Progressive and instantaneous nature of lithium nucleation discovered by dynamic and operando imaging

Strain-Modulated Deposition Mechanism on a Flexible Zinc Anode

Flexible aqueous zinc-ion batteries (AZIBs) are considered one of the most attractive flexible devices owing to their high theoretical capacity, low cost, and high security. However, the formation of Zn dendrites and the poor flexibility of the Zn material greatly impede the application of wearable AZIBs. Herein, by transferring graphene onto the surface of polyethylene terephthalate-indium tin oxide (PET-ITO-G), a substrate combining excellent flexibility and dendrite suppression ability was prepared. Meanwhile, a quantitative in situ strain application system was proposed to investigate the electrochemical and morphological characteristics of flexible Zn anode interface. The plating/stripping performance of the Zn|PET-ITO-G flexible device was demonstrated under various strains. Subsequent analysis indicated that the origin of its high stability under static bending strain came from the formation of densely packed Zn (101) upon cycling. In addition, PET-ITO-G could quickly recover to Zn (002) after the strain was relieved. A failure model of strain-modulated Zn deposition was proposed based on the formation of surface cracks and distorted surface current distribution. This work identified the main factors that constrained the long cycling life of a flexible metal anode and provided a feasible approach for a systematic study on the influence of in situ strain on flexible batteries.

High energy electron beam irradiation on the electrolyte enables fast-charging of lithium metal batteries with long-term cycling stability

Electron beam (E-beam) irradiation serves as a pivotal tool within the realms of materials science, nanotechnology, and microelectronics. Its application is instrumental in altering the physical and chemical properties of materials, thereby enabling the exploration of material characteristics and fostering the advent of novel technological advancements. In this study, we irradiated the commercially available carbonate-based electrolyte LB-085 using a 10 MeV electron beam to examine the effects of electron beam (E-beam) irradiation on the electrolyte of lithium-metal batteries and explore the quantitative relationship between the absorbed radiation dose and battery's electrochemical performance. The applied absorbed radiation doses were 10, 25, and 50 kGy. Among these, the electrolyte irradiated with an absorbed radiation dose of 50 kGy effectively mitigated interfacial side reactions that occurred during the cycles of an electrode, securing a stable solid-state electrolyte interphase (SEI), which was characterized by a high ionic conductivity. This, in turn, facilitated rapid charging performance of the battery. The lithium metal full-cell assembled with LiNi0.91Co0.06Mn0.03O2 (NCM91) demonstrated superior capacity retention, exceeding 80% after 450 cycles at 4C rate (1C = 220 mA g-1, with charge times under 15 min) and also exceeding 80% after 600 cycles at 6C rate with an absorbed radiation dose of 50 kGy on the electrolyte. Thus, this research provides fresh perspectives for electrolyte optimization, focusing on enhancing the rapid charging performance of batteries.

Investigations into the Nucleation Dynamics of the Stable Na-Metal Anode: Revealing the Role of a Tin-Infused Carbon Nanofiber Interlayer

Fundamental understanding and controlling of sodium nucleation are essential for enhancing the performance, safety, and longevity of sodium metal batteries, which is not yet clearly understood in the case of sodium metal batteries. The present study showcases how a modification in the host material influences nucleation kinetics. Current-time transient studies on copper, carbon nanofiber, and tin-embedded carbon nanofiber interlayers employing the Scharifker-Hills model elucidate the mode of nucleation. This work tries to delve deep and presents a case study on how a tin-based interlayer can not only minimize the barrier for sodium nucleation but also direct the sequential progressive and instantaneous nucleation of sodium metal while reducing the overpotential substantially, resulting in crystalline, uniform Na-metal deposition. Further, to account for the complex dynamics of solid electrolyte interphase (SEI) formation distinctly associated with alkali metal deposition, the SEI-fracture model has been included, and the quantification of electrochemical nucleation parameters is obtained. The results provide important insights into the sodium nucleation mechanism, paving the way to counter dendrite formation and SEI dissolution issues of the Na-metal anode.

Key Anodic Interfacial Phenomena and their Control in Next-Generation Lithium and Sodium Metal Batteries

Advancing next-generation battery technologies requires a thorough understanding of the intricate phenomena occurring at anodic interfaces. This focused review explores key interfacial processes, examining their thermodynamics and consequences in ion transport and charge transfer kinetics. It begins with a discussion on the formation of the electro chemical double layer, based on the GuoyChapman model, and explores how charge carriers achieve equilibrium at the interface. This review then delves into essential interfacial processes, including metal nucleation and growth, the development and stability of the solid electrolyte interphase (SEI), and ion movement across the interface. In addition, it analyzes the impact of different electrolyte solutions-such as low- and high-concentration electrolytes and localized high-concentration electrolytes-on these interfacial processes. The role of additives, co-solvents, and diluents in modifying these interfaces is also covered. This review further evaluates techniques for characterizing the SEI layer, highlighting their strengths and limitations in both aqueous and nonaqueous battery systems. By comparing the challenges and opportunities associated with interfaces next-generation nonaqueous metal battery systems, this review aims to offer new insights into their respective advantages and limitations, ultimately guiding the design and optimization of anodic interfaces to enhance the safety and efficiency of future energy storage technologies.

Electrochemical In Situ Characterization Techniques in the Field of Energy Conversion

With the proposal of the "carbon peak and carbon neutrality" goals, the utilization of renewable energy sources such as solar energy, wind energy, and tidal energy has garnered increasing attention. Consequently, the development of corresponding energy conversion technologies has become a focal point. In this context, the demand for electrochemical in situ characterization techniques in the field of energy conversion is gradually increasing. Understanding the microscopic electrochemical reactions and their mechanisms in depth is a common concern shared by both academia and industry. Therefore, the development of electrochemical in situ characterization techniques holds critical significance. This paper comprehensively reviews electrochemical in situ characterization techniques in the field of energy conversion from three aspects: spectral characterization techniques of electrochemical reactions, characterization techniques for the spatial distribution of electrochemical reactions, and optical characterization techniques for the surface refractive index associated with the spatial distribution of electrochemical reactions. These characteristics are described in detail, and the future development direction of in situ characterization technology is prospected, with the aim of promoting the advancement of electrochemical in situ characterization technology in the field of energy conversion, facilitating energy transformation, and thus advancing the goals of "carbon peak and carbon neutrality."

The Impact of Supersaturated Electrode on Heterogeneous Lithium Nucleation and Growth Dynamics

The concept of a lithiophilic electrode proves inadequate in describing carbon-based electrode materials due to their substantial mismatch in surface energy with lithium metal. However, their notable capacity for lithium chemisorption can increase active lithium concentration required for nucleation and growth, thereby enhancing the electrochemical performance of lithium metal anodes (LMAs). In this study, we elucidate the effects of the supersaturated electrode which has high active lithium capacity around equilibrium lithium potential on LMAs through an in-depth electrochemical comparison using two distinct carbon electrode platforms with differing carbon structures but similar two-dimensional morphologies. In the supersaturated electrode, both the dynamics and thermodynamic states involved in lithium nucleation and growth mechanisms are significantly improved, particularly under continuous current supply conditions. Furthermore, the chemical structures of the solid-electrolyte-interface layers (SEIs) are greatly influenced by the elevated surface lithium concentration environment, resulting in the formation of more conductive lithium-rich SEI layers. The improved dynamics and thermodynamics of surface lithium, coupled with the formation of enhanced SEI layers, contribute to higher power capabilities, enhanced Coulombic efficiencies, and improved cycling performances of LMAs. These results provide new insight into understanding the enhancements in heterogeneous lithium nucleation and growth kinetics on the supersaturated electrode.

Breaking the capacity bottleneck of lithium-oxygen batteries through reconceptualizing transport and nucleation kinetics

The practical capacity of lithium-oxygen batteries falls short of their ultra-high theoretical value. Unfortunately, the fundamental understanding and enhanced design remain lacking, as the issue is complicated by the coupling processes between Li2O2 nucleation, growth, and multi-species transport. Herein, we redefine the relationship between the microscale Li2O2 behaviors and the macroscopic electrochemical performance, emphasizing the importance of the inherent modulating ability of Li+ ions through a synergy of visualization techniques and cross-scale quantification. We find that Li2O2 particle distributed against the oxygen gradient signifies a compatibility match for the nucleation and transport kinetics, thus enabling the output of the electrode's maximum capacity and providing a basis for evaluating operating protocols for future applications. In this case, a 150% capacity enhancement is further achieved through the development of a universalizing methodology. This work opens the door for the rules and control of energy conversion in metal-air batteries, greatly accelerating their path to commercialization.

Understanding the nanoscale phenomena of nucleation and crystal growth in electrodeposition

Electrodeposition is used at the industrial scale to make coatings, membranes, and composites. With better understanding of the nanoscale phenomena associated with the early stage of the process, electrodeposition has potential to be adopted by manufacturers of energy storage devices, advanced electrode materials, fuel cells, carbon dioxide capturing technologies, and advanced sensing electronics. The ability to conduct precise electrochemical measurements using cyclic voltammetry, chronoamperometry, and chronopotentiometry in addition to control of precursor composition and concentration makes electrocrystallization an attractive method to investigate nucleation and early-stage crystal growth. In this article, we review recent findings of nucleation and crystal growth behaviors at the nanoscale, paying close attention to those that deviate from the classical theories in various electrodeposition systems. The review affirms electrodeposition as a valuable method both for gaining new insights into nucleation and crystallization on surfaces and as a low-cost scalable technology for the manufacturing of advanced materials and devices.

Dual-Mode Imaging of Dynamic Interaction between Bubbles and Single Nanoplates during the Electrocatalytic Hydrogen Evolution Process

Gas bubble formation at electrochemical interfaces can significantly affect the efficiency and durability of electrocatalysts. However, obtaining comprehensive details on bubble evolution dynamics, particularly their dynamic interaction with high-performance structured electrocatalysts, poses a considerable challenge. Herein, dual-mode interference/total internal reflection fluorescence microscopy is introduced, which allows for the simultaneous capture of the evolution pathway of bubbles and the 3D motion of nanoplate electrocatalysts, providing high-resolution and accurate spatiotemporal information. During the hydrogen evolution reaction, the dynamics of hydrogen bubble generation and their interactions with single nanoplate electrocatalysts at the electrochemical interface are observed. The results unveiled that, under constant potential, bubbles initially manifest as fast-moving nanobubbles, transforming into stationary microbubbles subsequently. The morphology of stationary nanoplates regulates the trajectories of these moving nanobubbles while the pinned microbubbles induce the motion of the electrocatalysts. The dual-mode microscopy can be employed to scrutinize numerous multiphase electrochemical interactions with high spatiotemporal resolution, which can facilitate the rational design of high-performance electrocatalysts.

Kelvin Probe Force Microscopy and Electrochemical Atomic Force Microscopy Investigations of Lithium Nucleation and Growth: Influence of the Electrode Surface Potential

Lithium metal is promising for high-capacity batteries because of its high theoretical specific capacity of 3860 mAh g-1 and low redox potential of -3.04 V versus the standard hydrogen electrode. However, it encounters challenges, such as dendrite formation, which poses risks of short circuits and safety hazards. This study examines Li deposition using electrochemical atomic force microscopy (EC-AFM) and Kelvin probe force microscopy (KPFM). KPFM provides insights into local surface potential, while EC-AFM captures the surface response evolution to electrochemical reactions. We selectively removed metallic coatings from current collectors to compare lithium deposition on coated and exposed copper surfaces. Observations from the Ag-coated Cu (Ag/Cu), Pt-coated Cu (Pt/Cu), and Au-coated Cu (Au/Cu) samples revealed variations in lithium deposition. Ag/Cu and Au/Cu exhibited two-dimensional growth, whereas Pt/Cu exhibited three-dimensional growth, highlighting the impact of electrode materials on morphology. These insights advance the development of safer lithium metal batteries.

Anchoring Active Li Metal in Oriented Channel by In Situ Formed Nucleation Sites Enabling Durable Lithium-Metal Batteries

Lithium metal is the ultimate anode material for pursuing the increased energy density of rechargeable batteries. However, fatal dendrites growth and huge volume change seriously hinder the practical application of lithium metal batteries (LMBs). In this work, a lithium host that preinstalled CoSe nanoparticles on vertical carbon vascular tissues (VCVT/CoSe) is designed and fabricated to resolve these issues, which provides sufficient Li plating space with a robust framework, enabling dendrite-free Li deposition. Their inherent N sites coupled with the in situ formed lithiophilic Co sites loaded at the interface of VCVT not only anchor the initial Li nucleation seeds but also accelerate the Li+ transport kinetics. Meanwhile, the Li2Se originated from the CoSe conversion contributes to constructing a stable solid-electrolyte interphase with high ionic conductivity. This optimized Li/VCVT/CoSe composite anode exhibits a prominent long-term cycling stability over 3000 h with a high areal capacity of 10 mAh cm-2. When paired with a commercial nickel-rich LiNi0.83Co0.12Mn0.05O2 cathode, the full-cell presents substantially enhanced cycling performance with 81.7% capacity retention after 300 cycles at 0.2 C. Thus, this work reveals the critical role of guiding Li deposition behavior to maintain homogeneous Li morphology and pave the way to stable LMBs.

Regulating Li Nucleation and Growth Heterogeneities via Near-Surface Lithium-Ion Irrigation for Stable Anode-Less Lithium Metal Batteries

The inhomogeneous nucleation and growth of Li dendrite combined with the spontaneous side reactions with the electrolytes dramatically challenge the stability and safety of Li metal anode (LMA). Despite tremendous endeavors, current success relies on the use of significant excess of Li to compensate the loss of active Li during cycling. Herein, a near-surface Li+ irrigation strategy is developed to regulate the inhomogeneous Li deposition behavior and suppress the consequent side reactions under limited Li excess condition. The conformal polypyrrole (PPy) coating layer on Cu surface via oxidative chemical vapor deposition technique can induce the migration of Li+ to the interregional space between PPy and Cu, creating a near-surface Li+-rich region to smooth diffusion of ion flux and uniform the deposition. Moreover, as evidenced by multiscale characterizations including synchrotron high-energy X-ray diffraction scanning, a robust N-rich solid-electrolyte interface (SEI) is formed on the PPy skeleton to effectively suppress the undesired SEI formation/dissolution process. Strikingly, stable Li metal cycling performance under a high areal capacity of 10 mAh cm-2 at 2.0 mA cm-2 with merely 0.5 × Li excess is achieved. The findings not only resolve the long-standing poor LMA stability/safety issues, but also deepen the mechanism understanding of Li deposition process.