Injecting Excess Na into a P2-Type Layered Oxide Cathode to Achieve Presodiation in a Na-Ion Full Cell.

The initial Na loss limits the theoretical specific capacity of cathodes in Na-ion full cell applications, especially for Na-deficient P2-type cathodes. In this study, we propose a presodiation strategy for cathodes to compensate for the initial Na loss in Na-ion full cells, resulting in a higher specific capacity and a higher energy density. By employing an electrochemical presodiation approach, we inject 0.32 excess active Na into P2-type Na0.67Li0.1Fe0.37Mn0.53O2 (NLFMO), aiming to compensate for the initial Na loss in hard carbon (HC) and the inherent Na deficiency of NLFMO. The structure of the NLFMO cathode converts from P2 to P'2 upon active Na injection, without affecting subsequent cycles. As a result, the HC||NLFMOpreNa full cell exhibits a specific capacity of 125 mAh/g, surpassing the value of 61 mAh/g of the HC||NLFMO full cell without presodiation due to the injected active Na. Moreover, the presodiation effect can be achieved through other engineering approaches (e.g., Na-metal contact), suggesting the scalability of this methodology.

The Progress of Hard Carbon as an Anode Material in Sodium-Ion Batteries.

When compared to expensive lithium metal, the metal sodium resources on Earth are abundant and evenly distributed. Therefore, low-cost sodium-ion batteries are expected to replace lithium-ion batteries and become the most likely energy storage system for large-scale applications. Among the many anode materials for sodium-ion batteries, hard carbon has obvious advantages and great commercial potential. In this review, the adsorption behavior of sodium ions at the active sites on the surface of hard carbon, the process of entering the graphite lamellar, and their sequence in the discharge process are analyzed. The controversial storage mechanism of sodium ions is discussed, and four storage mechanisms for sodium ions are summarized. Not only is the storage mechanism of sodium ions (in hard carbon) analyzed in depth, but also the relationships between their morphology and structure regulation and between heteroatom doping and electrolyte optimization are further discussed, as well as the electrochemical performance of hard carbon anodes in sodium-ion batteries. It is expected that the sodium-ion batteries with hard carbon anodes will have excellent electrochemical performance, and lower costs will be required for large-scale energy storage systems.

Preferential Pyrolysis Construction of Carbon Anodes with 8400†h Lifespan for High-Energy-Density K-ion Batteries.

Carbonaceous materials are promising anodes for practical potassium-ion batteries, but fail to meet the requirements for durability and high capacities at low potentials. Herein, we constructed a durable carbon anode for high-energy-density K-ion full cells by a preferential pyrolysis strategy. Utilizing S and N volatilization from a π-π stacked supermolecule, the preferential pyrolysis process introduces low-potential active sites of sp2 hybridized carbon and carbon vacancies, endowing a low-potential "vacancy-adsorption/intercalation" mechanism. The as-prepared carbon anode exhibits a high capacity of 384.2 mAh g-1 (90 % capacity locates below 1 V vs. K/K+ ), which contributes to a high energy density of 163 Wh kg-1 of K-ion full battery. Moreover, abundant vacancies of carbon alleviate volume variation, boosting the cycling stability over 14 000 cycles (8400 h). Our work provides a new synthesis approach for durable carbon anodes of K-ion full cells with high energy densities.

In Situ Nitrogen Retention of Carbon Anode for Enhancing the Electrochemical Performance for Sodium-Ion Battery.

Retaining nitrogen for polyacrylonitrile (PAN) based carbon anode is a cost-effective way to make full use of the advantages of PAN for sodium-ion batteries (SIBs). Here, a simple strategy has been successfully adopted to retain N atoms in situ and increase production yield of a novel composite PAZ by mixing 3 wt % of zinc borate (ZB) with poly (acrylonitrile-co-itaconic acid) (PANIA). Among the prepared carbonised fibre (CF) samples, PAZ-CF-700 maintains the highest N content, retaining 90 % of the original N from PANIA. It represents the highest capacity storage contribution (80.55 %) and the lowest impedance Rct (117 Ω). Consequently, the specific capacity increases from 60 mAh g-1 of PANIA-CF-700 to 190 mAh g-1 of PAZ-CF-700 at a current density of 100 mA g-1 . At the same time, PAZ-CF-700 exhibits a good rate performance and excellent long-term cycling stability with a specific capacity of 94 mAh g-1 after 4000 cycles at 1.6 A g-1 .

Evolution of the Solid-Electrolyte Interphase on Carbonaceous Anodes Visualized by Atomic-Resolution Cryogenic Electron Microscopy.

The stability of modern lithium-ion batteries depends critically on an effective solid-electrolyte interphase (SEI), a passivation layer that forms on the carbonaceous negative electrode as a result of electrolyte reduction. However, a nanoscopic understanding of how the SEI evolves with battery aging remains limited due to the difficulty in characterizing the structural and chemical properties of this sensitive interphase. In this work, we image the SEI on carbon black negative electrodes using cryogenic transmission electron microscopy (cryo-TEM) and track its evolution during cycling. We find that a thin, primarily amorphous SEI nucleates on the first cycle, which further evolves into one of two distinct SEI morphologies upon further cycling: (1) a compact SEI, with a high concentration of inorganic components that effectively passivates the negative electrode; and (2) an extended SEI spanning hundreds of nanometers. This extended SEI grows on particles that lack a compact SEI and consists primarily of alkyl carbonates. The diversity in observed SEI morphologies suggests that SEI growth is a highly heterogeneous process. The simultaneous emergence of these distinct SEI morphologies highlights the necessity of effective passivation by the SEI, as large-scale extended SEI growths negatively impact lithium-ion transport, contribute to capacity loss, and may accelerate battery failure.

From Microparticles to Nanowires and Back: Radical Transformations in Plated Li Metal Morphology Revealed via in Situ Scanning Electron Microscopy.

Li metal is the preferred anode material for all-solid-state Li batteries. However, a stable plating and stripping of Li metal at the anode-solid electrolyte interface remains a significant challenge particularly at practically feasible current densities. This problem usually relates to high and/or inhomogeneous Li-electrode-electrolyte interfacial impedance and formation and growth of high-aspect-ratio dendritic Li deposits at the electrode-electrolyte interface, which eventually shunt the battery. To better understand details of Li metal plating, we use operando electron microscopy and Auger spectroscopy to probe nucleation, growth, and stripping of Li metal during cycling of a model solid-state Li battery as a function of current density and oxygen pressure. We find a linear correlation between the nucleation density of Li clusters and the charging rate in an ultrahigh vacuum, which agrees with a classical nucleation and growth model. Moreover, the trace amount of oxidizing gas (≈10-6 Pa of O2) promotes the Li growth in a form of nanowires due to a fine balance between the ion current density and a growth rate of a thin lithium-oxide shell on the surface of the metallic Li. Interestingly, increasing the partial pressure of O2 to 10-5 Pa resumes Li plating in a form of 3D particles. Our results demonstrate the importance of trace amounts of preexisting or ambient oxidizing species on lithiation processes in solid-state batteries.

Slope-Dominated Carbon Anode with High Specific Capacity and Superior Rate Capability for High Safety Na-Ion Batteries.

The comprehensive performance of carbon anodes for Na-ion batteries (NIBs) is largely restricted by their inferior rate capability and safety issues. Herein, a slope-dominated carbon anode is achieved at a low temperature of 800 °C, which delivers a high reversible capacity of 263 mA h g-1 at 0.15C with an impressive initial Coulombic efficiency (ICE) of 80 %. When paired with the NaNi1/3 Fe1/3 Mn1/3 O2 cathode, the reversible capacity at 6C is still 75 % of that at 0.15C, and 73 % of the capacity is retained after 1000 cycles at 3C. The enhanced Na storage performance could be attributed to the unique microstructure with randomly oriented short carbon layers and the relatively higher defect concentration. Given its robustness, such a low-temperature carbonization strategy could also be applicable to other precursors and provide a new opportunity to design slope-dominated carbon anodes for high safety, low-cost NIBs with excellent ICE and superior rate capability.

Hydrogenotrophic denitrification process efficiency and the number of denitrifying bacteria (MPN) in the sequencing batch biofilm reactor (SBBR) with platinum and carbon anodes.

This work reports on the effect of electric current density and anode material (platinum, carbon) on the concentration of oxidized and mineral forms of nitrogen, on physical parameters (pH, redox potential, electrical conductivity) and the number of denitrifying bacteria in the biofilm (MPN). Experiments were conducted under anaerobic conditions without and with the flow of electric current (with density of 79 mA · m(-2) and 132 mA · m(-2)). Results obtained in the study enabled concluding that increasing density of electric current caused a decreasing concentration of nitrate in the reactor with platinum anode (R1) and carbon anode (R2). Its concentration depended on anode material. The highest hydrogenotrophic denitrification efficiency was achieved in R2 in which the process was aided by inorganic carbon (CO2) that originated from carbon anode oxidation and the electrical conductivity of wastewater increased as a result of the presence of HCO3(-) and CO3(2-) ions. Strong oxidizing properties of the platinum anode (R1) prevented the accumulation of adverse forms of nitrogen, including nitrite and ammonia. The increase in electric current density affected also a lower number of denitrifying bacteria (MPN) in the biofilm in both reactors (R1 and R2). Metal oxides accumulated on the surface of the cathode had a toxic effect upon microorganisms and impaired the production of a hydrogen donor.

Insight into roles of carbon anodes for removal of refractory organic contaminants in electro-peroxone system: Mechanism, performance and stability.

Electro-peroxone (EP) is a novel technique for the removal of refractory organic contaminants (ROCs), while the role of anode in this system is neglected. In this work, the EP system with graphite felt anode (EP-GF) and activated carbon fiber anode (EP-ACF) was developed to enhance ibuprofen (IBP) removal. The results showed that 91.2% and 98.6% of IBP was removed within 20 min in EP-GF and EP-ACF, respectively. Hydroxy radical (O⋅H) was identified as the dominant reactive species, contributing 80.9% and 54.0% of IBP removal in EP-ACF and EP-GF systems, respectively. The roles of adsorption in EP-ACF and direct electron transfer in EP-GF cannot be ignored. Due to the differences in mechanism, EP-GF and EP-ACF systems were suitable for the removal of O⋅H-resistant ROCs (e.g., oxalic acid and pyruvic acid) and non-O⋅H-resistant ROCs (e.g., IBP and nitrobenzene), respectively. Both systems had excellent stability relying on the introduction of oxygen functional groups on the anode, and their electrolysis energy consumption was significantly lower than that of EP-Pt system. The three degradation pathways of IBP were proposed, and the toxicity of intermediates were evaluated. In general, carbon anodes have a good application prospect in the removal of ROCs in EP systems.

Halide-mediated endogenous ZnO domain-confined etching strategy: Realizing superior potassium storage in carbon anode.

Coupling sites of nitrogen-dopants and intrinsic carbon defects (N/DC) are highly attractive to improve potassium-storage capacity and cycling stability, yet it is hard to effectively construct them. Herein, a novel strategy is proposed to establish abundant N/DC sites in N-doped carbon (ZIF8/NaBr-1-900) by pyrolyzing the mixture of metal-organic framework (ZIF8)/sodium bromide (NaBr). Systematic investigations disclose that the introduced NaBr can promote the full conversion of Zn-N4 moieties into zinc oxide (ZnO) via a "bait and switch" mechanism. Such formed endogenous ZnO can etch the carbon matrix of the confined domains around the N dopants during pyrolysis process, and meanwhile the released N-atoms from Zn-N4 moieties can largely form edge-N. As such, these N/DC coupling sites enable the resultant carbon to have a more significant capacitive behavior related to fast K-ion migration and high structural stability, leading to 255.3 mAh/g at 2 A/g with a prolonged cycle lifespan over 2000 cycles. Moreover, the assembled K-full battery presents a high energy density of 171.2 Wh kg-1 and excellent cyclability over 5000 cycles. This NaBr-mediated endogenous ZnO domain-confined etching strategy provides a new insight into the exploration of advanced carbon anode.

Reutilization of Silicon-Cutting Waste via Constructing Multilayer Si@SiO2@C Composites as Anode Materials for Li-Ion Batteries.

The rapid development of the photovoltaic industry has also brought some economic losses and environmental problems due to the waste generated during silicon ingot cutting. This study introduces an effective and facile method to reutilize silicon-cutting waste by constructing a multilayer Si@SiO2@C composite for Li-ion batteries via two-step annealing. The double-layer structure of the resultant composite alleviates the severe volume changes of silicon effectively, and the surrounding slightly graphitic carbon, known for its high conductivity and mechanical strength, tightly envelops the silicon nanoflakes, facilitates ion and electron transport and maintains electrode structural integrity throughout repeated charge/discharge cycles. With an optimization of the carbon content, the initial coulombic efficiency (ICE) was improved from 53% to 84%. The refined Si@SiO2@C anode exhibits outstanding cycling stability (711.4 mAh g-1 after 500 cycles) and rate performance (973.5 mAh g-1 at 2 C). This research presents a direct and cost-efficient strategy for transforming photovoltaic silicon-cutting waste into high-energy-density lithium-ion battery (LIB) anode materials.

Modulating porous silicon-carbon anode stability: Carbon/silicon carbide semipermeable layer mitigates silicon-fluorine reaction and enhances lithium-ion transport.

Silicon-based material is regarded as one of the most promising anodes for next-generation high-performance lithium-ion batteries (LIBs) due to its high theoretical capacity and low cost. Harnessing silicon carbide's robustness, we designed a novel porous silicon with a sandwich structure of carbon/silicon carbide/Ag-modified porous silicon (Ag-PSi@SiC@C). Different from the conventional SiC interface characterized by a frail connection, a robust dual covalent bond configuration, dependent on SiC and SiOC, has been successfully established. Moreover, the innovative sandwich structure effectively reduces detrimental side reactions on the surface, eases volume expansion, and bolsters the structural integrity of the silicon anode. The incorporation of silver nanoparticles contributes to an improvement in overall electron transport capacity and enhances the kinetics of the overall reaction. Consequently, the Ag-PSi@SiC@C electrode, benefiting from the aforementioned advantages, demonstrates a notably elevated lithium-ion mobility (2.4 * 10-9 cm2·s-1), surpassing that of silicon (5.1 * 10-12 cm2·s-1). The half-cell featuring Ag-PSi@SiC@C as the anode demonstrated robust rate cycling stability at 2.0 A/g, maintaining a capacity of 1321.7 mAh/g, and after 200 cycles, it retained 962.6 mAh/g. Additionally, the full-cell, featuring an Ag-PSi@SiC@C anode and a LiFePO4 (LFP) cathode, exhibits outstanding longevity. Hence, the proposed approach has the potential to unearth novel avenues for the extended exploration of high-performance silicon-carbon anodes for LIBs.

One-Step Construction of Closed Pores Enabling High Plateau Capacity Hard Carbon Anodes for Sodium-Ion Batteries: Closed-Pore Formation and Energy Storage Mechanisms.

Closed pores play a crucial role in improving the low-voltage (<0.1 V) plateau capacity of hard carbon anodes for sodium-ion batteries (SIBs). However, the lack of simple and effective closed-pore construction strategies, as well as the unclear closed-pore formation mechanism, has severely hindered the development of high plateau capacity hard carbon anodes. Herein, we present an effective closed-pore construction strategy by one-step pyrolysis of zinc gluconate (ZG) and elucidate the corresponding mechanism of closed-pore formation. The closed-pore formation mechanism during the pyrolysis of ZG mainly involves (i) the precipitation of ZnO nanoparticles and the ZnO etching on carbon under 1100 °C to generate open pores of 0.45-4 nm and (ii) the development of graphitic domains and the shrinkage of the partial open pores at 1100-1500 °C to convert the open pores to closed pores. Benefiting from the considerable closed-pore content and suitable microstructure, the optimized hard carbon achieves an ultrahigh reversible specific capacity of 481.5 mA h g-1 and an extraordinary plateau capacity of 389 mA h g-1 for use as the anode of SIBs. Additionally, some in situ and ex situ characterizations demonstrate that the high-voltage slope capacity and the low-voltage plateau capacity stem from the adsorption of Na+ at the defect sites and Na-cluster formation in closed pores, respectively.

Low-Temperature Molten Salt Electrochemical CO2 Upcycling for Advanced Energy Materials.

One strategy for addressing the climate crisis caused by CO2 emissions is to efficiently convert CO2 to advanced materials suited for green and clean energy technology applications. Porous carbon is widely used as an advanced energy storage material because of its enhanced energy storage capabilities as an anode. Herein, we report electrochemical CO2 upcycling to solid carbon with a controlled microstructure and porosity in a ternary molten carbonate melt at 450 °C. Controlling the electrochemical parameters (voltage, temperature, cathode material) enabled the conversion of CO2 to porous carbon with a tunable morphology and porosity for the first time at such a low temperature. Additionally, a well-controlled morphology and porosity are beneficial for reversible energy storage. In fact, these carbon materials delivered high specific capacity, stable cycling performances, and exceptional rate capability even under extremely fast charging conditions when integrated as an anode in lithium-ion batteries (LIBs). The present approach not only demonstrated efficient upcycling of CO2 into porous carbon suitable for enhanced energy storage but can also contribute to a clean and green energy technology that can reduce carbon emissions to achieve sustainable energy goals.

Preparation of nitrogen doped hyper-crosslinked polymer-based hard carbon for high performance Li+/Na+ battery anode.

Hyper cross-linked polymers (HCPs), as a key precursor of hard carbon (HC) anode materials, stand out because of their capacity for molecular-scale structural design and comparatively straightforward preparation techniques, which are not seen in other porous materials synthesized procedure. A novel synthesis method of HCPs is developed in this paper, which is through the incorporation of functional macromolecules, the structural control and heteroatom doping of the product has been achieved, thus augmenting its electrochemical performance in batteries. In this work, carbonized tetraphenylporphyrin zinc (TPP-Zn) doped HCP-based hard carbon (CTHCP) with stable structure was prepared by Friedel-Crafts reaction and carbonization by using naphthalene and trace TPP-Zn as monomers, dimethoxybenzene (DMB) as crosslinking agent and FeCl3 as catalyst. The introduction of TPP-Zn, a functional macromolecule with unique two-dimensional structure, realized the pore structure regulation and N doping of the raw carbonized HCP-based hard carbon (CHCP). The results showed that CTHCP had higher mesoporous volume, N content and wider layer spacing than CHCP. In addition, CTHCP anode exhibited excellent Li+/Na+ storage performance, initial reversible capacity, rate performance and long cycle life. More amount of N-containing (N-5) active sites and mesoporous content in CTHCP anode was the main reason for the improvement of Na+ storage effect. While the increased interlayer spacing had a greater effect on the lithium storage capacity. This study uncovered the design rules of HC anode materials suitable for Li+/Na+ batteries and provided a new idea for the preparation of high-performance HC anode materials.

Invasive alien plant biomass-derived hard carbon anode for sodium-ion batteries.

In the context of rampant growth of invasive plants, finding suitable ways for resource utilization has become the optimal choice for invasive plant management. In the field of energy storage, sodium-ion batteries have been limited by the lack of appropriate anode materials, and hard carbon stands out as the most promising candidate. Therefore, this study focuses on the preparation of biomass-derived carbons from three invasive plant species, namely Spartina alterniflora Loisel., Solidago canadensis L., and Erigeron canadensis L., through high-temperature carbonization. The resulting biomass carbons are then subjected to cleaning and activation processes to prepare sodium-ion anode materials. The internal structure of the materials was characterized using SEM, TEM, XRD, XPS, Raman spectroscopy, and BET. The materials exhibited a significant amount of pore structures, with interlayer spacing around 0.37 nm, which is larger than the original graphite interlayer spacing. The plant anode materials were assembled into full batteries for cyclic charge/discharge tests. The results show that all three anode materials have good multiplicative performance and excellent cyclable charge/discharge. After 100 cycles at a current of 50 mA in the voltage range of 0-3.0 V, the reversible capacities of the three materials reached 245.3, 207.19, and 227.12 mAh/g, respectively. Among them, the material derived from Spartina alterniflora maintained a capacity of 141.63 mAh/g even after 1000 cycles at a current of 200 mA, demonstrating the best capacity performance.

High-Energy Ball Milling Promoted Sulfur Immobilization for Constructing High-Performance Na-Storage Carbon Anodes.

Sulfur (S) doping is an effective method for constructing high-performance carbon anodes for sodium-ion batteries. However, traditional designs of S-doped carbon often exhibit low initial Coulombic efficiency (ICE), poor rate capability, and impoverished cycle performance, limiting their practical applications. This study proposes an innovative design strategy to fabricate S-doped carbon using sulfonated sugar molecules as precursors via high-energy ball milling. The results show that the high-energy ball milling can immobilize S for sulfonated sugar molecules by modulating the chemical state of S atoms, thereby creating a S-rich carbon framework with a doping level of 15.5 wt %. In addition, the S atoms are present mainly in the form of C-S bonds, facilitating a stable electrochemical reaction; meanwhile, S atoms expand the spacing between carbon layers and contribute sufficient capacitance-type Na-storage sites. Consequently, the S-doped carbon exhibits a large capacity (>600 mAh g-1), a high ICE (>90%), superior cycling stability (490 mAh g-1 after 1100 cycles at 5 A g-1), and outstanding rate performance (420 mAh g-1 at a high current density of 50 A g-1). Such excellent Na-storage properties of S-doped carbon have rarely been reported in the literatures before.

Chelation-Assisted formation of carbon nanotubes interconnected Yolk-Shell Silicon/Carbon anodes for High-Performance Lithium-ion batteries.

As a viable replacement to commercial graphite anodes, silicon (Si) anodes have gained much attention from academics because of their considerable theoretical specific capacity and appropriate reaction voltage. Nevertheless, some limitations still exist in developing silicon anodes, including significant volume expansion and poor electrical conductivity. Herein, the carbon nanotubes (CNTs) interconnected yolk-shell silicon/carbon anodes (YS-Si@CoNC) were prepared via the chelation competition induced polymerization (CCIP) approach. The YS-Si@CoNC anode, designed in this study, demonstrates improved performance. At the current density of 0.5 A g-1 and 1 A g-1, a capacity of 1001 mAh g-1 and 956.5 mAh g-1 can be achieved after 150 cycles and after 300 cycles, respectively. In particular, at the current density of 5 A g-1, the reversible specific capacity of 688 mAh g-1 is realized. The exceptional outcomes are mainly attributed to the internal voids that adequately alleviate the volumetric expansion and the CNTs and carbon shells that provide an efficient conducting matrix to fasten the diffusion of electrons and lithium-ions. Our research presents a convenient way of designing Si/C anode materials with a yolk-shell structure to guarantee impressive electrical conductivity and robust structural integrity for high-performance LIBs.

Revisiting Lithium- and Sodium-Ion Storage in Hard Carbon Anodes.

The galvanostatic lithiation/sodiation voltage profiles of hard carbon anodes are simple, with a sloping drop followed by a plateau. However, a precise understanding of the corresponding redox sites and storage mechanisms is still elusive, which hinders further development in commercial applications. Here, a comprehensive comparison of the lithium- and sodium-ion storage behaviors of hard carbon is conducted, yielding the following key findings: 1) the sloping voltage section is presented by the lithium-ion intercalation in the graphitic lattices of hard carbons, whereas it mainly arises from the chemisorption of sodium ions on their inner surfaces constituting closed pores, even if the graphitic lattices are unoccupied; 2) the redox sites for the plateau capacities are the same as those for the closed pores regardless of the alkali ions; 3) the sodiation plateau capacities are mostly determined by the volume of the available closed pore, whereas the lithiation plateau capacities are primarily affected by the intercalation propensity; and 4) the intercalation preference and the plateau capacity have an inverse correlation. These findings from extensive characterizations and theoretical investigations provide a relatively clear elucidation of the electrochemical footprint of hard carbon anodes in relation to the redox mechanisms and storage sites for lithium and sodium ions, thereby providing a more rational design strategy for constructing better hard carbon anodes.

Reversible Oxygen-Rich Functional Groups Grafted 3D Honeycomb-Like Carbon Anode for Super-Long Potassium Ion Batteries.

Studies have found that oxygen-rich-containing functional groups in carbon-based materials can be used as active sites for the storage performance of K+, but the basic storage mechanism is still unclear. Herein, we construct and optimize 3D honeycomb-like carbon grafted with plentiful COOH/C = O functional groups (OFGC) as anodes for potassium ion batteries. The OFGC electrode with steady structure and rich functional groups can effectively contribute to the capacity enhancement and the formation of stable solid electrolyte interphase (SEI) film, achieving a high reversible capacity of 230 mAh g-1 at 3000 mA g-1 after 10,000 cycles (almost no capacity decay) and an ultra-long cycle time over 18 months at 100 mA g-1. The study results revealed the reversible storage mechanism between K+ and COOH/C = O functional groups by forming C-O-K compounds. Meanwhile, the in situ electrochemical impedance spectroscopy proved the highly reversible and rapid de/intercalation kinetics of K+ in the OFGC electrode, and the growth process of SEI films. In particular, the full cells assembled by Prussian blue cathode exhibit a high energy density of 113 Wh kg-1 after 800 cycles (calculated by the total mass of anode and cathode), and get the light-emitting diodes lamp and ear thermometer running.