Jinlin Yang

Achieving high ionic conductivity and stable performance at low temperatures remains a significant challenge in sodium‐metal batteries (SMBs). In this study, we propose a novel electrolyte design strategy that elucidates the solvation structure‐function relationship within mixed solvent systems. A mixture of diglyme and 1,3‐dioxolane was developed to optimize the solvation structure towards superior low‐temperature electrolyte. Molecular dynamics simulations and Raman spectra results reveal the solvent‐separated ion pairs and contact ion pairs dominated solvation structure in the designed electrolyte, displaying a superior ionic conductivity of 1.78×10⁻³ S cm⁻¹ at −40 °C. Besides, comprehensive kinetic analysis shows Na⁺ transportation in the electrolyte shows a greater impact on sodium plating than Na⁺ transport through the solid electrolyte interphase or charge transfer. As a result, the electrolyte enables stable operation for over 12,000 hours in Na Na cells at −40 °C. In Na Na_2/3Ni_1/4Cu_1/12Mn_2/3O₂ full cells, it maintains a high capacity retention of 92.4 % over 600 cycles with an initial specific capacity of 89.4 mAh g⁻¹ at −40 °C, and achieves 81.7 % capacity retention after 50 cycles with an initial specific capacity of 75.3 mAh g⁻¹ at −78 °C. These results pave the way for the development of high‐performance SMBs capable of operating under ultralow temperatures.

Achieving high ionic conductivity and stable performance at low temperatures remains a significant challenge in sodium‐metal batteries (SMBs). In this study, we propose a novel electrolyte design strategy that elucidates the solvation structure‐function relationship within mixed solvent systems. A mixture of diglyme and 1,3‐dioxolane was developed to optimize the solvation structure towards superior low‐temperature electrolyte. Molecular dynamics simulations and Raman spectra results reveal the solvent‐separated ion pairs and contact ion pairs dominated solvation structure in the designed electrolyte, displaying a superior ionic conductivity of 1.78×10⁻³ S cm⁻¹ at −40 °C. Besides, comprehensive kinetic analysis shows Na⁺ transportation in the electrolyte shows a greater impact on sodium plating than Na⁺ transport through the solid electrolyte interphase or charge transfer. As a result, the electrolyte enables stable operation for over 12,000 hours in Na Na cells at −40 °C. In Na Na_2/3Ni_1/4Cu_1/12Mn_2/3O₂ full cells, it maintains a high capacity retention of 92.4 % over 600 cycles with an initial specific capacity of 89.4 mAh g⁻¹ at −40 °C, and achieves 81.7 % capacity retention after 50 cycles with an initial specific capacity of 75.3 mAh g⁻¹ at −78 °C. These results pave the way for the development of high‐performance SMBs capable of operating under ultralow temperatures.

A critical challenge in solid polymer lithium batteries is developing a polymer matrix that can harmonize ionic transportation, electrochemical stability, and mechanical durability. We introduce a novel polymer matrix design by deciphering the structure‐function relationships of polymer side chains. Leveraging the molecular orbital‐polarity‐spatial freedom design strategy, a high ion‐conductive hyperelastic ternary copolymer electrolyte (CPE) is synthesized, incorporating three functionalized side chains of poly‐2,2,2‐Trifluoroethyl acrylate (PTFEA), poly(vinylene carbonate) (PVC), and polyethylene glycol monomethyl ether acrylate (PEGMEA). It is revealed that fluorine‐rich side chain (PTFEA) contributes to improved stability and interfacial compatibility; the highly polar side chain (PVC) facilitates the efficient dissociation and migration of ions; the flexible side chain (PEGMEA) with high spatial freedom promotes segmental motion and interchain ion exchanges. The resulting CPE demonstrates an ionic conductivity of 2.19×10⁻³ S cm⁻¹ (30 °C), oxidation resistance voltage of 4.97 V, excellent elasticity (2700 %), and non‐flammability. The outer elastic CPE and the inner organic–inorganic hybrid SEI buffer intense volume fluctuation and enable uniform Li⁺ deposition. As a result, symmetric Li cells realize a high CCD of 2.55 mA cm⁻² and the CPE‐based Li||NCM811 full cell exhibits a high‐capacity retention (~90 %, 0.5 C) after 200 cycles.

A critical challenge in solid polymer lithium batteries is developing a polymer matrix that can harmonize ionic transportation, electrochemical stability, and mechanical durability. We introduce a novel polymer matrix design by deciphering the structure‐function relationships of polymer side chains. Leveraging the molecular orbital‐polarity‐spatial freedom design strategy, a high ion‐conductive hyperelastic ternary copolymer electrolyte (CPE) is synthesized, incorporating three functionalized side chains of poly‐2,2,2‐Trifluoroethyl acrylate (PTFEA), poly(vinylene carbonate) (PVC), and polyethylene glycol monomethyl ether acrylate (PEGMEA). It is revealed that fluorine‐rich side chain (PTFEA) contributes to improved stability and interfacial compatibility; the highly polar side chain (PVC) facilitates the efficient dissociation and migration of ions; the flexible side chain (PEGMEA) with high spatial freedom promotes segmental motion and interchain ion exchanges. The resulting CPE demonstrates an ionic conductivity of 2.19×10⁻³ S cm⁻¹ (30 °C), oxidation resistance voltage of 4.97 V, excellent elasticity (2700 %), and non‐flammability. The outer elastic CPE and the inner organic–inorganic hybrid SEI buffer intense volume fluctuation and enable uniform Li⁺ deposition. As a result, symmetric Li cells realize a high CCD of 2.55 mA cm⁻² and the CPE‐based Li||NCM811 full cell exhibits a high‐capacity retention (~90 %, 0.5 C) after 200 cycles.

An anion-rich electric double layer (EDL) region is favorable for fabricating an inorganic-rich solid–electrolyte interphase (SEI) towards stable lithium metal anode in ester electrolyte. Herein, cetyltrimethylammonium bromide (CTAB), a cationic surfactant, is adopted to draw more anions into EDL by ionic interactions that shield the repelling force on anions during lithium plating. In situ electrochemical surface-enhanced Raman spectroscopy results combined with molecular dynamics simulations validate the enrichment of NO₃⁻/FSI⁻ anions in the EDL region due to the positively charged CTA⁺. In-depth analysis of SEI structure by X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry results confirmed the formation of the inorganic-rich SEI, which helps improve the kinetics of Li⁺ transfer, lower the charge transfer activation energy, and homogenize Li deposition. As a result, the Li||Li symmetric cell in the designed electrolyte displays a prolongated cycling time from 500 to 1300 h compared to that in the blank electrolyte at 0.5 mA cm⁻² with a capacity of 1 mAh cm⁻². Moreover, Li||LiFePO₄ and Li||LiCoO₂ with a high cathode mass loading of > 10 mg cm⁻² can be stably cycled over 180 cycles.

To enable the practical implementation of alkali metal batteries (AMBs), significant endeavors have been focused on enhancing the stability of alkali metal anodes (AMAs) using a range of strategies, such as optimizing electrolyte compositions, constructing anode deposition hosts, and establishing artificial protective layers. Despite significant progress in enhancing battery performance, limited attention has been given to comprehending the interaction mechanisms between alkali metals and protective materials, which is pivotal for the informed development of novel protective materials. Thus, aiming to enhance the comprehension of interaction processes between AMAs and organic protective materials containing various nitrogen groups, we conducted a mechanism study utilizing 1,4,5,8,9,11‐hexaazatriphenylenehexacarbonitrile (HATCN) as the model material, based on in‐situ x‐ray and ultraviolet photoelectron spectroscopy (XPS/UPS), and near edge x‐ray absorption fine structure (NEXAFS), as well as density functional theory (DFT) calculations. Through the investigation of interaction processes between HATCN and Li/Na, we find that Li or Na interacts with the two different nitrogen‐containing groups of HATCN in the same order: preferentially interacts with the inner imine groups of HATCN before interacting with the outer nitrile groups. Interestingly, our findings also reveal that the two distinct nitrogen‐containing groups exhibit a smaller difference in their sodiophilicity compared to their difference in lithiophilicity. These valuable insights shed light on the intricate interactions between nitrogen‐containing protective materials and AMAs, paving the way for the development of more effective protective materials in the future.

A small amount of methoxide additive is found to effectively induce preferential adsorption of anions ( i.e. , TFSI ⁻ and NO ₃ ⁻ ) on the surface of the Li metal anode, contributing to an inorganic-rich SEI and enabling stable Li metal batteries.

Uncontrollable sodium dendrite growth results in poor cycling performance and severe safety issues, hindering practical applications of sodium metal batteries (SMBs). To stabilize sodium metal anodes (SMAs), various strategies have been developed including employing anode hosts and electrolyte additives to establish protective layers. Nevertheless, the understanding of interaction mechanisms between protective materials and SMAs is still limited, which is crucial for the rational design of protective materials. In this work, we investigated the interaction mechanism between sodium metal and sulfur-containing functional groups with comparative model systems of α-sexithiophene (6T) and p-sexiphenyl (6P) through in-situ photoelectron spectroscopy investigations and density functional theory (DFT) calculations. Our results show that sodium atoms tend to interact with sulfur atoms and their connected carbon atoms simultaneously as well as the aromatic carbon atoms of the end groups of 6T molecules, while no chemical interaction between Na and 6P molecules is observed. The observed sulfurization-induced sodiophilic sites can shed light on the rational design of sulfur-containing protective materials and the relevant interface engineering to stabilize SMAs.

Like phosphorene, phosphorene nanoribbon (PNR) promises exotic properties but unzipping phosphorene into edge‐defined PNR is non‐trivial because of uncontrolled cutting of phosphorene along random directions. Here a facile electrochemical strategy to fabricate zigzag‐edged PNRs in high yield (>80%) is reported. The presence of chemically active zigzag edges in PNR allows it to spontaneously react with Li to form a Li⁺ ion conducting Li₃P phase, which can be used as a protective layer on Li metal anode in lithium metal batteries (LMBs). PNR protective layer prevents the parasitic reaction between lithium metal and electrolyte and promotes Li⁺ ion diffusion kinetics, enabling homogenous Li⁺ ion flux and long‐time cycling stability up to 1100 h at a current density of 1 mA cm⁻². LiFePO₄|PNR‐Li full‐cell batteries with an areal capacity of 2 mAh cm⁻², a lean electrolyte (20 µl mAh⁻¹) and a negative/positive (N/P) electrodes ratio of 3.5 can be stably cycled over 100 cycles.