In Situ Constructing Coordination Compounds Interphase to Stabilize Zn Metal Anode for High-Performance Aqueous Zn-SeS2 Batteries.

Aqueous zinc (Zn) metal batteries have been regarded as the most promising aqueous batteries due to their low redox potential, high theoretical capacity, and abundant Zn resources. Unfortunately, Zn dendrite growth and serious side reactions drastically curtail the cycle life, severely affecting their large-scale application. Herein, a multifunctional ordered Zn-aminotrimethylene phosphonic acid (Zn-ATMP) film is in situ modified on the surface of metal Zn via a facile etching process. The modified layer can not only retard the side reactions and suppress the corrosion rate, but also lower the Zn nucleation overpotential and accelerate diffusion and homogenize deposition of Zn2+ due to the strong Zn affinity. Consequently, the as-prepared Zn-ATMP@Zn anode in the symmetric cell enables long-term lifespan (over 1000 h) at 10.0 mA cm-2 with a high areal capacity of 5 mAh cm-2 . Furthermore, when assembled with a SeS2 -based cathode, a long lifespan for over 280 cycles at 2 C can be achieved for the aqueous Zn-SeS2 battery. This work provides a reliable strategy for constructing stabilized Zn anode and accelerating the development of an aqueous energy storage system.

A Supramolecular Complex of C60 -S with High-Density Active Sites as a Cathode for Lithium-Sulfur Batteries.

The well-known "shuttle effect" of the intermediate lithium polysulfides (LiPSs) and low sulfur utilization hinder the practical application of lithium-sulfur (Li-S) batteries. Herein, we describe a novel C60 -S supramolecular complex with high-density active sites for LiPS adsorption that was formed by a simple one-step process as a cathode material for Li-S batteries. Benefiting from the cocrystal structure, 100 % of the C60 molecules in the complex can offer active sites to adsorb LiPSs and catalyze their conversion. Furthermore, the lithiated C60 cores promote internal ion transport inside the composite cathode. At a low electrolyte/sulfur ratio of 5 µL mg-1 , the C60 -S cathode with a sulfur loading of 4 mg cm-2 exhibited a high capacity of 809 mAh g-1 (3.2 mAh cm-2 ). The development of the C60 -S supramolecular complex will inspire the invention of a new family of S/fullerenes as cathodes for high-performance Li-S batteries and extend the application of fullerenes.

Recent Advances in Cathode Materials for Room-Temperature Sodium-Sulfur Batteries.

Room-temperature sodium-sulfur (RT-Na/S) batteries hold great promise to meet the requirements of large-scale energy storage due to their high theoretical energy density, low material cost, resource abundance, and environmental benignity. However, the poor cycle performance and low utilization of active sulfur greatly hinder their practical application. As the essential part directly related to the battery performance, the S-based cathode has attracted tremendous research interests in recent years. This review highlights recent progress in cathode materials for RT-Na/S batteries. Particularly, basic insights into the Na/S reaction mechanism are presented and representative works on S-based cathode materials are systematically summarized. The remaining challenges and developing trends of RT-Na/S batteries are also discussed. We hope this review can shed light on the field of next-generation metal-sulfur batteries.

Multifunctional Additive Enables a "5H" PEO Solid Electrolyte for High-Performance Lithium Metal Batteries.

The solid-state battery with a lithium metal anode is a promising candidate for next-generation batteries with improved energy density and safety. However, the current polymer electrolytes still cannot fulfill the demands of solid-state batteries. In this work, we propose a "5H" poly(ethylene oxide) (PEO) electrolyte via introducing a multifunctional additive of tris(pentafluorophenyl)borane (TPFPB) for high-performance lithium metal batteries. The addition of TPFPB improves the ionic conductivity from 6.08 × 10-5 to 1.54 × 10-4 S cm-1 via reducing the crystallinity of the PEO electrolyte and enhances the lithium-ion transference number from 0.19 to 0.53 via anion trapping due to its Lewis acid nature. Furthermore, the fluorine and boron segments from TPFPB can optimize the composition of the solid-electrolyte interphase and cathode-electrolyte interphase, providing a high electrochemical stability window over 4.6 V of the PEO electrolyte along with significantly improved interface stability. At last, TPFPB can ensure improved safety through a self-extinguishing effect. As a result, the "5H" electrolyte enables the Li/Li symmetric cells to achieve a stable cycle over 2200 h at the current density of 0.2 mA cm-2 with a capacity of 0.2 mA h cm-2; the LiFePO4/Li full cells with a high LFP loading of 8 mg cm-2 exhibits decay-free capacity of 140 mA h g-1 (99% capacity retention) after 100 cycles; and the NCM811/Li cells exhibit a high capacity of 160 mA h g-1 after 50 cycles at 0.5 C. This work presents an innovative approach to utilizing a "5H" electrolyte for high-performance solid-state lithium batteries.

Solvent-Mediated Synthesis and Characterization of Li3InCl6 Electrolytes for All-Solid-State Li-Ion Battery Applications.

Superionic halides have attracted widespread attention as solid electrolytes due to their excellent ionic conductivity, soft texture, and stability toward high-voltage electrode materials. Among them, Li3InCl6 has aroused interest since it can be easily synthesized in water or ethanol. However, investigations into the influence of solvents on both the crystal structure and properties remain unexplored. In this work, Li3InCl6 is synthesized by three different solvents: water, ethanol, and water-ethanol mixture, and the difference in properties has been studied. The results show that the product obtained by the ethanol solvent demonstrates the largest unit cell parameters with more vacancies, which tend to crystallize on the (131) plane and provide the 3D isotropic network migration for lithium-ions. Thus, it exhibits the highest ionic conductivity (1.06 mS cm-1) at room temperature and the lowest binding energy (0.272 eV). The assembled all-solid-state lithium metal batteries (ASSLMBs) employing Li3InCl6 electrolytes demonstrate a high initial discharge capacity of 153.9 mA h g-1 at 0.1 C (1 C = 170 mA h g-1) and the reversible capacity retention rate can reach 82.83% after 50 cycles. This work studies the difference in ionic conductivity between Li3InCl6 electrolytes synthesized by different solvents, which can provide a reference for the future synthesis of halide electrolytes and enable their practical application in halide-based ASSLMBs with a high energy density.

Rational design of zinc powder anode with high utilization and long cycle life for advanced aqueous Zn-S batteries.

Aqueous zinc-sulfur (Zn-S) batteries are regarded as excellent candidates for energy storage applications due to their low cost, non-toxicity, and high theoretical energy density. However, the low utilization of the traditional thick foil-type Zn anode would severely restrict the overall energy density of Zn-S batteries. Herein, a mechanically and chemically stable powder-Zn/indium (pZn/In) anode with finite Zn loading was designed and constructed for enhancing the cycle stability of aqueous Zn-S batteries. Notably, the bifunctional In protective layer can inhibit the corrosion rate of highly active pZn and homogenize the Zn2+ flux during Zn plating/stripping. As a result, the obtained pZn/In anode exhibits a greatly improved cyclability of over 285 h even under a much harsh test condition (10 mA cm-2, 2.5 mA h cm-2, Zn utilization rate: ∼38.5%). Furthermore, when assembled with an S-based cathode at a negative/positive (N/P) capacity ratio ∼2, the full cell delivers a high initial specific capacity of ∼803 mA h g-1 and operates stably for over 300 cycles at 2C with a low capacity fading rate of ∼0.17% per cycle.

Interface Engineering via Regulating Electrolyte for High-Voltage Layered Oxide Cathodes-Based Li-Ion Batteries.

Li-rich and Ni-rich layered oxides as next-generation high-energy cathodes for lithium-ion batteries (LIBs) possess the catalytic surface, which leads to intensive interfacial reactions, transition metal ion dissolution, gas generation, and ultimately hinders their applications at 4.7 V. Here, robust inorganic/organic/inorganic-rich architecture cathode-electrolyte interphase (CEI) and inorganic/organic-rich architecture anode-electrolyte interphase (AEI) with F-, B-, and P-rich inorganic components through modulating the frontier molecular orbital energy levels of lithium salts are constructed. A ternary fluorinated lithium salts electrolyte (TLE) is formulated by mixing 0.5 m lithium difluoro(oxalato)borate, 0.2 m lithium difluorophosphate with 0.3 m lithium hexafluorophosphate. The obtained robust interphase effectively suppresses the adverse electrolyte oxidation and transition metal dissolution, significantly reduces the chemical attacks to AEI. Li-rich Li1.2 Mn0.58 Ni0.08 Co0.14 O2 and Ni-rich LiNi0.8 Co0.1 Mn0.1 O2 in TLE exhibit high-capacity retention of 83.3% after 200 cycles and 83.3% after 1000 cycles under 4.7 V, respectively. Moreover, TLE also shows excellent performances at 45 °C, demonstrating this inorganic rich interface successfully inhibits the more aggressive interface chemistry at high voltage and high temperature. This work suggests that the composition and structure of the electrode interface can be regulated by modulating the frontier molecular orbital energy levels of electrolyte components, so as to ensure the required performance of LIBs.

Post-Synthetic and In Situ Vacancy Repairing of Iron Hexacyanoferrate Toward Highly Stable Cathodes for Sodium-Ion Batteries.

Iron hexacyanoferrate (FeHCF) is a promising cathode material for sodium-ion batteries. However, FeHCF always suffers from a poor cycling stability, which is closely related to the abundant vacancy defects in its framework. Herein, post-synthetic and in-situ vacancy repairing strategies are proposed for the synthesis of high-quality FeHCF in a highly concentrated Na4Fe(CN)6 solution. Both the post-synthetic and in-situ vacancy repaired FeHCF products (FeHCF-P and FeHCF-I) show the significant decrease in the number of vacancy defects and the reinforced structure, which can suppress the side reactions and activate the capacity from low-spin Fe in FeHCF. In particular, FeHCF-P delivers a reversible discharge capacity of 131 mAh g-1 at 1 C and remains 109 mAh g-1 after 500 cycles, with a capacity retention of 83%. FeHCF-I can deliver a high discharge capacity of 158.5 mAh g-1 at 1 C. Even at 10 C, the FeHCF-I electrode still maintains a discharge specific capacity of 103 mAh g-1 and retains 75% after 800 cycles. This work provides a new vacancy repairing strategy for the solution synthesis of high-quality FeHCF.

A Lithium-Ion Pump Based on Piezoelectric Effect for Improved Rechargeability of Lithium Metal Anode.

Lithium metal is widely studied as the "crown jewel" of potential anode materials due to its high specific capacity and low redox potential. Unfortunately, the Li dendrite growth limits its commercialization. Previous research has revealed that the uniform Li-ion flux on electrode surface plays a vital role in achieving homogeneous Li deposition. In this work, a new strategy is developed by introducing a multifunctional Li-ion pump to improve the homogenous distribution of Li ions. Via coating a ß-phase of poly(vinylidene fluoride) (ß-PF) film on Cu foil (Cu@ß-PF), a piezoelectric potential across such film is established near the electrode surface because of its piezoelectric property, which serves as a driving force to regulate the migration of Li ions across the film. As a result, uniform Li-ion distribution is attained, and the Cu@ß-PF shows coulombic efficiency around 99% throughout 200 cycles. Meanwhile, the lithium-sulfur full cell paired with Li-Cu@ß-PF anode exhibits excellent performance. This facile strategy via regulating the Li-ion migration provides a new perspective for safe and reliable Li metal anode.