Mesoporous Carbon for High-Performance Near-Neutral Zinc-Air Batteries.

Near-neutral zinc-air batteries (ZABs) have garnered significant research interest due to their high energy density, exceptional electrochemical reversibility, and adaptability to ambient air. However, these batteries suffer from substantial electrochemical polarization, low energy efficiency, and poor rate performance. In this study, a mesoporous carbon (meso-C) with a high specific surface area (1081 m2 g-1 ) and abundant porous structure for the cathode of near-neutral ZABs using a scalable synthesis method is prepared. The meso-C-based cathode is endowed with stable hydrophobicity and abundant electrochemical active sites, which considerably improve the energy efficiency, rate performance, and cycle life of the battery compare to commercial carbon black-based cathode when applied to near-neutral ZABs with 1 mol kg-1 (1 m) zinc acetate and 1 m zinc trifluoromethanesulfonate electrolytes. Additionally, the mesopores of meso-C facilitate the construction of better three-phase reaction interfaces and contribute to better electrochemical reversibility. The work presents a general and scalable approach for carbon materials in the cathode of near-neutral ZABs.

Molecular Tailoring of p-type Organics for Zinc Batteries with High Energy Density.

P-type organic electrode materials are known for their high redox voltages and fast kinetics. However, single-electron p-type organic materials generally exhibit low capacity despite high operating voltage and stability, while some multi-electron p-type organic materials have high theoretical capacity but low stability. To address this challenge, we explore the possibility of combining single-electron and multi-electron units to create high-capacity and stable p-type organic electrodes. We demonstrate the design of a new molecule, 4,4'-(10H-phenothiazine-3,7-diyl) bis (N,N-diphenylaniline) (PTZAN), which is created by coupling the triphenylamine molecule and the phenothiazine molecule. The resulting PTZAN||Zn battery shows excellent stability (2000 cycles), high voltage (1.3 V), high capacity (145 mAh g-1 ), and energy density of 187.2 Wh kg-1 . Theoretical calculations and in/ex situ analysis reveal that the charge storage of the PTZAN electrode is mainly driven by the redox of phenothiazine heterocycles and triphenylamine unit, accompanied by the combination/release of anions and Zn2+ .

Pilot-Scale Synthesis Sodium Iron Fluorophosphate Cathode with High Tap Density for a Sodium Pouch Cell.

Sodium-ion batteries (SIBs) have attracted wide interest for energy storage because of the sufficient sodium element reserve on the earth; however, the electrochemical performance of SIBs cannot achieve the requirements so far, especially, the limitation of cathode materials. Here, a kilogram-scale route to synthesize Na2 FePO4 F/carbon/multi-walled carbon nanotubes microspheres (NFPF@C@MCNTs) composite with a high tap density of 1.2 g cm-3 is reported. The NFPF@C@MCNTs cathode exhibits a reversible specific capacity of 118.4 mAh g-1 at 0.1 C. Even under 5 C with high mass loading (10 mg cm-2 ), the specific capacity still maintains at 56.4 mAh g-1 with a capacity retention rate of 97% after 700 cycles. In addition, a hard carbon||NFPF@C@MCNTs pouch cell is assembled and tested, which exhibits a volumetric energy density of 325 Wh L-1 and gravimetrical energy density of 210 Wh kg-1 (base on electrode massing), and it provides more than 200 cycles with a capacity retention rate of 92%. Furthermore, the pouch cell can operate in an all-climate environment ranging from -40 to 80 °C. These results demonstrate that the NFPF@C@MCNTs microspheres are a promising candidate cathode for SIBs and facilitate its practical application in sodium cells.

Realizing All-Climate Li-S Batteries by Using a Porous Sub-Nano Aromatic Framework.

Lithium-sulfur (Li-S) batteries with high energy density are currently receiving enormous attention. However, their redox kinetics at low temperature is extremely tardy, and polysulfides shuttling is serious at high temperature, which severely hinders the implementation of wide-temperature Li-S batteries. Herein, we propose an all-climate Li-S battery based on an ether-based electrolyte by using a porous sub-nano aromatic framework (SAF) modified separator. It's demonstrated that the fully conjugated SAF-3 with a small pore size (0.97 nm) and narrow band gap (1.72 eV) could efficiently block the polysulfides shuttling at elevated temperature and boost the polysulfides conversion at low temperature. Consequently, the SAF-3 modified cells work well in a wide temperature ranging from -40 to 60 °C. Furthermore, when operated at room temperature, the modified cell exhibits 90 % capacity retention over 100 cycles under high-sulfur loading (5.0 mg cm-2 ) and lean electrolyte (5 µL mg-1 ).

VPO4 F Fluorophosphates Polyanion Cathodes for High-Voltage Proton Storage.

Proton batteries are emerging in electrochemical energy storage because of the associated fast kinetics, low cost and high safety. However, their development is hindered by the relatively low energy density due to the limited choice of cathode materials. Herein, metal phosphate polyanion cathodes are proposed as the proton cathode for the first time. Combining experimental results and theoretical simulations, a universal criterion for the proton cathode was put forward. Vanadium fluorophosphate (VPO4 F) was demonstrated as a promising high-voltage proton cathode material with a specific capacity of 116 mAh g-1 at a high potential of 1.0 V (vs. SHE). The proton insertion/extraction mechanism in the VPO4 F electrode was also verified through X-ray diffraction (XRD) and photoelectron spectroscopy (XPS). Furthermore, the stability of VPO4 F was investigated in various electrolytes and the optimized electrolyte enabled the stable operation of VPO4 F for 300 cycles. This work provides new inspiration in the exploitation of new electrode materials for electrochemical proton storage devices.

Air stable and fast-charging cathode material for all climate sodium-ion batteries.

The off-stoichiometric compound Na3.12Fe2.44(P2O7)2 (NFPO) is a highly promising, cost-effective, and structurally robust cathode material for sodium-ion batteries (SIBs). However, the slowing Na-ion migration kinetics and poor interface stability have seriously limited its rate capability and air stability. In this work, we successfully synthesis a sodium titanium pyrophosphate (NaTiP2O7 donated as NTPO) coating NFPO (denoted as NFPO-NTPO) cathode material via a liquid phase coating method for SIBs. After optimizing NTPO content, at 0.1C, NFPO-NTPO-4 % cathode achieves a reversible specific capacity of 108.4 mAh g-1. Remarkably, it maintains 88.39 % capacity at 10C comparing to 0.1C and stabilizes over 3000 cycles with 92.66 % retention rate. Moreover, it retains 88.89 % capacity after 5000 cycles at 20C, even after 28 days of air exposure. The NFPO-Ti cathode, alongside the complete battery system, exhibits remarkable electrochemical performance across a broad temperature range spanning from -40 to 60 ℃.

A self-charging salt water battery for antitumor therapy.

Implantable devices on the tumor tissue as a local treatment are able to work in situ, which minimizes systemic toxicities and adverse effects. Here, we demonstrated an implantable self-charging battery that can regulate tumor microenvironment persistently by the well-designed electrode redox reaction. The battery consists of biocompatible polyimide electrode and zinc electrode, which can consume oxygen sustainably during battery discharge/self-charge cycle, thus modulating hypoxia level in tumor microenvironment. The oxygen reduction in battery leads to the formation of reactive oxygen species, showing 100% prevention on tumor formation. Sustainable consumption of oxygen causes adequate intratumoral hypoxic conditions over the course of 14 days, which is helpful for the hypoxia-activated prodrugs (HAPs) to kill tumor cells. The synergistic effect of the battery/HAPs can deliver more than 90% antitumor rate. Using redox reactions in electrochemical battery provides a potential approach for the tumor inhibition and regulation of tumor microenvironment.

Solvent-free protic liquid enabling batteries operation at an ultra-wide temperature range.

Nowadays, electrolytes for commercial batteries are mostly liquid solutions composed of solvent and salt to migrate the ions. However, solvents of the electrolyte bring several inherent limitations, either the electrochemical window, working temperature, volatility or flammability. Herein, we report polyphosphoric acid as a solvent-free protic liquid electrolyte, which excludes the demerits of solvent and exhibits unprecedented superiorities, including nonflammability, wider electrochemical stability window (>2.5 V) than aqueous electrolyte, low volatility and wide working temperature range (>400 °C). The proton conductive electrolyte enables MoO3/LiVPO4F rocking-chair battery to operate well in a wide temperature range from 0 °C to 250 °C and deliver a high power density of 4975 W kg-1 at a high temperature of 100 °C. The solvent-free electrolyte could provide a viable route for the stable and safe batteries working under harsh conditions, opening up a route towards designing wide-temperature electrolytes.