Toward robust solid-state lithium metal batteries by stabilizing a polyethylene oxide-based solid electrolyte interface with a biomass polymer filler

Towards Ultra-Stable Wide-Temperature Zinc-Ion Batteries by Using Ion-Sieving Organic Framework Membrane

Aqueous zinc-ion batteries (AZIBs) offer notable advantages in safety and cost-efficiency, but Zn dendrite growth and unstable interfacial reactions hinder their commercial viability. A crucial factor in addressing these challenges lies in optimizing the separator to regulate ion transport and stabilize electrode interfaces. Herein, we propose a covalent organic framework (COF)-based separator with quasi-single-ion conduction, specifically a Zn2+-substituted sulfonate COF (COF-Zn) membrane, designed to tackle these issues. Featuring a high Zn transference number (0.87) and a thin 25 μm profile, the COF-Zn separator allows for reduced electrolyte usage (20 μL mg-1) while effectively minimizing cathode dissolution. Its quasi-single-ion conductivity and electronegative properties improve Zn anode's stability by lowering water activity. This separator enables ultra-stable AZIBs, as demonstrated in various full cells including Zn//4,5,9,10-pyrenetetrone (PTO), Zn//I2 and Zn//V2O5. Remarkably, the Zn//PTO cell achieves an energy density of 260 Wh kg-1, 100 % capacity retention under reduced electrolyte conditions, and stable all-weather cycling from -40 to +100 °C with a customized electrolyte.

Environmental Sustainability of Natural Biopolymer-Based Electrolytes for Lithium Ion Battery Applications

Biopolymer based electrolytes can overcome current performance limitations of lithium-ion batteries (LIBs). Biopolymers enable electrolytes with high ionic conductivities and wide electrochemical stability windows. While the biobased character of natural materials is claimed as an inherent advantage in meeting current environmental sustainability challenges, further research is required to quantify and compare their environmental impacts as electrolytes. The challenge is addressed by identifying the most promising biopolymer electrolytes for LIBs, measuring ionic conductivities and electrochemical stability windows, and quantifying environmental impacts using life cycle assessment. The environmental impacts of the cost to isolate cellulose derivatives, nanocelluloses, chitin/nanochitin, chitosan, lignin, agar, and silk are reported for climate change, acidification, freshwater ecotoxicity, marine eutrophication, human toxicity, and water use. Material criticality, circularity index, and material circularity indicator, emerging impact categories are prioritized to help integrate biopolymers into circular and sustainable materials. The electrochemical properties and environmental impacts of natural biopolymer membrane-liquid electrolyte pairs, gel electrolytes, and solid electrolytes are quantified and benchmarked against conventional fossil-based electrolytes, providing consistent and comparable electrochemical properties of the most relevant biopolymer electrolytes fabricated so far. This study highlights the significant functional and environmental benefits of biopolymer electrolytes and identifies the most electrochemically competitive biopolymer electrolytes in LIBs.

Multiple Na+ transport pathways and interfacial compatibility enable high-capacity, room-temperature quasi-solid sodium batteries

Sodium-metal batteries (SMBs) are ideal for large-scale energy storage due to their stable operation and high capacity. However, they have safety issues caused by severe dendrite growth and side reactions, particularly when using liquid electrolytes. Therefore, it is critically important to develop electrolytes with high ionic conductivity and improved safety that are non-flammable and resistant to dendrites. Here, we developed polymerized polyethylene glycol diacrylate (PEGDA)-modified poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) electrolytes (PPEs) with highly conductive sodium bis(trifluoromethanesulfonyl)imide and corrosion-inhibitive sodium bis(oxalato)borate salts for SMBs. Well-complexed PEGDA not only increases the amorphicity of the PVDF matrix, but also offers numerous Lewis basic sites through the polar groups of carbonyl and ether groups (i.e., electron donors). The presence of the Lewis basic sites facilitates the dissociation of sodium salt and transportation of Na+ within the PVDF matrix. This results in the generation of additional Na+ transport pathways, which can enhance the performance of the battery. Among PPEs, the optimized PPE-50 exhibits a high ionic conductivity of 3.42 × 10-4 S cm-1 and a mechanical strength of 14.0 MPa. A Na||Na symmetric cell with PPE-50 displays high stability at 0.2 mA cm-2 for 800 h. PPE-50 further displays high capacity, e.g., a Na3V2(PO4)3|PPE-50|Na battery delivers a decent discharge capacity of 101.5 mAh g-1 at 1.0C after 650 cycles. Our work demonstrates the development of high-performance quasi-solid polymer electrolytes with multiple transport pathways suitable for room-temperature SMBs.

Polymeric Electrolytes for Solid-state Lithium Ion Batteries: Structure Design, Electrochemical Properties and Cell Performances

Solid-state electrolytes are key to achieving high energy density, safety, and stability for lithium-ion batteries. In this Review, core indicators of solid polymer electrolytes are discussed in detail including ionic conductivity, interface compatibility, mechanical integrity, and cycling stability. Besides, we also summarize how above properties can be improved by design strategies of functional monomers, groups, and assembly of batteries. Structures and properties of polymers are investigated here to provide a basis for all-solid-state electrolyte design strategies of multi-component polymers. In addition, adjustment strategies of quasi-solid-state polymer electrolytes such as adding functional additives and carrying out structural design are also investigated, aiming at solving problems caused by simply adding liquids or small molecular plasticizer. We hope that fresh and established researchers can achieve a general perspective of solid polymer electrolytes via this Review and spur more extensive interests for exploration of high-performance lithium-ion batteries.