A Rechargeable Li‐CO2 Battery with a Gel Polymer Electrolyte

The utilization of CO₂ in Li‐CO₂ batteries is attracting extensive attention. However, the poor rechargeability and low applied current density have remained the Achilles’ heel of this energy device. The gel polymer electrolyte (GPE), which is composed of a polymer matrix filled with tetraglyme‐based liquid electrolyte, was used to fabricate a rechargeable Li‐CO₂ battery with a carbon nanotube‐based gas electrode. The discharge product of Li₂CO₃ formed in the GPE‐based Li‐CO₂ battery exhibits a particle‐shaped morphology with poor crystallinity, which is different from the contiguous polymer‐like and crystalline discharge product in conventional Li‐CO₂ battery using a liquid electrolyte. Accordingly, the GPE‐based battery shows much improved electrochemical performance. The achieved cycle life (60 cycles) and rate capability (maximum applied current density of 500 mA g⁻¹) are much higher than most of previous reports, which points a new way to develop high‐performance Li‐CO₂ batteries.     

Reversible S0/MgSx Redox Chemistry in a MgTFSI2/MgCl2/DME Electrolyte for Rechargeable Mg/S Batteries

The redox chemistry of magnesium and its application in rechargeable Mg batteries has received increasing attention owing to the unique benefits of Mg metal electrodes, namely high reversibility without dendrite formation, low reduction potentials, and high specific capacities. The Mg/S couple is of particular interest owing to its high energy density and low cost. Previous reports have confirmed the feasibility of a rechargeable Mg/S battery; however, only limited cycling stability was achieved, and the complicated procedure for the preparation of the electrolytes has significantly compromised the benefits of Mg/S chemistry and hindered the development of Mg/S batteries. Herein, we report the development of the first rechargeable Mg/S battery with a MgTFSI₂/MgCl₂/DME electrolyte (DME=1,2‐dimethoxyethane, TFSI=bis(trifluoromethanesulfonyl)imide) and realize the best cycling stability among all reported Mg/S batteries by suppressing polysulfide dissolution. Mechanistic studies show that the battery works via S⁰/MgS_x redox processes and that the large voltage hysteresis is mainly due to the Mg anode overpotential.     

An Antiaromatic Electrode‐Active Material Enabling High Capacity and Stable Performance of Rechargeable Batteries

Although aromatic compounds occupy a central position in organic chemistry, antiaromatic compounds have demonstrated little practical utility. Herein we report the application of an antiaromatic compound as an electrode‐active material in rechargeable batteries. The performance of dimesityl‐substituted norcorrole nickel(II) complex (NiNC) as a cathode‐active material was examined with a Li metal anode. A maximum discharge capacity of about 207 mAhg^?1 was maintained after 100 charge/discharge cycles. Moreover, the bipolar redox property of NiNC enables the construction of a Li metal free rechargeable battery. The high performance of NiNC batteries demonstrates a prospective feature of stable antiaromatic compounds as electrode‐active materials.     

Li‐N2 Batteries: A Reversible Energy Storage System?

Tremendous energy consumption is required for traditional artificial N₂ fixation, leading to additional environmental pollution. Recently, new Li‐N₂ batteries have inextricably integrated energy storage with N₂ fixation. In this work, graphene is introduced into Li‐N₂ batteries and enhances the cycling stability. However, the instability and hygroscopicity of the discharge product Li₃N lead to a rechargeable but irreversible system. Moreover, strong nonpolar N≡N covalent triple bonds with high ionization energies also cause low efficiency and irreversibility of Li‐N₂ batteries. In contrast, the modification with in situ generated Li₃N and LiOH restrained the loss and volume change of Li metal anodes during stripping and plating, thereby promoting the rechargeability of the Li‐N₂ batteries. The mechanistic study here will assist in the design of more stable Li‐N₂ batteries and create more versatile methods for N₂ fixation.     

Rocking‐Chair Ammonium‐Ion Battery: A Highly Reversible Aqueous Energy Storage System

Aqueous rechargeable batteries are promising solutions for large‐scale energy storage. Such batteries have the merit of low cost, innate safety, and environmental friendliness. To date, most known aqueous ion batteries employ metal cation charge carriers. Here, we report the first “rocking‐chair” NH₄‐ion battery of the full‐cell configuration by employing an ammonium Prussian white analogue, (NH₄)_1.47Ni[Fe(CN)₆]_0.88, as the cathode, an organic solid, 3,4,9,10‐perylenetetracarboxylic diimide (PTCDI), as the anode, and 1.0 m aqueous (NH₄)₂SO₄ as the electrolyte. This novel aqueous ammonium‐ion battery demonstrates encouraging electrochemical performance: an average operation voltage of ca. 1.0 V, an attractive energy density of ca. 43 Wh kg⁻¹ based on both electrodes’ active mass, and excellent cycle life over 1000 cycles with 67 % capacity retention. Importantly, the topochemistry results of NH₄⁺ in these electrodes point to a new paradigm of NH₄⁺‐based energy storage.     

A Dual‐Ion Organic Symmetric Battery Constructed from Phenazine‐Based Artificial Bipolar Molecules

Symmetric batteries received an increasing research interest in the past few years because of their simplified fabrication process and reduced manufacturing cost. In this study, we propose the first dual‐ion organic symmetric cell based on a molecular anion of 4,4′‐(phenazine‐5,10‐diyl)dibenzoate. The alkali salt of 4,4′‐(phenazine‐5,10‐diyl)dibenzoate allows a facile transport of cations and large anions, and remains stable in both oxidized and reduced states. The large potential difference between phenazine and benzoate results in a high cell voltage of 2.5 V and an energy density of 127 Wh kg^?1 at a current rate of 1 C. The introduction of bipolar organic materials may further consolidate the development of symmetric batteries that are fabricated from abundant elements and environmentally friendly materials.     

Organotrisulfide: A High Capacity Cathode Material for Rechargeable Lithium Batteries

An organotrisulfide (RSSSR, R is an organic group) has three sulfur atoms which could be involved in multi‐electron reduction reactions; therefore it is a promising electrode material for batteries. Herein, we use dimethyl trisulfide (DMTS) as a model compound to study its redox reactions in rechargeable lithium batteries. With the aid of XRD, XPS, and GC‐MS analysis, we confirm DMTS could undergo almost a 4 e^? reduction process in a complete discharge to 1.0 V. The discharge products are primarily LiSCH₃ and Li₂S. The lithium cell with DMTS catholyte delivers an initial specific capacity of 720 mAh g^?1_DMTS and retains 82 % of the capacity over 50 cycles at C/10 rate. When the electrolyte/DMTS ratio is 3:1 mL g^?1, the reversible specific energy for the cell including electrolyte can be 229 Wh kg^?1. This study shows organotrisulfide is a promising high‐capacity cathode material for high‐energy rechargeable lithium batteries.     

Dendrite-Free Sodium Metal Anodes Enabled by a Sodium Benzenedithiolate-Rich Protection Layer

Sodium metal is an ideal anode material for metal rechargeable batteries, owing to its high theoretical capacity (1166 mAh g⁻¹), low cost, and earth-abundance. However, the dendritic growth upon Na plating, stemming from unstable solid electrolyte interphase (SEI) film, is a major and most notable problem. Here, a sodium benzenedithiolate (PhS₂Na₂)-rich protection layer is synthesized in situ on sodium by a facile method that effectively prevents dendrite growth in the carbonate electrolyte, leading to stabilized sodium metal electrodeposition for 400 cycles (800 h) of repeated plating/stripping at a current density of 1 mA cm⁻². The organic salt, PhS₂Na₂, is found to be a critical component in the protection layer. This finding opens up a new and promising avenue, based on organic sodium slats, to stabilize sodium metals with a protection layer.     

A Porphyrin Complex as a Self‐Conditioned Electrode Material for High‐Performance Energy Storage

The novel functionalized porphyrin [5,15‐bis(ethynyl)‐10,20‐diphenylporphinato]copper(II) (CuDEPP) was used as electrodes for rechargeable energy‐storage systems with an extraordinary combination of storage capacity, rate capability, and cycling stability. The ability of CuDEPP to serve as an electron donor or acceptor supports various energy‐storage applications. Combined with a lithium negative electrode, the CuDEPP electrode exhibited a long cycle life of several thousand cycles and fast charge–discharge rates up to 53 C and a specific energy density of 345 Wh kg⁻¹ at a specific power density of 29 kW kg⁻¹. Coupled with a graphite cathode, the CuDEPP anode delivered a specific power density of 14 kW kg⁻¹. Whereas the capacity is in the range of that of ordinary lithium‐ion batteries, the CuDEPP electrode has a power density in the range of that of supercapacitors, thus opening a pathway toward new organic electrodes with excellent rate capability and cyclic stability.     

A Bipolar and Self‐Polymerized Phthalocyanine Complex for Fast and Tunable Energy Storage in Dual‐Ion Batteries

Bipolar redox organics have attracted interest as electrode materials for energy storage owing to their flexibility, sustainability and environmental friendliness. However, an understanding of their application in all‐organic batteries, let alone dual‐ion batteries (DIBs), is in its infancy. Herein, we propose a strategy to screen a variety of phthalocyanine‐based bipolar organics. The self‐polymerizable bipolar Cu tetraaminephthalocyanine (CuTAPc) shows multifunctional applications in various energy storage systems, including lithium‐based DIBs using CuTAPc as the cathode material, graphite‐based DIBs using CuTAPc as the anode material and symmetric DIBs using CuTAPc as both the cathode and anode materials. Notably, in lithium‐based DIBs, the use of CuTAPc as the cathode material results in a high discharge capacity of 236 mAh g^?1 at 50 mA g^?1 and a high reversible capacity of 74.3 mAh g^?1 after 4000 cycles at 4 A g^?1. Most importantly, a high energy density of 239 Wh kg^?1 and power density of 11.5 kW kg^?1 can be obtained in all‐organic symmetric DIBs.     

Lithium Azide as an Electrolyte Additive for All‐Solid‐State Lithium–Sulfur Batteries

Of the various beyond‐lithium‐ion battery technologies, lithium–sulfur (Li–S) batteries have an appealing theoretical energy density and are being intensely investigated as next‐generation rechargeable lithium‐metal batteries. However, the stability of the lithium‐metal (Li°) anode is among the most urgent challenges that need to be addressed to ensure the long‐term stability of Li–S batteries. Herein, we report lithium azide (LiN₃) as a novel electrolyte additive for all‐solid‐state Li–S batteries (ASSLSBs). It results in the formation of a thin, compact and highly conductive passivation layer on the Li° anode, thereby avoiding dendrite formation, and polysulfide shuttling. It greatly enhances the cycling performance, Coulombic and energy efficiencies of ASSLSBs, outperforming the state‐of‐the‐art additive lithium nitrate (LiNO₃).     

Solvent Molecule Cooperation Enhancing Lithium Metal Battery Performance at Both Electrodes

Developing electrolytes compatible with efficient and reversible cycling of electrodes is critical to the success of rechargeable Li metal batteries (LMBs). The Coulombic efficiencies and cycle lives of LMBs with ethylene carbonate (EC), dimethyl carbonate, ethylene sulfite (ES), and their combinations as electrolyte solvents show that in a binary‐solvent electrolyte the extent of electrolyte decomposition on the electrode surface is dependent on the solvent component that dominates the solvation sheath of Li⁺. This knowledge led to the development of an EC‐ES electrolyte exhibiting high performance for Li||LiFePO₄ batteries. Carbonate molecules occupy the solvation sheath and improve the Coulombic efficiencies of both the anode and cathode. Sulfite molecules lead to desirable morphology and composition of the solid electrolyte interphase and extend the cycle life of the Li metal anode. The cooperation between these components provides a new example of electrolyte optimization for improved LMBs.     

An Insoluble Benzoquinone‐Based Organic Cathode for Use in Rechargeable Lithium‐Ion Batteries

Application of organic electrode materials in rechargeable batteries has attracted great interest because such materials contain abundant carbon, hydrogen, and oxygen elements. However, organic electrodes are highly soluble in organic electrolytes. An organic electrode of 2,3,5,6‐tetraphthalimido‐1,4‐benzoquinone (TPB) is reported in which rigid groups coordinate to a molecular benzoquinone skeleton. The material is insoluble in aprotic electrolyte, and demonstrates a high capacity retention of 91.4 % (204 mA h g⁻¹) over 100 cycles at 0.2 C. The extended π‐conjugation of the material contributes to enhancement of the electrochemical performance (155 mA h g⁻¹ at 10 C). Moreover, density functional theory calculations suggest that favorable synergistic reactions between multiple carbonyl groups and lithium ions can enhance the initial lithium ion intercalation potential. The described approach may provide a novel entry to next‐generation organic electrode materials with relevance to lithium‐ion batteries.     

Engineering Fast Ion Conduction and Selective Cation Channels for a High‐Rate and High‐Voltage Hybrid Aqueous Battery

The rechargeable aqueous metal‐ion battery (RAMB) has attracted considerable attention due to its safety, low costs, and environmental friendliness. Yet the poor‐performance electrode materials lead to a low feasibility of practical application. A hybrid aqueous battery (HAB) built from electrode materials with selective cation channels could increase the electrode applicability and thus enlarge the application of RAMB. Herein, we construct a high‐voltage K–Na HAB based on K₂FeFe(CN)₆ cathode and carbon‐coated NaTi₂(PO₄)₃ (NTP/C) anode. Due to the unique cation selectivity of both materials and ultrafast ion conduction of NTP/C, the hybrid battery delivers a high capacity of 160 mAh g^?1 at a 0.5 C rate. Considerable capacity retention of 94.3 % is also obtained after 1000 cycles at even 60 C rate. Meanwhile, high energy density of 69.6 Wh kg^?1 based on the total mass of active electrode materials is obtained, which is comparable and even superior to that of the lead acid, Ni/Cd, and Ni/MH batteries.     

有机电极材料过渡态的研究进展

有机电极材料具有理论比容量大、结构可设计性强、加工使用过程环境友好等优点被广泛应用于二次电池的研究中。有机电极材料在氧化还原过程会产生具有不成对电子的自由基中间体,自由基中间体的稳定程度影响电极材料的电化学性能。通过改变材料的结构可以调控自由基中间体的稳定性,从而优化有机电极材料的电化学性能。本文对有机电极材料在电化学过程中产生的自由基中间体进行了分类介绍,阐明了材料结构、自由基中间体稳定性和电化学性能之间的关系。     

Sulfur‐Based Electrodes that Function via Multielectron Reactions for Room‐Temperature Sodium‐Ion Storage

Emerging rechargeable sodium‐ion storage systems—sodium‐ion and room‐temperature sodium–sulfur (RT‐NaS) batteries—are gaining extensive research interest as low‐cost options for large‐scale energy‐storage applications. Owing to their abundance, easy accessibility, and unique physical and chemical properties, sulfur‐based materials, in particular metal sulfides (MS_x) and elemental sulfur (S), are currently regarded as promising electrode candidates for Na‐storage technologies with high capacity and excellent redox reversibility based on multielectron conversion reactions. Here, we present current understanding of Na‐storage mechanisms of the S‐based electrode materials. Recent progress and strategies for improving electronic conductivity and tolerating volume variations of the MS_x anodes in Na‐ion batteries are reviewed. In addition, current advances on S cathodes in RT‐NaS batteries are presented. We outline a novel emerging concept of integrating MS_x electrocatalysts into conventional carbonaceous matrices as effective polarized S hosts in RT‐NaS batteries as well. This comprehensive progress report could provide guidance for research toward the development of S‐based materials for the future Na‐storage techniques.     

Electrochemistry of Electrode Materials Containing S−Se Bonds for Rechargeable Batteries

Sulfur (S) and selenium (Se) have been considered as promising high capacity cathode materials for rechargeable batteries. They have differences in their physical properties (e.g., electronic conductivity) but the same number of electrons in their outermost shells, which leads to similarity in their electrochemical behavior in batteries. In recent years, some efforts have been taken to combine them in electrodes in the hope of improved battery performance. The S−Se bonds of these electrode materials lead to unusual properties and intriguing electrochemical behavior, which have attracted increasing interest. In this Minireview, electrode materials containing S−Se bonds are summarized, including inorganic S_xSe_y solid solutions, organic compounds, and organic–inorganic hybrid materials. Our understanding in these materials is still premature, but they have shown unique properties to be electrode materials. We hope this Minireview could provide a new insight into the design, synthesis, and understanding of these materials, which could enable high energy density rechargeable batteries.     

Understanding High‐Rate K+‐Solvent Co‐Intercalation in Natural Graphite for Potassium‐Ion Batteries

Graphite shows great potential as an anode material for rechargeable metal‐ion batteries because of its high abundance and low cost. However, the electrochemical performance of graphite anode materials for rechargeable potassium‐ion batteries needs to be further improved. Reported herein is a natural graphite with superior rate performance and cycling stability obtained through a unique K⁺‐solvent co‐intercalation mechanism in a 1 m KCF₃SO₃ diethylene glycol dimethyl ether electrolyte. The co‐intercalation mechanism was demonstrated by ex situ Fourier transform infrared spectroscopy and in situ X‐ray diffraction. Moreover, the structure of the [K‐solvent]⁺ complexes intercalated with the graphite and the conditions for reversible K⁺‐solvent co‐intercalation into graphite are proposed based on the experimental results and first‐principles calculations. This work provides important insights into the design of natural graphite for high‐performance rechargeable potassium‐ion batteries.     

Ammonium Ion Batteries: Material,Electrochemistry and Strategy

Ammonium-ion batteries (AIBs) have recently attracted increasing attention in the field of aqueous batteries owing to their high safety and fast diffusion kinetics. The NH₄⁺ storage mechanism is quite different from that of spherical metal ions (e.g. Li⁺, Na⁺, K⁺, Mg²⁺, and Zn²⁺) because of the formation of hydrogen bonds between NH₄⁺ and host materials. Although many materials have been proposed as electrode materials for AIBs, their performances hardly meet the requirement of future electrochemical energy storage devices. It is thus urgent to design and exploit advanced materials for AIBs. This review highlights the state-of-the-art research on AIBs. The insights into the basic configuration, operating mechanism and recent progress of electrode materials and corresponding electrolytes for AIBs have been comprehensively outlined. The electrode materials are classified and compared according to different NH₄⁺ storage behaviour in the structure. The challenges, design strategies and perspectives are also discussed for the future development of AIBs.     

Multi‐Electron Reactions Enabled by Anion‐Based Redox Chemistry for High‐Energy Multivalent Rechargeable Batteries

The development of multivalent metal (such as Mg and Ca) based battery systems is hindered by lack of suitable cathode chemistry that shows reversible multi‐electron redox reactions. Cationic redox centres in the classical cathodes can only afford stepwise single‐electron transfer, which are not ideal for multivalent‐ion storage. The charge imbalance during multivalent ion insertion might lead to an additional kinetic barrier for ion mobility. Therefore, multivalent battery cathodes only exhibit slope‐like voltage profiles with insertion/extraction redox of less than one electron. Taking VS₄ as a model material, reversible two‐electron redox with cationic–anionic contributions is verified in both rechargeable Mg batteries (RMBs) and rechargeable Ca batteries (RCBs). The corresponding cells exhibit high capacities of >300 mAh g^?1 at a current density of 100 mA g^?1 in both RMBs and RCBs, resulting in a high energy density of >300 Wh kg^?1 for RMBs and >500 Wh kg^?1 for RCBs. Mechanistic studies reveal a unique redox activity mainly at anionic sulfides moieties and fast Mg²⁺ ion diffusion kinetics enabled by the soft structure and flexible electron configuration of VS₄.