能源化学最新文献

Fluorinated carbons CF_x hold the highest theoretical energy density (e.g., 2180 W h kg⁻¹ when x = 1) among all cathode materials of lithium primary batteries. However, the low conductivity and severe polarization limit it to achieve its theory. In this study, we design a new electrolyte, namely 1 M LiBF₄ DMSO:DOL (1:9 vol.), achieving a high energy density in Li/CF_x primary cells. The DMSO with a small molecular size and high donor number successfully solvates Li⁺ into a defined Li⁺-solvation structure. Such solvated Li⁺ can intercalate into the large-spacing carbon layers and achieve an improved capacity. Consequently, when discharged to 1.0 V, the CF_1.12 cathode demonstrates a specific capacity of 1944 mA h g⁻¹ with a specific energy density of 3793 W h kg⁻¹. This strategy demonstrates that designing the electrolyte is powerful in improving the electrochemical performance of CF_x cathode.

The sluggish kinetics of the oxygen reduction reaction (ORR) is the bottleneck for various electrochemical energy conversion devices. Regulating the electronic structure of electrocatalysts by ligands has received particular attention in deriving valid ORR electrocatalysts. Here, the surface electronic structure of Pt-based noble metal aerogels (NMAs) was modulated by various organic ligands, among which the electron-withdrawing ligand of 4-methylphenylene effectively boosted the ORR electrocatalysis. Theoretical calculations suggested the smaller energy barrier for the transformation of O* to OH* and downshift the d-band center of Pt due to the interaction between 4-methylphenylene and the surface metals, thus enhancing the ORR intrinsic activity. Both Pt₃Ni and PtPd aerogels with 4-methylphenylene decoration performed significant enhancement in ORR activity and durability in different media. Remarkably, the 4-methylphenylene modified PtPd aerogel exhibited the higher half-wave potential of 0.952 V and the mass activity of 10.2 times of commercial Pt/C. This work explained the effect of electronic structure on ORR electrocatalytic properties and would promote functionalized NMAs as efficient ORR electrocatalysts.

Hydrogen is known for its elevated energy density and environmental compatibility and is a promising alternative to fossil fuels. Alkaline water electrolysis utilizing renewable energy sources has emerged as a means to obtain high-purity hydrogen. Nevertheless, electrocatalysts used in the process are fabricated using conventional wet chemical synthesis methods, such as sol–gel, hydrothermal, or surfactant-assisted approaches, which often necessitate intricate pretreatment procedures and are vulnerable to post-treatment contamination. Therefore, this study introduces a streamlined and environmentally conscious one-step potential-cycling approach to generate a highly efficient trimetallic nickel-iron-copper electrocatalyst in situ on nickel foam. The synthesized material exhibited remarkable performance, requiring a mere 476 mV to drive electrochemical water splitting at 100 mA cm⁻² current density in alkaline solution. Furthermore, this material was integrated into an anion exchange membrane water-splitting device and achieved an exceptionally high current density of 1 A cm⁻² at a low cell voltage of 2.13 V, outperforming the noble-metal benchmark (2.51 V). Additionally, ex situ characterizations were employed to detect transformations in the active sites during the catalytic process, revealing the structural transformations and providing inspiration for further design of electrocatalysts.

Lithium-sulfur battery (LSB) has brought much attention and concern because of high theoretical specific capacity and energy density as one of main competitors for next-generation energy storage systems. The widely commercial application and development of LSB is mainly hindered by serious “shuttle effect” of lithium polysulfides (LiPSs), slow reaction kinetics, notorious lithium dendrites, etc. In various structures of LSB materials, array structured materials, possessing the composition of ordered micro units with the same or similar characteristics of each unit, present excellent application potential for various secondary cells due to some merits such as immobilization of active substances, high specific surface area, appropriate pore sizes, easy modification of functional material surface, accommodated huge volume change, enough facilitated transportation for electrons/lithium ions, and special functional groups strongly adsorbing LiPSs. Thus many novel array structured materials are applied to battery for tackling thorny problems mentioned above. In this review, recent progresses and developments on array structured materials applied in LSBs including preparation ways, collaborative structural designs based on array structures, and action mechanism analyses in improving electrochemical performance and safety are summarized. Meanwhile, we also have detailed discussion for array structured materials in LSBs and constructed the structure-function relationships between array structured materials and battery performances. Lastly, some directions and prospects about preparation ways, functional modifications, and practical applications of array structured materials in LSBs are generalized. We hope the review can attract more researchers' attention and bring more studying on array structured materials for other secondary batteries including LSB.

For large-scale in-service electric vehicles (EVs) that undergo potential maintenance, second-hand transactions, and retirement, it is crucial to rapidly evaluate the health status of their battery packs. However, existing methods often rely on lengthy battery charging/discharging data or extensive training samples, which hinders their implementation in practical scenarios. To address this issue, a rapid health estimation method based on short-time charging data and limited labels for in-service battery packs is proposed in this paper. First, a digital twin of battery pack is established to emulate its dynamic behavior across various aging levels and inconsistency degrees. Then, increment capacity sequences (△Q) within a short voltage span are extracted from charging process to indicate battery health. Furthermore, data-driven models based on deep convolutional neural network (DCNN) are constructed to estimate battery state of health (SOH), where the synthetic data is employed to pre-train the models, and transfer learning strategies by using fine-tuning and domain adaptation are utilized to enhance the model adaptability. Finally, field data of 10 EVs exhibiting different SOHs are used to verify the proposed methods. By using the △Q with 100 mV voltage change, the SOH of battery packs can be accurately estimated with an error around 3.2%.

Advancing high-voltage stability of layered sodium-ion oxides represents a pivotal avenue for their progress in energy storage applications. Despite this, a comprehensive understanding of the mechanisms underpinning their structural deterioration at elevated voltages remains insufficiently explored. In this study, we unveil a layer delamination phenomenon of Na_0.67Ni_0.3Mn_0.7O₂ (NNM) within the 2.0–4.3 V voltage, attributed to considerable volumetric fluctuations along the c-axis and lattice oxygen reactions induced by the simultaneous Ni³⁺/Ni⁴⁺ and anion redox reactions. By introducing Mg doping to diminished Ni–O antibonding, the anion oxidation-reduction reactions are effectively mitigated, and the structural integrity of the P2 phase remains firmly intact, safeguarding active sites and precluding the formation of novel interfaces. The Na_0.67Mg_0.05Ni_0.25Mn_0.7O₂ (NMNM-5) exhibits a specific capacity of 100.7 mA h g⁻¹, signifying an 83% improvement compared to the NNM material within the voltage of 2.0–4.3 V. This investigation underscores the intricate interplay between high-voltage stability and structural degradation mechanisms in layered sodium-ion oxides.