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Combining photodynamic therapy (PDT), chemodynamic therapy (CDT), and ferroptosis is a valuable means for an enhanced anticancer effect. However, traditional combination of PDT/CDT/ferroptosis faces several hurdles, including excess glutathione (GSH) neutralization and preparation complexity. In this work, a versatile multifunctional nanoparticle (HCNP) self-assembled from two porphyrin molecules, chlorin e6 and hemin, is developed. The as-constructed HCNPs exhibit a peroxidase-mimic catalytic activity, which can lead to the in situ generation of endogenous O

Lithium storage in aluminum stems from a phase transformation from lithium-poor α phase (Al, face-centered cubic) to lithium-rich β phase (LiAl, cubic) at room temperature. We investigate the electrochemical lithiation of polycrystalline Al using operando light microscopy coupled with electron backscatter diffraction. The operando videos reveal that the β phase patches expand radially from discrete nuclei with inhibition observed for specific Al grains at the α/β interface. Statistical analyses indicate that these grains have a preferred out-of-plane orientation. This study suggests that lithiation of Al is a whole-grain process that is influenced by grain textures rather than grain boundaries.

Aluminum is well-known to possess attractive properties for possible use as an anode material in Li-ion batteries (LIBs), but effort is still needed to understand how and why it degrades. Herein, investigations of the delithiation and the re-lithiation processes in Al thin films using an established operando light microscopic platform are pursued. Operando videos highlight that the extraction of Li from the β phase (LiAl) is accompanied by fracture and crack formation leading to the detachment of the α phase (Al) from the rest of the electrode. The evolution of mechanical stress in Al thin film electrodes is tracked and shows severe stress asymmetry as phase transformations progress. Combining with the observations from light and electron microscopy, the mechanical stress during dealloying can be explained by Li solubility with the β phase, formation of cracks and of a highly porous Al nanostructure. Although the results pave a difficult path for utilization of the Al/LiAl/Al (α/β/α) phase transformations in future LIBs, they also suggest excellent opportunities when structural changes can be prevented, which otherwise impact the stability of Al-based electrodes.

Despite the tremendous theoretical capacities of new materials for lithium-ion battery (LIB) anodes (e.g. Si, Sn, etc.), the conventional design of these electrodes with binders, current collectors, and conductivity enhancers inhibit the translation of performance gains during commercialization. Therefore, consideration should be given to monolithic materials systems which can increase performance while simultaneously reducing design complexity. In the present study, aluminum–silicon thin-films were synthesized with compositions ranging from 0 to 45 at% Si, and the structure, morphology, and electrochemical behavior of the material as an electrode for LIBs were investigated. This analysis confirms that the Li9AlSi3 phase is formed during initial lithiation, prior to the formation of the β phase, and is recognized as the dominant phase in the Al–Si–Li alloy system. These findings also show that by preventing the formation of the β phase during lithiation of the electrode results in an excellent cycling life performance of 70 at% Al–30 at% Si electrode over 100 cycles at the rate of C/20 and a specific capacity of 650 mA h g−1. In situ stress measurements and ex situ SEM analysis performed during cycling confirm the reversibility such that no degradation or delamination is observed in the films despite the high capacity and long-term cycling.

Lithium-ion battery electrodes contain a substantial amount of electrochemically inactive materials, including binders, conductive agents, and current collectors. These extra components significantly dilute the specific capacity of whole electrodes and thus have led to efforts to utilize foils, for example, Al, as the sole anode material. Interestingly, the literature has many reports of fast degradation of Al electrodes, where less than a dozen cycles can be achieved. However, in some studies, Al anodes demonstrate stable cycling life with several hundred cycles. In this work, we present a successful pathway for enabling long-term cycling of simple Al foil anodes: the β-LiAl phase grown from Al foil (α-Al) exhibits a cycling life of 500 cycles with a ∼96% capacity retention when paired with a commercial cathode. The excellent performance stems from strategic utilization of the Li solubility range of β-LiAl that can be (de-)lithiated without altering its crystal structure. This solubility range at room temperature is determined to be ∼6 at %. Consequently, this design circumvents the critical issues associated with the α/β/α phase transformations, such as volume change, mechanical strain, and formation of nanopores. Application-wise, the maturity of the aluminum industry, combined with excellent sustainability prospects, makes this anode an important option for future devices.

Among elemental semiconductors, tellurium (Te) exhibits unique mechanical and electromechanical properties due to its highly anisotropic crystal structure and mixed interatomic bonding modes. A lac...

Stability studies are essential to understanding the limitations of capacitive deionization (CDI) technology and to future commercialization efforts. In this work, the effect of trapped salt ions on stability degradation is explored. The extraction results indicate that Na+ and Cl− exist in aged electrodes and are metastably trapped. Accordingly, a schematic illustration based on the classical Gouy–Chapman–Stern (GCS) model is made to present the dynamic movement of ions near degraded electrodes with regard to the inversion effect. Moreover, a two-electrode voltage sweep test (voltage of null conductivity change (Vncc) test) is developed to simultaneously monitor the active voltage window for CDI. This voltage sweep test is conducted along with long-term operation of CDI cells. The results indicate that the active voltage window between the electrodes decreases gradually, with prolonged cycling, or increases immediately, by inverting the applied voltage of the cell. The shift of Vncc and the desalination ability are found to be strongly correlated, regardless of the cycling history of the electrodes. Therefore, the Vncc test can be a practical tool for sensing both the active voltage window and the desalination ability of carbon-based electrodes during prolonged or continuous CDI operations.

Methane-producing bioelectrochemical systems (BESs) are a promising technology to convert renewable surplus electricity into the form of storable methane. One of the key challenges for this technology is the search for suitable cathode materials with improved biocompatibility and low cost. Here, we study heat-treated stainless steel felt (HSSF) for its performance as biocathode. The HSSF had superior electrocatalytic properties for hydrogen evolution compared to untreated stainless steel felt (SSF) and graphite felt (GF), leading to a faster start-up of the biocathodes. At cathode potentials of −1.3 and −1.1 V, the methane production rates for HSSF biocathodes were higher than the SSF, while its performance was similar to GF biocathodes at −1.1 V and lower than GF at −1.3 V. The HSSF biocathodes had a current-to-methane efficiency of 60.8% and energy efficiency of 21.9% at −1.3 V. HSSF is an alternative cathode material with similar performance compared to graphite felt, suited for application in methane-producing BESs., Our study increases methane-producing BESs’ applicability with a novel cathode, heat-treated stainless steel felt, showing great promise in renewable energy storage.

Limitations of capacitive deionization (CDI) and future commercialization efforts are intrinsically bound to electrode stability. In this work, thermal treatments are explored to understand their ability to regenerate aged CDI electrodes. We demonstrate that a relatively low thermal treatment temperature of ∼500 °C can sufficiently recover the lost salt adsorption capacity of degraded electrodes. Furthermore, a systematic study of electrode replacement clarifies that the desalination ability loss and regeneration for a CDI cell are isolated to the aged anode, as expected. Characterizations of surface functionalities support that the acidic oxygen-containing functional groups formed in situ during cycling undergo thermal decomposition during treatment. The modified Donnan model quantitatively confirms that the surface charges originate from the formation/decomposition of functional groups. Accordingly, the lost pore volume and the increased resistance are recovered during thermal treatments, while the surface morphologies and pore structure of the electrodes are well-preserved. Therefore, thermal treatment can be applied practically to extend the lifetime of aged electrodes. This study also offers insights into strategies for minimizing electrode degradation or in situ regeneration such that the technology gains momentum for future commercialization.

Aluminum is an attractive anode material for lithium-ion batteries (LIBs) owing to its low cost, light weight, and high specific capacity. However, utilization of Al-based anodes is significantly limited by drastic capacity fading during cycling. Herein, a systematic study is performed to investigate the kinetics of electrochemical lithiation of Al thin films to understand the mechanisms governing the phase transformation, by using an operando light microscopy platform. Operando videos reveal that nuclei appear at random positions and expand to form quasi-circular patches that grow and merge until the phase transformation is complete. Based on this direct evidence, models of the lithiation processes in Al anodes are discussed and reaction-controlled kinetics are suggested. The growth rate of LiAl depends on the potential and increases considerably as higher overpotentials are approached. Lastly, improved cycling performance of Al-based anodes can be realized by two approaches: 1) by controlling the lithiation extent, the cycling life of Al thin film is extended from 5 cycles to 25 cycles; 2) the performance can be optimized by adjusting the kinetics. Together, this work offers a renewed promise for the commercialization of Al-based anodes in LIBs where the performance requirements are compatible with the proposed cycle life-extending strategies.

Alloy anodes have been extensively studied over past decades to replace the graphite of lithium-ion batteries (LIBs). Most efforts are made towards those anode materials with high specific capacities such as silicon and germanium. To minimize the negative impacts of the volume expansions during Li incorporation, protective coatings or specific micro- and nanostructures have been suggested, but a commercialization on a larger scale was impeded by such preparation costly procedures. Therefore, the optimal alloy anode candidate should balance the cost, capacity and manufacturing complexity rather than solely maximize the specific capacity. Aluminum, an underappreciated anode material, possesses intrinsic properties that fulfill the criteria mentioned above. The origin of the main capacity of aluminum anode is upon the formation of the β phase (LiAl; ca. 1Ah/g). However, the (de-)alloying processes of Al remain poorly understood, especially at room temperature under which LIBs usually operate. In this study, we investigate the (de-)lithiation that occurs within the solubility range of the β phase Although this Li solubility is highlighted by multiple versions of the Li-Al phase diagrams, the solubility range at low temperatures was not specified yet due to the experimental conditions of previous phase diagram studies (> 400 °C). Various electrochemical analytic tools and methods are used to shed light on the Li solubility within the β phase. The Li solubility range of the β phase is determined to be roughly 5 at% by a potentiostatic charge counting experiment at room temperature. Moreover, the cyclic voltammetry of partially lithiated Al foils shows that the β phase can be (de-)saturated without propagating the phase front towards the α phase. If galvanostatic charge and discharge is smartly controlled by taking into consideration of the solubility range, the cycling life of β-LiAl anode can be significantly improved. Not only does this piece of work provide fundamental data for the β-LiAl phase at room temperature that complements the existing phase diagrams, but also implies that aluminum foil holds great potential as an anode material for the next generation of lithium-based batteries.

Based on current trends in lithium-ion battery (LIB) production and forecasts for immense demand of these energy storage devices, it is evident that all cell components will need dramatic improvement in the future. Although anode materials may be considered by some to be a lower priority, compared to cathode materials, the cost of the anode (and Cu foil current collector) comprise nearly 25% of the materials cost of a LIB cell, and consume ~30% of the volume. Among the possible alternative anode materials for LIBs to replace slurry-based graphite electrodes, alloying materials such as Si, Sn, Al and Ge are promising candidates. Despite the attractive advantages of aluminum-based electrodes (such as low cost, good geographic dispersity and high abundancy), capacity fade due to a large volume change associated with the α/β (Al/LiAl) phase transformation during cycling is the key problem. Al alloy or composite electrodes are a promising strategy for improving the reliability of Al-based electrodes. Among the Al-based monolithic anode materials for LIBs, to the best of our knowledge, Al-rich Al-Si alloys or composites have rarely been investigated. The present work highlights a new achievement towards realizing monolithic, free-standing alloy anodes which can significantly reduce both the cost and processing complexity of LIB electrodes. Herein, we propose a novel strategy to enable the use of aluminum-silicon alloys as monolithic anodes for LIBs. Accordingly, the microstructural, morphological, and electrochemical evolution of Al-Si thin-films of various compositions were investigated, with a focus on understanding the process of Al-Si-Li ternary phase formation during lithiation (in the particular case of excess Al). Ex situ microscopy observations, along with comprehensive electrochemical analysis, suggests that remarkable performance can be achieved by controlling the electrochemical condition for the formation of Al-Si-Li ternary phase, such that no LiAl (β phase) forms during lithiation. In other words, Al-Si-Li ternary phase is cycled within a soft aluminum matrix, thereby avoiding the degradation associated with the de-/lithiation of the β phase [1]. [1] M. H. Tahmasebi, D. Kramer, R. Mönig, and S. T. Boles, “Insights into Phase Transformations and Degradation Mechanisms in Aluminum Anodes for Lithium-Ion Batteries,” J. Electrochem. Soc., vol. 166, no. 3, pp. A5001–A5007, 2019.