Energy advances最新文献

The rapid growth of lithium-ion battery (LiB) production calls for chemistries that combine high energy density with low environmental and economic impact. The GREENcell-concept addresses this challenge by pairing a fluorine (F)-free polyisobutylene (PIB) binder-based LiMn₂O₄ (LMO) cathode with an anode based on commercial aluminum (Al) alloy foil, whose theoretical capacity (993 mAh g⁻¹) far exceeds that of graphite (372 mAh g⁻¹). In this study cycling stability was improved through iterative optimization of the GREENcell-concept, targeting cathode formulation as well as Al foil composition, Al foil hardness, and Al surface passivation. Substituting polyvinylidene fluoride (PVDF)-based commercial LMO with a F-free PIB-based formulation reduced cathodic capacity fade by 17%, yet ∼20% of total losses in the full-cell set up remained cathode-related. To evaluate anode optimization strategies, full-cells incorporating the F-free LMO cathode were employed. Al alloy 8011 containing iron and silicon impurities outperformed high-purity Al 1050 reference foil, improving capacity retention by ∼10% through more uniform lithiation, while strain-hardened foils effectively suppressed plastic deformation compared with annealed counterparts. Surface passivation of the 8011 Al alloy foil provided further gains: a chrome(III)-based passivation improved capacity retention by 11%, and an Al silicate layer enabled the most durable cell performance, maintaining a stable capacity profile for 100 cycles after the initial losses were overcome, likely by promoting a robust solid–electrolyte interface (SEI) able to accommodate anode volume changes. Collectively, these strategies increased capacity retention after 100 cycles from 4% for uncoated annealed high-purity Al 1050 foil to 67% for the strain-hardened, Al silicate-passivated 8011 Al alloy foil, demonstrating GREENcell's promise as a scalable, low-cost, and environmentally benign LiB architecture, as demonstrated in laboratory coin cells.

Solid composite polymer electrolytes (CPEs) have emerged as a promising option due to their excellent ionic conductivity, mechanical flexibility, and compatibility with Li metal electrodes. In this study, polyethylene oxide (PEO) was selected as the base polymer, and a composite was formed with LLZTO and oxygen-vacancy LLZTO (OV-LLZTO) as an active ceramic filler. The surface defects in OV-LLZTO enhance its bonding with the PEO chains, leading to improved interfacial resistance, enhanced mechanical stability, prevention of PEO crystallization, mitigation of LLZTO nanoparticle agglomeration, and improved Li⁺ ion conductivity. The removal of oxygen atoms from the LLZTO crystal results in lattice contraction, which strengthens the interaction between the LLZTO and PEO polymer chains, thereby reducing interfacial resistance and improving lithium-ion conductivity. In solid-state battery performance, the ionic conductivity and transference number of the solid electrolyte are crucial, along with thermal, mechanical, and electrochemical stability. While pristine PEO electrolytes exhibit higher conductivity than composites, they have a lower transference number and inferior stability compared to the composite electrolytes. As the temperature increases, the transference number of the polymer electrolyte increases due to increased ion mobility; however, with aging it decreases due to the formation of a passivation layer. A solid-state full cell employing the PEO/OV-LLZTO electrolyte was used to demonstrate high-rate capability (10C rate) and excellent capacity retention at 60 °C with a cathode areal loading of ∼0.2 mAh cm⁻², underscoring its potential for high-performance battery applications.

Using a diffusion differential model, this paper presents models that have been developed to predict the photovoltaic characteristics of Zr-doped TiO₂ dye-sensitized solar cells (DSSCs) by incorporating a CNT–TiO₂ core–shell (CNT@TiO₂) with mono- and double-layer photoanode configurations. The monolayer cells are composed of Zr-doped TiO₂ nanoparticles with different molar concentrations of Zr, while the double-layer devices are composed of Zr-doped TiO₂ nanoparticles with optimum Zr content (i.e., 0.025 mol%) as the under-layer and CNT@TiO₂, with varying CNT weight content, as the over-layer. The model evaluates the impact of critical parameters, including Zr concentration, CNT@TiO₂ content, operating temperature, and photoanode thickness, on the photovoltaic characteristics of the devices. The model predictions are validated, demonstrating their capability to accurately represent the photocurrent density–voltage behavior of the devices. Results indicate that the photocurrent density of monolayer DSSCs increases with increasing Zr content up to 0.025 mol% and then decreases with further increases in Zr molar percentage. Moreover, both photocurrent density and open-circuit voltage of the double-layer devices first increase with the introduction of CNT@TiO₂ and then decrease, reaching the highest value at 0.025 wt%. It is found that high operating temperatures lead to a decrease in the open-circuit voltage for all photoanode thicknesses, while the photocurrent density first increases with an increase in operating temperature and then decreases with a further temperature increase, reaching a maximum at 30 °C. For monolayer DSSCs, photocurrent density increases with electrode thickness up to 15 µm, after which it declines. These findings present essential knowledge for optimizing the design and efficiency of DSSCs.

PEO is the most investigated polymer for battery solid electrolytes, and continues to be considered state of the art to this day. It is often prepared by tape casting in a solvent-based process. However, solvent-free production of battery electrolytes has become a prominent topic in the recent years in science and industry. This is due to the elimination of one process step – the evaporation of a solvent – sparing production time, material, energy, solvent disposal and thus substantially reducing the production costs. Herein we propose the quick and simple solvent-free preparation of a PEO-LiTFSI electrolyte by kneading on a larger scale with reduced production times compared to conventional solvent based techniques. 50 g of electrolyte are produced at 60 °C within ∼15 min of kneading and another ∼5 min for calendering at 120 °C, whilst for the solvent-based solid electrolyte processing, ∼1.5 h followed by drying over night was required to prepare one solid electrolyte film. The processing and properties of the electrolyte are thoroughly discussed, comparing different conducting salts, polymer molecular weights and polymer–salt concentrations that are evaluated by EIS at different temperatures. An SEM and 4K light microscope-supported post mortem analysis was performed to provide insights on the surface processes of the electrodes that occur during galvanostatic cycling. Moreover, we report the first application of this solvent-free based PEO solid electrolyte in Li–S cells with different electrolyte thicknesses at 50 °C.

Mismatched complex oxide thin films and heterostructures based on perovskites have key applications in technologies such as solid oxide fuel cells, batteries, and solar cells because of emerging properties at the interface. Although lattice mismatch and resulting misfit dislocations are one of the fundamental reasons for the emergence of new properties at the interface, their precise role is not well understood. In light of this, we have used first principles calculations to study BaZrO₃(110)/SrTiO₃(100) heterostructures for thin film electrolyte applications and predict the interfacial stability as a function of termination layer chemistry. Atomic scale structure and electronic structure of oxygen vacancies at doped interfaces was further studied to comprehend their stability and location preference at the interface. Strong dependence of oxygen vacancy formation on termination layer chemistry is observed. Among the four possible interfaces, oxygen vacancies exhibit a thermodynamic preference to form at the TiO₂–ZrO₂ interface. Results herein shed light on the fundamental aspects of mismatched perovskite oxide interfaces and their influence on thermodynamic stability of oxygen vacancy defects, which influences ionic transport and is imperative to design next-generation thin film oxide electrolytes.

Heterogeneous aging of lithium-ion (Li-ion) battery cells within a battery pack is a major challenge that limits the pack's overall performance, safety, and life. Variations in cell degradation rates lead to nonuniform charge/discharge behavior among cells in a pack, accelerated aging in some cells turning them into “weak links”, and reducing energy throughput at the pack level. While previous studies have investigated uneven aging driven by differences in capacity or resistance, limited attention has been given to the root causes of these variations, particularly those arising from manufacturing-induced differences in the electrode microstructure. This study addresses this gap by investigating the effects of variations in the mean active material particle size across cells, a key design parameter of a porous electrode, on the aging behavior of these cells when connected in series and parallel. Using an electrochemical battery model, the aging behavior of individual cells and the pack as a whole is investigated for three electrical configurations (i.e., 1S4P, 4S1P, and 2S2P) at select C-rates and voltage windows. Results indicate that cells with smaller mean particle size degrade faster despite having a thinner SEI layer at the end of life, and even a minor variation of 1 µm in the mean active material particle size across cells can lead to significant uneven capacity fade across cells and accelerated aging of the pack, particularly at low C-rates. These findings highlight the critical impact that variability in the microstructure has on pack-level aging and provide insights into effective cell and pack manufacturing.

Fe–N–C catalysts have emerged as the most promising class of non-precious metal electrocatalysts for the oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs), offering favourable activity, structure tunability, and cost-effectiveness. However, challenges remain in achieving the performance and durability required for practical applications. This review systematically summarizes recent progress in Fe–N–C catalyst development, with a focus on synthetic strategies aimed at increasing the active site density, optimizing Fe–N_x coordination environments and potential engineering solutions to the membrane electrode assembly (MEA) based on Fe–N–C, particular attention is given to the pyrolysis atmosphere control, post-synthesis treatment, and optimizing the microstructure and catalytic performance. Furthermore, this review explores emerging approaches to integrate Fe–N–C catalysts into membrane electrode assemblies (MEAs), including ionomer–catalyst interaction tuning and electrode architecture optimization, with the goal of bridging the gap from laboratory activity to real-world fuel cell operation.

We report ether-functionalised lithium salts as molten salt electrolytes for Li-ion batteries. Flexible ether chains in asymmetric anions suppress crystallinity and promote nano-segregation, lowering melting points below 100 °C. In the molten state, they deliver high ionic conductivity and near-unity Li⁺ transference numbers, establishing a molecular design principle for high-performance, solvent-free electrolytes for next-generation energy storage.

In this paper, we identify the degradation mechanisms occurring with these coatings, in this way, we can identify more suitable coatings whose chemistry avoids these degradation pathways. Two such coating technologies used in other applications are perfluoropolyether (PFPE) and 1H,1H,2H,2H-perfluorodecyltriethoxysilane (FAS-17). These polymeric hydrophobic coatings were deposited on soda–lime glass substrates and tested for 1000 hours in an accelerated UV exposure test and a damp heat test in a laboratory environment. After 1000 hours of UV exposure, the coatings experienced degradation with the PFPE coating degrading via β scission of the central ether bond whilst the FAS-17 underwent photo-oxidation at the C–Si bond. During damp heat testing the PFPE degraded by hydrolysis at the central ether bond whilst FAS-17 exhibited resistance to hydrolysis. The chemical mechanisms responsible for the degradation are identified. The objective is to discover alternative transparent hydrophobic materials that do not contain the same weaknesses in their chemical structure.

Lithium metal is regarded as an ultimate anode for rechargeable batteries, ascribed to its extremely high capacity. Its implementation can remarkably boost the energy density of the resultant lithium metal batteries. However, it is very challenging to commercialize lithium metal anodes, primarily due to the intertwined nature of the formation of a solid electrolyte interphase (SEI) and the growth of lithium dendrites. To understand these issues and therefore develop technical solutions, various instrumental techniques have been employed. This review highlights the most recent advancements of in situ and operando microscopy studies that are critical for investigating and addressing the issues related to SEI and lithium dendrites, including optical, electron, and atomic force microscopies. Low magnification in situ optical microscopy techniques are used to analyze dendrite morphology behaviors, the development of capping layers after cycling, and the impact of various dendrite suppression methods. High magnification in situ scanning electron microscopy enables more detailed dendrites and interface evolution analysis, revealing complex behavior mechanisms over extended cycling. While in situ transmission electron microscopy techniques can also investigate dendrite nucleation and morphology, they are particularly valuable in characterizing the SEI layer development at unparalleled spatial resolution. Additionally, in situ atomic force microscopy contributes valuable information for identifying the SEI layer growth through surface topology and force mapping. Together, these microscopy studies help us advance a better understanding on the underlying mechanisms of the formation of the SEI and lithium dendrites. They also are valuable for us to develop solutions for commercializing lithium metal anodes for high-energy lithium metal batteries.