Exposing {010} Active Facets by Multiple‐Layer Oriented Stacking Nanosheets for High‐Performance Capacitive Sodium‐Ion Oxide Cathode

As one of the most promising cathodes for rechargeable sodium‐ion batteries (SIBs), O3‐type layered transition metal oxides commonly suffer from inevitably complicated phase transitions and sluggish kinetics. Here, a Na[Li_0.05Ni_0.3Mn_0.5Cu_0.1Mg_0.05]O₂ cathode material with the exposed {010} active facets by multiple‐layer oriented stacking nanosheets is presented. Owing to reasonable geometrical structure design and chemical substitution, the electrode delivers outstanding rate performance (71.8 mAh g^?1 and 16.9 kW kg^?1 at 50C), remarkable cycling stability (91.9% capacity retention after 600 cycles at 5C), and excellent compatibility with hard carbon anode. Based on the combined analyses of cyclic voltammograms, ex situ X‐ray absorption spectroscopy, and operando X‐ray diffraction, the reaction mechanisms behind the superior electrochemical performance are clearly articulated. Surprisingly, Ni²⁺/Ni³⁺ and Cu²⁺/Cu³⁺ redox couples are simultaneously involved in the charge compensation with a highly reversible O3–P3 phase transition during charge/discharge process and the Na⁺ storage is governed by a capacitive mechanism via quantitative kinetics analysis. This optimal bifunctional regulation strategy may offer new insights into the rational design of high‐performance cathode materials for SIBs.     

Direct Visualization of the Reversible O2−/O− Redox Process in Li‐Rich Cathode Materials

Conventional cathodes of Li‐ion batteries mainly operate through an insertion–extraction process involving transition metal redox. These cathodes will not be able to meet the increasing requirements until lithium‐rich layered oxides emerge with beyond‐capacity performance. Nevertheless, in‐depth understanding of the evolution of crystal and excess capacity delivered by Li‐rich layered oxides is insufficient. Herein, various in situ technologies such as X‐ray diffraction and Raman spectroscopy are employed for a typical material Li_1.2Ni_0.2Mn_0.6O₂, directly visualizing O^?? O^? (peroxo oxygen dimers) bonding mostly along the c‐axis and demonstrating the reversible O^2?/O^? redox process. Additionally, the formation of the peroxo O? O bond is calculated via density functional theory, and the corresponding O? O bond length of ≈1.3 Å matches well with the in situ Raman results. These findings enrich the oxygen chemistry in layered oxides and open opportunities to design high‐performance positive electrodes for lithium‐ion batteries.     

Ultrahigh Capacity Due to Multi‐Electron Conversion Reaction in Reduced Graphene Oxide‐Wrapped MoO2 Porous Nanobelts

Multivalent transition metal oxides (MO_x) containing redox centers which can theoretically accept more than one electron have been suggested as promising anode materials for high‐performance lithium ion batteries (LIBs). The Li‐storage mechanism of these oxides is suggested to involve an unusual conversion reaction leading to the formation of metallic nanograins and Li₂O; however, a full‐scale conversion reaction is seldom observed in molybdenum dioxide (MoO₂) at room temperature due to slow kinetics. Herein, a full‐scale multi‐electron conversion reaction, leading to a high reversible capacity (974 mA h g^?1 charging capacity at 60 mA g^?1) in LIBs, is realized in a hybrid consisting of reduced graphene oxide (rGO) sheet‐wrapped MoO₂ porous nanobelts (rGO/MoO₂ NBs). The rGO wrapping layers stabilize the nanophase transition in MoO₂ and alleviate volume swing effects during lithiation/delithiation processes. This enables the hybrid to exhibit great cycle stability (tested to around 1900 cycles) and ultrafast rate capability (tested up to 50 A g^?1).     

Intercalating Ti2Nb14O39 Anode Materials for Fast‐Charging,High‐Capacity and Safe Lithium–Ion Batteries

Ti–Nb–O binary oxide materials represent a family of promising intercalating anode materials for lithium‐ion batteries. In additional to their excellent capacities (388–402 mAh g^–1), these materials show excellent safety characteristics, such as an operating potential above the lithium plating voltage and minimal volume change. Herein, this study reports a new member in the Ti–Nb–O family, Ti₂Nb₁₄O₃₉, as an advanced anode material. Ti₂Nb₁₄O₃₉ porous spheres (Ti₂Nb₁₄O₃₉‐S) exhibit a defective shear ReO₃ crystal structure with a large unit cell volume and a large amount of cation vacancies (0.85% vs all cation sites). These morphological and structural characteristics allow for short electron/Li⁺‐ion transport length and fast Li⁺‐ion diffusivity. Consequently, the Ti₂Nb₁₄O₃₉‐S material delivers significant pseudocapacitive behavior and excellent electrochemical performances, including high reversible capacity (326 mAh g^?1 at 0.1 C), high first‐cycle Coulombic efficiency (87.5%), safe working potential (1.67 V vs Li/Li⁺), outstanding rate capability (223 mAh g^–1 at 40 C) and durable cycling stability (only 0.032% capacity loss per cycle over 200 cycles at 10 C). These impressive results clearly demonstrate that Ti₂Nb₁₄O₃₉‐S can be a promising anode material for fast‐charging, high capacity, safe and stable lithium‐ion batteries.     

A High‐Capacity O2‐Type Li‐Rich Cathode Material with a Single‐Layer Li2MnO3 Superstructure

A high capacity cathode is the key to the realization of high‐energy‐density lithium‐ion batteries. The anionic oxygen redox induced by activation of the Li₂MnO₃ domain has previously afforded an O3‐type layered Li‐rich material used as the cathode for lithium‐ion batteries with a notably high capacity of 250–300 mAh g^?1. However, its practical application in lithium‐ion batteries has been limited due to electrodes made from this material suffering severe voltage fading and capacity decay during cycling. Here, it is shown that an O2‐type Li‐rich material with a single‐layer Li₂MnO₃ superstructure can deliver an extraordinary reversible capacity of 400 mAh g^?1 (energy density: ≈1360 Wh kg^?1). The activation of a single‐layer Li₂MnO₃ enables stable anionic oxygen redox reactions and leads to a highly reversible charge–discharge cycle. Understanding the high performance will further the development of high‐capacity cathode materials that utilize anionic oxygen redox processes.     

A Single‐Step Hydrothermal Route to 3D Hierarchical Cu2O/CuO/rGO Nanosheets as High‐Performance Anode of Lithium‐Ion Batteries

As anodes of Li‐ion batteries, copper oxides (CuO) have a high theoretical specific capacity (674 mA h g^?1) but own poor cyclic stability owing to the large volume expansion and low conductivity in charges/discharges. Incorporating reduced graphene oxide (rGO) into CuO anodes with conventional methods fails to build robust interaction between rGO and CuO to efficiently improve the overall anode performance. Here, Cu₂O/CuO/reduced graphene oxides (Cu₂O/CuO/rGO) with a 3D hierarchical nanostructure are synthesized with a facile, single‐step hydrothermal method. The Cu₂O/CuO/rGO anode exhibits remarkable cyclic and high‐rate performances, and particularly the anode with 25 wt% rGO owns the best performance among all samples, delivering a record capacity of 550 mA h g^?1 at 0.5 C after 100 cycles. The pronounced performances are attributed to the highly efficient charge transfer in CuO nanosheets encapsulated in rGO network and the mitigated volume expansion of the anode owing to its robust 3D hierarchical nanostructure.     

MOF‐Derived CuS@Cu‐BTC Composites as High‐Performance Anodes for Lithium‐Ion Batteries

The CuS(x wt%)@Cu‐BTC (BTC = 1,3,5‐benzenetricarboxylate; x = 3, 10, 33, 58, 70, 99.9) materials are synthesized by a facile sulfidation reaction. The composites are composed of octahedral Cu₃(BTC)₂·(H₂O)₃ (Cu‐BTC) with a large specific surface area and CuS with a high conductivity. The as‐prepared CuS@Cu‐BTC products are first applied as the anodes of lithium‐ion batteries (LIBs). The synergistic effect between Cu‐BTC and CuS components can not only accommodate the volume change and stress relaxation of electrodes but also facilitate the fast transport of Li ions. Thus, it can greatly suppress the transformation process from Li₂S to polysulfides by improving the reversibility of the conversion reaction. Benefiting from the unique structural features, the optimal CuS(70 wt%)@Cu‐BTC sample exhibits a remarkably improved electrochemical performance, showing an over‐theoretical capacity up to 1609 mAh g^?1 after 200 cycles (100 mA g^?1) with an excellent rate‐capability of ≈490 mAh g^?1 at 1000 mA g^?1. The outstanding LIB properties indicate that the CuS(70 wt%)@Cu‐BTC sample is a highly desirable electrode material candidate for high‐performance LIBs.     

Investigation of Binary Metal (Ni,Co) Selenite as Li‐Ion Battery Anode Materials and Their Conversion Reaction Mechanism with Li Ions

Highly efficient anode materials with novel compositions for Li‐ion batteries are actively being researched. Multicomponent metal selenite is a promising candidate, capable of improving their electrochemical performance through the formation of metal oxide and selenide heterostructure nanocrystals during the first cycle. Here, the binary nickel–cobalt selenite derived from Ni–Co Prussian blue analogs (PBA) is chosen as the first target material: the Ni–Co PBA are selenized and partially oxidized in sequence, yielding (NiCo)SeO₃ phase with a small amount of metal selenate. The conversion mechanism of (NiCo)SeO₃ for Li‐ion storage is studied by cyclic voltammetry, in situ X‐ray diffraction, ex situ X‐ray photoelectron spectroscopy, in situ electrochemical impedance spectroscopy, and ex situ transmission electron microscopy. The reversible reaction mechanism of (NiCo)SeO₃ with the Li ions is described by the reaction: NiO + CoO + xSeO₂ + (1 ‐ x)Se + (4x + 6)Li⁺ + (4x + 6)e^? ? Ni + Co + (2x + 2)Li₂O + Li₂Se. To enhance electrochemical properties, polydopamine‐derived carbon is uniformly coated on (NiCo)SeO₃, resulting in excellent cycling and rate performances for Li‐ion storage. The discharge capacity of C‐coated (NiCo)SeO₃ is 680 mAh g^?1 for the 1500th cycle when cycled at a current density of 5 A g^?1.     

Synthesis Process of CoSeO3 Microspheres for Unordinary Li‐ion Storage Performances and Mechanism of Their Conversion Reaction with Li ions

Multicomponent materials with various double cations have been studied as anode materials of lithium‐ion batteries (LIBs). Heterostructures formed by coupling different‐bandgap nanocrystals enhance the surface reaction kinetics and facilitate charge transport because of the internal electric field at the heterointerface. Accordingly, metal selenites can be considered efficient anode materials of LIBs because they transform into metal selenide and oxide nanocrystals in the first cycle. However, few studies have reported synthesis of uniquely structured metal selenite microspheres. Herein, synthesis of high‐porosity CoSeO₃ microspheres is reported. Through one‐pot oxidation at 400 °C, CoSe_x–C microspheres formed by spray pyrolysis transform into CoSeO₃ microspheres showing unordinary cycling and rate performances. The conversion mechanism of CoSeO₃ microspheres for lithium‐ion storage is systematically studied by cyclic voltammetry, in situ X‐ray diffraction and electrochemical impedance spectroscopy, and transmission electron microscopy. The reversible reaction mechanism of the CoSeO₃ phase from the second cycle onward is evaluated as CoO + xSeO₂ + (1 ? x)Se + 4(x + 1)Li⁺+ 4( x + 1)e^? ? Co + (2x + 1)Li₂O + Li₂Se. The CoSeO₃ microspheres show a high reversible capacity of 709 mA h g^?1 for the 1400th cycle at a current density of 3 A g^?1 and a high reversible capacity of 526 mA h g^?1 even at an extremely high current density of 30 A g^?1.     

Multi‐Step Phase Transitions of Mn3O4 During Galvanostatic Lithiation: An In Situ Transmission Electron Microscopic Investigation

For study of electrochemical reaction mechanisms at nanoscale, in situ electrochemical transmission electron microscopy (EC‐TEM) exceeds many other methods due to its high temporal and spatial resolution. However, the limited amount of active materials used in previous in situ TEM studies prevents the model EC cells to operate in the constant‐current (galvanostatic) charge/discharge mode that is required for accurate control of electrochemical processes. Herein, a new in situ EC‐TEM technique is developed to investigate multi‐step phase transitions of Mn₃O₄ electrodes under the galvanostatic charge/discharge mode and constant‐voltage discharge mode. In galvanostatic mode, the lithiation of Mn₃O₄ undergoes multi‐step phase transitions following a reaction pathway of Mn₃O₄ + Li⁺ → LiMn₃O₄ + Li⁺ → MnO + Li₂O → Mn + Li₂O. It is also found that lithium ions prefer to enter Mn₃O₄ along the {101} direction to form LiMn₃O₄ with the help of transitional boundary phase of Li_xMn₃O₄. These results are in sharp contrast to that obtained under a constant‐voltage discharge mode, where only a single‐step lithiation process of Mn₃O₄ + Li⁺ → Mn + Li₂O is observed.     

Graphene Oxide Sieving Membrane for Improved Cycle Life in High‐Efficiency Redox‐Mediated Li–O2 batteries

As soluble catalysts, redox‐mediators (RMs) endow mobility to catalysts for unconstrained access to tethered solid discharge products, lowering the energy barrier for Li₂O₂ formation/decomposition; however, this desired mobility is accompanied by the undesirable side effect of RM migration to the Li metal anode. The reaction between RMs and Li metal degrades both the Li metal and the RMs, leading to cell deterioration within a few cycles. To extend the cycle life of redox‐mediated Li–O₂ batteries, herein graphene oxide (GO) membranes are reported as RM‐blocking separators. It is revealed that the size of GO nanochannels is narrow enough to reject 5,10‐dihydro‐5,10‐dimethylphenazine (DMPZ) while selectively allowing the transport of smaller Li⁺ ions. The negative surface charges of GO further repel negative ions via Donnan exclusion, greatly improving the lithium ion transference number. The Li–O₂ cells with GO membranes efficiently harness the redox‐mediation activity of DMPZ for improved performance, achieving energy efficiency of above 80% for more than 25 cycles, and 90% for 78 cycles when the capacity limits were 0.75 and 0.5 mAh cm^‐2, respectively. Considering the facile preparation of GO membranes, RM‐sieving GO membranes can be cost‐effective and processable functional separators in Li–O₂ batteries.     

Ultrathin Nanosheet Assembled Sn0.91Co0.19S2 Nanocages with Exposed (100) Facets for High‐Performance Lithium‐Ion Batteries

Ultrathin 2D inorganic nanomaterials are good candidates for lithium‐ion batteries, as well as the micro/nanocage structures with unique and tunable morphologies. Meanwhile, as a cost‐effective method, chemical doping plays a vital role in manipulating physical and chemical properties of metal oxides and sulfides. Thus, the design of ultrathin, hollow, and chemical doped metal sulfides shows great promise for the application of Li‐ion batteries by shortening the diffusion pathway of Li ions as well as minimizing the electrode volume change. Herein, ultrathin nanosheet assembled Sn_0.91Co_0.19S₂ nanocages with exposed (100) facets are first synthesized. The as‐prepared electrode delivers an excellent discharge capacity of 809 mA h g^?1 at a current density of 100 mA g^?1 with a 91% retention after 60 discharge–charge cycles. The electrochemical performance reveals that the Li‐ion batteries prepared by Sn_0.91Co_0.19S₂ nanocages have high capacity and great cycling stability.     

A Double‐Buffering Strategy to Boost the Lithium Storage of Botryoid MnOx/C Anodes

Transition metal oxides (TMOs) are regarded as promising candidates for anodes of lithium ion batteries, but their applications have been severely hindered by poor material conductivity and lithiated volume expansion. As a potential solution, herein is presented a facile approach, by electrospinning a manganese‐based metal organic framework (Mn‐MOF), to fabricate yolk–shell MnO_x nanostructures within carbon nanofibers in a botryoid morphology. While the yolk–shell structure accomodates the lithiated volume expansion of MnO_x, the fiber confinement ensures the structural integrity during charge/discharge, achieving a so‐called double‐buffering for cyclic volume fluctuation. The formation mechanism of the yolk–shell structure is well elucidated through comprehensive instrumental characterizations and cogitative control experiments, following a combined Oswald ripening and Kirkendall process. Outstanding electrochemical performances are demonstrated with prolonged stability over 1000 cycles, boosted by the double‐buffering design, as well as the “breathing” effect of lithiation/delithiation witnessed by ex situ imaging. Both the fabrication methodology and electrochemical understandings gained here for nanostructured MnO_x can also be extended to other TMOs toward their ultimate implementation in high‐performance lithium ion batteries (LIBs).     

A Flexible Ionic Liquid Gelled PVA‐Li2SO4 Polymer Electrolyte for Semi‐Solid‐State Supercapacitors

A novel high‐performance flexible gel polymer electrolyte (FGPE) for supercapacitors is prepared by a freeze‐drying method. In the presence of 1‐butyl‐3‐methylimidazolium chloride (BMIMCl) ionic liquid, Li₂SO₄ can easily be added into poly(vinyl alcohol) (PVA) aqueous solution over a large concentration range. The resultant FGPE demonstrates considerably high ionic conductivity (37 mS cm⁻¹) and a high fracture strain at 100% elongation at the optimal weight ratio of PVA:BMIMCl:Li₂SO₄ = 1:3:2.2. The supercapacitor fabricated with the resultant FGPE and activated carbon electrodes shows an electrode‐specific capacitance of 136 F g⁻¹ with a stable operating voltage of 1.5 V, a maximum energy density of 10.6 Wh kg⁻¹, and a power density of 3400 W kg⁻¹. Double supercapacitors in series can efficiently drive a light emitting diode (LED) bulb for over 5 min and the retention of the specific capacitance reaches 90% even after 3000 charge–discharge cycles. The ionic conductivity and charge–discharge behaviors of the resultant FGPE are not affected by bending up to 180°. The flexible supercapacitor device shows only a small capacitance loss of 18% after 1000 cycles of 135° bending.     

One‐Step Route Synthesized Co2P/Ru/N‐Doped Carbon Nanotube Hybrids as Bifunctional Electrocatalysts for High‐Performance Li–O2 Batteries

The large‐scale commercial application of lithium–oxygen batteries (LOBs) is overwhelmed by the sluggish kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) associated with insoluble and insulated Li₂O₂. Herein, an elaborate design on a highly catalytic LOBs cathode constructed by N‐doped carbon nanotubes (CNT) with in situ encapsulated Co₂P and Ru nanoparticles is reported. The homogeneously dispersed Co₂P and Ru catalysts can effectively modulate the formation and decomposition behavior of Li₂O₂ during discharge/charge processes, ameliorating the electronically insulating property of Li₂O₂ and constructing a homogenous low‐impedance Li₂O₂/catalyst interface. Compared with Co/CNT and Ru/CNT electrodes, the Co₂P/Ru/CNT electrode delivers much higher oxygen reduction triggering onset potential and higher ORR and OER peak current and integral areas, showing greatly improved ORR/OER kinetics due to the synergistic effects of Co₂P and Ru. Li–O₂ cells based on the Ru/Co₂P/CNT electrode demonstrate improved ORR/OER overpotential of 0.75 V, excellent rate capability of 12 800 mAh g^?1 at 1 A g^?1, and superior cycle stability for more than 185 cycles under a restricted capacity of 1000 mAh g^?1 at 100 mA g^?1. This work paves an exciting avenue for the design and construction of bifunctional catalytic cathodes by coupling metal phosphides with other active components in LOBs.     

A Robust and Conductive Black Tin Oxide Nanostructure Makes Efficient Lithium‐Ion Batteries Possible

SnO₂‐based lithium‐ion batteries have low cost and high energy density, but their capacity fades rapidly during lithiation/delithiation due to phase aggregation and cracking. These problems can be mitigated by using highly conducting black SnO_2?x , which homogenizes the redox reactions and stabilizes fine, fracture‐resistant Sn precipitates in the Li₂O matrix. Such fine Sn precipitates and their ample contact with Li₂O proliferate the reversible Sn → Li _x Sn → Sn → SnO₂/SnO_2?x cycle during charging/discharging. SnO_2?x electrode has a reversible capacity of 1340 mAh g^?1 and retains 590 mAh g^?1 after 100 cycles. The addition of highly conductive, well‐dispersed reduced graphene oxide further stabilizes and improves its performance, allowing 950 mAh g^?1 remaining after 100 cycles at 0.2 A g^?1 with 700 mAh g^?1 at 2.0 A g^?1. Conductivity‐directed microstructure development may offer a new approach to form advanced electrodes.     

Early Lithium Plating Behavior in Confined Nanospace of 3D Lithiophilic Carbon Matrix for Stable Solid‐State Lithium Metal Batteries

Considerable efforts are devoted to relieve the critical lithium dendritic and volume change problems in the lithium metal anode. Constructing uniform Li⁺ distribution and lithium “host” are shown to be the most promising strategies to drive practical lithium metal anode development. Herein, a uniform Li nucleation/growth behavior in a confined nanospace is verified by constructing vertical graphene on a 3D commercial copper mesh. The difference of solid‐electrolyte interphase (SEI) composition and lithium growth behavior in the confined nanospace is further demonstrated by in‐depth X‐ray photoelectron spectrometer (XPS) and line‐scan energy dispersive X‐ray spectroscopic (EDS) methods. As a result, a high Columbic efficiency of 97% beyond 250 cycles at a current density of 2 mA cm^?2 and a prolonged lifespan of symmetrical cell (500 cycles at 5 mA cm^?2) can be easily achieved. More meaningfully, the solid‐state lithium metal cell paired with the composite lithium anode and LiNi_0.5Co_0.2Mn_0.3O₂ (NCM) as the cathode also demonstrate reduced polarization and extended cycle. The present confined nanospace–derived hybrid anode can further promote the development of future all solid‐state lithium metal batteries.     

Manganese‐Based Na‐Rich Materials Boost Anionic Redox in High‐Performance Layered Cathodes for Sodium‐Ion Batteries

To improve the energy and power density of Na‐ion batteries, an increasing number of researchers have focused their attention on activation of the anionic redox process. Although several materials have been proposed, few studies have focused on the Na‐rich materials compared with Li‐rich materials. A key aspect is sufficient utilization of anionic species. Herein, a comprehensive study of Mn‐based Na_1.2Mn_0.4Ir_0.4O₂ (NMI) O3‐type Na‐rich materials is presented, which involves both cationic and anionic contributions during the redox process. The single‐cation redox step relies on the Mn³⁺/Mn⁴⁺, whereas Ir atoms build a strong covalent bond with O and effectively suppress the O₂ release. In situ Raman, ex situ X‐ray photoelectron spectroscopy, and soft‐X‐ray absorption spectroscopy are employed to unequivocally confirm the reversibility of O₂^2? species formation and suggest a high degree of anionic reaction in this NMI Na‐rich material. In operando X‐ray diffraction study discloses the asymmetric structure evolution between the initial and subsequent cycles, which also explains the effect of the charge compensation mechanism on the electrochemical performance. The research provides a novel insight on Na‐rich materials and a new perspective in materials design towards future applications.     

Composition and Architecture Design of Double‐Shelled Co0.85Se1−xSx@Carbon/Graphene Hollow Polyhedron with Superior Alkali (Li,Na, K)‐Ion Storage

The exploration of materials with reversible and stable electrochemical performance is crucial in energy storage, which can (de) intercalate all the alkali‐metal ions (Li⁺, Na⁺, and K⁺). Although transition‐metal chalcogenides are investigated continually, the design and controllable preparation of hierarchical nanostructure and subtle composite withstable properties are still great challenges. Herein, component‐optimal Co_0.85Se_1?xS_x nanoparticles are fabricated by in situ sulfidization of metal organic framework, which are wrapped by the S‐doped graphene, constructing a hollow polyhedron framework with double carbon shells (CoSSe@C/G). Benefiting from the synergistic effect of composition regulation and architecture design by S‐substitution, the electrochemical kinetic is enhanced by the boosted electrochemistry‐active sites, and the volume variation is mitigated by the designed structure, resulting in the advanced alkali‐ion storage performance. Thus, it delivers an outstanding reversible capacity of 636.2 mAh g^?1 at 2 A g^?1 after 1400 cycles for Li‐ion batteries. Remarkably, satisfactory initial charge capacities of 548.1 and 532.9 mAh g^?1 at 0.1 A g^?1 can be obtained for Na‐ion and K‐ion batteries, respectively. The prominent performance combined with the theory calculation confirms that the synergistic strategy can improve the alkali‐ion transportation and structure stability, providing an instructive guide for designing high‐performance anode materials for universal alkali‐ion storage.     

A Long‐Cycle‐Life Lithium–CO2 Battery with Carbon Neutrality

Lithium–CO₂ batteries are attractive energy‐storage systems for fulfilling the demand of future large‐scale applications such as electric vehicles due to their high specific energy density. However, a major challenge with Li–CO₂ batteries is to attain reversible formation and decomposition of the Li₂CO₃ and carbon discharge products. A fully reversible Li–CO₂ battery is developed with overall carbon neutrality using MoS₂ nanoflakes as a cathode catalyst combined with an ionic liquid/dimethyl sulfoxide electrolyte. This combination of materials produces a multicomponent composite (Li₂CO₃/C) product. The battery shows a superior long cycle life of 500 for a fixed 500 mAh g^?1 capacity per cycle, far exceeding the best cycling stability reported in Li–CO₂ batteries. The long cycle life demonstrates that chemical transformations, making and breaking covalent C? O bonds can be used in energy‐storage systems. Theoretical calculations are used to deduce a mechanism for the reversible discharge/charge processes and explain how the carbon interface with Li₂CO₃ provides the electronic conduction needed for the oxidation of Li₂CO₃ and carbon to generate the CO₂ on charge. This achievement paves the way for the use of CO₂ in advanced energy‐storage systems.