Dual-Intermetallic Heterostructure on Hierarchical Nanoporous Metal for Highly Efficient Alkaline Hydrogen Electrocatalysis.

Constructing well-defined active multisites is an effective strategy to break linear scaling relationships to develop high-efficiency catalysts toward multiple-intermediate reactions. Here, dual-intermetallic heterostructure composed of tungsten-bridged Co3W and WNi4 intermetallic compounds seamlessly integrated on hierarchical nanoporous nickel skeleton is reported as a high-performance nonprecious electrocatalyst for alkaline hydrogen evolution and oxidation reactions. By virtue of interfacial tungsten atoms configuring contiguous multisites with proper adsorptions of hydrogen and hydroxyl intermediates to accelerate water dissociation/combination and column-nanostructured nickel skeleton facilitating electron and ion/molecule transportations, nanoporous nickel-supported Co3W-WNi4 heterostructure exhibits exceptional hydrogen electrocatalysis in alkaline media, with outstanding durability and impressive catalytic activities for hydrogen oxidation reaction (geometric exchange current density of ≈6.62 mA cm-2) and hydrogen evolution reaction (current density of ≈1.45 A cm-2 at overpotential of 200 mV). Such atom-ordered intermetallic heterostructure alternative to platinum group metals shows genuine potential for hydrogen production and utilization in hydroxide-exchange-membrane water electrolyzers and fuel cells.

Lamellar Nanoporous Metal/Intermetallic Compound Heterostructure Regulating Dendrite-Free Zinc Electrodeposition for Wide-Temperature Aqueous Zinc-Ion Battery.

Aqueous zinc-ion batteries are attractive post-lithium battery technologies for grid-scale energy storage because of their inherent safety, low cost and high theoretical capacity. However, their practical implementation in wide-temperature surroundings persistently confronts irregular zinc electrodeposits and parasitic side reactions on metal anode, which leads to poor rechargeability, low Coulombic efficiency and short lifespan. Here, this work reports lamellar nanoporous Cu/Al2Cu heterostructure electrode as a promising anode host material to regulate high-efficiency and dendrite-free zinc electrodeposition and stripping for wide-temperatures aqueous zinc-ion batteries. In this unique electrode, the interconnective Cu/Al2Cu heterostructure ligaments not only facilitate fast electron transfer but work as highly zincophilic sites for zinc nucleation and deposition by virtue of local galvanic couples while the interpenetrative lamellar channels serving as mass transport pathways. As a result, it exhibits exceptional zinc plating/stripping behaviors in aqueous hybrid electrolyte of diethylene glycol dimethyl ether and zinc trifluoromethanesulfonate at wide temperatures ranging from 25 to -30 °C, with ultralow voltage polarizations at various current densities and ultralong lifespan of >4000 h. The outstanding electrochemical properties enlist full cell of zinc-ion batteries constructed with nanoporous Cu/Al2Cu and ZnxV2O5/C to maintain high capacity and excellent stability for >5000 cycles at 25 and -30 °C.

In Situ Engineering Multifunctional Active Sites of Ruthenium-Nickel Alloys for pH-Universal Ampere-Level Current-Density Hydrogen Evolution.

Developing robust non-platinum electrocatalysts with multifunctional active sites for pH-universal hydrogen evolution reaction (HER) is crucial for scalable hydrogen production through electrochemical water splitting. Here ultra-small ruthenium-nickel alloy nanoparticles steadily anchored on reduced graphene oxide papers (Ru-Ni/rGOPs) as versatile electrocatalytic materials for acidic and alkaline HER are reported. These Ru-Ni alloy nanoparticles serve as pH self-adaptive electroactive species by making use of in situ surface reconstruction, where surface Ni atoms are hydroxylated to produce bifunctional active sites of Ru-Ni(OH)2 for alkaline HER, and selectively etched to form monometallic Ru active sites for acidic HER, respectively. Owing to the presence of Ru-Ni(OH)2 multi-site surface, which not only accelerates water dissociation to generate reactive hydrogen intermediates but also facilitates their recombination into hydrogen molecules, the self-supported Ru90Ni10/rGOP hybrid electrode only takes overpotential of as low as ≈106 mV to deliver current density of 1000 mA cm-2, and maintains exceptional stability for over 1000 h in 1 m KOH. While in 0.5 m H2SO4, the Ru90Ni10/rGOP hybrid electrode exhibits acidic HER catalytic behavior comparable to commercially available Pt/C catalyst due to the formation of monometallic Ru shell. These electrochemical behaviors outperform some of the best Ru-based catalysts and make it attractive alternative to Pt-based catalysts toward highly efficient HER.

Dynamic Molecular Interphases Regulated by Trace Dual Electrolyte Additives for Ultralong-Lifespan and Dendrite-Free Zinc Metal Anode.

Metallic zinc is a promising anode material for rechargeable aqueous multivalent metal-ion batteries due to its high capacity and low cost. However, the practical use is always beset by severe dendrite growth and parasitic side reactions occurring at anode/electrolyte interface. Here we demonstrate dynamic molecular interphases caused by trace dual electrolyte additives of D-mannose and sodium lignosulfonate for ultralong-lifespan and dendrite-free zinc anode. Triggered by plating and stripping electric fields, the D-mannose and lignosulfonate species are alternately and reversibly (de-)adsorbed on Zn metal, respectively, to accelerate Zn2+ transportation for uniform Zn nucleation and deposition and inhibit side reactions for high Coulombic efficiency. As a result, Zn anode in such dual-additive electrolyte exhibits highly reversible and dendrite-free Zn stripping/plating behaviors for >6400 hours at 1 mA cm-2, which enables long-term cycling stability of Zn||ZnxMnO2 full cell for more than 2000 cycles.

Benzoquinone-Lubricated Intercalation in Manganese Oxide for High-Capacity and High-Rate Aqueous Aluminum-Ion Battery.

Aqueous aluminum-ion batteries are attractive post-lithium battery technologies for large-scale energy storage in virtue of abundant and low-cost Al metal anode offering ultrahigh capacity via a three-electron redox reaction. However, state-of-the-art cathode materials are of low practical capacity, poor rate capability, and inadequate cycle life, substantially impeding their practical use. Here layered manganese oxide that is pre-intercalated with benzoquinone-coordinated aluminum ions (BQ-AlxMnO2) as a high-performance cathode material of rechargeable aqueous aluminum-ion batteries is reported. The coordination of benzoquinone with aluminum ions not only extends interlayer spacing of layered MnO2 framework but reduces the effective charge of trivalent aluminum ions to diminish their electrostatic interactions, substantially boosting intercalation/deintercalation kinetics of guest aluminum ions and improving structural reversibility and stability. When coupled with Zn50Al50 alloy anode in 2 m Al(OTf)3 aqueous electrolyte, the BQ-AlxMnO2 exhibits superior rate capability and cycling stability. At 1 A g-1, the specific capacity of BQ-AlxMnO2 reaches ≈300 mAh g-1 and retains ≈90% of the initial value for more than 800 cycles, along with the Coulombic efficiency of as high as ≈99%, outperforming the AlxMnO2 without BQ co-incorporation.

Ultrafast Nucleation Reverses Dissolution of Transition Metal Ions for Robust Aqueous Batteries.

The dissolution of transition metal ions causes the notorious peeling of active substances and attenuates electrochemical capacity. Frustrated by the ceaseless task of pushing a boulder up a mountain, Sisyphus of the Greek myth yearned for a treasure to be unearthed that could bolster his efforts. Inspirationally, by using ferricyanide ions (Fe(CN)63-) in an electrolyte as a driving force and taking advantage of the fast nucleation rate of copper hexacyanoferrate (CuHCF), we successfully reversed the dissolution of Fe and Cu ions that typically occurs during cycling. The capacity retention increased from 5.7% to 99.4% at 0.5 A g-1 after 10,000 cycles, and extreme stability of 99.8% at 1 A g-1 after 40,000 cycles was achieved. Fe(CN)63- enables atom-by-atom substitution during the electrochemical process, enhancing conductivity and reducing volume change. Moreover, we demonstrate that this approach is applicable to various aqueous batteries (i.e., NH4+, Li+, Na+, K+, Mg2+, Ca2+, and Al3+).

Achieving volatile potassium promoted ammonia synthesis via mechanochemistry.

Potassium oxide (K2O) is used as a promotor in industrial ammonia synthesis, although metallic potassium (K) is better in theory. The reason K2O is used is because metallic K, which volatilizes around 400 °C, separates from the catalyst in the harsh ammonia synthesis conditions of the Haber-Bosch process. To maximize the efficiency of ammonia synthesis, using metallic K with low temperature reaction below 400 °C is prerequisite. Here, we synthesize ammonia using metallic K and Fe as a catalyst via mechanochemical process near ambient conditions (45 °C, 1 bar). The final ammonia concentration reaches as high as 94.5 vol%, which was extraordinarily higher than that of the Haber-Bosch process (25.0 vol%, 450 °C, 200 bar) and our previous work (82.5 vol%, 45 °C, 1 bar).

Lamella-heterostructured nanoporous bimetallic iron-cobalt alloy/oxyhydroxide and cerium oxynitride electrodes as stable catalysts for oxygen evolution.

Developing robust nonprecious-metal electrocatalysts with high activity towards sluggish oxygen-evolution reaction is paramount for large-scale hydrogen production via electrochemical water splitting. Here we report that self-supported laminate composite electrodes composed of alternating nanoporous bimetallic iron-cobalt alloy/oxyhydroxide and cerium oxynitride (FeCo/CeO2-xNx) heterolamellas hold great promise as highly efficient electrocatalysts for alkaline oxygen-evolution reaction. By virtue of three-dimensional nanoporous architecture to offer abundant and accessible electroactive CoFeOOH/CeO2-xNx heterostructure interfaces through facilitating electron transfer and mass transport, nanoporous FeCo/CeO2-xNx composite electrodes exhibit superior oxygen-evolution electrocatalysis in 1 M KOH, with ultralow Tafel slope of ~33 mV dec-1. At overpotential of as low as 360 mV, they reach >3900 mA cm-2 and retain exceptional stability at ~1900 mA cm-2 for >1000 h, outperforming commercial RuO2 and some representative oxygen-evolution-reaction catalysts recently reported. These electrochemical properties make them attractive candidates as oxygen-evolution-reaction electrocatalysts in electrolysis of water for large-scale hydrogen generation.

Interface Reversible Electric Field Regulated by Amphoteric Charged Protein-Based Coating Toward High-Rate and Robust Zn Anode.

Metallic interface engineering is a promising strategy to stabilize Zn anode via promoting Zn2+ uniform deposition. However, strong interactions between the coating and Zn2+ and sluggish transport of Zn2+ lead to high anodic polarization. Here, we present a bio-inspired silk fibroin (SF) coating with amphoteric charges to construct an interface reversible electric field, which manipulates the transfer kinetics of Zn2+ and reduces anodic polarization. The alternating positively and negatively charged surface as a build-in driving force can expedite and homogenize Zn2+ flux via the interplay between the charged coating and adsorbed ions, endowing the Zn-SF anode with low polarization voltage and stable plating/stripping. Experimental analyses with theoretical calculations suggest that SF can facilitate the desolvation of [Zn(H2O)6]2+ and provide nucleation sites for uniform deposition. Consequently, the Zn-SF anode delivers a high-rate performance with low voltage polarization (83 mV at 20 mA cm-2) and excellent stability (1500 h at 1 mA cm-2; 500 h at 10 mA cm-2), realizing exceptional cumulative capacity of 2.5 Ah cm-2. The full cell coupled with ZnxV2O5·nH2O (ZnVO) cathode achieves specific energy of ~ 270.5/150.6 Wh kg-1 (at 0.5/10 A g-1) with ~ 99.8% Coulombic efficiency and retains ~ 80.3% (at 5.0 A g-1) after 3000 cycles.

Surface-Alloyed Nanoporous Zinc as Reversible and Stable Anodes for High-Performance Aqueous Zinc-Ion Battery.

Metallic zinc (Zn) is one of the most attractive multivalent-metal anode materials in post-lithium batteries because of its high abundance, low cost and high theoretical capacity. However, it usually suffers from large voltage polarization, low Coulombic efficiency and high propensity for dendritic failure during Zn stripping/plating, hindering the practical application in aqueous rechargeable zinc-metal batteries (AR-ZMBs). Here we demonstrate that anionic surfactant-assisted in situ surface alloying of Cu and Zn remarkably improves Zn reversibility of 3D nanoporous Zn electrodes for potential use as high-performance AR-ZMB anode materials. As a result of the zincophilic ZnxCuy alloy shell guiding uniform Zn deposition with a zero nucleation overpotential and facilitating Zn stripping via the ZnxCuy/Zn galvanic couples, the self-supported nanoporous ZnxCuy/Zn electrodes exhibit superior dendrite-free Zn stripping/plating behaviors in ambient aqueous electrolyte, with ultralow polarizations under current densities up to 50 mA cm‒2, exceptional stability for 1900 h and high Zn utilization. This enables AR-ZMB full cells constructed with nanoporous ZnxCuy/Zn anode and KzMnO2 cathode to achieve specific energy of as high as ~ 430 Wh kg‒1 with ~ 99.8% Coulombic efficiency, and retain ~ 86% after long-term cycles for > 700 h.

Aluminum-copper alloy anode materials for high-energy aqueous aluminum batteries.

Aqueous aluminum batteries are promising post-lithium battery technologies for large-scale energy storage applications because of the raw materials abundance, low costs, safety and high theoretical capacity. However, their development is hindered by the unsatisfactory electrochemical behaviour of the Al metal electrode due to the presence of an oxide layer and hydrogen side reaction. To circumvent these issues, we report aluminum-copper alloy lamellar heterostructures as anode active materials. These alloys improve the Al-ion electrochemical reversibility (e.g., achieving dendrite-free Al deposition during stripping/plating cycles) by using periodic galvanic couplings of alternating anodic α-aluminum and cathodic intermetallic Al2Cu nanometric lamellas. In symmetric cell configuration with a low oxygen concentration (i.e., 0.13 mg L-1) aqueous electrolyte solution, the lamella-nanostructured eutectic Al82Cu18 alloy electrode allows Al stripping/plating for 2000 h with an overpotential lower than ±53 mV. When the Al82Cu18 anode is tested in combination with an AlxMnO2 cathode material, the aqueous full cell delivers specific energy of ~670 Wh kg-1 at 100 mA g-1 and an initial discharge capacity of ~400 mAh g-1 at 500 mA g-1 with a capacity retention of 83% after 400 cycles.

Synergistic Effect of Active Sites of Double-Atom Catalysts for Nitrogen Reduction Reaction.

Nitrogen fixation to produce ammonia is a vital process since nitrogen is an essential element for the human body. Industrial nitrogen fixation mainly relies on the Haber-Bosch process. However, this process requires huge energy consumption and leads to pollution emission. In this study, the behaviors of intermediates in the nitrogen reduction reaction (NRR) are investigated for fifteen double-atom catalysts (DACs) through density functional theory calculations, revealing that under the synergistic effect of active sites on appropriate DACs, intermediates can be adsorbed through different configurations according to the activity improvement needs. VFe-N-C shows the best catalytic activity for electrochemical NRR with a limiting potential of -0.36 V vs. the reversible hydrogen electrode. The proposed synergistic effect of active sites on DACs for NRR could provide a new method for design of NRR catalysts.

Nanoporous Intermetallic Cu3 Sn/Cu Hybrid Electrodes as Efficient Electrocatalysts for Carbon Dioxide Reduction.

Designing highly selective and cost-effective electrocatalysts toward electrochemical carbon dioxide (CO2 ) reduction is crucial for desirable transformation of greenhouse gas into fuels or high-value chemical products. Here, the authors report intermetallic Cu3 Sn that is in situ formed and seamlessly integrated on self-supported bimodal nanoporous Cu skeleton (Cu3 Sn/Cu) via a spontaneous alloying of Sn and Cu as robust electrocatalyst for selective electroreduction of CO2 to CO. By virtue of Sn atoms strengthening CO adsorption on Cu atoms, the intermetallic Cu3 Sn has an intrinsic activity of ≈10.58 µA cm-2 , more than 80-fold higher than that of monometallic Cu. By virtue of hierarchical bicontinuous nanoporous Cu architecture facilitating electron transfer and CO2 and proton mass transport and offering high specific surface areas for full use of electroactive Cu3 Sn sites, the nanoporous Cu3 Sn/Cu hybrid electrodes produce CO at a low overpotential of 0.09 V, and exhibit high partial current density of ≈15 mA cm-2 geo at overpotential of 0.59 V, along with excellent stability and selectivity of 91.5% Faradaic efficiency. The outstanding electrochemical performance make them attractive alternatives to precious Au- and Ag-based electrocatalysts for building low-cost CO2 electrolyzers to selectively produce CO.

Steric Hindrance- and Work Function-Promoted High Performance for Electrochemical CO Methanation on Antisite Defects of MoS2 and WS2.

CO methanation from electrochemical CO reduction reaction (CORR) is significant for sustainable environment and energy, but electrocatalysts with excellent selectivity and activity are still lacking. Selectivity is sensitive to the structure of active sites, and activity can be tailored by work function. Moreover, intrinsic active sites usually possess relatively high concentration compared to artificial ones. Here, antisite defects MoS2 and WS2 , intrinsic atomic defects of MoS2 and WS2 with a transition metal atom substituting a S2 column, were investigated for CORR by density functional theory calculations. The steric hindrance from the special bowl structure of MoS2 and WS2 ensured good selectivity towards CO methanation. Coordination environment variation of the active sites, the under-coordinated Mo or W atoms, effectively lowered the work function, making MoS2 and WS2 highly active for CO methanation with the required potential of -0.47 and -0.49 V vs. reversible hydrogen electrode, respectively. Moreover, high concentration of active sites and minimal structural deformation during the catalytic process of MoS2 and WS2 enhanced their attraction for future commercial application.

Spontaneously separated intermetallic Co3Mo from nanoporous copper as versatile electrocatalysts for highly efficient water splitting.

Developing robust nonprecious electrocatalysts towards hydrogen/oxygen evolution reactions is crucial for widespread use of electrochemical water splitting in hydrogen production. Here, we report that intermetallic Co3Mo spontaneously separated from hierarchical nanoporous copper skeleton shows genuine potential as highly efficient electrocatalysts for alkaline hydrogen/oxygen evolution reactions in virtue of in-situ hydroxylation and electro-oxidation, respectively. The hydroxylated intermetallic Co3Mo has an optimal hydrogen-binding energy to facilitate adsorption/desorption of hydrogen intermediates for hydrogen molecules. Associated with high electron/ion transport of bicontinuous nanoporous skeleton, nanoporous copper supported Co3Mo electrodes exhibit impressive hydrogen evolution reaction catalysis, with negligible onset overpotential and low Tafel slope (~40 mV dec-1) in 1 M KOH, realizing current density of -400 mA cm-2 at overpotential of as low as 96 mV. When coupled to its electro-oxidized derivative that mediates efficiently oxygen evolution reaction, their alkaline electrolyzer operates with a superior overall water-splitting output, outperforming the one assembled with noble-metal-based catalysts.

Lamella-nanostructured eutectic zinc-aluminum alloys as reversible and dendrite-free anodes for aqueous rechargeable batteries.

Metallic zinc is an attractive anode material for aqueous rechargeable batteries because of its high theoretical capacity and low cost. However, state-of-the-art zinc anodes suffer from low coulombic efficiency and severe dendrite growth during stripping/plating processes, hampering their practical applications. Here we show that eutectic-composition alloying of zinc and aluminum as an effective strategy substantially tackles these irreversibility issues by making use of their lamellar structure, composed of alternating zinc and aluminum nanolamellas. The lamellar nanostructure not only promotes zinc stripping from precursor eutectic Zn88Al12 (at%) alloys, but produces core/shell aluminum/aluminum sesquioxide interlamellar nanopatterns in situ to in turn guide subsequent growth of zinc, enabling dendrite-free zinc stripping/plating for more than 2000 h in oxygen-absent aqueous electrolyte. These outstanding electrochemical properties enlist zinc-ion batteries constructed with Zn88Al12 alloy anode and KxMnO2 cathode to deliver high-density energy at high levels of electrical power and retain 100% capacity after 200 hours.

Intermetallic Cu5Zr Clusters Anchored on Hierarchical Nanoporous Copper as Efficient Catalysts for Hydrogen Evolution Reaction.

Designing highly active and robust platinum-free electrocatalysts for hydrogen evolution reaction is vital for large-scale and efficient production of hydrogen through electrochemical water splitting. Here, we report nonprecious intermetallic Cu5Zr clusters that are in situ anchored on hierarchical nanoporous copper (NP Cu/Cu5Zr) for efficient hydrogen evolution in alkaline medium. By virtue of hydroxygenated zirconium atoms activating their nearby Cu-Cu bridge sites with appropriate hydrogen-binding energy, the Cu5Zr clusters have a high electrocatalytic activity toward the hydrogen evolution reaction. Associated with unique architecture featured with steady and bicontinuous nanoporous copper skeleton that facilitates electron transfer and electrolyte accessibility, the self-supported monolithic NP Cu/Cu5Zr electrodes boost violent hydrogen gas release, realizing ultrahigh current density of 500 mA cm-2 at a low potential of -280 mV versus reversible hydrogen electrode, with exceptional stability in 1 M KOH solution. The electrochemical properties outperform those of state-of-the-art nonprecious metal electrocatalysts and make them promising candidates as electrodes in water splitting devices.

Flexible Co-Mo-N/Au Electrodes with a Hierarchical Nanoporous Architecture as Highly Efficient Electrocatalysts for Oxygen Evolution Reaction.

Designing highly active and robust electrocatalysts for oxygen evolution reaction (OER) is crucial for many renewable energy storage and conversion devices. Here, self-supported monolithic hybrid electrodes that are composed of bimetallic cobalt-molybdenum nitride nanosheets vertically aligned on 3D and bicontinuous nanoporous gold (NP Au/CoMoNx ) are reported as highly efficient electrocatalysts to boost the sluggish reaction kinetics of water oxidation in alkaline media. By virtue of the constituent CoMoNx nanosheets having large accessible CoMoOx surface with remarkably enhanced electrocatalytic activity and the nanoporous Au skeleton facilitating electron transfer and mass transport, the NP Au/CoMoNx electrode exhibits superior OER electrocatalysis in 1 m KOH, with low onset overpotential (166 mV) and Tafel slope (46 mV dec-1 ). It only takes a low overpotential of 370 mV to reach ultrahigh current density of 1156 mA cm-2 , ≈140-fold higher than free CoMoNx nanosheets. The electrocatalytic performance makes it an attractive candidate as the OER catalyst in the water electrolysis.

Dual-phase nanostructuring of layered metal oxides for high-performance aqueous rechargeable potassium ion microbatteries.

Aqueous rechargeable microbatteries are promising on-chip micropower sources for a wide variety of miniaturized electronics. However, their development is plagued by state-of-the-art electrode materials due to low capacity and poor rate capability. Here we show that layered potassium vanadium oxides, KxV2O5·nH2O, have an amorphous/crystalline dual-phase nanostructure to show genuine potential as high-performance anode materials of aqueous rechargeable potassium-ion microbatteries. The dual-phase nanostructured KxV2O5·nH2O keeps large interlayer spacing while removing secondary-bound interlayer water to create sufficient channels and accommodation sites for hydrated potassium cations. This unique nanostructure facilitates accessibility/transport of guest hydrated potassium cations to significantly improve practical capacity and rate performance of the constituent KxV2O5·nH2O. The potassium-ion microbatteries with KxV2O5·nH2O anode and KxMnO2·nH2O cathode constructed on interdigital-patterned nanoporous metal current microcollectors exhibit ultrahigh energy density of 103 mWh cm-3 at electrical power comparable to carbon-based microsupercapacitors.

Extraordinary pseudocapacitive energy storage triggered by phase transformation in hierarchical vanadium oxides.

Pseudocapacitance holds great promise for improving energy densities of electrochemical supercapacitors, but state-of-the-art pseudocapacitive materials show capacitances far below their theoretical values and deliver much lower levels of electrical power than carbon-based materials due to poor cation accessibility and/or long-range electron transferability. Here we show that in situ corundum-to-rutile phase transformation in electron-correlated vanadium sesquioxide can yield nonstoichiometric rutile vanadium dioxide layers that are composed of highly sodium ion accessible oxygen-deficiency quasi-hexagonal tunnels sandwiched between conductive rutile slabs. This unique structure serves to boost redox and intercalation kinetics for extraordinary pseudocapacitive energy storage in hierarchical isomeric vanadium oxides, leading to a high specific capacitance of ~1856 F g-1 (almost sixfold that of the pristine vanadium sesquioxide and dioxide) and a bipolar charge/discharge capability at ultrafast rates in aqueous electrolyte. Symmetric wide voltage window pseudocapacitors of vanadium oxides deliver a power density of ~280 W cm-3 together with an exceptionally high volumetric energy density of ~110 mWh cm-3 as well as long-term cycling stability.