Highly Rechargeable Lithium‐CO2 Batteries with a Boron‐ and Nitrogen‐Codoped Holey‐Graphene Cathode

Metal‐air batteries, especially Li‐air batteries, have attracted significant research attention in the past decade. However, the electrochemical reactions between CO₂ (0.04 % in ambient air) with Li anode may lead to the irreversible formation of insulating Li₂CO₃, making the battery less rechargeable. To make the Li‐CO₂ batteries usable under ambient conditions, it is critical to develop highly efficient catalysts for the CO₂ reduction and evolution reactions and investigate the electrochemical behavior of Li‐CO₂ batteries. Here, we demonstrate a rechargeable Li‐CO₂ battery with a high reversibility by using B,N‐codoped holey graphene as a highly efficient catalyst for CO₂ reduction and evolution reactions. Benefiting from the unique porous holey nanostructure and high catalytic activity of the cathode, the as‐prepared Li‐CO₂ batteries exhibit high reversibility, low polarization, excellent rate performance, and superior long‐term cycling stability over 200 cycles at a high current density of 1.0 A g⁻¹. Our results open up new possibilities for the development of long‐term Li‐air batteries reusable under ambient conditions, and the utilization and storage of CO₂.     

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.     

Effect of CO2-induced side reactions on the deposition in the non-aqueous Li-air batteries

This paper presents a non-aqueous Li-air battery model that considers the side reactions of lithium carbonate (Li₂CO₃) formation from both electrolyte decomposition and carbon dioxide (CO₂) in the ambient air. The deposition and decomposition behaviors of discharge products, the voltage, and capacity evolutions during the cycling operation of the Li-air batteries are investigated. The deposition behavior analysis implies that the Li₂CO₃ generated by electrolyte decomposition is mainly distributed near the separator side, while it is dominantly generated by Li-O₂/CO₂ reaction near the air side. The formation of Li₂CO₃ by side reactions makes the Li-air batteries exhibit a peak discharge deposition inside the cathode. Moreover, Li₂CO₃ is difficult to decompose and gradually accumulates with cycles, especially near the air side. The severe accumulation of Li₂CO₃ near the air side significantly reduces the O₂ diffusion into the electrode, which induces severe cycling performance decay of the Li-air batteries. According to the distribution and evolution of the deposition, three simple hierarchical cathode structures with high porosities near the air side are finally studied. The simulation results indicate that the increase of the local porosity near the air side substantially improves the cycling performance of the Li-air batteries.

     

Light/Electricity Energy Conversion and Storage for a Hierarchical Porous In2S3@CNT/SS Cathode towards a Flexible Li-CO2 Battery

A photoinduced flexible Li-CO₂ battery with well-designed, hierarchical porous, and free-standing In₂S₃@CNT/SS (ICS) as a bifunctional photoelectrode to accelerate both the CO₂ reduction and evolution reactions (CDRR and CDER) is presented. The photoinduced Li-CO₂ battery achieved a record-high discharge voltage of 3.14 V, surpassing the thermodynamic limit of 2.80 V, and an ultra-low charge voltage of 3.20 V, achieving a round trip efficiency of 98.1 %, which is the highest value ever reported (<80 %) so far. These excellent properties can be ascribed to the hierarchical porous and free-standing structure of ICS, as well as the key role of photogenerated electrons and holes during discharging and charging processes. A mechanism is proposed for pre-activating CO₂ by reducing In³⁺ to In⁺ under light illumination. The mechanism of the bifunctional light-assisted process provides insight into photoinduced Li-CO₂ batteries and contributes to resolving the major setbacks of the system.     

Predicting solvent stability in aprotic electrolyte Li-air batteries: nucleophilic substitution by the superoxide anion radical (O2(•-))

There is increasing evidence that cyclic and linear carbonates, commonly used solvents in Li ion battery electrolytes, are unstable in the presence of superoxide and thus are not suitable for use in rechargeable Li-air batteries employing aprotic electrolytes. A detailed understanding of related decomposition mechanisms provides an important basis for the selection and design of stable electrolyte materials. In this article, we use density functional theory calculations with a Poisson-Boltzmann continuum solvent model to investigate the reactivity of several classes of aprotic solvents in nucleophilic substitution reactions with superoxide. We find that nucleophilic attack by O(2)(?-) at the O-alkyl carbon is a common mechanism of decomposition of organic carbonates, sulfonates, aliphatic carboxylic esters, lactones, phosphinates, phosphonates, phosphates, and sulfones. In contrast, nucleophilic reactions of O(2)(?-) with phenol esters of carboxylic acids and O-alkyl fluorinated aliphatic lactones proceed via attack at the carbonyl carbon. Chemical functionalities stable against nucleophilic substitution by superoxide include N-alkyl substituted amides, lactams, nitriles, and ethers. The results establish that solvent reactivity is strongly related to the basicity of the organic anion displaced in the reaction with superoxide. Theoretical calculations are complemented by cyclic voltammetry to study the electrochemical reversibility of the O(2)/O(2)(?-) couple containing tetrabutylammonium salt and GCMS measurements to monitor solvent stability in the presence of KO(2)(?) and a Li salt. These experimental methods provide efficient means for qualitatively screening solvent stability in Li-air batteries. A clear correlation between the computational and experimental results is established. The combination of theoretical and experimental techniques provides a powerful means for identifying and designing stable solvents for rechargeable Li-air batteries.     

Hydrogen-Bonded Organic Framework to Upgrade Cycling Stability and Rate Capability of Li-CO2 Batteries

Elaborately designed multifunctional electrocatalysts capable of promoting Li⁺ and CO₂ transport are essential for upgrading the cycling stability and rate capability of Li-CO₂ batteries. Hydrogen-bonded organic frameworks (HOFs) with open channels and easily functionalized surfaces hold great potential for applications in efficient cathodes of Li-CO₂ batteries. Herein, a robust HOF_S (HOF-FJU-1) is introduced for the first time as a co-catalyst in the cathode material of Li-CO₂ batteries. HOF-FJU-1 with cyano groups located periodically in the pore can induce homogeneous deposition of discharge products and accommodate volumetric expansion of discharge products during cycling. Besides, HOF-FJU-1 enables effective interaction between Ru⁰ nanoparticles and cyano groups, thus forming efficient and uniform catalytic sites for CRR/CER. Moreover, HOF-FJU-1 with regularly arranged open channels are beneficial for CO₂ and Li⁺ transport, enabling rapid redox kinetic conversion of CO₂. Therefore, the HOF-based Li-CO₂ batteries are capable of stable operation at 400 mA g⁻¹ for 1800 h and maintain a low overpotential of 1.96 V even at high current densities up to 5 A g⁻¹. This work provides valuable guidance for developing multifunctional HOF-based catalysts to upgrade the longevity and rate capability of Li-CO₂ batteries.     

Unlocking Reversible Silicon Redox for High-Performing Chlorine Batteries

Chlorine (Cl)-based batteries such as Li/Cl₂ batteries are recognized as promising candidates for energy storage with low cost and high performance. However, the current use of Li metal anodes in Cl-based batteries has raised serious concerns regarding safety, cost, and production complexity. More importantly, the well-documented parasitic reactions between Li metal and Cl-based electrolytes require a large excess of Li metal, which inevitably sacrifices the electrochemical performance of the full cell. Therefore, it is crucial but challenging to establish new anode chemistry, particularly with electrochemical reversibility, for Cl-based batteries. Here we show, for the first time, reversible Si redox in Cl-based batteries through efficient electrolyte dilution and anode/electrolyte interface passivation using 1,2-dichloroethane and cyclized polyacrylonitrile as key mediators. Our Si anode chemistry enables significantly increased cycling stability and shelf lives compared with conventional Li metal anodes. It also avoids the use of a large excess of anode materials, thus enabling the first rechargeable Cl₂ full battery with remarkable energy and power densities of 809 Wh kg⁻¹ and 4,277 W kg⁻¹, respectively. The Si anode chemistry affords fast kinetics with remarkable rate capability and low-temperature electrochemical performance, indicating its great potential in practical applications.     

The Stabilization Effect of CO2 in Lithium–Oxygen/CO2 Batteries

The lithium (Li)–air battery has an ultrahigh theoretical specific energy, however, even in pure oxygen (O₂), the vulnerability of conventional organic electrolytes and carbon cathodes towards reaction intermediates, especially O₂⁻, and corrosive oxidation and crack/pulverization of Li metal anode lead to poor cycling stability of the Li-air battery. Even worse, the water and/or CO₂ in air bring parasitic reactions and safety issues. Therefore, applying such systems in open-air environment is challenging. Herein, contrary to previous assertions, we have found that CO₂ can improve the stability of both anode and electrolyte, and a high-performance rechargeable Li–O₂/CO₂ battery is developed. The CO₂ not only facilitates the in situ formation of a passivated protective Li₂CO₃ film on the Li anode, but also restrains side reactions involving electrolyte and cathode by capturing O₂⁻. Moreover, the Pd/CNT catalyst in the cathode can extend the battery lifespan by effectively tuning the product morphology and catalyzing the decomposition of Li₂CO₃. The Li–O₂/CO₂ battery achieves a full discharge capacity of 6628 mAh g⁻¹ and a long life of 715 cycles, which is even better than those of pure Li–O₂ batteries.     

Realizing Stable Carbonate Electrolytes in Li–O2/CO2 Batteries†

The increasing demand for high-energy storage systems has propelled the development of Li-air batteries and Li-O₂/CO₂ batteries to elucidate the mechanism and extend battery life. However, the high charge voltage of Li₂CO₃ accelerates the decomposition of traditional sulfone and ether electrolytes, thus adopting high-voltage electrolytes in Li-O₂/CO₂ batteries is vital to achieve a stable battery system. Herein, we adopt a commercial carbonate electrolyte to prove its excellent suitability in Li-O₂/CO₂ batteries. The generated superoxide can be captured by CO₂ to form less aggressive intermediates, stabilizing the carbonate electrolyte without reactive oxygen species induced decomposition. In addition, this electrolyte permits the Li metal plating/stripping with a significantly improved reversibility, enabling the possibility of using ultra-thin Li anode. Benefiting from the good rechargeability of Li₂CO₃, less cathode passivation, and stabilized Li anode in carbonate electrolyte, the Li-O₂/CO₂ battery demonstrates a long cycling lifetime of 167 cycles at 0.1 mA·cm^–2 and 0.25 mAh·cm^–2. This work paves a new avenue for optimizing carbonate-based electrolytes for Li-O₂ and Li-O₂/CO₂ batteries.      

Three-in-one Fe-porphyrin based hybrid nanosheets for enhanced CO2 reduction and evolution kinetics in Li-CO2 battery

Efficient cathode-catalysts with multi-functional properties are essential for Li-CO₂ battery, while the construction of them with simultaneously enhanced CO₂ reduction and evolution kinetics is still challenging. Here, a kind of hybrid nanosheets based on Ru nanoparticles, Fe-TAPP and grapheme oxide (GO) has been designed through a one-pot self-assembly strategy. The Ru, Fe-porphyrin and GO based hybrid nanosheets (denoted as Ru/Fe-TAPP@GO) with integrated multi-components offer characteristics of ultrathin thickness (∼4 nm), high electro-redox property, uniformly dispersed morphology, and high electrical conductivity, etc. These features endow Ru/Fe-TAPP@GO with ultra-low overpotential (0.82 V) and fully reversible discharge/charge property with a high specific-capacity of 39,000 mAh/g within 2.0–4.5 V at 100 mA/g, which are much superior to Ru@GO and Fe-TAPP@GO. The achieved performance was presented as one of the best cathode-catalysts reported to date. The synergistically enhanced activity originated from the integrated hybrid nanosheets may provide a new pathway for designing efficient cathode-catalysts for Li-CO₂ batteries.     

Rechargeable Room‐Temperature Na–CO2 Batteries

Developing rechargeable Na–CO₂ batteries is significant for energy conversion and utilization of CO₂. However, the reported batteries in pure CO₂ atmosphere are non‐rechargeable with limited discharge capacity of 200 mAh g^?1. Herein, we realized the rechargeability of a Na–CO₂ battery, with the proposed and demonstrated reversible reaction of 3 CO₂+4 Na?2 Na₂CO₃+C. The battery consists of a Na anode, an ether‐based electrolyte, and a designed cathode with electrolyte‐treated multi‐wall carbon nanotubes, and shows reversible capacity of 60000 mAh g^?1 at 1 A g^?1 (≈1000 Wh kg^?1) and runs for 200 cycles with controlled capacity of 2000 mAh g^?1 at charge voltage <3.7 V. The porous structure, high electro‐conductivity, and good wettability of electrolyte to cathode lead to reduced electrochemical polarization of the battery and further result in high performance. Our work provides an alternative approach towards clean recycling and utilization of CO₂.     

A Long‐Life Lithium–Air Battery in Ambient Air with a Polymer Electrolyte Containing a Redox Mediator

Lithium–air batteries when operated in ambient air generally exhibit poor reversibility and cyclability, because of the Li passivation and Li₂O₂/LiOH/Li₂CO₃ accumulation in the air electrode. Herein, we present a Li–air battery supported by a polymer electrolyte containing 0.05 m LiI, in which the polymer electrolyte efficiently alleviates the Li passivation induced by attacking air. Furthermore, it is demonstrated that I⁻/I₂ conversion in polymer electrolyte acts as a redox mediator that facilitates electrochemical decomposition of the discharge products during recharge process. As a result, the Li–air battery can be stably cycled 400 times in ambient air (relative humidity of 15 %), which is much better than previous reports. The achievement offers a hope to develop the Li–air battery that can be operated in ambient air.     

A Long-Life Lithium–Air Battery in Ambient Air with a Polymer Electrolyte Containing a Redox Mediator

Lithium–air batteries when operated in ambient air generally exhibit poor reversibility and cyclability, because of the Li passivation and Li₂O₂/LiOH/Li₂CO₃ accumulation in the air electrode. Herein, we present a Li–air battery supported by a polymer electrolyte containing 0.05 m LiI, in which the polymer electrolyte efficiently alleviates the Li passivation induced by attacking air. Furthermore, it is demonstrated that I⁻/I₂ conversion in polymer electrolyte acts as a redox mediator that facilitates electrochemical decomposition of the discharge products during recharge process. As a result, the Li–air battery can be stably cycled 400 times in ambient air (relative humidity of 15 %), which is much better than previous reports. The achievement offers a hope to develop the Li–air battery that can be operated in ambient air.     

Synthesis of silk-like FeS2/NiS2 hybrid nanocrystals with improved reversible oxygen catalytic performance in a Zn-air battery

The development of highly active and stable reversible oxygen electrocatalysts is crucial for improving the efficiency of metal-air battery devices. Herein, an efficient liquid exfoliation strategy was designed for producing silk-like FeS₂/NiS₂ hybrid nanocrystals with enhanced reversible oxygen catalytic performance that displayed excellent properties for Zn-air batteries. Because of the unique silk-like morphology and interface nanocrystal structure, they can catalyze the oxygen evolution reaction (OER) efficiently with a low overpotential of 233 mV at j = 10 mA cm^?2. This is an improvement from the recently reported catalysts in 1.0 M KOH. Meanwhile, the oxygen reduction reaction (ORR) activity of the silk-like FeS₂/NiS₂ hybrid nanocrystals showed an onset potential of 911 mV and a half-wave potential of 640 mV. In addition, the reversible oxygen electrode activity of the silk-like FeS₂/NiS₂ hybrid nanocrystals was calculated to be 0.823 V, based on the potential of the OER and ORR. Further, the homemade rechargeable Zn-air batteries using FeS₂/NiS₂ hybrid nanocrystals as the air-cathode displayed a high open-circuit voltage of 1.25 V for more than 17 h and an excellent rechargeable performance for 25 h. The solid Zn-air batteries exhibited an excellent rechargeable performance for 15 h. This study provided a new method for designing interface nanocrystals with a unique morphology for efficient multifunctional electrocatalysts in electrochemical reactions and renewable energy devices.     

Recent Advances in the Research of Photo-Assisted Lithium-Based Rechargeable Batteries

The application of solar energy is crucial for alleviating the energy crisis and achieving sustainable development. In recent years, photo-assisted rechargeable batteries have attracted researchers because they can directly convert and store solar energy in the batteries. And it also can be used like a normal battery without light illumination. Photo-assisted lithium-based batteries have received more attention than other energy storage systems due to their higher energy density and relatively mature development. This Review focuses on the design of various photo-assisted lithium-based batteries including Li-ion, Li-S, Li-O₂, Li-CO₂ and Li-I batteries, as well as the working mechanism of photoelectrodes in these battery systems. The basic understanding and challenge of photo-assisted lithium-based batteries are also discussed. At last, perspectives for the photoelectrode development are provided in the summary to advance photo-assisted energy storage systems.     

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.     

Single-atom catalysts for high-energy rechargeable batteries

Clean and sustainable electrochemical energy storage has attracted extensive attention. It remains a great challenge to achieve next-generation rechargeable battery systems with high energy density, good rate capability, excellent cycling stability, efficient active material utilization, and high coulombic efficiency. Many catalysts have been explored to promote electrochemical reactions during the charge and discharge process. Among reported catalysts, single-atom catalysts (SACs) have attracted extensive attention due to their maximum atom utilization efficiency, homogenous active centres, and unique reaction mechanisms. In this perspective, we summarize the recent advances of the synthesis methods for SACs and highlight the recent progress of SACs for a new generation of rechargeable batteries, including lithium/sodium metal batteries, lithium/sodium–sulfur batteries, lithium–oxygen batteries, and zinc–air batteries. The challenges and perspectives for the future development of SACs are discussed to shed light on the future research of SACs for boosting the performances of rechargeable batteries.

Single-atom catalysts are reviewed, aiming to achieve optimized properties to boost electrochemical performances of high-energy batteries.     

From K-O2 to K-Air Batteries: Realizing Superoxide Batteries on the Basis of Dry Ambient Air

Although using an air cathode is the goal for superoxide-based potassium-oxygen (K-O₂) batteries, prior studies were limited to pure oxygen. Now, the first K-air (dry) battery based on reversible superoxide electrochemistry is presented. Spectroscopic and gas chromatography analyses are applied to evaluate the reactivity of KO₂ in ambient air. Although KO₂ reacts with water vapor and CO₂ to form KHCO₃, it is highly stable in dry air. With this knowledge, rechargeable K-air (dry) batteries were successfully demonstrated by employing dry air cathode. The reduced partial pressure of oxygen plays a critical role in boosting battery lifespan. With a more stable environment for the K anode, a K-air (dry) battery delivers over 100 cycles (>500 h) with low round-trip overpotentials and high coulombic efficiencies as opposed to traditional K-O₂ battery that fails early. This work sheds light on the benefits and restrictions of employing the air cathode in superoxide-based 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.     

Enhancing the process of CO2 reduction reaction by using CTAB to construct contact ion pair in Li-CO2 battery

Aprotic Li-CO₂ batteries have attracted growing interest due to their high theoretical energy density and its ability to use green house gas CO₂ for energy storage.However,the poor ability of activating CO₂ in organic electrolyte often leads to the premature termination of CO₂ reduction reaction （CO₂RR） directly.Here in this work,cetyl trimethyl ammonium bromide （CTAB） was introduced into a dimethyl sulfoxide（DMSO） based Li-CO₂ ba...