Lithium transition-metal oxides (LiMn₂O₄ and LiMO₂ where M = Ni, Mn, Co, etc.) are widely applied as cathode materials in lithium-ion batteries due to their considerable capacity and energy density. However, multiple processes occurring at the cathode/electrolyte interface lead to overall performance degradation. One key failure mechanism is the dissolution of transition metals from the cathode. This work presents results combining scanning electrochemical microscopy with inductively coupled plasma (ICP) and electron paramagnetic resonance (EPR) spectroscopies to examine cathode degradation products. Our effort employs a LiMn₂O₄ (LMO) thin film as a model cathode to monitor the Mn dissolution process without the potential complications of conductive additive and polymer binders. We characterize the electrochemical behavior of LMO degradation products in various electrolytes, paired with ICP and EPR, to better understand the properties of Mn complexes formed following metal dissolution. We find that the identity of the lithium salt anions in our electrolyte systems [ClO₄^–, PF₆^–, and (CF₃SO₂)₂N^–] appears to affect the Mn dissolution process significantly as well as the electrochemical behavior of the generated Mn complexes. This implies that the mechanism for Mn dissolution is at least partially dependent on the lithium salt anion.

A low cost, high throughput deposition method for films of nickel oxide (NiO) and lithium-doped nickel oxide with improved electrochromic performance is demonstrated. This method is based on ultrasonic spray deposition of aqueous-based precursor solutions in air at atmospheric pressure, which represents a significant cost savings compared to vacuum deposition methods. The resultant materials are characterized by X-ray diffraction, Raman spectroscopy, electron microscopy, and electrochemical measurements. Electrochromic performance is demonstrated with in situ optical transmission measurements during electrochemical characterization. Nickel oxide materials color anodically and are thereby ideally suited to be used as counter electrode for the well-known tungsten oxide system in “smart” window applications. The coloration of nickel oxide materials is known to be slow when compared to and thereby limits the overall response time of a tandem device. The analysis of potential step response data shows that our lithium-doped nickel oxide material achieves 90% of its total coloration change in , which is comparable to reported measurements for . These results significantly mitigate a potential bottleneck to the adoption of metal oxide electrochromic windows not only by demonstrating similar performance between NiO and , but by achieving this result via low cost, highly scalable processing methods.

Insulating glass unit (IGU) degradation has been studied extensively. However, there is limited understanding of how present durability evaluation standards relate to product lifetime. Furthermore, there is debate on how to quantify performance of installed windows over time to better understand degradation processes. More knowledge on these topics is required to link durability evaluation to product lifetime projections based on energy performance. Energy models provide helpful estimations of total annual building energy consumption. However, most models are based on “as installed” performance of envelope components and fail to account for performance degradation. This can lead to an underestimation of building lifetime energy consumption. A better understanding of the relationship between durability and energy performance can inform integration of degradation dynamics into energy modeling software. This will improve lifetime building energy consumption estimations as well as inform appropriate retrofit strategies and timing. This paper reviews current durability literature, various standards for window performance ratings and weathering methods, existing in situ IGU energy performance measurement techniques, and whole-building energy effects. The challenges and disparities among various studies are analyzed and discussed. The authors hope that further work in this area will lead to the development of improved in situ test methods to assess IGU degradation in the field and link this knowledge to improved energy performance modeling approaches.

SECM can characterize the interfacial properties and electrochemical activities of different materials for LIBs. This review focuses on the studies of electrode/electrolyte properties, battery degradation and kinetic parameters by SECM.

Lithium-ion batteries (LIBs) have been widely employed as energy storage devices in portable electronics and electric vehicles. Many processes occurring at the electrode/electrolyte interphases lead to performance degradation over time and yet remain poorly understood. We demonstrate new methods based on scanning electrochemical microscopy (SECM) to characterize LIB electrolyte oxidation, which is a key process occurring at the cathode/electrolyte interphase. Our technique leverages a combination of feedback mode and generation/collection mode SECM to provide an electrochemical reversal technique like commonly used cyclic voltammetry or rotating-ring disk electrode methods but one potentially more easily applicable at shorter time scales. We use our method to probe the oxidation of LIB electrolyte components at nonintercalating electrodes including Pt and glassy carbon. We study the oxidation of a common commercially used electrolyte, 1.2 M LiPF₆ 30% ethylene carbonate and 70% ethyl methyl carbonate electrolyte (LP58), as well as formulations using only the individual carbonates. Our results indicate that all electrolyte formulations characterized oxidize through multiple processes that are detected at distinct voltages. Some processes generate soluble and reducible products that are detected by the SECM tip electrode and may be consistent with deprotonation of carbonate solvents. However, several other oxidation processes do not appear to generate soluble and reducible species and may be connected to the formation of either nonelectroactive products or of processes only occurring on the substrate electrode surface. This work provides information about the electrochemical oxidation of commonly used carbonate electrolytes for comparison to studies involving potentially more complex processes in the presence of LIB cathode materials.