Upcycling the Spent Graphite Anode Into the Prelithiation Catalyst: A Separator Strategy Toward Anode-Free Cell Prototyping.

The substantial manufacturing of lithium-ion batteries (LIBs) requires sustainable, circular, and decarbonized recycling strategies. While efforts are concentrated on extracting valuable metals from cathodes using intricate chemical process, the direct, efficient cathode regeneration remains a technological challenge. More urgently, the battery supply chain also requires the value-added exploitation of retired anodes. Here, a "closed-loop" approach is proposed to upcycle spent graphite into the prelithiation catalyst, namely the fewer-layer graphene flakes (FGF), upon the exquisite tuning of interlayer spacing and defect concentration. Since the catalytic FGF mitigates the delithiation energy barrier from calcinated Li5FeO4 nanocrystalline, the composite layer of which cast on the polyolefin substrate thus enables a customized prelithiation capability (98% Li+ utilization) for the retired LiFePO4 recovery. Furthermore, the hydrophobic polymeric modification guarantees the moisture tolerance of Li5FeO4 agents, aligning with commercial battery manufacturing standards. The separator strategy well regulates the interfacial chemistry in the anode-free pouch cell (LiFePO4||Cu), the prototype of which balances the robust cyclability, energy density up to 386.6 Wh kg-1 as well as the extreme power output of 1159.8 W kg-1. This study not only fulfills the sustainable supply chain with graphite upcycling, but also establishes a generic, viable protocol for the anode-free cell prototyping.

An in-situ polymerization strategy for gel polymer electrolyte Si||Ni-rich lithium-ion batteries.

Coupling the Si-based anodes with nickel-rich LiNixMnyCo1-x-yO2 cathodes (x ≥ 0.8) in the energy-dense cell prototype suffers from the mechanical instability of the Li-Si alloys, cathode collapse upon the high-voltage cycling, as well as the severe leakage current at elevated temperatures. More seriously, the cathode-to-anode cross-talk effect of transitional metal aggravates the depletion of the active Li reservoir. To reconcile the cation utilization degree, stress dissipation, and extreme temperature tolerance of the Si-based anode||NMC prototype, we propose a gel polymer electrolyte to reinforce the mechanical integrity of Si anode and chelate with the transitional cations towards the stabilized interfacial property. As coupling the conformal gel polymer electrolyte encapsulation with the spatial arranged Si anode and NMC811 cathode, the 2.7 Ah pouch-format cell could achieve the high energy density of 325.9 Wh kg-1 (based on the whole pouch cell), 88.7% capacity retention for 2000 cycles, self-extinguish property as well as a wide temperature tolerance. Therefore, this proposed polymerization strategy provides a leap toward the secured Li batteries.

A Hydrogel Electrolyte toward a Flexible Zinc-Ion Battery and Multifunctional Health Monitoring Electronics.

The compact design of an environmentally adaptive battery and effectors forms the foundation for wearable electronics capable of time-resolved, long-term signal monitoring. Herein, we present a one-body strategy that utilizes a hydrogel as the ionic conductive medium for both flexible aqueous zinc-ion batteries and wearable strain sensors. The poly(vinyl alcohol) hydrogel network incorporates nano-SiO2 and cellulose nanofibers (referred to as PSC) in an ethylene glycol/water mixed solvent, balancing the mechanical properties (tensile strength of 6 MPa) and ionic diffusivity at -20 °C (2 orders of magnitude higher than 2 M ZnCl2 electrolyte). Meanwhile, cathode lattice breathing during the solvated Zn2+ intercalation and dendritic Zn protrusion at the anode interface are mitigated. Besides the robust cyclability of the Zn∥PSC∥V2O5 prototype within a wide temperature range (from -20 to 80 °C), this microdevice seamlessly integrates a zinc-ion battery with a strain sensor, enabling precise monitoring of the muscle response during dynamic body movement. By employing transmission-mode operando XRD, the self-powered sensor accurately documents the real-time phasic evolution of the layered cathode and synchronized strain change induced by Zn deposition, which presents a feasible solution of health monitoring by the miniaturized electronics.

Unleashing the Potential of High-Capacity Anodes through an Interfacial Prelithiation Strategy.

The scalable development of an environmentally adaptive and homogeneous Li+ supplementary route remains a formidable challenge for the existing prelithiation technologies, restricting the full potential of high-capacity anodes. In this study, we present a moisture-tolerant interfacial prelithiation approach through casting a hydrophobic poly(vinylidene-co-hexafluoropropylene) membrane blended with a deep-lithiated alloy (Li22Si5@C/PVDF-HFP) onto Si based anodes. This strategy could not only extend to various high-capacity anode systems (SiOx@C, hard carbon) but also align with industrial roll-to-roll assembly processes. By carefully adjusting the thickness of the prelithiation layer, the densely packed Si@C electrode (4.5 mAh cm-2) exhibits significantly improved initial Coulombic efficiency until a close-to-unit value, as well as extreme moisture tolerance (60% relative humidity). Furthermore, it achieves more than 10-fold enhancement of ionic conductivity across the electrode. As pairing the prelithiated Si@C anode with the LiNi0.8Co0.1Mn0.1O2 cathode, the 2 Ah pouch-format prototype balances an energy density of ∼371 Wh kg-1 and an extreme power output of 2450 W kg-1 as well as 83.8% capacity retention for 1000 cycles. The combined operando phase tracking and spatial arrangement analysis of the intermediate alloy elucidate that the enhanced Li utilization derives from the gradient stress dissipation model upon a spontaneous Li+ redistribution process.

Enhancing Temperature Adaptability of Aqueous Zinc Batteries via Antifreezing Electrolyte and Site-Selective ZnSe-Ag Interface Layer Design.

Rechargeable aqueous zinc batteries (RAZBs) represent a sustainable, environmentally benign, cost-efficient energy storage solution for the scaled renewable power system. However, the cycling endurance and temperature adaptability of RAZBs are hindered by practical technological barriers such as the subzero freezing point of aqueous electrolyte, severe cation dissolution of the cathode, and dendrite growth on the Zn anode. Herein, we optimize the hybrid electrolyte formulation of 8 M ZnCl2 in the ethylene glycol-water mixed solvent to reconfigure the hydrogen bonding and [Zn(H2O)1.80(EG)0.23]2+ solvation sheath, which well balances the ionic conductivity and the antifreezing property until -125 °C. As monitored by operando X-ray diffraction, meanwhile, the structural dissolution of the V2O5 cathode upon the dynamic cycling and static idling storage at elevated temperature are effectively restrained. At the anode side, the thermally induced substitution between the Ag2Se overcoating and Zn foil in situ constructs the site-selective, mosaic interface layer, in which the solvophilic ZnSe facilitates the desolvation, while the Ag species provide zincophilic nucleation sites for high-throughput Zn deposition. The synergistic coupling of the antifreezing electrolyte and anode interfacial design enables the wide-temperature-range adaptability of the RAZB prototype (10 µm Zn foil and 1 mAh cm-2 V2O5 cathode), which balances the cycling endurance (92.5% capacity retention rate for 1000 cycles), 84.7% mitigation of the self-discharge rate at 55 °C, as well as the secured cyclability even at -40 °C.

Efficient Polysulfide Redox Enabled by Lattice-Distorted Ni3Fe Intermetallic Electrocatalyst-Modified Separator for Lithium-Sulfur Batteries.

Exploring efficient electrocatalysts for lithium-sulfur (Li-S) batteries is of great significance for the sulfur/polysulfide/sulfide multiphase conversion. Herein, we report nickel-iron intermetallic (Ni3Fe) as a novel electrocatalyst to trigger the highly efficient polysulfide-involving surface reactions. The incorporation of iron into the cubic nickel phase can induce strong electronic interaction and lattice distortion, thereby activating the inferior Ni phase to catalytically active Ni3Fe phase. Kinetics investigations reveal that the Ni3Fe phase promotes the redox kinetics of the multiphase conversion of Li-S electrochemistry. As a result, the Li-S cells assembled with a 70 wt % sulfur cathode and a Ni3Fe-modified separator deliver initial capacities of 1310.3 mA h g-1 at 0.1 C and 598 mA h g-1 at 4 C with excellent rate capability and a long cycle life of 1000 cycles at 1 C with a low capacity fading rate of ∼0.034 per cycle. More impressively, the Ni3Fe-catalyzed cells exhibit outstanding performance even at harsh working conditions, such as high sulfur loading (7.7 mg cm-2) or lean electrolyte/sulfur ratio (∼6 µL mg-1). This work provides a new concept on exploring advanced intermetallic catalysts for high-rate and long-life Li-S batteries.

Facile Synthesis of a "Two-in-One" Sulfur Host Featuring Metallic-Cobalt-Embedded N-Doped Carbon Nanotubes for Efficient Lithium-Sulfur Batteries.

The exploration of efficient host materials of sulfur is significant for the practical lithium-sulfur (Li-S) batteries, and the hosts are expected to be highly conductive for high sulfur utilization and exhibit strong interaction toward polysulfides to suppress the shuttle effect for long-lasting cycle stability. Herein, we propose a simple synthesis of metallic cobalt-embedded N-doping carbon nanotubes (Co@NCNT) as a "two-in-one" host of sulfur for efficient Li-S batteries. In the binary host, the N-doped CNTs, cooperating with metallic Co nanoparticles, can serve as 3D conductive networks for fast electron transportation, while the synergetic effect of metallic Co and doping N heteroatoms helps to chemically confine polysulfides, acting as active sites to accelerate electrochemical kinetics. With these advantages, the S/Co@NCNT composite delivers an excellent cycling stability with a capacity decay of 0.08% per cycle averaged within 500 cycles at a current density of 1 A g-1 and a high rate performance of 530 mA h g-1 at 5 A g-1. Further, the superior electrochemical performance of the S/Co@NCNT electrode can be maintained under a high sulfur loading up to 4 mg cm-2. Our work demonstrates a feasible strategy to design promising host materials simultaneously featuring high conductivity and strong confinement toward polysulfides for high-performance Li-S batteries.