Key Takeaways & Executive Findings
- •• Anions critically influence the formation and repair of the solid electrolyte interphase (SEI) and modulate the electric double layer, directly impacting battery stability and lifespan. • Anion chemistry regulates the solvation structure of Li-ions, enhancing desolvation kinetics and improving the electrolyte's anti-oxidative properties, which reduces side reactions and extends cycle life. • Certain anions, such as halogens, impart flame-retardant properties, significantly enhancing battery safety without compromising performance. • Strategic anion design can alter reaction pathways and accelerate reactions, thereby increasing both energy density and power density of lithium batteries.
Abstract
Electrolytes are crucial components in electrochemical energy storage devices, sparking considerable research interest. However, the significance of anions in the electrolytes is often underestimated. In fact, the anions have significant impacts on the performance and stability of lithium batteries. Therefore, comprehensively understanding anion chemistry in electrolytes is of crucial importance. Herein, in-depth comprehension of anion chemistry and its positive effects on the interface, solvation structure of Li-ions, as well as the electrochemical performance of the batteries have been emphasized and summarized. This review aims to present a full scope of anion chemistry and furnish systematic cognition for the rational design of advanced electrolytes for better lithium batteries with high energy density, lifespan, and safety. Furthermore, insightful analysis and perspectives based on the current research are proposed. We hope that this review sheds light on new perspectives on understanding anion chemistry in electrolytes.
1. Introduction
In today's energy field, lithium-ion battery (LIB) is one important electrochemical energy storage device, which has closely connected with our daily life. With the increasing requirement of sustainability, durable LIBs with long lifespans and safety are highly needed [1, 2]. The electrolyte, as one of the core components of batteries, bears the important responsibility of ensuring the stability and performance of the battery during the operation [3–5]. It is well known that there are some typical electrolyte models, such as high-concentration electrolyte (HCE) [6–9], localized high-concentration electrolyte (LHCE) [10, 11], and weakly solvating electrolyte (WSE) [12–15], all of which focus on the solvents, such as decreasing the proportion of solvents and modifying the solvating ability of the solvents. Recently, the anions of Li-salts are applied for regulating the solvation structure of the electrolytes [16–18], which is a facile and effective strategy to achieve good electrochemical performance of LIBs. The anion is also an important component of the electrolyte, the effect of which, however, is often underestimated or overlooked.
Recent studies have shown that anions play multiple roles in interfacial electrochemistry and tuning the solvation sheath of Li-ions, which is very important for the formation of a solid electrolyte interphase (SEI) [19–23], the reaction kinetics at the electrode surface, and the stability of electrochemical performances [24–26]. Firstly, anions can decompose and help to form a solid SEI on the electrode surface [27–29], which is crucial for preventing solvents and salts from irreversible reactions at the electrode surface. Secondly, anions can participate in repairing the damaged SEI layer [30–32], thereby improving the stability of electrochemical performance and extending the electrode's lifespan. Additionally, anions can regulate the structure of the electric double layer (EDL) between the electrolyte and electrode surface [32–34], affecting the kinetic of charge transfer, ion transport, and distribution of species at interfaces. By adjusting the solvation environment, anions can also enhance the electrolyte's antioxidative and desolvation capabilities [35–38], thereby reducing side reactions in the electrolyte and improving battery cycle life. Furthermore, certain specific anions, such as halogens, possess flame-retardant properties, which can enhance battery safety [39, 40]. In recent years, Zhi et al. have thoroughly elucidated the critical role of anion chemistry in various energy storage devices, such as supercapacitors, cation rechargeable batteries, and metal–oxygen batteries [41]. Zhang et al. have emphasized the historical evolution and fundamental properties of salt anions [42]. The previous works provide profound insights into the critical role of anion chemistry in energy storage devices, while the design and functionalization of salt anions in new battery systems are not mentioned.
In this review, we will provide a detailed introduction to the key roles of anions, focusing on the precise design of anion structure and properties for better design of the LIBs (mainly focusing on the electrolyte). The typical anions we will introduce are displayed in Fig. 1, accompanied by the ...
Loading authentic research manuscript (Pages 1–5)...
Hecong Xiao, Xiang Li, Yongzhu Fu (2025). Advances in Anion Chemistry in the Electrolyte Design for Better Lithium Batteries. Nano-Micro Letters. https://doi.org/10.1007/s40820-024-01629-5
Research & Educational Purpose Only:The translations, structured abstracts, analytical annotations, and data reports provided by SinoTechIntel are intended exclusively for academic research, internal corporate R&D, and educational benchmarking. They do not constitute formal engineering, chemical safety, legal, or professional advice.
Copyright & Intellectual Property Notice: Original copyright of the underlying source articles and experimental data remains with the respective authors, institutions, and original publishing journals. SinoTechIntel claims intellectual property only over its proprietary translations, analytical syntheses, and AEO structured enhancements in accordance with international fair use and academic citation principles.
Frequently Asked Questions
What is the role of anions in the formation of the solid electrolyte interphase (SEI) in lithium batteries?
Anions decompose on the electrode surface to form a stable SEI layer, which prevents irreversible reactions between the electrolyte and electrode, thereby enhancing battery stability and lifespan.
How do anions influence the solvation structure of Li-ions in electrolytes?
Anions can regulate the solvation sheath of Li-ions, promoting desolvation and improving the anti-oxidative properties of the electrolyte, which reduces side reactions and improves cycle life.
Can anions improve the safety of lithium batteries?
Yes, certain anions, such as halogens, possess flame-retardant properties that enhance battery safety by reducing flammability risks.
What are the key strategies for designing advanced electrolytes using anion chemistry?
Key strategies include selecting anions that facilitate SEI formation, enhance desolvation, modulate the electric double layer, and provide flame retardancy, all of which contribute to higher energy density, longer lifespan, and improved safety.
Why is anion chemistry often underestimated in electrolyte design?
Historically, research focused on solvents, but recent studies reveal that anions play critical roles in interfacial chemistry and solvation structure, making them essential for optimizing battery performance.
Related Technical Papers & Translations
Direct Repair of the Crystal Structure and Coating Surface of Spent LiFePO4 Materials Enables Superfast Li-Ion Migration
The rapid accumulation of spent LiFePO4 (LFP) cathodes from retired lithium-ion batteries necessitates the development of effective and environmental-friendly recycling strategies. In this context, direct regeneration has emerged as a promising approach for reclaiming LFP cathode materials, offering a streamlined pathway to restore their electrochemical functionality. We report an integrated regeneration protocol that simultaneously repairs the degraded crystal structure and reconstructs the damaged carbon coating in spent LFP. The regenerated cathode material had superfast lithium-ion diffusion kinetics and a stable cathode–electrolyte interface, giving a remarkable rate capability with specific capacities of 122 mAh g−1 at 5C and 106 mAh g−1 at 10C (1C = 170 mA g−1). It also maintained capacities of 110.7 mAh g−1 (5C) and 84.1 mAh g−1 (10C) after 400 cycles. It could be used in harsh environments and could be stably cycled at subzero temperatures (−10 and −20 °C) and in solid-state electrolyte batteries. Life cycle assessment combined with economic evaluation using the EverBatt model reveals that this direct regeneration approach has high economic and environmental benefits.
Oxide Semiconductor for Advanced Memory Architectures: Atomic Layer Deposition, Key Requirement and Challenges
Oxide semiconductors (OSs), introduced by the Hosono group in the early 2000s, have evolved from display backplane materials to promising candidates for advanced memory and logic devices. The exceptionally low leakage current of OSs and compatibility with three-dimensional (3D) architectures have recently sparked renewed interest in their use in semiconductor applications. This review begins by exploring the unique material properties of OSs, which fundamentally originate from their distinct electronic band structure. Subsequently, we focus on atomic layer deposition (ALD), a core technique for growing excellent OS films, covering both basic and advanced processes compatible with 3D scaling. The basic surface reaction mechanisms—adsorption and reaction—and their roles in film growth are introduced. Furthermore, material design strategies, such as cation selection, crystallinity control, anion doping, and heterostructure engineering, are discussed. We also highlight challenges in memory applications, including contact resistance, hydrogen instability, and lack of p-type materials, and discuss the feasibility of ALD-grown OSs as potential solutions. Lastly, we provide an outlook on the role of ALD-grown OSs in memory technologies. This review bridges material fundamentals and device-level requirements, offering a comprehensive perspective on the potential of ALD-driven OSs for next-generation semiconductor memory devices.
Laser powder bed fusion of biodegradable Zn-4Cu alloy: Processing, microstructure and properties
Zn's natural degradability and biocompatibility make it a promising candidate for implants, however, its mechanical properties remain insufficient for bone applications. In this study, the performance of Zn was enhanced by developing Zn-Cu alloys via laser powder bed fusion (LPBF). Optimal LPBF parameters for forming stable tracks were achieved by adjusting laser power and scanning speed. Under optimized conditions of 100 W and 100 mm/s, high-density (99.58%) Zn-Cu alloys with improved hardness (68.2HV) and yield strength (160 MPa) were achieved. These improvements are attributed to solid solution strengthening, segregation strengthening, and grain refinement. The Zn-Cu alloys also demonstrated favorable degradation behavior, with a rate of 0.16 mm/year. This degradation is primarily driven by micro-galvanic corrosion between the CuZn5 phase and Zn matrix, along with refined grains and increased grain boundary density. This work demonstrates a viable strategy for fabricating Zn-based implants with enhanced structural integrity and mechanical performance via LPBF.