Ultralow-Temperature Li/CFx Batteries Enabled by Fast-Transport and Anion-Pairing Liquefied Gas Electrolytes

Lithium fluorinated-carbon (Li/CF_x ) is one of the most promising chemistries for high-energy-density primary energy-storage systems in applications where rechargeability is not required. Though Li/CF_x demonstrates high energy density (>2100 Wh kg^-1 ) under ambient conditions, achieving such a high energy density when exposed to subzero temperatures remains a challenge, particularly under high current density. Here, a liquefied gas electrolyte with an anion-pair solvation structure based on dimethyl ether with a low melting point (-141 °C) and low viscosity (0.12 mPa s, 20 °C), leading to high ionic conductivity (>3.5 mS cm^-1 ) between -70 and 60 °C is reported. Besides that, through systematic X-ray photoelectron spectroscopy integrated with transmission electron microscopy characterizations, the interface of CF_x is evaluated for low-temperature performance. The fast transport and anion-pairing solvation structure of the electrolyte are concluded to bring about reduced charge-transfer resistance at low temperatures, which results in significantly enhanced performance of Li/CF_x cells (1690 Wh kg^-1 , -60 °C based on active materials). Utilizing 50 mg cm^-2 loading electrodes, the Li/CF_x still displays 1530 Wh kg^-1 at -60 °C. This work provides insights into the electrolyte design that may overcome the operational limits of batteries in extreme environments.

Simultaneous Regulation on Solvation Shell and Electrode Interface for Dendrite-Free Zn Ion Batteries Achieved by a Low-Cost Glucose Additive

Dendrite growth and by-products in Zn metal aqueous batteries have impeded their development as promising energy storage devices. We utilize a low-cost additive, glucose, to modulate the typical ZnSO₄ electrolyte system for improving reversible plating/stripping on Zn anode for high-performance Zn ion batteries (ZIBs). Combing experimental characterizations and theoretical calculations, we show that the glucose in ZnSO₄ aqueous environment can simultaneously modulate solvation structure of Zn²⁺ and Zn anode-electrolyte interface. The electrolyte engineering can alternate one H₂ O molecule from the primary Zn²⁺ -6H₂ O solvation shell and restraining side reactions due to the decomposition of active water. Concomitantly, glucose molecules are inclined to absorb on the surface of Zn anode, suppressing the random growth of Zn dendrite. As a proof of concept, a symmetric cell and Zn-MnO₂ full cell with glucose electrolyte achieve boosted stability than that with pure ZnSO₄ electrolyte.

Nanoengineered Organic Electrodes for Highly Durable and Ultrafast Cycling of Organic Sodium-Ion Batteries

Sodium-ion batteries (SIBs) have become increasingly important as next-generation energy storage systems for application in large-scale energy storage. It is very crucial to develop an eco-friendly and green SIB technique with superior performance for sustainable future use. Replacing the conventional inorganic electrode materials with green and safe organic electrodes will be a promising approach. However, the poor electrochemical kinetics, unstable electrode-electrolyte interface, high solubility of the electrodes in the electrolyte, and large amount of conductive carbon present great challenges for organic SIBs. In this study, the issues of organic electrodes are addressed through atomic-level manipulation of these organic molecules using a series of ultrathin (Å-level) metal oxide coatings (Al₂ O₃ , ZnO, and TiO₂ ). Uniform and precise coatings on the perylene-3,4,9,10-tetracarboxylicacid dianhydride by gas-phase atomic layer deposition technique shows a stable interphase, enhanced electrochemical kinetics (71C, 10 A g^-1 ), and excellent stability (89%-500 cycles) compared to conventional organic electrode (70%-200 cycles). Further studies reveal that the chemical stability of the metal oxide coating layer plays a critical role in influencing the redox behavior, and improving kinetics of organic electrodes. This study opens a new avenue for developing high-energy organic SIBs with performance equivalent to inorganic counterparts.