Full Discharge Capacity Research Articles

A multi-site strategy for boosting Li-CO2 batteries performance

Herein, we develop a multi-site strategy to boost Li-CO2 battery performance using Co nanoparticles (NPs) loaded nitrogen-doped holey carbon nanotubes (Co@N-hCNT) as high-efficiency cathode catalyst. The Co@N-hCNT possesses high-efficiency multiple active sites of defects, nitrogen sites and Co NPs for reversible conversion of insulating Li2CO3 as well as rapid charge and ion transport provided by the nitrogen-doped holey CNTs. Benefiting from these excellent properties, the as-assembled Li-CO2 battery with Co@N-hCNT cathode shows outstanding electrochemical performance with a low overpotential of 1.03 V at 0.05 A g−1 and a high full discharge capacity of 27952 mA h g−1 at 0.2 A g−1. More importantly, the Li-CO2 battery with Co@N-hCNT exhibits a long-term durability over 220 cycles even at a high current density of 0.5 A g−1. This work opens a new venture for the development of high-efficiency cathode catalysts for Li-CO2 batteries and beyond via a multi-site strategy.

Enhancing reaction kinetics in aprotic magnesium-air batteries using a freestanding flexible metal-free carbon fiber cathode

Metal-air batteries hold great promises for future energy storage, driven by their impressive energy density. However, practical applications encounter challenges due to the sluggish kinetics of oxygen reduction and evolution reactions taking place at cathode interface, particularly in demanding conditions such as high-current density and open-air scenarios. Addressing these challenges requires cathodes with high reactivity and optimized structure to efficiently facilitate electrochemical reactions. This necessitates the development of self-supporting cathodes that eliminate the current electrode fabrication process, which can lead to binder-induced blockage of reactive sites and reduce energy density due to heavy current collectors. Here, we propose an effective strategy to design freestanding cathodes with high reactivity and a well-designed hierarchical pore structure. This cathode significantly enhances battery reaction kinetics while accommodating insoluble discharge products and preserving air and electrolyte transport pathways for high-performance Mg-air batteries. The freestanding flexible metal-free carbon fiber cathode (E-CNFs) enables a Mg-air battery operating in an open-air condition to exhibit an ultralow overvoltage of 0.4 V as well as delivered a long-term lifetime of 280 h. As a result, an impressive full discharge capacity of 5772 mAh/g under a current density of 800 mA g−1 is achieved, surpassing those in all previously reported Mg-O2/air batteries.

Revealing the Indispensable Role of In Situ Electrochemically Reconstructed Mn(II)/Mn(III) in Improving the Performance of Lithium-Carbon Dioxide Batteries.

Li-CO2 batteries are regarded as promising high-energy-density energy conversion and storage devices, but their practicability is severely hindered by the sluggish CO2 reduction/evolution reaction (CORR/COER) kinetics. Due to the various crystal structures and unique electronic configuration, Mn-based cathode catalysts have shown considerable competition to facilitate CORR/COER. However, the specific active sites and regulation principle of Mn-based catalysts remain ambiguous and limited. Herein, this work designs novel Mn dual-active sites (MOC) supported on N-doped carbon nanofibers and conduct a comprehensive investigation into the underlying relationship between different Mn active sites and their electrochemical performance in Li-CO2 batteries. Impressively, this work finds that owing to the in situ generation and stable existence of Mn(III), MOC undergoes obvious electrochemical reconstruction during battery cycling. Moreover, a series of characterizations and theoretical calculations demonstrate that the different electronic configurations and coordination environments of Mn(II) and Mn(III) are conducive to promoting CORR and COER, respectively. Benefiting from such a modulating behavior, the Li-CO2 batteries deliver a high full discharge capacity of 10.31 mAh cm-2, and ultra-long cycle life (327 cycles/1308h). This fundamental understanding of MOC reconstruction and the electrocatalytic mechanisms provides a new perspective for designing high-performance multivalent Mn-integrated hybrid catalysts for Li-CO2 batteries.

Cold-plasma activation converting conductive agent in spent Li-ion batteries to bifunctional oxygen reduction/evolution electrocatalyst for zinc-air batteries

Considerable amount of high-value transition metals components can be recycled in spent ternary lithium-ion batteries. In this study, we utilized the conductive agent carbon black, obtained from the leaching waste resulting from the chemical recovery of spent lithium-nickel-manganese-cobalt (NCM) oxide cathode materials. This process allows us to create valuable bifunctional catalysts for the oxygen reduction reaction and oxygen evolution reaction (ORR/OER), facilitated by a facile cold plasma activation method, as a part of lithium batteries circular economy. The activated conductive agent (RCA-30) exhibited an ORR half-wave potential of 0.74 V (vs. RHE) in 0.1 mol/L KOH solution, and an OER overpotential of 360 mV at 10 mA cm-2 in 1 mol/L KOH electrolyte, owing to nitrogen doping of carbon black and activation of surface metal oxides. The complete zinc-air batteries incorporating the activated catalysts at the cathode exhibited an open circuit potential of up to 1.48 V and sustained cycling for 100 h at a current density of 5 mA cm-2. Additionally, the activated catalysts contributed to a power density of 92 mW cm-2 and a full discharge capacity of 640 mAh/g.

Enhanced TiO2/SiCx Active Layer Formed In Situ on Coal Gangue/Ti3C2 MXene Electrocatalyst as Catalytic Integrated Units for Efficient Li-O2 Batteries

The pursuit of efficient cathode catalysts to improve cycle stability at ultra-high rates plays an important role in boosting the practical utilization of Li-O2 batteries. Featured as industrial solid waste, coal gangue with rich electrochemical active components could be a promising candidate for electrocatalysts. Here, a coal gangue/Ti3C2 MXene hybrid with a TiO2/SiCx active layer is synthesized and applied as a cathode catalyst in Li-O2 batteries. The coal gangue/Ti3C2 MXene hybrid has a tailored amorphous/crystalline heterostructure, enhanced active TiO2 termination, and a stable SiCx protective layer; thereby, it achieved an excellent rate stability. The Li-O2 battery, assembled with a coal gangue/Ti3C2 MXene cathode catalyst, was found to obtain a competitive full discharge capacity of 3959 mAh g−1 and a considerable long-term endurance of 180 h (up to 175 cycles), with a stable voltage polarization of 1.72 V at 2500 mA g−1. Comprehensive characterization measurements (SEM, TEM, XPS, etc.) were applied; an in-depth analysis was conducted to reveal the critical role of TiO2/SiCX active units in regulating the micro-chemical constitution and the enhanced synergistic effect between coal gangue and Ti3C2 MXene. This work could provide considerable insights into the rational design of catalysts derived from solid waste gangue for high-rate Li-O2 batteries.

State of Health Estimation Procedure for Lithium-Ion Batteries Using Partial Discharge Data and Support Vector Regression

Battery aging is a complex phenomenon, and precise state of health (SoH) monitoring is essential for effective battery management. This paper presents a data-driven method for SoH estimation based on support vector regression (SVR), utilizing features built from both full and partial discharge capacity curves, as well as battery temperature data. It provides an in-depth discussion of the novel features constructed from different voltage intervals. Moreover, three combinations of features were analyzed, demonstrating how their efficacy changes across different voltage ranges. Successful results were obtained using the full discharge capacity curves, built from the full interval of 2 to 3.4 V and achieving a mean R2 value of 0.962 for the test set, thus showcasing the adequacy of the selected SVR strategy. Finally, the features constructed from the full voltage range were compared with ones built from 10 small voltage ranges. Similar success was observed, evidenced by a mean R2 value ranging between 0.939 and 0.973 across different voltage ranges. This indicates the practical applicability of the developed models in real-world scenarios. The tuning and evaluation of the proposed models were carried out using a substantial dataset created by Toyota, consisting of 124 lithium iron phosphate batteries.

Epitaxial Growth of Li2O2 Achieved by a Rational Designed Fe3O4@N‐doped Carbon Nanoflower Structure for Improving the Performance of Li−O2 Batteries

AbstractThe insulated and insoluble discharge product Li2O2 can cause excessive charge overpotential, eventually leading to the deactivation of the Li−O2 battery. Here, a nanoflower structure (Fe3O4@NC) fabricated by coating Fe3O4 with N‐doped carbon was used as an effective catalyst for Li−O2 cathode. The N‐doped defective carbon layer provides sufficient active sites for the formation of discharge intermediates and exhibits a coating effect on Fe3O4, thereby facilitating the maintenance of structural stability. The hierarchical structure of Fe3O4 can effectively mitigate the agglomeration of the carbon layer, thus promoting a homogeneous distribution and optimal utilization of active sites on the carbon layer. As a result, the synergistic effect of Fe3O4 combined with the N‐doped carbon layer enhances the Li+/e− transfer rate and effectively accelerates the kinetic of oxygen reduction/evolution reaction (ORR/OER). Furthermore, the unique functionality of Fe3O4@NC induces the epitaxial growth of Li2O2 into uniform nanosheets, thereby increasing the utilization of cathode space and ultimately promoting the energy release of Li−O2 batteries. The Li−O2 battery with Fe3O4@NC cathode exhibits remarkable full discharge capacity of 16495 mAh g−1 and significantly improved round‐trip performances for 120 cycles at a cutoff capacity of 1000 mAh g−1 with a current density of 200 mA g−1.

Mesoporous SiO2 anode armour for lithium oxygen battery

We are reporting a new lithium (Li) anode protective strategy using mesoporous silicon dioxide (mSiO2) to extend the operation lifetime for Li oxygen batteries (LOBs). The fabrication method is simple and easy for mass production. The mSiO2 protective layer inhibits the growth of Li dendrites and prevents the intrinsic Li corrosion phenomenon that occurs in all Li-metal-based batteries during charge/discharge cycles, the porous structure of nanoparticles within the mSiO2 also actively created parallel pathways for Li+ transport thus enhancing the mass transfer. Propylene carbonate/Li with a 100 μL drop amount of mSiO2 protective layer (mPL100) showed excellent per-formance in the Li||Li battery charge/discharge cycle test, withstanding 2,276 h of continuous operation, almost 16 times longer than the battery without the protective layer, and the LOB charge/discharge cycle test with the mSiO2 protective layer reached 382 cycles, another significant increase of 6.2 times over the unprotected battery, the full discharge capacity also reached 56,902 mAh/g that is nearly 19 times higher than the unprotected cell. Because the mSiO2 made Li+ flux more homogeneous meanwhile promoting the uniform distribution of positive electrode products and accelerating their decomposition, thus the overpotential is reduced. This layer also blocked any H2O and peroxide molecules which attack the Li anode, therefore the retention of Li has been kept at a satisfactory level.

Preparation of Composite Single‐Ion Conductor Membrane and Its Application in Lithium–Oxygen Battery

Redox mediators (RMs) are reported to effectually encourage the inactive decomposition of discharge products in lithium–oxygen batteries (LOBs); however, oxidized RMs and other injurious species still attack the Li anodes. An ionic liquid (IL)‐modified PVDF single‐lithium‐ion conducting composite membrane that can permit Li+ only but blocks anions and other molecules is prepared. The PVDF is combined with the strong‐acid cation styrene exchange resin with cation exchange characteristics to make a heterogeneous composite single‐ionic conductor membrane and the IL modification causes the formation of a more‐dense groove inside the PVDF membrane apparently strengthening the conductivity of the membrane without losing its impermeability to cations and discharge intermediates. The utility of the modified composite PVDF (MCP) separator greatly extends the cycle life of the LOB from 66 to 347 cycles at 1000 mAg−1 and 1000 mAhg−1 compared to cells using glass fiber separators. Rate performance is significantly enhanced at 3000 and 5000 mAg−1, increasing from 33 and 21 cycles to 171 and 137 cycles. The full discharge capacity also expands from 3702 to 51 205 mAhg−1. The MCP separator enables iodide‐assisted cathode processes and improves lithium anode stripping/plating, which is essential to improve the performance of nonelectrolytic LOBs.

Modulating Bidirectional Catalytic Activity Through a RuNi Nanoalloy on Facile Candle Soot Carbon Towards Efficient Lithium‐CO2Mars Batteries

AbstractLithium‐CO2 batteries have been at the forefront of reducing CO2 emissions and addressing the present energy crisis. As the Martian atmosphere is 95 % CO2, this battery technology is ideal as a stand‐alone energy storage device on the planet. However, challenges such as low reversibility, high charging voltages, and poor cycling life restrict its practicability. The current study addresses these by increasing the reversibility of the active reaction sites on the cathode via a synergistic interaction between the RuNi nanoparticle catalyst and candle soot carbon (CSC). This helps the system achieve a full discharge capacity of 15207 mAh g−1 at a high current density of 200 mA g−1 with 99.3 % coulombic efficiency and an efficient cycling life of over 100 cycles at a higher current density of 500 mA g−1 for a limited capacity of 500 mAh g−1. Further, combining ex‐situ physical characterizations and density functional theory helps understand the underlying mechanism for improving the bidirectional CO2 reduction and evolution activities during discharging and charging. The study, thus using a bimetallic catalyst and carbon, provides an approach for a single solution towards addressing the dual challenges of regulating CO2 emissions on Earth and providing a constant energy source on Mars.

Modeling Improved Li-Ion Cell Capacity through Suppression of Temperature with Internal Electrolyte Flow

Lithium-ion cells are ubiquitous in portable electronic applications and are growing in popularity for electric vehicles including passenger cars. Yet, a dramatic reduction in global emissions to combat climate change calls for significantly broader adoption of carbon neutral technologies in electric vehicles and in stationary energy storage to complement variable renewable sources and growing electricity demand.1 For lithium-ion batteries, a critical barrier to such broader adoption is the inability to sustain high rate while also accessing the full capacity of cells. In addition to mass transport effects, overheating commonly limits the duration of high-rate discharge or charge due to excessive heat generation and inadequate heat removal.Here, we provide a brief illustrative tutorial of these coupled effects in a pseudo two-dimensional electrochemical model and build on our previous modeling and dimensional analyses2-4 of how internal electrolyte flow across Li-ion cells reduces both mass and thermal transport limitations.First, we describe the intentional and sudden onset of internal electrolyte convection to curb or to avert further temperature rise in a Li-ion cell during high-rate discharge. We examine two modes for introducing electrolyte flow: temperature-triggered (“reactive”) and discharge-rate triggered (“proactive”) modes. In the reactive case, flow is introduced in the simulation when a cell under high-rate discharge reaches a high safety cutoff temperature. In the proactive case, flow begins as the discharge rate is step changed from midrate to high rate. A practical application of proactive mode is that a battery thermal management system could be programmed to initiate electrolyte flow in anticipation of greater heat generation at a higher rate.Next, using the aforementioned continuum modeling with circulation through an external tank, we compare and contrast Li-ion cell thermal responses to the onset of flow in reactive mode versus in proactive mode. In both cases, the threshold flow rate (~μm/s) to suppress temperature rise agrees in order of magnitude with dimensionless group estimates reported in our previous work.4 Namely, temperature rise is suppressed when the heat generation rate becomes lower than the heat removal rate. At the highest electrolyte flow rates simulated (>>μm /s), the heat removal by internal electrolyte flow dominates, and the cell achieves nearly full discharge capacity without prematurely crossing temperature or voltage cutoffs. For low flow rates (<μm /s), the proactive and reactive cases show quantitatively different transient temperature trajectories due to the temperature dependences of heat generation and removal. Heat generation rate decreases with elevated cell temperature due to facile mass transfer and resultant concentration uniformity, optimal electrolyte conductivity, and ease of charge transfer kinetics. Also, heat removal using internal electrolyte flow becomes more effective with high cell temperature relative to ambient inlet temperature. Hence, the flow rate needed to cool a cell that has reached a high safety cutoff temperature (in reactive mode) is lower than the flow rate required to curb temperature rise in a cell just above ambient temperature (in proactive mode) as high-rate discharge starts.

Revealing the construction of Cu[sbnd]O[sbnd]Ce interfacial sites via increased support utilization for enhanced CO2 electroreduction and Li-CO2 batteries

Leveraging designed electronic oxide-metal interactions (EOMI), cerium-supported copper demonstrates remarkable competitiveness in the carbon dioxide reduction reaction (CO2RR). Nevertheless, the limited utilization efficiency of conventional cerium oxide (CeO2) support hampers the EOMI effect. Furthermore, a comprehensive understanding of the influence of distinct crystalline surfaces of CeO2 on the loaded active copper (Cu) species remains elusive. Herein, oxide carriers with diverse crystal facets are acquire for loading to load Cu species through the incorporation of cerium-based metal organic frameworks (MOFs) precursors. Simultaneously, owing to the elevated specific surface area conferred by MOF precursors, Cu/CeO2 hosts ample catalytically active sites for carbon dioxide (CO2) electrocatalytic reactions and as catalytic cathodes for lithium-CO2 (Li-CO2) batteries. Furthermore, the carbon converted from organic ligands in MOFs precursors not only proficiently immobilizes and disperses the active sites, but also enhances the inherent conductive stability of the oxide while augmenting energy utilization efficiency. Leveraging these advantages, the electrocatalyst derived from MOFs achieves a peak CO2-to-methane Faradaic efficiency of 57.9 %, whereas the assembled Li-CO2 batteries exhibit notable activity and durability, boasting a substantial full-discharge capacity of 8907 mAh/g, a discharge voltage of 2.65 V, and an extended cycle life exceeding 1000 h. Mechanistic investigations were conducted using density functional theory (DFT) calculations to thoroughly explore the impact of CeO2 carrier crystal facets, specifically (111), (100), and (110), on the loaded copper species. Notably, (110) was identified as the optimal facet due to its favorable contributions to electronic structure optimization and stability enhancement.

Efficient Biorenewable Membranes in Lithium-Oxygen Batteries.

Lithium-oxygen batteries, with their very high energy density (3500 Wh kg-1), could represent a real breakthrough in the envisioned strategies towards more efficient energy storage solutions for a less and less carbonated energy mix. However, the problems associated with this technology are numerous. A first one is linked to the high reactivity of the lithium metal anode, while a second one is linked to the highly oxidative environment created by the cell's O2 saturation. Keeping in mind the necessity for greener materials in future energy storage solutions, in this work an innovative lithium protective membrane is prepared based on chitosan, a polysaccharide obtained from the deacetylation reaction of chitin. Chitosan was methacrylated through a simple, one-step reaction in water and then cross-linked by UV-induced radical polymerization. The obtained membranes were successively activated in liquid electrolyte and used as a lithium protection layer. The cells prepared with protected lithium were able to reach a higher full discharge capacity, and the chitosan's ability to slow down degradation processes was verified by post-mortem analyses. Moreover, in long cycling conditions, the protected lithium cell performed more than 40 cycles at 0.1 mA cm-2, at a fixed capacity of 0.5 mAh cm-2, retaining 100% coulombic efficiency, which is more than twice the lifespan of the bare lithium cell.

High Areal Capacity, Long Cycle Life Li-Air Batteries Enabled by Nano/Micro Hierarchical Porous Cathode.

The limited cycle life of Li-air batteries (LABs) with high areal capacity remains the chief challenge that hinders their practical applications. Here, the study proposes a hierarchical porous electrode (HPE) design strategy, in which porous MnO nanoflowers are built into mesopore/macropore electrodes through a combination of chemical dealloying and physical de-templating procedures. The MnO nanoflowers with 10-30nm pore provides active sites to catalyze the O2 reduction and decomposition of discharged products. The 5-10µm macroscopic pores in the cathode serve as channels of O2 transportation and facilitate the electrolyte permeation. The proposed HPE exhibits a full discharge capacity of 17.49mAhcm-2 and stable cycle life >2000h with a limited capacity of 6mAhcm-2 . These results suggest that the HPE design strategy for LABs can simultaneously provide large capacity and robust cycle life, which is promising for advanced metal-air batteries.

Garnet Electrolyte‐Based Integrated Architecture for High‐Performance All‐Solid‐State Lithium‐Oxygen Batteries

AbstractAll‐solid‐state lithium‐oxygen (Li‐O2) battery is considered to be a promising next‐generation energy storage system to address the issues related to low specific capacity, unsafety and unstable electrochemistry that exist in conventional liquid Li‐O2 batteries. However, current solid‐state Li‐O2 batteries still encounter the challenge of high impedance at the electrode/electrolyte interface. In addition, the deficiency of triple‐phase boundaries (containing Li+, e− and O2) limits the active sites for electrochemical reaction in the battery cathode. Herein, an integrated architecture based on a garnet electrolyte Li6.4La3Zr1.4Ta0.6O12 (LLZTO) and a porous composite cathode for high‐performance all‐solid‐state Li‐O2 batteries is developed. The unique internal structure effectively reduces the interfacial impedance of the battery, provides a large number of active sites at triple‐phase boundaries and increases the electrochemical stability. As a result, the obtained batteries can deliver a superior high full discharge capacity of 13.04 mA h cm−2 and an excellent cyclic performance (86 cycles). In addition, X‐ray photoelectron spectroscopy, differential electrochemical mass spectrometry and theoretical calculations further demonstrate the effectiveness of this design in enhancing the interfacial performance, electrochemical performance, and stability of the battery. This study is thus expected to facilitate practical applications for truly all‐solid‐state Li‐O2 batteries, and even for other systems of metal‐oxygen (air) batteries.

Data-driven battery health prognosis with partial-discharge information

The unpredictability of battery degradation behavior is a challenging issue impeding the development of battery applications, due to the complexity of the degradation and the limitation of state measurement methods. Nowadays, with accessible battery aging datasets and machine learning algorithms, there are opportunities for data-driven battery health prognosis. However, most of the previous work is restricted in the scope of full-discharge capacity records extrapolation, which has insufficient prospects in real-life applications. In this work, we propose using partial discharge information for degradation estimation and prediction. Our Gaussian process regression model achieves good performance by limited partial discharge information without requirements of feature selection. The accurate battery health prognosis in 300 cycles can be carried out by one partial-discharge cycle at any degradation stage. The capacity estimation gives around 1 % root mean square error (RMSE) when using 30 % information on the discharge process. As full-cycle discharge is not required, the proposed model can diagnose the battery state of health (SOH) with a limited portion of battery operation information extracted during the discharge process and reduce the effort of capacity tests. Further development of this method brings opportunities for battery state evaluation and prediction in real applications with better applicability and accuracy.

Copper Indium Sulfide Enables Li‐CO2 Batteries with Boosted Reaction Kinetics and Cycling Stability

High energy density Li‐CO2 batteries have attracted much attention owing to the “two birds with one stone” feature in fixing greenhouse gas CO2 and providing renewable energy. However, poor reversibility of the discharge product Li2CO3 is one of the main problems that limit its application, resulting in poor cycling stability and severe polarization. Herein, copper indium sulfide (CIS), a semiconducting non‐precious metal sulfide, is fabricated as cathode catalysts for high‐performance Li‐CO2 batteries. Combined with the synergistic effect of bimetallic valence bonding and coordinated electron transfer, Li‐CO2 batteries using CIS cathodes exhibit high full specific discharge capacity, excellent rate capability and cycle stability, namely it delivers a high specific full discharge capacity of 8878 μAh cm−2, runs steadily from 10 to 100 μA cm−2, and performs a stable long‐term cycling behavior (&gt;1050 h) under a high energy efficiency of 84% and a low charge voltage of approximately 3.4 V at 20 μA cm−2 within 100 μAh cm−2. In addition, a flexible Li‐CO2 pouch cell is constructed to reveal the potential of employing CIS to fabricate flexible high energy storage devices in practical applications. This work shows a promising development pathway toward next‐generation sustainable energy storage devices.

Isolated Metalloid Tellurium Atomic Cluster on Nitrogen-Doped Carbon Nanosheet for High-Capacity Rechargeable Lithium-CO2 Battery.

Rechargeable Li-CO2 battery represents a sustainable technology by virtue of CO2 recyclability and energy storage capability. Unfortunately, the sluggish mass transport and electron transfer in bulky high-crystalline discharge product of Li2 CO3 , severely hinder its practical capacity and rechargeability. Herein, a heterostructure of isolated metalloid Te atomic cluster anchored on N-doped carbon nanosheets is designed (TeAC @NCNS) as a metal-free cathode for Li-CO2 battery. X-ray absorption spectroscopy analysis demonstrates that the abundant and dispersed Te active centers can be stabilized by C atoms in form of the covalent bond. The fabricated battery shows an unprecedented full-discharge capacity of 28.35mAhcm-2 at 0.05mAcm-2 and long-term cycle life of up to 1000h even at a high cut-off capacity of 1mAhcm-2 . A series of ex situ characterizations combined with theoretical calculations demonstrate that the abundant Te atomic clusters acting as active centers can drive the electron redistribution of carbonate via forming TeO bonds, giving rise to poor-crystalline Li2 CO3 film during the discharge process. Moreover, the efficient electron transfer between the Te centers and intermediate species is energetically beneficial for nucleation and accelerates the decomposition of Li2 CO3 on the TeAC @NCNS during the discharge/charge process.

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.

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.