Rechargeable Research Articles

Rechargeable Mg-Br2 Battery with Ultrafast Bromine Chemistry.

A sustainable society necessitates the support of diversified energy storage systems. Magnesium metal batteries, known for the environmental friendliness, safety of dendrite-less, cost-effective, and high volumetric capacity of magnesium metal, exhibit promising prospects. However, the high charge density of the magnesium ion leads to sluggish ion diffusion in cathodes, posing challenges for developing magnesium metal battery systems with high power and high energy density. Here, inspired by the Hard-Soft-Acid-Base theory, we propose a soft-anion-induced bond weakening strategy to address the diffusion difficulty. The bulky and broadly electron-distributed succinimide ion (SN-) in SN-Mg-Br significantly weakens the Mg-Br bond, promoting rapid magnesium ion transport and enabling ultrafast bromine chemistry, thus realizing a highly rechargeable Mg-Br2 battery prototype. Benefiting from the solubilization of SN-, the Mg-Br2 batteries achieve a high discharge plateau of 2.7 V, a remarkable specific capacity of 326 mAh gBr-1, and an impressive lifespan of 400 cycles. Attributed to the half-half diffusion/adsorption-desorption control process mechanism, the batteries can be well cycled under high-rate charging at 10 C and ultralow temperatures down to -55 °C. This bond weakening strategy may stimulate the development of battery systems with similar high charge density to magnesium ion, toward high power and high energy density, paving the way for sustainable energy storage systems.

A Novel Self‐Reconfigurable Battery Pack Design with and without Active Cell Balancing

In electric vehicle industry, rechargeable multicell battery packs commonly with fixed configurations are adopted. Such fixed battery configurations have several drawbacks, including limited fault tolerance during unusual operating situations, poor cell state variation management, etc. Thus, this article proposes a self‐reconfigurable battery pack design considering two scenarios: with and without active cell balancing. Herein, the issue of cell state variation is mostly solved by the proposed configuration mode, and further monitoring, control, and protection can be easily appended to accomplish other functionalities, for example, meeting dynamic voltage requirement. Each proposed design is validated by simulation results for a six‐cell polymer lithium‐ion battery pack. The proposed design can maximally utilize the battery's capacity and help to protect cells from over‐charging and over‐discharging as well. This research could be further extended to other application scenarios involving wide‐range dynamic voltage requirements.

Built-in Electric Field in 1D/2D Heterostructure Boosts Zinc Air Battery Performance.

The realization of a rechargeable zinc-air battery (ZAB) is hindered by the low intrinsic oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) activities. In this work, an abundant built-in electric field is noticed in a 1D/2D CoO/CoS2 heterostructure, triggering electron transfer from CoO to CoS2 associated with a downshifted d band center of the Co atom mitigating the strong electrochemical adsorption of *OH species on active sites; thereby, boosted OER and ORR performance are achieved. Namely, the OER specific activity of CoO/CoS2 is enhanced by 3.8- and 2.2-fold compared to the counterpart of CoO and CoS2, respectively. Furthermore, the kinetic current density of CoO/CoS2, a fingerprint of intrinsic ORR activity, is promoted by 46 and 6.6 times relative to CoO and CoS2. The rechargeable ZAB performance attains 215.6 mW cm-2, 1.6-times better than Pt/C-IrO2. Moreover, the superior performance remained for 600 h. Besides, the battery performance of the all-solid-state ZAB reaches 83.8 mW cm-2, revealing its promising application in wearable device.

Optimal estimation of SoC, SoH using machine learning models and design of control algorithm for active cell balancing in lithium ion batteries

Abstract Electric vehicles transform the automotive industry by replacing
traditional vehicles powered by fossil fuels with less polluting and efficient vehicles.
They are powered by rechargeable Li-ion batteries. While there are drawbacks
associated with Li-ion battery technology, it’s important to note that these challenges
can be addressed or mitigated effectively. A battery management system ensures the
tracking of all functions performed by the battery. An advanced battery management
system should accurately estimate the battery’s state of health and state of charge.
This paper aims to develop machine learning models for the estimation of the state of
health and state of charge and to implement cell balancing in a battery management
system. A dataset of battery charging and discharging profiles was used to train
various machine learning models for estimation. These methods are computationally
less complex than conventional methods. In addition, a cell balancing algorithm is
implemented to control the charging and discharging of individual cells in a battery
pack and balance the state of charge of each cell. The machine learning solution is
created using several machine learning models, including Gradient Boosting, Random
Forest, Linear Regression, AdaBoost, and Multi-layer Perceptron. Among the models

Gradient Boosting and Random Forest provide good MSE and R2 score. The use of
machine learning algorithms for the assessment of state of health and charge estimation
combined with the design of an efficient control algorithm for active cell balancing
offers significant advancements in the battery management system to optimise the
performance, reliability, and useful life of Li-ion batteries. The paper also presents
a case study utilising a combination of deep learning-based SoC, SoH estimation
algorithms in a simulated data set. A well-designed control algorithm for active
cell balancing presents a holistic and effective approach to optimise Li-ion batteries' performance,
reliability, and lifespan.

Grid-integrated solutions for sustainable EV charging: a comparative study of renewable energy and battery storage systems

IntroductionThe integration of electric vehicles (EVs) into the power network challenges the 1) grid capacity, 2) stability, and 3) management. This is due to the 1) increased peak demand, 2) infrastructure strain, and 3) intermittent charging patterns. Previous studies lack comprehensive integration of renewable energy and battery storage with EV charging.MethodsTo address these challenges, this study explores the effectiveness of incorporating renewable energy resources (RERs) and battery energy storage systems (BESS) alongside the traditional grid. The proposed study utilizes the HOMER Grid® and conducted a comprehensive analysis.ResultsThe proposed study compares two grid integrated scenarios: 1) Case-1 (grid and photovoltaic (PV) systems), and 2) Case-2 (grid, PV systems, and BESS). Both these scenarios are compared against a Base case relying solely on grid power. The evaluation employed techno-economic analysis while focusing on 1) net present cost (NPC), 2) cost of energy, and 3) annualized savings. Additionally, the proposed study analyzed 4) seasonal variations in EV charging demand, 5) grid interactions, 6) PV production, and 7) the operation of BESS in both summer and winter. The comparative analysis reveals that the Base case incurs a net present cost (NPC) of $546,977 and a cost of energy (COE) of $0.354 per kWh. In contrast, Case-1, which integrates a 100 kW PV system, shows a significantly lower NPC of -$122,962 and a reduced COE of -$0.043 per kWh, with annualized savings of $61,492. Case-2, incorporating both the 100 kW PV system and a BESS with a capacity of 9.8 kWh, has a higher NPC of $309,667 but a COE of $0.112 per kWh and provides annual savings of $51,233 compared to the Base case.DiscussionSeasonal analysis highlights that Case-2 achieves the lowest carbon emissions in summer, ranging from 2.0 to 2.5 tons, while Case-1 shows the lowest emissions in winter, ranging from 3.2 to 3.4 tons. This model 1) reduces operational costs, 2) minimizes carbon emissions, while 3) making it compelling for future energy systems in increasing EV adoption.

Toward Practical Li–S Batteries: On the Road to a New Electrolyte

AbstractThe lithium–sulfur (Li–S) battery system has attracted considerable attention due to its ultrahigh theoretical energy density and promising applications. However, with the increasing demands on S loading and electrolyte content, practical Li–S batteries still face several serious challenges, such as slow reaction kinetics at the cathode interface, unstable anode interface reactions, and undesirable crosstalk effects between the cathode and anode. Traditional electrolyte systems often struggle to address these challenges under practical conditions, thereby rendering it imperative to establish a new electrolyte system for practical Li–S batteries. This review first discusses the necessity of establishing a new electrolyte and propose specific parameter requirements, such as the electrolyte‐to‐sulfur mass ratio (Em/S). Subsequently, some electrolyte modification strategies proposed by researchers are summarized to address the different challenges associated with practical Li–S batteries. Finally, the combination of different strategies is reviewed, aiming to reveal more effective design approaches that simultaneously address multiple challenges, while providing guidance for establishing a new balanced electrolyte for practical Li–S batteries. This article promotes the development of new electrolytes for practical Li–S batteries and can act as a reference for the development of electrolytes for other secondary batteries.

Pyridinic N[sbnd]B pair-doped carbon microspheres with refined hierarchical architectures for rechargeable zinc-air batteries

Refined architectures are of vital importance in determining the electrocatalytic activity of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Herein, pyridinic NB pair doped carbon microspheres (NB-CMS) with hierarchical micropore-mesopore structure are prepared via a SiO2 hard template assisted CO2 activation strategy. The pyridinic NB pair accounts for ≈ 59.9 % of all N species in NB-CMS, accelerating the ORR process with onset potential (0.996 V) and half-wave potential (0.889 V). Meanwhile, the NB-CMS also exhibits high OER performance with overpotential of 384 mV at 10 mA cm−2. The assembled Zinc-air battery exhibits maximum power density of 134 mW cm−2 and long-term charging and discharging stability over 358 h. Density functional theory (DFT) simulations reveal that the pyridinic NB pair exhibits the highest electrocatalytic performance in dual-functional catalysis, owing to the highest charge density and readily accepts electrons from *OOH adsorbate of N active site neighboring B.

Unraveling the Dynamic Properties of New-Age Energy Materials Chemistry Using Advanced In Situ Transmission Electron Microscopy

The field of energy storage and conversion materials has witnessed transformative advancements owing to the integration of advanced in situ characterization techniques. Among them, numerous real-time characterization techniques, especially in situ transmission electron microscopy (TEM)/scanning TEM (STEM) have tremendously increased the atomic-level understanding of the minute transition states in energy materials during electrochemical processes. Advanced forms of in situ/operando TEM and STEM microscopic techniques also provide incredible insights into material phenomena at the finest scale and aid to monitor phase transformations and degradation mechanisms in lithium-ion batteries. Notably, the solid–electrolyte interface (SEI) is one the most significant factors that associated with the performance of rechargeable batteries. The SEI critically controls the electrochemical reactions occur at the electrode–electrolyte interface. Intricate chemical reactions in energy materials interfaces can be effectively monitored using temperature-sensitive in situ STEM techniques, deciphering the reaction mechanisms prevailing in the degradation pathways of energy materials with nano- to micrometer-scale spatial resolution. Further, the advent of cryogenic (Cryo)-TEM has enhanced these studies by preserving the native state of sensitive materials. Cryo-TEM also allows the observation of metastable phases and reaction intermediates that are otherwise challenging to capture. Along with these sophisticated techniques, Focused ion beam (FIB) induction has also been instrumental in preparing site-specific cross-sectional samples, facilitating the high-resolution analysis of interfaces and layers within energy devices. The holistic integration of these advanced characterization techniques provides a comprehensive understanding of the dynamic changes in energy materials. This review highlights the recent progress in employing state-of-the-art characterization techniques such as in situ TEM, STEM, Cryo-TEM, and FIB for detailed investigation into the structural and chemical dynamics of energy storage and conversion materials.

Exploring Lignin Biosynthesis Genes in Rice: Evolution, Function, and Expression

Lignin is nature’s second most abundant vascular plant biopolymer, playing significant roles in mechanical support, water transport, and stress responses. This study identified 90 lignin biosynthesis genes in rice based on phylogeny and motif constitution, and they belong to PAL, C4H, 4CL, HCT, C3H, CCoAOMT, CCR, F5H, COMT, and CAD families. Duplication events contributed largely to the expansion of these gene families, such as PAL, CCoAOMT, CCR, and CAD families, mainly attributed to tandem and segmental duplication. Microarray data of 33 tissue samples covering the entire life cycle of rice suggested fairly high PAL, HCT, C3H, CCoAOMT, CCR, COMT, and CAD gene expressions and rather variable C4H, 4CL, and F5H expressions. Some members of lignin-related genes (OsCCRL11, OsHCT1/2/5, OsCCoAOMT1/3/5, OsCOMT, OsC3H, OsCAD2, and OsPAL1/6) were expressed in all tissues examined. The expression patterns of lignin-related genes can be divided into two major groups with eight subgroups, each showing a distinct co-expression in tissues representing typically primary and secondary cell wall constitutions. Some lignin-related genes were strongly co-expressed in tissues typical of secondary cell walls. Combined HPLC analysis showed increased lignin monomer (H, G, and S) contents from young to old growth stages in five genotypes. Based on 90 genes’ microarray data, 27 genes were selected for qRT-PCR gene expression analysis. Four genes (OsPAL9, OsCAD8C, OsCCR8, and OsCOMTL4) were significantly negatively correlated with lignin monomers. Furthermore, eleven genes were co-expressed in certain genotypes during secondary growth stages. Among them, six genes (OsC3H, OsCAD2, OsCCR2, OsCOMT, OsPAL2, and OsPAL8) were overlapped with microarray gene expressions, highlighting their importance in lignin biosynthesis.

Cobalt-doped copper sulfide nanocomposite integrated with graphene oxide as a high-performance conversion anode for aqueous zinc-ion batteries

Rechargeable aqueous zinc-ion batteries (ZIBs) encounter substantial obstacles arising from the inherent dilemmas of dendrite growth, hydrogen gas evolution, and corrosion affiliated with zinc metal anodes, thereby highlighting the necessity for researching conversion anode materials as a promising pathway forward. Copper sulfide (CuS) has been demonstrated as a promising conversion anode material for ZIBs due to its notable electrochemical performance, while challenges persist regarding the Coulombic interactions between Zn2+ and host anions, coupled with the material’s fundamental conductivity that remains less than fully satisfactory. To address the above issues, we have designed and synthesized a nanostructured composite of cobalt doped CuS integrated in graphene oxide frames (GO/Co-CuS) as anode for ZIBs. The cobalt doping serves to alleviate Coulomb interaction (Coulomb attraction) between Zn2+ and host anions, thereby enhancing the kinetics of Zn2+ diffusion. Furthermore, the incorporation of GO framework improves the electrical conductivity of the material and mitigates volume expansion during the reaction process. The synergistic effect engendered by the combination of cobalt doping and the incorporation of a GO framework results in the remarkable electrochemical performance exhibited by GO/Co-CuS. The GO/Co-CuS composite nanostructure exhibited commendable rate capability and cycling stability. Specifically, it exhibits remarkable rate capability, delivering 296 mAh g−1 at 1 A/g and 168 mAh g−1 at 10 A/g. Furthermore, after 1000 cycles at a high current density of 10 A/g, it maintains a capacity of 166 mAh g−1, demonstrating exceptional cycling stability. Additionally, the full-cell configuration of GO/Co-CuS//MnO2@CNTs, when cycled 241 times at 2 A/g, retains a capacity of 79 mAh g−1, thereby confirming the practical efficacy of the GO/Co-CuS nanocomposite as an efficient conversion anode for ZIBs.

Superlattice cathodes endow cation and anion co-intercalation for high-energy-density aluminium batteries

Conventionally, rocking-chair batteries capacity primarily depends on cation shuttling. However, intrinsically high-charge-density metal-ions, such as Al3+, inevitably cause strong Coulombic ion-lattice interactions, resulting in low practical energy density and inferior long-term stability towards rechargeable aluminium batteries (RABs). Herein, we introduce tunable quantum confinement effects and tailor a family of anion/cation co-(de)intercalation superlattice cathodes, achieving high-voltage anion charge compensation, with extra-capacity, in RABs. The optimized superlattice cathode with adjustable van der Waals not only enables facile traditional cation (de)intercalation, but also activates O2– compensation with an extra anion reaction. Furthermore, the constructed cathode delivers high energy-density (466 Wh kg–1 at 107 W kg−1) and one of the best cycle stability (225 mAh g–1 over 3000 cycles at 2.0 A g–1) in RABs. Overall, the anion-involving redox mechanism overcomes the bottlenecks of conventional electrodes, thereby heralding a promising advance in energy-storage-systems.

High Performance and Selective Sequestration of Cd(II) from Water by Layered Thiophosphate.

The extensive use of toxic cadmium (Cd) in energy conversion and industrial applications ranging from solar cells and battery appliances to paints and pigments contaminates water bodies. However, the upper limit of Cd contamination in drinking water is to be only 3 ppb by the WHO and 5 ppb by the USA-EPA, which underscores the need for cost-effective, efficient, and ppb level capture of Cd from contaminated water. Leveraging the selectivity due to Lewis's hard-soft acid-base (HSAB) theory, we have achieved swift and highly selective capture of Cd(II) ions from aqueous mediums using layered potassium manganese thiophosphate (K-MnPS3). K-MnPS3 effectively removes Cd(II) ions from extremely dilute aqueous solutions (ppb levels), achieving a maximum sorption capacity of 405.43 mg/g and a removal rate exceeding 97% within 20 min. Even in the presence of competing ions such as Na+, Mg2+, Ca2+, and Pb2+, K-MnPS3 remains selective. Additionally, it operates efficiently across a wide pH range (1.78-11.19) with a high distribution coefficient (∼104 mL/g). Breakthrough experiments using a 1 wt % K-MnPS3 and 99 wt % sand column showed complete breakthrough of Cd(II) after 62 h, leading K-MnPS3 as a promising candidate for Cd(II) removal from industrial effluents.

Electrolyte Engineering with TFA- Anion-Rich Solvation Structure to Construct Highly Stable Zn2+/Na+ Dual-Salt Batteries.

Electrolyte engineering is recognized as an effective technique for high-performance aqueous zinc-ion rechargeable batteries, addressing difficulties such as free water decomposition, zinc anode corrosion, and zinc dendrite growth. Different from traditional strategies in aqueous electrolyte systems, this work focuses on organic electrolytes involving zinc trifluoroacetate hydrate (Zn(TFA)2·xH2O), sodium trifluoroacetate (NaTFA) dual-salt and acetonitrile (AN) solvent, in which trifluoroacetate anions (TFA- anions) have strong affinity toward zinc ions to form anion-rich solvates, thus inducing an inorganic-rich solid electrolyte interphase (SEI) to protect Zn from dendrite growth and side reactions. The Zn anode manifests long-term cycling over 2400h at a current density of 0.5mAcm-2 with a high Coulombic efficiency (CE) of 99.75%, showing an areal capacity as high as 5mAhcm-2. Owing to the high reversibility of the sodium ions intercalation/deintercalation process in Na2MnFe(CN)6, the Zn//Na2MnFe(CN)6 full cells with the dual-salt electrolyte perform much better in terms of capacity retention than a device with Zn(TFA)2/AN electrolyte. This approach may open a new avenue for efficient zinc-ion rechargeable batteries via developing organic electrolytes.

Synthesis, technological prospects and applications of MXene in biomedicine, supercapacitors and sensors: A review

MXenes are one of the most important classes of materials discussed worldwide by many researchers of diverse fields for diverse applications in recent years. It is a nanomaterial with a wide range of applications due to its multiple forms and structures with fascinating properties, for example, high surface area and porosity, biocompatibility, ease of fictionalizing with various active chemical moieties, benefit of high metallic conductivity, activated metallic hydroxide sites, and sensitivity to moisture. MXenes have great chances for potential applications in environmental issues, water purification, biological applications, and energy storage devices and sensors. MXenes show great selectivity towards the absorption of heavy metals and a good capability to reduce chemical and biological pollutants present in the water. The present review article critically analyzed advancements in water purification using the adsorption and reduction abilities of MXenes and their composites. The mechanism of various procedures, important challenges, and associated problems using MXene and their composites are discussed in detail. The future research directions can be extracted from this article efficiently and comprehensively. The energy storage issues of rechargeable lithium-ion batteries, batteries other than lithium-ion batteries, and electrochemical capacitors are also discussed in detail.

A Rechargeable Urea-Assisted Zn-Air Battery with High Energy Efficiency and Fast-Charging Enabled by Engineering High-Energy Interfacial Structures.

Electrochemical urea oxidation reaction (UOR) offers a promising alternative to the oxygen evolution reaction (OER) in clean energy conversion and storage systems. Nickel-based catalysts are highly regarded as promising electrocatalysts for the UOR. However, their effectiveness is significantly hindered by the unavoidable self-oxidation reaction of nickel species during UOR. To address this challenge, we proposed an interface chemistry modulation strategy to boost UOR kinetics by creating a high-energy interfacial heterostructure. This heterostructure features the incorporation of Ag at the CoOOH@NiOOH heterojunction interface. Strong interactions significantly promote the electron exchanges in the heterointerface between the -OH and -O. Consequently, the improved electron delocalization led to the formation of stronger bonds between Co sites and urea CO(NH2)2, promoting a preference for urea to occupy Co active sites over OH*. The resulting catalyst, Ag-CoOOH@NiOOH, affords an ultrahigh UOR activity with a low potential of 1.33 V at 100 mA cm-2. The fabricated catalyst exhibits a mass activity exceeding that of initial cobalt oxyhydroxide by over 11.9 times. The rechargeable urea-assisted zinc-air batteries (ZABs) achieves a record-breaking energy efficiency of 74.56% at 1 mA cm-2, remarkable durability (1000 hours at even a current density of 50 mA cm-2), and quick charge performances.

Overview of Startups Developing Artificial Intelligence for the Energy Sector

The energy industry is experiencing a major change due to fast progress in artificial intelligence (AI). Startup companies in this revolution use AI technologies like Machine Learning (ML), predictive analytics, and optimization algorithms to improve energy efficiency, optimize grid management, and incorporate renewable energy sources. AI-powered solutions allow for a more accurate prediction of demand, immediate monitoring, and automated decision-making processes, significantly enhancing operational efficiency and sustainability. Through promoting a more effective energy system, these advancements play a vital role in the worldwide battle against climate change and carbon dioxide emissions. Adding to the progress of AI, quantum computing (QC) shows great potential despite being a nascent area. The collaboration of AI and QC is poised to transform the energy industry by offering unmatched computational capabilities. This blend of technologies can tackle intricate energy obstacles like enhancing power grids and enhancing battery storage, which traditional computers cannot currently handle. Combining QC with AI speeds up innovation, providing advanced solutions that improve the resilience and efficiency of energy networks. This paper discusses the latest advancements, possible effects, and upcoming paths of new companies leading in AI and QC innovations within the energy industry. Their joint responsibility is highlighted in advancing a sustainable and intelligent energy future, as well as tackling crucial environmental issues and lessening the impact of climate change.

Porous Silicon-Supported Catalytic Materials for Energy Conversion and Storage.

Porous silicon (Si) has a tetrahedral structure similar to that of sp3- hybridized carbon atoms in a typical diamond structure, which affords it unique chemical and physical properties including an adjustable intrinsic bandgap, a high-speed carrier transfer efficiency. It has shown great potential in photocatalysis, rechargeable batteries, solar cells, detectors, and electrocatalysis. This review introduces various porous Si-supported electrocatalysts and analyzes the reasons why porous Si is used as a new carrier/active sites from the perspectives of its molecular structure, electronic properties, synthesis methods, etc. The electrochemical applications of porous Si-based electrocatalysts in energy conversion reactions such as hydrogen evolution reaction, oxygen evolution reaction, oxygen reduction reaction, and total water decomposition together with lithium-ion batteries (LIBs) and supercapacitors in energy storage are summarized. The challenges and future research directions for porous Si are also discussed. This review aims to deepen the understanding of porous Si and promote the development and applications of this new type of Si material.

A voltage-decoupled Zn-Br2 flow battery for large-scale energy storage

The flow battery represents a highly promising energy storage technology for the large-scale utilization of environmentally friendly renewable energy sources. However, the increasing discharge power of rechargeable battery results in a higher charge voltage due to its coupling relationship in charge-discharge processes, intensifying the burden of renewable energy power systems. Herein, we proposed a voltage-decoupled Na+-conducting Zn-Br2 flow battery (Ud-Na-ZBFB). Within a pH-regulation strategy, both neutral Zn/Zn2+ and alkaline Zn/Zn(OH)42− negative redox couples are integrated into one device, so as to increase discharge voltage a 0.5 V theoretical increase while remains a low charge voltage. The proof-of-concept Ud-Na-ZBFB demonstrates an unprecedented voltage characteristic, achieving a discharge voltage of up to 2.18 V while maintaining a remarkably low charge voltage of 1.78 V at a current density of 20 mA cm−2. Benefiting from the high discharge voltage, the peak power density of Ud-Na-ZBFB reaches 580 mW cm−2, nearly twice higher than the traditional ZBFB. Besides, the Ud-Na-ZBFB cycling operates for 45 h with excellent stability and resilience. With the “cycle-to-stage” operational mode, battery state of Ud-Na-ZBFB can be completely recovered after a long-term operation stage with several cycles, which electrolyte utilization efficiency of one stage is up to 41 %. This work offers a brand-new utilization pattern for high-power rechargeable battery that possesses a great potential in energy storage application scenes.

Solvent-mediated oxide hydrogenation in layered cathodes.

Self-discharge and chemically induced mechanical effects degrade calendar and cycle life in intercalation-based electrochromic and electrochemical energy storage devices. In rechargeable lithium-ion batteries, self-discharge in cathodes causes voltage and capacity loss over time. The prevailing self-discharge model centers on the diffusion of lithium ions from the electrolyte into the cathode. We demonstrate an alternative pathway, where hydrogenation of layered transition metal oxide cathodes induces self-discharge through hydrogen transfer from carbonate solvents to delithiated oxides. In self-discharged cathodes, we further observe opposing proton and lithium ion concentration gradients, which contribute to chemical and structural heterogeneities within delithiated cathodes, accelerating degradation. Hydrogenation occurring in delithiated cathodes may affect the chemo-mechanical coupling of layered cathodes as well as the calendar life of lithium-ion batteries.

Bimetallic Coupling Strategy Modulating Electronic Construction to Accelerate Sulfur Redox Reaction Kinetics for High-Energy Flexible Li-S Batteries.

Lithium-sulfur (Li-S) batteries are considered the most promising energy storage battery due to their low cost and high theoretical energy density. However, the low utilization rate of sulfur and slow redox kinetics have seriously limited the development of Li-S batteries. Herein, the electronic state modulation of metal selenides induced by the bi-metallic coupling strategy is reported to enhance the redox reaction kinetics and sulfur utilization, thereby improving the electrochemical performance of Li-S batteries. Theoretical calculations reveal that the electronic structure can be modulated by Ni-Co coupling, thus lowering the conversion barrier of lithium polysulfides (LiPSs)and Li+, and the synergistic interaction between NiCoSe nanoparticles and nitrogen-doped porous carbon (NPC) is facilitating to enhance electron transport and ion transfer kinetics of the NiCoSe@NPC-S electrodes. As a result, the assembled Li-S batteries based on NiCoSe@NPC-S exhibit high capacities (1020mAhg-1 at 1C) and stable cycle performance (80.37% capacity retention after 500 cycles). The special structural design and bimetallic coupling strategy promote the batteries working even under lean electrolyte (7.2µLmg-1) with a high sulfur loading (6.5mgcm-2). The proposed bimetallic coupling strategy modulating electronic construction with N-doping porous carbon has jointly contributed the good redox reaction kinetics and high sulfur utilization.