C. LiFe1−x Co x PO4 can achieve a higher discharge plateau (∼3.5V) than does pure LiFePO4 (∼3.4V). The results indicate that the Co-doped sample exhibits improved electrochemical performance at low discharge rates. However, XPS results show that the Li–O band stabilises further as the doping amount increase, which is not beneficial to the lithium diffusion coefficient of the compound. [Copyright &y& Elsevier]

Instable surface structure and low capacity retention hinder the further application of high voltage LiNi 0.5 Mn 1.5 O 4 (LNMO) cathode in lithium-ion battery. In order to promote its electrochemical performances, Li 6.4 La 3 Al 0.2 Zr 2 O 12 (LLAZO) with the intrinsic property of fast ion conductivity has been employed as a protective layer to modify surface of LNMO. By regulating the LLAZO contents, 1 wt % LLAZO coated LNMO (LLAZO-1) cathode shows a high capacity of 92.1 mAh g−1 over 600 cycles with a capacity retention of 72.6% at 1 C and a reversible capacity of 57.9 mAh g−1 at 20 C, much higher than those of pristine LNMO. Further investigation indicates that the greatly improved electrochemical performances of LLAZO-1 can be attributed to the LLAZO modification, which including the LLAZO surface coating and La3+ and Zr4+ gradient co-doping. In addition, the LLAZO precursor significantly restricts the growth of LNMO precursor particles during calcination process, shorting Li+ migration pathway. Thus, modification strategy effectively improves the structure stability of LNMO, accompanied with the enhancement in lithium-ion diffusion kinetics performances and confinement in particle growth. This optimization approach with tri-functions sheds light on novel electrode design and construction in rechargeable batteries. Image 1 • The novel strategy of modification for cathode precursor proposed in this work. • Restricting the particle growth of LNMO during the calcination process. • Gradient doping of La3+ and Zr4+ facilitate Li+ transportation at the interface. [ABSTRACT FROM AUTHOR]

[Display omitted] • The structure of MnOx@aTiOy showed the increasing capacity being activated to maintain for a long-term cycling (829.5 mAh g−1 at 1 A g−1 after 2000 cycles). • The oxygen defects in the coating layer of modified TiO 2 boosted the pseudocapacitance effect for electrochemical performance. • The DFT calculations reveals the oxygen defects, the transformation of α-MnO 2 into Bixbyite-O Mn 2 O 3 , would decrease the kinetics of Li+ on lithium migrating paths and energy barriers. In this work, we developed Manganese and Titanium based oxide composites with oxygen defects (MnO x @aTiO y) via plasma processing as anodes of lithium ion batteries. By appropriately adjusting the defect concentration, the ion transport kinetics and electrical conductivity of the electrodes are significantly improved, showing stable capacity retention. Furthermore, the incremental capacity is further activated and long-term stable cycling performance is achieved, with a specific capacity of 829.5 mAh/g at 1 A/g after 2000 cycles. To scrutinize the lithium migration paths and energy barriers in MnO 2 and Mn 2 O 3 , the density functional theory (DFT) calculations is performed to explore the lithium migration paths and energy barriers. Although the transformation of MnO 2 into Mn 2 O 3 through oxygen defects was initially surmised to inhibit Li ions along their standard routes, our results indicate quite the contrary. In fact, the composite's lithium diffusion rate saw a substantial increase. This can be accredited to the pronounced enhancement of conductivity and ion transport efficiency in the amorphous and porous TiO y. [ABSTRACT FROM AUTHOR]

Highlights • A method for thermal management of battery using phase change material is proposed. • Temperature of battery is rapidly decreased using flexible phase change material. • Flexible phase change material fills the gap due to low thermal contact resistance. • The usage time of the battery pack is effectively extended. • Simulation results show good agreement with experimental results. Abstract A method for thermal management of Li-ion battery pack with the application of various flexible form-stable composite phase change materials (CPCMs) is proposed, and investigated both numerically and experimentally. Flexible CPCMs embedded in battery pack lower the thermal contact resistance, thereby improving the thermal control performance. Experimental results show that with the application of flexible CPCMs, the battery temperature drops by 18 °C at 10 C discharge rate. In addition, flexible CPCM has better thermal control performance than the case of conventional CPCMs. This allows Li-ion battery pack to safely work for an extended period of time without exceeding upper temperature limits. The thermal control performance is observed to vary considerably with three factors: the phase change temperature of flexible CPCMs, working condition, and the ambient temperature. One flexible CPCM with phase change temperature of 33 °C is found to be optimal for small power levels and low ambient temperatures. Another flexible CPCM with 47 °C of phase change temperature is suitable for high power levels, short-term high heat fluxes, and high ambient temperatures. The numerical results are in reasonable accordance with experimental ones. [ABSTRACT FROM AUTHOR]

Abstract SnS-based materials show great potential as high-capacity anode candidates of Li-ion batteries owing to their dual-mechanisms of conversion and alloying reactions. However, the practical application is substantially hampered by its poor electrochemical utilization and stability. Herein, we demonstrate three-dimensional SnS/C microflowers prepared by a controllable self-polymerization and carbonization of polydopamine-coated SnS 2 precursors. The building nanosheet consists of uniform encapsulation of ultrafine SnS nanoparticles into the conductive carbon framework. Benefiting from the nanoscaled building blocks and the porous three-dimensional architecture, the carbon-encapsulated nano-SnS microflowers show a significant enhancement in the electrochemical reaction kinetics and durability. As a result, the hybrid exhibits a high specific capacity of ∼1000 mAh g−1 at 0.1 A g−1 with a high initial Coulombic efficiency of 84.2%, good rate capability, and stable cyclability. The present work provides a reliable strategy for the rational fabrication of carbon-encapsulated SnS composites for high-performance Li-ion batteries. Graphical abstract Image 1 Highlights • Three-dimensional microflowers assembled by SnS/C nanosheets are prepared. • SnS nanoparticles are uniformly encapsulated by carbon framework. • The SnS/S hybrid delivers a high specific capacity of ∼1000 mAh g−1. • The SnS/S hybrid exhibits excellent rate/cycling performance. [ABSTRACT FROM AUTHOR]

[Display omitted] Here, we proposed a new strategy to build the integrated graphene cube (Gr) framework@TiO 2 composite to improve the ion transport kinetics and electrical conductivity of TiO 2 as a long-life and high-capacity anode for lithium ion batteries. Combined with the salt template method for ultra-thin framework, the distinct structure of Gr@TiO 2 shows an excellent electrochemical performance, e.g., initial coulombic efficiency (ICE), rate performance and specific capacity, due to the increased kinetics of lithium ions. Through this method, the integrity is dramatically improved and the pulverization and agglomeration of the anode after long-term cycles are restrained. The optimized Gr@TiO 2 displays a high stable reversible capacity of 179.5 mAh g−1 after 4000 cycles at 1 A g−1, excellent rate performance (125.5 mAh g−1 at 5 A g−1). Kinetic studies through Electrochemical Impedance Spectra, Galvanostatic Intermittent Titration Technique and Linear Sweep Voltammetry confirm that the electrical conductivity and ion transport kinetics are dramatically improved through the ultra-thin graphene cube framework as a heterojunction structure of Gr@TiO 2. [ABSTRACT FROM AUTHOR]

Here graphene coating magnetite/N-doped carbon hybrid materials (G@Fe 3 O 4 /NC) have been synthesized. Structural characterizations revealed that Fe 3 O 4 /N-doped carbon was wrapped tightly and uniformly by graphene nanosheets via π-π interactions, which preventing the volume expansion of the material during the charge/discharge processes. G@Fe 3 O 4 /NC hybrid composites exhibited a large discharge specific capacity of 958 mAh g −1 after 65 cycles at a current density of 200 mA g −1 . [ABSTRACT FROM AUTHOR]

• Conducting polymer (polypyrrole)-intercalated V 2 O 5 is synthesized by a simple hydrothermal technique. • Polypyrrole enlarges the layer spacing of V 2 O 5 and forming a highway for ion diffusion. • Charge storage mechanism of Zn2+ and H+ co-intercalation layer is confirmed. • The electrode exhibits excellent electrochemical performance in aqueous zinc-ion batteries. Aqueous secondary zinc-ion batteries are promising candidates to replace lithium-ion batteries for large-scale energy storage, due to their high safety and low cost. However, the developed cathodes materials are facing low capacity or low cycle life due to sluggish diffusion kinetics. Therefore, the design of a cathode with ultrafast ion diffusion kinetics remains a great challenge. Here, we propose an in-situ intercalation strategy of polypyrrole to improve the cation diffusion kinetics of V 2 O 5. The polypyrrole as a guest significantly enlarges the interlayer spacing, paving the "superhighway" for cation diffusion. In addition, thanks to the unique π-conjugated structure, polypyrrole can shield the electrostatic force of Zn2+ and the host oxygen-sublattice. The energy storage mechanism of the cathode was shown to be a stepwise H+/Zn2+co-intercalation by means of galvanostatic intermittent titration technique (GITT), electrochemical impedance spectroscopy (EIS) and ex situ X-ray diffraction (XRD). Based on the above advantages, the polypyrrole-intercalated V 2 O 5 demonstrates high capacities and excellent cycling performance (220 mA h g−1 after 2000 cycles at 10 A g−1). We report an in-situ intercalation strategy of polypyrrole to improve the cation diffusion kinetics of V 2 O 5. The polypyrrole as a guest significantly enlarges the layer spacing, paving the "superhighway" for Zn2+ and H+ diffusion. [Display omitted] [ABSTRACT FROM AUTHOR]