CO2 Batteries Research Articles

Single‐Atom Cadmium‐N4 Sites for Rechargeable Li–CO2 Batteries with High Capacity and Ultra‐Long Lifetime

AbstractThe rechargeable Li–CO2 battery shows great potential in civil, military, and aerospace fields due to its high theoretical energy density and CO2 capture capability. To facilitate the practical application of Li–CO2 battery, the design of efficient, low‐cost, and robust non‐noble metal cathodes to boost CO2 reduction/evolution kinetics is highly desirable yet remains a challenge. Herein, single‐atom cadmium is reported with a Cd‐N4 coordination structure enable rapid kinetics of both the discharge and recharge process when employed as a cathode catalyst, and thus facilitates exceptional rate performance in a Li–CO2 battery, even up to 10 A g−1, and remains stable at a high current density (100 A g−1). An unprecedented discharge capacity of 160045 mAh g−1 is attained at 500 mA g−1. Excellent cycling stability is maintained for 1685 and 669 cycles at 1 A g−1 and capacities of 0.5 and 1 Ah g−1, respectively. Density functional theory calculations reveal low energy barriers for both Li2CO3 formation and decomposition reactions during the respective discharge and recharge process, evidencing the high catalytic activity of single Cd sites. This study provides a simple and effective avenue for developing highly active and stable single‐atom non‐precious metal cathode catalysts for advanced Li–CO2 batteries.

Intermetallic-driven highly reversible electrocatalysis in Li–CO2 battery over nanoporous Ni3Al/Ni heterostructure

Li–CO2 batteries, which integrate CO2 utilization and electrochemical energy storage, offer the prospect of utilizing a greenhouse gas and providing an alternative to the well-established lithium-ion batteries. However, they still suffer from rather limited reversibility, low energy efficiency, and sluggish CO2 redox reaction kinetics. To address these key issues, a nanoporous Ni3Al intermetallic/Ni heterojunction (NP–Ni3Al/Ni) is purposely engineered here via an alloying–etching protocol, whereby the unique interactions between Al and Ni in Ni3Al endow NP-Ni3Al/Ni with optimum reactant/product adsorption and thus unique catalytic performance for the CO2 redox reaction. Furthermore, the nanoporous spongy structure benefits mass transport as well as discharge product storage and enables a rich multiphase reaction interface. In situ Raman studies and theoretical simulations reveal that both CO2 reduction and the co-decomposition of Li2CO3 and C are distinctly promoted by NP-Ni3Al/Ni, thereby greatly improving catalytic activity and stability. NP-Ni3Al/Ni offers promising application potential in Li–CO2 batteries, with its scalable fabrication, low production cost, and superior catalytic performance.

A Durable Solid‐State Na–CO2 Battery with Solid Composite Electrolyte Na3.2Zr1.9Ca0.1Si2PO12–PVDF‐HFP

Na–CO2 batteries are important devices for immobilizing CO2 and storing renewable energy. However, the Na–CO2 batteries with liquid electrolytes have the issues of electrolyte volatilization and poor cyclability. Herein, a composite solid‐state electrolyte consisting of Ca‐doped Na3Zr2Si2PO12 and polyvinylidene fluoride‐co‐hexafluoropropylene (PVDF‐HFP) is synthesized. The solid composite electrolyte Na3.2Zr1.9Ca0.1Si2PO12–PVDF‐HFP shows a high ionic conductivity of 1.32 × 10−4 S cm−1 at room temperature and a broad electrochemical window up to 5.15 V, as well as excellent durability. The assembled solid‐state Na–CO2 battery with this composite electrolyte delivers a high discharge‐specific capacity up to 3320 mA h g−1 and excellent cycling stability.

Asymmetric coordinated single-atom Pd sites for high performance CO2 electroreduction and Zn–CO2 battery

Single-atom catalysts (SACs) have attracted great attention for electrocatalysis. The coordination configurations of heteroatoms surrounding the metal center have a significant influence on the catalytic performance. The construction of asymmetric coordination configurations has recently been found to be an efficient strategy to improve electrocatalytic performance. However, noble-metal-based SACs with an asymmetric coordination environment have seldom been achieved. Herein, we rationally design and construct single-atom Pd catalysts with asymmetric Pd1O3C1 or Pd1N3C1 sites anchored on oxidized mesoporous carbon with optimized porosity and hydrophobicity. The as-prepared catalyst (Pd1-O-CB) selectively produces CO with a high CO Faradaic efficiency (FECO) of 99.6 % at a low potential of –0.6 V versus reversible hydrogen electrode (RHE). Furthermore, the Pd1-O-CB-based gas diffusion layer exhibits a high current density of 280.4 mA cm−2 and long-term stability over 48 h benefitted from the regulated porosity and hydrophobicity of the tri-interface. Finally, a rechargeable Zn–CO2 battery is constructed with the optimal gas diffusion electrode to deliver a maximal power density of 1.72 mW cm−2.

One Stone Three Birds: An Aqueous Mg–CO2 Battery for Generation of Electricity, Syngas, and High-Value Phosphate

Mg–CO2 battery as a promising strategy for CO2 conversion and utilization is challenging, owing to the sluggish kinetics of CO2 reduction reaction (CO2RR) and the waste of the sacrificial Mg anode. Herein, by elaborately designing a highly selective Ni NPs/Ni–N–C SACs electrocatalyst toward CO2RR and rationally optimizing the electrolyte, an effective aqueous-phase Mg–CO2 battery is demonstrated to generate not only electricity, but also syngas with CO from the CO2RR and H2 from the chemical oxidation of Mg, together with higher-valued MgHPO4 phosphate. Notably, the output of electricity, the proportion of CO/H2 in syngas, and the yields/crystalline quality of MgHPO4 can be well regulated by manipulating the operation parameters. The Mg–CO2 battery generates a favorable open-circuit voltage of 1.44 V with a peak power density of 2.91 mW cm–2. Under the optimal condition, the Ni NPs/Ni–N–C SACs catalyst displays both a high FECO of 98.12% at −0.573 VRHE and a high CO2-to-CO current of −20.73 mA cm–2 at −0.973 VRHE, owing to the synergistic effect between Ni particles and Ni–N moieties. The proposed Mg–CO2 battery provides an intriguing approach for CO2 conversion and utilization in off-grid, with the advantage of coproduction of higher-valued chemicals at both electrodes.

Binuclear Cu complex catalysis enabling Li–CO2 battery with a high discharge voltage above 3.0 V

Li–CO2 batteries possess exceptional advantages in using greenhouse gases to provide electrical energy. However, these batteries following Li2CO3-product route usually deliver low output voltage (<2.5 V) and energy efficiency. Besides, Li2CO3-related parasitic reactions can further degrade battery performance. Herein, we introduce a soluble binuclear copper(I) complex as the liquid catalyst to achieve Li2C2O4 products in Li–CO2 batteries. The Li–CO2 battery using the copper(I) complex exhibits a high electromotive voltage up to 3.38 V, an increased output voltage of 3.04 V, and an enlarged discharge capacity of 5846 mAh g−1. And it shows robust cyclability over 400 cycles with additional help of Ru catalyst. We reveal that the copper(I) complex can easily capture CO2 to form a bridged Cu(II)-oxalate adduct. Subsequently reduction of the adduct occurs during discharge. This work innovatively increases the output voltage of Li–CO2 batteries to higher than 3.0 V, paving a promising avenue for the design and regulation of CO2 conversion reactions.

A Highly Reversible Lithium–Carbon Dioxide Battery Based on Soluble Oxalate

Li–CO2 batteries that integrate energy storage with CO2 fixation are expected to be a promising technology in the pursuit of carbon neutrality. However, cathode passivation and structural damage caused by the solid discharge product Li2CO3 are major challenges hindering the practical implementation of Li–CO2 batteries. To address these challenges, herein, a breakthrough Li–CO2 battery leading to a soluble and easily-decomposed discharge product, C2O42–, driven by regulating the solvation sheath of Li+, has been achieved by introducing the high-polarity dimethyl sulfoxide electrolyte. Experimental results and theoretical calculations show that the increased Li+ interaction and electrolyte molecule can induce the solution-phase formation of stabilized C2O42–, while simultaneously suppressing direct reduction of CO2 to Li2CO3. The tough problems with Li–CO2 batteries caused by solid products are effectively solved by production of soluble C2O42–, which provides a promising solution for research on non-aqueous metal–air batteries.

A comprehensive overview of the electrochemical mechanisms in emerging alkali metal–carbon dioxide batteries

AbstractAlkali metal–carbon dioxide (Li/Na/K‐CO2) batteries are emerging electrochemical energy storage technologies in the context of the energy crisis and the urgent demand for carbon neutrality. Alkali metal–CO2batteries offer a new strategy for CO2fixation and utilization, and thus has been receiving considerable attention in recent years. Considerable progress has been achieved since alkali metal–CO2batteries were invented, especially in terms of development of new electrode materials, and yet, research is lacking on the underlying mechanisms of the systems. This is the first typical review focusing on the electrochemical mechanisms of metal–CO2batteries that summarizes the current understanding of and provides insights into the thermodynamic reaction pathways, the kinetic characteristics, and the crucial factors determining the reaction mechanisms in alkali metal–CO2batteries. The review starts with the fundamental concepts of alkali metal–CO2batteries, followed by a comprehensive discussion of the working mechanisms on cathodes and anodes. Moreover, the operation mechanisms of state‐of‐the‐art electrolytes, including liquid and (quasi‐)solid‐state electrolytes, are also described. Finally, we identify the unsolved problems in current alkali metal–CO2batteries and propose potential topics for future research.

Fundamental Understanding of Nonaqueous and Hybrid Na-CO2 Batteries: Challenges and Perspectives.

Alkali metal-CO2 batteries, which combine CO2 recycling with energy conversion and storage, are a promising way to address the energy crisis and global warming. Unfortunately, the limited cycle life, poor reversibility, and low energy efficiency of these batteries have hindered their commercialization. Li-CO2 battery systems have been intensively researched in these aspects over the past few years, however, the exploration of Na-CO2 batteries is still in its infancy. To improve the development of Na-CO2 batteries, one must have a full picture of the chemistry and electrochemistry controlling the operation of Na-CO2 batteries and a full understanding of the correlation between cell configurations and functionality therein. Here, recent advances in CO2 chemical and electrochemical mechanisms on nonaqueous Na-CO2 batteries and hybrid Na-CO2 batteries (including O2 -involved Na-O2 /CO2 batteries) are reviewed in-depth and comprehensively. Following this, the primary issues and challenges in various battery components are identified, and the design strategies for the interfacial structure of Na anodes, electrolyte properties, and cathode materials are explored, along with the correlations between cell configurations, functional materials, and comprehensive performances are established. Finally, the prospects and directions for rationally constructing Na-CO2 battery materials are foreseen.

Recent Progress and Perspectives of Solid State Na-CO2 Batteries

Solid state Na-CO2 batteries are a kind of promising energy storage system, which can use excess CO2 for electrochemical energy storage. They not only have high theoretical energy densities, but also feature a high safety level of solid-state batteries and low cost owing to abundant sodium metal resources. Although many efforts have been made, the practical application of Na-CO2 battery technology is still hampered by some crucial challenges, including short cycle life, high charging potential, poor rate performance and lower specific full discharge capacity. This paper systematically reviews the recent research advances in Na-CO2 batteries in terms of understanding the mechanism of CO2 reduction, carbonate formation and decomposition reaction, design strategies of cathode electrocatalysts, solid electrolytes and their interface design. In addition, the application of advanced in situ characterization techniques and theoretical calculation of metal–CO2 batteries are briefly introduced, and the combination of theory and experiment in the research of battery materials is discussed as well. Finally, the opportunities and key challenges of solid-state Na-CO2 electrochemical systems in the carbon-neutral era are presented.

Cover Picture

Carbonate electrolytes are not stable in Li‐O2 batteries due to the attack of O2−. However, in Li‐O2/CO2 batteries the generated O2− can be captured by CO2 to stabilize carbonate electrolytes. Thanks to the high‐voltage resistance and good Li reversibility, they are excellent electrolytes for long‐life Li‐O2/CO2 batteries. More details are discussed in the article by Zhang et al. on page 314–321. image

Developing highly reversible Li–CO2 batteries: from on-chip exploration to practical application

A versatile on-chip electrochemical testing platform enables simultaneous catalyst screening and in situ analysis of chemical composition and morphological evolution of reaction products in Li–CO2 batteries, further guiding practical applications.

Structural engineering of metal–organic layers toward stable Li–CO2 batteries

A flower-like metal–organic layer with a rich catalytic surface and unique conductive structure was fabricated as an efficient cathodic catalyst for Li–CO2 batteries. The as-developed cells display remarkable cycling stability.

Magnetron sputtering of platinum on nitrogen-doped polypyrrole carbon nanotubes as an efficient and stable cathode for lithium-carbon dioxide batteries.

As an emerging green energy storage and conversion system, rechargeable Li-CO2 batteries have undergone extensive research due to their ultra-high energy density and their significant role in greenhouse gas CO2 conversion. However, current Li-CO2 batteries have some shortcomings that severely limit their large-scale application. The most critical problems involve the insulation of the discharge product Li2CO3 and the slow decomposition kinetics, meaning that the battery generates a large overpotential and has a low cycle life, so the rational design of an efficient cathode catalyst is imperative. Here, we prepared a composite material via the magnetron sputtering of Pt onto nitrogen-doped polypyrrole carbon nanotubes (NPPy-CNTs) as a high-efficiency cathode catalyst for Li-CO2 batteries. The three-dimensional hollow tubular NPPy-CNTs can provide efficient channels for CO2 diffusion and enough space for the uniform deposition and decomposition of Li2CO3. Benefiting from the doping of nitrogen, more defects and active sites are introduced into the polypyrrole carbon nanotubes. Furthermore, the introduction of a small amount of the precious metal Pt effectively improves the catalytic activity of the CO2 reduction reaction (CO2RR) and the CO2 release reaction (CO2ER), greatly improving the cycle life of the battery. The Pt-NPPy-CNT-based battery shows a much improved electrochemical performance. The overpotential of the battery is reduced to 0.75 V, and the battery shows a specific discharge capacity of up to 29 614 mA h g-1.

Candle Soot Nanoparticles versus Multiwalled Carbon Nanotubes as a High-Performance Cathode Catalyst for Li–CO2Mars Batteries for Mars Exploration

Increased CO2 emissions on the earth causing global warming and climate change have provided a thrust to explore Li–CO2 battery chemistry, where CO2 is used as an energy carrier. In addition, the occurrence of CO2 as a major natural abundant gas in the Martian atmosphere opens the possibility of using Li–CO2 batteries for interplanetary Mars missions. In this work, we aim to investigate facile and inexpensive candle soot carbon nanoparticles as a cathode catalyst against commercially available multiwalled carbon nanotubes (MWCNTs) for stable and high-performance Li–CO2 batteries for Mars exploration. The unique interconnected morphology and higher surface area of candle soot nanoparticles facilitate better reversibility (more than 80 cycles) compared to MWCNTs even at a high current density of 200 mA g–1 with a cutoff capacity of 500 mAh g–1. The full discharge capacity for candle soot nanoparticles was measured to be 5318 mAh g–1 with a coulombic efficiency of 42% as compared to 16% for MWCNTs. The rate capability studies were performed to establish the ability to operate the system reversibly at different current densities in a simulated Martian atmosphere. The outcome of this study paves the way toward developing a candle soot cathode-based practicable Li–CO2 battery for utilization on Mars.

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

Comprehensive SummaryThe 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.

Toward an Understanding of Bimetallic MXene Solid‐Solution in Binder‐Free Electrocatalyst Cathode for Advanced Li–CO2 Batteries

AbstractLi–CO2 batteries have received extensive attention due to their high energy storage capacity and utilization of CO2 resources. Herein, bimetallic MXene solid‐solution TiVC is prepared and combined with highly conductive graphene for the construction of binder‐free electrocatalyst cathodes for Li–CO2 batteries. Considering the electronic structure, the unique synergy effect between Ti and V in TiVC enhances the interfacial chemical bonding ability, facilitates sufficient exposure of active sites and promotes catalytic interfacial structural reformation, thereby promoting the reversible formation and decomposition of the chemically inert discharge product Li2CO3. Meanwhile, the abundant pores and excellent electron transfer ability of graphene aerogel are conducive to the gas diffusion and ion transport, thus reducing the mass and charge transfer resistance. As a result, the assembled Li–CO2 battery presents an excellent discharge capacity of 27 880 mAh g−1 with a stable discharge plateau of 2.77 V and low overpotential of 1.5 V based on the TiVC‐graphene aerogel electrocatalytic cathode. The density functional theory calculations are further performed to deeply reveal the unique electronic structure information between Ti and V in the solid‐solution TiVC. This study provides inspiration for exploring more bimetallic MXene solid solutions and developing advanced cathode catalysts for flexible Li–CO2 batteries.

Enhancing Zn–CO2 battery with a facile Pd doped perovskite cathode for efficient CO2 to CO conversion

Using aqueous Zn–CO2 batteries to store renewable energy and produce valuable chemicals using CO2 as the source is a promising method for CO2 mitigation, that is alternative to traditional energy-costing CO2 capture/storage technologies. However, the lack of efficient CO2-reduction catalysts significantly hinders the efficiency of such batteries. In this study, an efficient perovskite cathode, Pd-doped La2CuO4, was successfully developed for the cathodic CO2 reduction reaction (CO2RR), and the optimal doping ratio of La2Cu1-xPdxO4 (x = 0.05) was determined. Compared with the pristine La2CuO4 catalyst, the current density for the CO2RR in the H-cell and the Faraday efficiency of CO production are both increased by ∼50% when operated −1.0 V (vs RHE). As a result, the peak power density of a Zn–CO2 battery using the Pd-doped La2CuO4 catalyst reached 0.75 mW cm−2 at 2.23 mA cm−2 by an enhancement ratio of 25%. Density functional theory calculations revealed that the *CO desorption processes on the cathode were enhanced owing to Pd doping, which accounted for the enhanced CO2RR activity and selectivity. The findings of this study show the potential application of perovskite catalysts in the cathode of Zn–CO2 batteries and provide an effective method for battery performance enhancement via the facile Pd doping.

Chemically coupling SnO2 quantum dots and MXene for efficient CO2 electroreduction to formate and Zn–CO2 battery

Electrochemical conversion of CO2 into formate is a promising strategy for mitigating the energy and environmental crisis, but simultaneously achieving high selectivity and activity of electrocatalysts remains challenging. Here, we report low-dimensional SnO2 quantum dots chemically coupled with ultrathin Ti3C2Tx MXene nanosheets (SnO2/MXene) that boost the CO2 conversion. The coupling structure is well visualized and verified by high-resolution electron tomography together with nanoscale scanning transmission X-ray microscopy and ptychography imaging. The catalyst achieves a large partial current density of -57.8 mA cm-2 and high Faradaic efficiency of 94% for formate formation. Additionally, the SnO2/MXene cathode shows excellent Zn-CO2 battery performance, with a maximum power density of 4.28 mW cm-2, an open-circuit voltage of 0.83 V, and superior rechargeability of 60 h. In situ X-ray absorption spectroscopy analysis and first-principles calculations reveal that this remarkable performance is attributed to the unique and stable structure of the SnO2/MXene, which can significantly reduce the reaction energy of CO2 hydrogenation to formate by increasing the surface coverage of adsorbed hydrogen.

Phthalocyanine Based Metal–Organic Framework Ultrathin Nanosheet for Efficient Photocathode toward Light‐Assisted Li–CO2 Battery

AbstractLight‐assisted Li–CO2 battery, emerging as a powerful battery‐technology to utilize light‐energy, has attracted much attention yet it is still limited by the lack of efficient photocathode catalysts toward simultaneously promoted CO2 activation/evolution processes. Here, a kind of phthalocyanine‐based metal–organic framework nanosheet (CoPc–Mn–O) is prepared and applied as efficient photocathode catalyst in light‐assisted Li–CO2 battery. Thus‐produced CoPc–Mn–O shows nanosheet‐morphology (≈1 nm), dual active metal‐sites (i.e., Co–N4 and Mn–O4), high conductivity, and photosensitivity. The resulting battery delivers a high round‐trip efficiency of 98.5% with an ultralow voltage hysteresis of 0.05 V and superior cycling‐stability (81.3%) for 60 h at 0.02 mA cm−2, which is represented to be one of the best photo‐cathodes to date. Density functional theory calculations and characterizations prove that the presence of photosensitive CoPc–Mn–O with dual active metal‐sites endows an activation energy (3.2 eV) for CO2 activation under light condition and simultaneously promote the CO2 evolution to enhance the battery efficiency.