Ambient-Temperature All-Solid-State Sodium Batteries with a Laminated Composite Electrolyte

This study presents a sodium-ion conductive laminated polymer/ceramic-polymer solid-state electrolyte for the development of room-temperature all-solid-state sodium batteries. At the negative electrode side, a negative-electrode-benign poly(ethylene oxide) (PEO) is used as a polymer matrix into which succinonitrile (SN) is integrated to improve the room-temperature Na⁺-ion conductivity. At the positive electrode side, a cathode-friendly poly(acrylonitrile) (PAN) serves as a polymer matrix into which a NASICON-type ceramic solid-electrolyte (Na₃Zr₂Si₂PO₁₂) powder is incorporated toward both the enhancement of Na⁺-ion conductivity and the prevention of Na dendrite from penetrating through the electrolyte membrane. Through a strategical management of composition, the PAN-Na₃Zr₂Si₂PO₁₂-NaClO₄ composite and the PEO-SN-NaClO₄ polymer deliver a balanced Na⁺-ion conductivity. Combining the two electrolyte layers, the laminated PEO-SN-NaClO₄/PAN-Na₃Zr₂Si₂PO₁₂-NaClO₄ solid electrolyte provides a Na⁺-ion conductivity of 1.36 × 10⁻⁴ S cm⁻¹ at room temperature. With respect to the anodic friendly feature of the PEO-SN-NaClO₄ layer and the cathodic friendly feature of the PAN-Na₃Zr₂Si₂PO₁₂-NaClO₄ layer, the laminated solid electrolyte presents a stable electrochemical window of 0–4.8 V. Room-temperature all-solid-state sodium batteries fabricated with the laminated solid electrolyte, a Na-metal negative electrode, and a Na₂MnFe(CN)₆ positive electrode exhibit remarkably stable cyclability.     

Regulating Na-ion Solvation in Quasi-Solid Electrolyte to Stabilize Na Metal Anode

Sodium metal batteries are promising for cost-effective energy storage, however, the sluggish ion transport in electrolytes and detrimental sodium-dendrite growth stall their practical applications. Herein, a cross-linking quasi-solid electrolyte with a high ionic conductivity of 1.4 mS cm⁻¹ at 25 °C is developed by in-situ polymerizing poly (ethylene glycol) diacrylate-based monomer. Benefiting from the refined solvation structure of Na⁺ with a much lower desolvation barrier, random Na⁺ diffusion on the Na surface is restrained, so that the Na dendrite formation is suppressed. Consequently, symmetrical Na||Na cells employing the electrolyte can be cycled >2000 h at 0.1 mA cm⁻². Na₃V₂(PO₄)₃||Na batteries reveal a high discharge specific capacity of 66.1 mAh g⁻¹ at 15 C and demonstrate stable cycling over 1000 cycles with a capacity retention of 83% at a fast rate of 5 C.     

A Hetero-Layered,Mechanically Reinforced,Ultra-Lightweight Composite Polymer Electrolyte for Wide-Temperature-Range,Solid-State Sodium Batteries

The practical use of polyethylene oxide polymer electrolyte in the solid-state sodium metallic batteries (SSMBs) suffers from the retard Na⁺ diffusion at the room temperature, mechanical fragility as well as the oxidation tendency at high voltages. Herein, a hetero-layered composite polymeric electrolyte (CPE) is proposed to enable the simultaneous interfacial stability with the high voltage cathodes (till 4.2 V) and Na metallic anode. Being incorporated within the polymer matrix, the sand-milled Na₃Zr₂Si₂PO₁₂ nanofillers and nanocellulose scaffold collectively endow the thin-layer (25 µm), ultralightweight (1.65 mg cm⁻²) CPE formation with an order of magnitude enhancement of the mechanical strength (13.84 MPa) and ionic conductivity (1.62 × 10⁻⁴ S cm⁻¹) as compared to the pristine polymer electrolyte, more importantly, the improved dimension stability up to 180 °C. Upon the integration of the hetero-layered CPE with the iron hexacyanoferrate FeHCF cathode (1 mAh cm⁻²) and the Na foil, the cell model can achieve the room-temperature cycling stability (93.73% capacity retention for 200 cycles) as well as the high temperature tolerance till 80 °C, which inspires a quantum leap toward the surface-wetting-agent-free, energy-dense, wide-temperature-range SSMB prototyping.     

Multiscale Structural Gel Polymer Electrolytes with Fast Li+ Transport for Long-Life Li Metal Batteries

Li metal batteries (LMBs) are considered as promising candidates for future rechargeable batteries with high energy density. However, Li metal anode (LMA) is extensively sensitive to general liquid electrolytes, leading to unstable interphase and dendrites growth. Herein, a novel gel polymer electrolyte consisting of a micro-nanostructured poly(vinylidene fluoride-co-hexafluoropropylene) matrix and inorganic fillers of Zeolite Socony Mobil-5 (ZSM-5) and SiO₂ nanoparticles, is fabricated to expedite Li⁺ ions transport and suppress Li dendrite growth. Due to the Lewis acid interaction, SiO₂ can absorb amounts of PF₆⁻ and promote the dissociation of LiPF₆. The specific sub-nanometer pore structure of ZSM-5 greatly enhances the Li⁺ ion transference number. These structures can restrain the decomposition of electrolytes and build stable interphase on LMA. Therefore, the Li||Ni_0.8Co_0.1Mn_0.1O₂ full cell maintains 92% capacity retention after 300 cycles at 1 C (1 C ≈190 mAh g⁻¹) in carbonate electrolyte. This multiscale design provides an effective strategy for electrolyte exploration in high-performance LMBs.     

Controlled Nitrogen Doping in Crumpled Graphene for Improved Alkali Metal-Ion Storage under Low-Temperature Conditions

The significant performance decay in conventional graphite anodes under low-temperature conditions is attributed to the slow diffusion of alkali metal ions, requiring new strategies to enhance the charge storage kinetics at low temperatures. Here, nitrogen (N)-doped defective crumpled graphene (NCG) is employed as a promising anode to enable stable low-temperature operation of alkali metal-ion storage by exploiting the surface-controlled charge storage mechanisms. At a low temperature of −40 °C, the NCG anodes maintain high capacities of ≈172 mAh g⁻¹ for lithium (Li)-ion, ≈107 mAh g⁻¹ for sodium (Na)-ion, and ≈118 mAh g⁻¹ for potassium (K)-ion at 0.01 A g⁻¹ with outstanding rate-capability and cycling stability. A combination of density functional theory (DFT) and electrochemical analysis further reveals the role of the N-functional groups and defect sites in improving the utilization of the surface-controlled charge storage mechanisms. In addition, the full cell with the NCG anode and a LiFePO₄ cathode shows a high capacity of ≈73 mAh g⁻¹ at 0.5 °C even at −40 °C. The results highlight the importance of utilizing the surface-controlled charge storage mechanisms with controlled defect structures and functional groups on the carbon surface to improve the charge storage performance of alkali metal-ion under low-temperature conditions.     

A Quasi-Solid-State Polyether Electrolyte for Low-Temperature Sodium Metal Batteries

Taken the unlimited Na reservoir worldwide, battery technology based on Na-ion chemistry poses as an ideal candidate for large-scale energy storage systems. Especially, with metallic Na replacing traditional carbon anodes, it's able to maximize the energy density inexpensively. Nevertheless, sodium metal batteries (SMBs) face intrinsically poor stability due to their highly-reactive nature, where low Coulombic efficiency and short lifetime are often witnessed. The situation can be further aggravated at low temperatures due to insurmountable kinetic barriers. Herein, a 1,3-dioxolane-based quasi-solid-state electrolyte (PDGE) is proposed with a high ionic conductivity of 3.68 mS cm⁻¹ even at −20 ^◦C for SMBs. Moreover, a weak solvation environment is tailored by PDGE, which possesses a high Na⁺ transference number of 0.7. Concurrently, the solid electrolyte interphase induced from PDGE presents inorganic Na₂O, NaF as the major components, which offers accelerated Na⁺ diffusion and superior stability upon long-term cycling. With such a quasi-solid-state electrolyte, the Na/Na₃V₂(PO₄)₃ full cell exhibits great stability over 1000 cycles at −20 ^◦C. This study has significant implications to the development for SMBs under low-temperature conditions.     

Electrocatalytic MOF-Carbon Bridged Network Accelerates Li+-Solvents Desolvation for High Li+ Diffusion toward Rapid Sulfur Redox Kinetics

Lithium-sulfur batteries are famous for high energy density but prevented by shuttling effect and sluggish electrochemical conversion kinetics due to the high energy barriers of Li⁺ transport across the electrode/electrolyte interface. Herein, the Li⁺-solvents dissociation kinetics is catalyzed and stimulated by designing a carbon bridged metal-organic framework (MOF@CC), aimed at realizing increased bare Li⁺ transport for the rapid conversion kinetics of sulfur species. Theoretical simulations and spectroscopic results demonstrate that the bridged MOF@CC well grants a special transport channel for accelerating Li⁺ benefited from aggregated anion/cation clusters. Moreover, the C N bridge between -NH₂ ligand in MOF and carbon shell enhances electron exchange, and thus promotes polysulfide catalytic efficiency and hinder polysulfide aggregation and accumulation. With the MOF@CC-modified separators, the assembled Li/S batteries deliver a reversible capability of 1063 mAh g^-1 at 0.5 C, a capacity retention of 88% after 100 cycles, and a high-rate performance of 765 mAh g⁻¹ at 5 C. Moreover, the large areal pouch cell with 100 µm Li foil and lean electrolyte is capable of stabilizing 855 mAh g⁻¹ after 70 cycles. These results well demonstrate the efficiency of catalyzing desolvation for fast Li+ transport kinetics and the conversion of polysulfides.     

Dynamic Supramolecular Polymer Electrolyte to Boost Ion Transport Kinetics and Interfacial Stability for Solid-State Batteries

The key hurdle to the practical application of polymeric electrolytes in high-energy-density solid lithium-metal batteries is the sluggish Li⁺ mobility and inferior electrode/electrolyte interfacial stability. Herein, a dynamic supramolecular polymer electrolyte (SH-SPE) with loosely coordinating structure is synthesized based on poly(hexafluoroisopropyl methacrylate-co-N-methylmethacrylamide) (PHFNMA) and single-ion lithiated polyvinyl formal. The weak anti-cooperative H-bonds between the two polymers endow SH-SPE with a self-healing ability and improved toughness. Meanwhile, the good flexibility and widened energy gap of PHFNMA enable SH-SPE with efficient ion transport and superior interfacial stability in high-voltage battery systems. As a result, the as-prepared SH-SPE exhibits an ionic conductivity of 2.30 × 10⁻⁴ S cm⁻¹, lithium-ion transference number of 0.74, electrochemical stability window beyond 4.8 V, and tensile strength up to 11.9 MPa as well as excellent adaptability with volume change of the electrodes. In addition, no major electrolyte decomposition inside batteries made from SH-SPE and LiNi_0.8Mn_0.1Co_0.1O₂ cathode can be observed in the in situ differential electrochemical mass spectrometry test. This study provides a new methodology for the macromolecular design of polymer electrolytes to address the interfacial issues in high-voltage solid batteries.     

Advanced Zinc–Iodine Batteries with Ultrahigh Capacity and Superior Rate Performance Based on Reduced Graphene Oxide and Water-in-Salt Electrolyte

Aqueous rechargeable zinc–iodine batteries have received increasing attention in the field of portable electronics due to their high safety, low-cost, and great electrochemical performance. However, the insulated nature of iodine and the unrestricted shuttle effect of soluble triiodide seriously limit the lifespan and Coulombic efficiency (CE) of the batteries. Herein, a high-performance zinc–iodine energy storage system based on the hydrothermal reduced graphene oxide (rGO) and a high concentration zinc chloride water-in-salt electrolyte are promoted. The 3D microporous structures and outstanding electrical conductivity of rGO make it an excellent host for iodine, while the water-in-salt electrolyte effectively suppresses the shuttle effect of triiodide and improves the CE of the system. As a result, an ultra-high I₂ mass loading of 25.33 mg cm⁻² (loading ratio of 71.69 wt.%) is realized during the continuous charging/discharging process. The batteries deliver a high capacity of 6.5 mAh cm⁻² at 2 mA cm⁻² with a much-improved CE of 95% and a prominent rate performance with capacity of 1 mAh cm⁻² at 80 mA cm⁻². A stable long-term cycling performance is also achieved with capacity retention of 2 mAh cm⁻² after 2000 cycles at 50 mA cm⁻².     

In-Built Quasi-Solid-State Poly-Ether Electrolytes Enabling Stable Cycling of High-Voltage and Wide-Temperature Li Metal Batteries

Developing solid-state electrolytes with good compatibility for high-voltage cathodes and reliable operation of batteries over a wide-temperature-range are two bottleneck requirements for practical applications of solid-state metal batteries (SSMBs). Here, an in situ quasi solid-state poly-ether electrolyte (SPEE) with a nano-hierarchical design is reported. A solid-eutectic electrolyte is employed on the cathode surface to achieve highly-stable performance in thermodynamic and electrochemical aspects. This performance is mainly due to an improved compatibility in the electrode/electrolyte interface by nano-hierarchical SPEE and a reinforced interface stability, resulting in superb-cyclic stability in Li || Li symmetric batteries ( > 4000 h at 1 mA cm⁻²/1 mAh cm⁻²; > 2000 h at 1 mA cm⁻²/4 mAh cm⁻²), which are the same for Na, K, and Zn batteries. The SPEE enables outstanding cycle-stability for wide-temperature operation (15–100 ° C) and 4 V-above batteries (Li || LiCoO₂ and Li || LiNi_0.8Co_0.1Mn_0.1O₂). The work paves the way for development of practical SSMBs that meet the demands for wide-temperature applicability, high-energy density, long lifespan, and mass production.     

High-Capacity and Stable Sodium-Sulfur Battery Enabled by Confined Electrocatalytic Polysulfides Full Conversion

The efficient polysulfide capture and reversible sulfur recovery during reverse charging process are critical to exploiting the full potential of room temperature Na S batteries. Here, based on a core-shell design strategy, the structural and chemical synergistic manipulation of sodium polysulfides quasi-solid-state reversible conversion is proposed. The sulfur is encapsulated in the multi-pores of 3D interconnected carbon fiber as the core structure. The Fe(CN)₆⁴⁻-doped polypyrrole film serves as a redox-active polar shell to lock up polysulfides and promote complete polysulfide conversion. Importantly, the short-chain Na₂S₄ polysulfides are reduced to Na₂S directly leaving with a small fraction of soluble intermediates as the cation-transfer medium at the core/shell interface, and freeing up formation of solid Na₂S₂ incomplete product. Further, the redox mediator with open Fe species electrocatalytically lowers the Na₂S oxidation energy barrier and renders the high reversibility of electrodeposited Na₂S. The tunable quasi-solid-state reversible sulfur conversion under versatile polymer sheath greatly enhances sulfur utilization, affording a remarkable capacity of 1071 mAh g⁻¹ and a stable high capacity of 700 mAh g⁻¹ at 200 mA g⁻¹ after 200 cycles. The confined electrocatalytic effect provides a strategy for tuning electrochemical pathway of sulfur species and guarantees high-efficiency sulfur electrochemistry.     

Perfluoro Macrocyclic Ether as an Ambifunctional Additive for High-Performance SiO and Nickel 88%-Based High-Energy Li-ion Battery

State-of-the-art lithium (Li)-ion batteries employ silicon anode active material at a limited fraction while strongly relying on fluoroethylene carbonate (FEC) electrolyte additive exceeding 10 wt.% to enable stable cycling. The swelling issue of silicon in the aspect of solid electrolyte interphase (SEI) instability and a risk of safety hazards and high manufacturing cost due to FEC has motivated the authors to design a well-working fluorinated additive substitute. High-capacity cells employing nickel-rich oxide cathode are pursued by operating at > 4.2 V versus Li/Li⁺, for which anodic stability of electrolyte is required. Herein, a highly effective new ambifunctional additive of icosafluoro-15-crown 5-ether is proposed at a little fraction of 0.4 wt.% for the stabilized interfaces and reduced swelling of high capacity (3.5 mAh cm⁻²) 5 wt.% SiO-graphite anode and LiNi_0.88Co_0.08Mn_0.04O₂ cathode. Utilizing together with a lowered fraction of FEC, reversible long 300 cycles at 4.35 V and 1 C (225 mA g⁻¹) are achieved. Material characterization results reveal that such stabilization is derived from the surface passivation of both anode and cathode with perfluoro ether, LiF, and Li_xPF_y species. The present study gives insight into electrolyte formulation design with lower cost and both-side stabilization strategies for silicon and nickel-rich active materials and their interfaces.     

N-Rich Solid Electrolyte Interface Constructed In Situ Via a Binder Strategy for Highly Stable Silicon Anode

Silicon (Si) is regarded as a promising anode material for high-energy-density lithium-ion batteries due to its high specific capacity (4200 mAh g⁻¹) and low potential (0.3 V vs Li⁺/Li). However, the large volume change (over 300%) of Si during the lithiation/delithiation process leads to severe pulverization, electrode structure destruction, and finally capacity fading, which slows down its step to practical application. Herein, a poly(vinylamine) (PVAm) binder containing amino ( NH₂) and amide ( NH CHO) is proposed to improve the stability of Si anodes from particle to electrode structure. The N-containing functional groups show strong interaction with the Si particles and form a uniform and thin layer on the surface, which would decompose and form an N-rich inorganic solid electrolyte interphase (SEI) layer during discharging. The high mechanical stability N-rich SEI helps relieve the pulverization of Si particles through stress dissipation, maintains electrode structural stability, and reduces the loss of active materials. Thus, the Si anode with PVAm binder exhibits high capacity of ≈2000 mAh g⁻¹ after 200 cycles, which is much higher than that of using Poly(vinylidene fluoride) (PVDF) binder (66 mAh g⁻¹) and Poly(vinyl alcohol) PVA binder (820 mAh g⁻¹). This facile and practical strategy provides a new perspective for the application of Si anodes in advanced batteries.     

Unveiling the Effects of Cr Single Atoms with Controllable Configurations on Solid Electrolyte Interphase and Storage Mechanism of Sodium Ions

Single atomic metal (SAM) doping is reported as an effective strategy to promote the electrochemical property of carbon-based anode materials for high-power sodium-ion batteries (SIBs). However, the effects of SAM with different configurations on solid electrolyte interphase (SEI) and energy storage mechanism of Na⁺ are not revealed. Herein, Cr single atoms (CrSAs) are reported with controllable configurations (Cr–N₄ or Cr–N₂) implanted on the N, P co-doped carbon (NPC) anode materials (denoted as CrN₄SAs/NPC or CrN₂SAs/NPC). The CrN₄SAs/NPC anode displays a high specific capacity (318.2 mAh g⁻¹ at 0.05 A g⁻¹) and outstanding rate performance (145.1 mAh g⁻¹ at 5 A g⁻¹), better than those of CrN₂SAs/NPC and NPC. The superiority is originated from the difference of SEI and the energy storage mechanism of sodium ions during electrochemical process, which are unveiled through ex situ characterization and theoretical calculation. The full cell assembled with CrN₄SAs/NPC anode and Na₃V₂(PO₄)₂F₃@C cathode displays a high energy density at a high power density.     

Ultra-Fine Nano-Mg(OH)2 Electrodeposited in Flexible Confined Space and its Enhancement of the Performance of LiFePO4 Lithium-Ion Batteries

To improve the Li-ion diffusion and extreme-environment performance of LiFePO₄ (LFP) lithium-ion batteries, a composite cathode material is fabricated using ultra-fine nano-Mg(OH)₂ (MH). First, a flexible confined space is designed in the local area of the cathode surface, through the transition of charged xanthan gum polymer molecules under electric field force and the self-assembly of the xanthan gum network. Then, the 20 nm nano-Mg(OH)₂ is prepared through cathodic electrodeposition within the local flexible confined space, and subsequent in situ surface modification as it traverses the xanthan gum network under gravity. LFP-MH significantly changes the density and homogeneity of the cathode electrolyte interphase film and improves the electrolyte affinity. The Li||LFP-MH half-cell demonstrates excellent rate capability (110 mAh g⁻¹ at 5 C) and long-term cycle performance (116.6 mAh g⁻¹ at 1 C after 1000 cycles), and maintains over 100 mAh g⁻¹ after 150 cycles at 60 °C, as well as no structural collapse of the cathode material after 400 cycles at 5 V high cut-off voltage. The cell also shows an obvious decrease in inner resistance after 100 cycles (99.53/133.12 Ω). This work provides a significant advancement toward LiFePO₄ lithium-ion batteries with excellent electrochemical performance and tolerance to extreme-environment.     

Solvent-Free Electrolyte for High-Temperature Rechargeable Lithium Metal Batteries

The formation of lithiophobic inorganic solid electrolyte interphase (SEI) on Li anode and cathode electrolyte interphase (CEI) on the cathode is beneficial for high-voltage Li metal batteries. However, in most liquid electrolytes, the decomposition of organic solvents inevitably forms organic components in the SEI and CEI. In addition, organic solvents often pose substantial safety risks due to their high volatility and flammability. Herein, an organic-solvent-free eutectic electrolyte based on low-melting alkali perfluorinated-sulfonimide salts is reported. The exclusive anion reduction on Li anode surface results in an inorganic, LiF-rich SEI with high capability to suppress Li dendrite, as evidenced by the high Li plating/stripping CE of 99.4% at 0.5  mA cm⁻² and 1.0 mAh cm⁻², and 200-cycle lifespan of full LiNi_0.8Co_0.15Al_0.05O₂ (2.0 mAh cm⁻²) || Li (20 µm) cells at 80 °C. The proposed eutectic electrolyte is promising for ultrasafe and high-energy Li metal batteries.     

High-Performance Garnet-Type Solid-State Lithium Metal Batteries Enabled by Scalable Elastic and Li+-Conducting Interlayer

Promoting the interfacial Li⁺ transport and suppressing detrimental lithium dendrites are the main challenges for developing practical solid-state lithium metal batteries. In this respect, interface rationalizing to synergize the enhancement of ion transport and suppression of lithium dendrites is of paramount significance. Herein, a novel strategy is demonstrated to address those issues by a designed multifunctional composite interlayer. The photocrosslinkable polymer is introduced in a scalable elastic skeleton, which promotes the migration and diffusion of Li⁺. Moreover, adding perfluoropolyether in the interlayer benefits to regulating the formation of LiF-rich interface, sufficiently suppress the growth of lithium dendrites. Benefitting from the elasticity, high Li⁺ conductivity and the lithium dendrites suppression capability, the interlayer can significantly improve the interfacial performance of the solid electrolyte/lithium interface, thus leading to the greatly enhanced electrochemical performance of solid-state lithium metal batteries. A high critical current density of 3.6 mA cm⁻² and a long cycling life at 1.0 mA cm⁻² for >400 h are achieved for the symmetric cells. Besides, when used in a pouch-type full cell coupled with LiNi_0.6Co_0.2Mn_0.2O₂ cathode, a high charged capacity of 3.25 mAh cm⁻² can be maintained through 20 cycles, demonstrating its great potentials for practical application.     

Polyether-b-Amide Based Solid Electrolytes with Well-Adhered Interface and Fast Kinetics for Ultralow Temperature Solid-State Lithium Metal Batteries

Solid-state lithium metal batteries (SSLMBs) are highly desirable for energy storage because of the urgent need for higher energy density and safer batteries. However, it remains a critical challenge for stable cycling of SSLMBs at low temperature. Here, a highly viscoelastic polyether-b-amide (PEO-b-PA) based composite solid-state electrolyte is proposed through a one-pot melt processing without solvent to address this key process. By adjusting the molar ratio of PEO-b-PA to lithium bis(trifluoromethanesulphonyl)imide (ethylene oxide:Li = 6:1) and adding 20 wt.% succinonitrile, fast Li⁺ transport channel is conducted within the homogeneous polymer electrolyte, which enables its application at ultra-low temperature (−20 to 25 °C). The composite solid-state electrolyte utilizes dynamic hydrogen-bonding domains and ion-conducting domains to achieve a low interfacial charge transfer resistance (<600 Ω) at −20 °C and high ionic conductivity (25 °C, 3.7 × 10⁻⁴ S cm⁻¹). As a result, the LiFePO₄|Li battery based on composite electrolyte exhibits outstanding electrochemical performance with 81.5% capacity retention after 1200 cycles at −20 °C and high discharge specific capacities of 141.1 mAh g⁻¹ with high loading (16.1 mg cm⁻²) at 25 °C. Moreover, the solid-state SNCM811|Li cell achieves excellent safety performance under nail penetration test, showing great promise for practical application.     

High Power and Energy Density Aqueous Proton Battery Operated at −90 °C

Freezing electrolyte and sluggish ionic migration kinetics limited the low-temperature performance of rechargeable batteries. Here, an aqueous proton battery is developed, which achieves both high power density and energy density at the ultralow temperature conditions. Electrolyte including 2 m HBF₄  +  2 m Mn(BF₄)₂ is used for the ultralow freezing point of below − 160  ° C and high ionic conductivity of 0.21 mS cm⁻¹ at − 70  ° C. Spectroscopic and nuclear magnetic resonance analysis demonstrate the introduction of BF₄⁻ anions efficiently break the hydrogen-bond networks of original water molecules, resulting in ultralow freezing point. Based on H⁺ uptake/removal reaction in alloxazine (ALO) anode and MnO₂/Mn²⁺ conversion in carbon felt cathode, the aqueous proton battery can operate regularly even at − 90  ° C and obtain a high specific discharge capacity of 85 mA h g⁻¹. Benefiting from the rapid diffusion of proton and the pseudocapacitive character of ALO electrolyte, this battery shows a high specific energy density of 110 Wh kg⁻¹ at a specific power density of 1650 W kg⁻¹ at − 60  ° C. This work presents a new way of developing low-temperature batteries.     

Accelerated Li+ Desolvation for Diffusion Booster Enabling Low-Temperature Sulfur Redox Kinetics via Electrocatalytic Carbon-Grazfted-CoP Porous Nanosheets

Lithium–sulfur (Li–S) batteries are famous for their high energy density and low cost, but prevented by sluggish redox kinetics of sulfur species due to depressive Li ion diffusion kinetics, especially under low-temperature environment. Herein, a combined strategy of electrocatalysis and pore sieving effect is put forward to dissociate the Li⁺ solvation structure to stimulate the free Li⁺ diffusion, further improving sulfur redox reaction kinetics. As a protocol, an electrocatalytic porous diffusion-boosted nitrogen-doped carbon-grafted-CoP nanosheet is designed via forming the N Co P active structure to release more free Li⁺ to react with sulfur species, as fully investigated by electrochemical tests, theoretical simulations and in situ/ex situ characterizations. As a result, the cells with diffusion booster achieve desirable lifespan of 800 cycles at 2 C and excellent rate capability (775 mAh g⁻¹ at 3 C). Impressively, in a condition of high mass loading or low-temperature environment, the cell with 5.7 mg cm⁻² stabilizes an areal capacity of 3.2 mAh cm⁻² and the charming capacity of 647 mAh g⁻¹ is obtained under 0 °C after 80 cycles, demonstrating a promising route of providing more free Li ions toward practical high-energy Li–S batteries.