ACS Materials Letters最新文献

All-solid-state battery (ASSB) technology is one of the most promising approaches to energy storage due to its great safety and energy density. However, the detrimental effects of cathodal structure/morphology/composition/conductivity evolution on electrochemical performance significantly restrict the development of ASSBs. To elaborately investigate these cathodal dynamic evolution processes and deterioration mechanisms of ASSBs, in situ transmission electron microscopy (TEM) technology has been extensively introduced into the ASSB research. This paper discusses the latest important scientific discoveries toward cathodal dynamic evolution in multitype ASSBs through in situ TEM and highlights key challenges for in situ TEM to analyze ASSB cathodes with a higher spatial resolution. Lastly, insights for future directions of in situ TEM monitoring multiscale electro-chemo-mechanical evolution of ASSBs are prospectively provided. This Review will deepen the fundamental understanding of cathodal dynamic mechanisms and open new opportunities for the optimization and development of in situ TEM in ASSBs.

MoS₂ is regarded as one of the most promising potassium-ion battery (PIB) anodes. Despite the great progress to enhance its electrochemical performance, understanding of the electrochemical mechanism to store K-ions in MoS₂ remains unclear. This work reports that the K storage process in MoS₂ follows a complex reaction pathway involving the conversion reactions of Mo and S, showing both cationic redox activity of Mo and anionic redox activity of S. The presence of dual redox activity, characterized in-depth through synchrotron X-ray absorption, X-ray photoelectron, Raman, and UV-vis spectroscopies, reveals that the irreversible Mo oxidation during the depotassiation process directs the reaction pathway toward S oxidation, which leads to the occurrence of K-S electrochemistry in the (de)potassiation process. Moreover, the dual reaction pathway can be adjusted by controlling the discharge depth at different cycling stages of MoS₂, realizing a long-term stable cycle life of MoS₂ as a PIB anode.

Here, we report gas-quenched quasi-2D (GA)(MA)₅Pb₅I₁₆ perovskites for single junction solar cells and monolithic-silicon tandem solar cells. This is the first time quasi-2D (GA)(MA)₅Pb₅I₁₆ perovskite cells have been tested with proton beams, showing excellent tolerance. A representative tandem cell also passed the IEC 61215 Thermal Cycling Test (−40 °C ↔ 85 °C) twice, retaining 95.0% of its initial PCE after 400 cycles.

The study included characterization of the components of fire and smoke during thermal runaway for NMC and LFP cells, modules, and batteries and to determine if the size and volume of fire and smoke released scaleup linearly when one goes from the cell to module and then to a battery configuration for the same cathode chemistry. Thermal runaway tests were conducted in ambient as well as inert environments to characterize gas release with and without combustion. During thermal runaway, the test articles exhibited fire, smoke, or both. Gas analysis exhibited hydrocarbons as well as hydrogen and carbon dioxide that could accumulate above the lower flammability limit (LFL) of the gas mixture if released into an enclosure. The nature of fire and volume of smoke released do not always scale linearly with an increasing number of cells, showing that testing in the relevant configuration and environment is imperative. A good understanding of gases released into a certain enclosed space will help with safer vent and deflagration designs and provide a warning to first responders and firefighters of the expected nature of gases.

The performance of organic photodetectors (OPDs) using conjugated polymer donors and molecular acceptors has improved rapidly, but many polymers are difficult to upscale due to their complex structures. This study examines two low-complexity thiophene copolymers with substituted benzooxadiazole (FO6-BO-T) or benzothiadiazole (FO6-T). Substituting sulfur with oxygen in FO6-BO-T increased its ionization energy without affecting the optical gap. When blended with the nonfullerene acceptor IDSe, FO6-BO-T showed a significantly lower dark current density (2.06·10^-9 A cm^-2 at -2 V) compared to FO6-T. Grazing incidence wide-angle X-ray scattering (GIWAXS) measurements demonstrated that pristine FO6-BO-T exhibited a more ordered morphology than FO6-T. However, blending resulted in a significant disruption to the ordered domains in both cases, with a loss of orientational order, suggesting that FO6-BO-T's improved performance is largely related to its increased ionization energy. This study demonstrates the potential of chalcogen atom engineering to enhance the performance of the OPD in scalable polymers.

Tin-based perovskites (Sn-PVK) are promising lead-free alternatives for efficient photovoltaic technology, but they face challenges related to bulk and surface defects due to suboptimal crystallization and Sn²⁺ oxidation. Introducing thiophene-2-ethylammonium halides (TEAX, where X = I, Br, Cl) improves FASnI₃ crystallization and reduces Sn⁴⁺ formation. This is achieved by adjusting the crystallization dynamics through the formation of a complex between S and Sn during the preparation of the precursor solution, which also inhibits Sn²⁺ oxidation in the resulting films. In solar cells, these additives boost power conversion efficiency (PCE) from 6.6% (without additives) to 9.4% (using TEABr), with further enhancement to 12% by adjusting selective contacts. The addition of TEAX also increases the Sn²⁺ content, outperforming control. Devices with TEABr maintained over 95% of their initial PCE after 2000 h in N₂ under continuous operation with 1 sun simulated illumination.

High-performance polymer electrolyte systems for lithium–metal batteries (LMBs) commonly contain a relatively high amount of fluorine to stabilize the electrode|electrolyte interfaces, particularly that with lithium metal. Herein, we report an advanced single-ion conducting polymer electrolyte that contains less fluorine in the backbone than previous systems, enabling a significant cost reduction, while still providing highly stable cycling of LMB cells containing LiNi_0.6Co_0.2Mn_0.2O₂ (NCM₆₂₂) and LiNi_0.8Co_0.1Mn_0.1O₂ (NCM₈₁₁) positive electrodes. Moreover, we show that the choice of the incorporated “molecular transporters”, i.e., small molecules with high mobility and a high dielectric constant to facilitate the Li⁺ transport, is essential for achieving high-performance LMB cells. In fact, the transition from pure ethylene carbonate to a mixture with propylene carbonate allows for an extended electrochemical stability toward oxidation and higher limiting current density, resulting in enhanced rate capability and cycling stability of Li∥NCM cells─and the possibility to cycle these cells also at ambient temperature.

The stabilization and enhanced performance of lithium metal batteries (LMBs) depend on the formation and evolution of the Solid Electrolyte Interphase (SEI) layer as a critical component for regulating the Li metal electrodeposition processes. This study employs a first-principles kinetic Monte Carlo (kMC) model to simulate the SEI formation and Li⁺ electrodeposition processes on a lithium metal anode, integrating both the electrochemical electrolyte reduction reactions and the diffusion events giving place to the SEI aggregation processes during battery charge and discharge processes. The model replicates the competitive interactions between organic and inorganic SEI components, emphasizing the influence of the cycling regime. Results indicate that grain boundaries within the SEI facilitate faster lithium-ion transport compared to crystalline regions, crucial for improving the performance and stability of LMBs. The findings underscore the importance of dynamic SEI modeling for further development of next-generation high-energy-density batteries.

The intricate correlation between microstructural properties and performance in lithium rechargeable batteries necessitates advanced methods to elucidate their mechanisms. In this regard, digital twin simulations have been utilized by creating virtual replicas that simulate battery behaviors and performances under various conditions. However, the relationship between microstructural parameters and battery performances is still not fully understood. This focus review aims to revisit the state of digital twin simulations, with a particular focus on its effectiveness for analyzing microstructures and unraveling the hidden parameters. For this purpose, we explore microstructure formation and validation methods as top-down and bottom-up simulation techniques and provide a comprehensive view of multiphysics approaches for understanding the electrochemical, mechanical, and thermal behaviors. Finally, we discuss the potential of artificial intelligence (AI)-driven multiscale modeling strategies and dynamic simulations, offering insights into how digital twin technology can advance battery design and optimization for enhanced performance and safety.

Despite extensive efforts to reduce the costs of high-performance electrochemical devices, incorporating catalyst materials frequently falls short of achieving performance targets. Platinum alloys, known for their high oxygen reduction activity, exemplify this challenge due to integration difficulties. Here, we introduce an in situ X-ray diffraction approach to investigate structural changes in PtCo and PtNi catalysts during ink preparation. Contrary to previous assumptions that acidity is the main factor driving catalyst dissolution, our findings demonstrate that temperature plays a more critical role. Additionally, we observe rapid structural degradation during the hot-pressing of catalyst-coated membranes (CCMs), a critical yet often unavoidable processing step. These results indicate that significant catalyst deactivation can occur before operation, emphasizing the need for optimized fabrication processes. This study highlights the importance of refining ink formulation and processing protocols to fully leverage advanced materials in CCM-based energy conversion systems.