Adv. Energy Mater. 2023, 13, 2300325 DOI: 10.1002/aenm.202300325

Finding a high CO-tolerance Pt-based catalyst plays a critical role for direct methanol fuel cells. Therefore, it is necessary to design controllable nanostructure and composition. Herein, a synthesis of ultrathin PtNiGaSnMoRe senary nanowires (SNWs) that features the virtues of partial amorphous structure, multimetallic ensembles, and ultrathin diameter is reported. For the alkaline methanol oxidation reaction (MOR), the SNWs deliver an excellent mass activity of 6.2 A mg−1Pt and a specific activity of 12.3 mA cm−2, respectively. More significantly, after undergoing 10 000 s of a durability test, its mass activity remains 13.0 times higher than that of commercial Pt/C catalyst, which is mainly attributed to the faster CO-intermediate (CO*) removal and advanced nanostructure. In situ Fourier transform infrared (FTIR) spectroscopies and CO stripping experiments indicate its remarkable resistance to CO poisoning. Theoretical studies further reveal that the SNWs enable reduced energy barriers for the conversion of CO* into COOH* derived from the decreased CO* binding and intensified OH adsorption that accelerate the combination of both, thus essentially improving the MOR performance and CO tolerance.

In terms of high capacity and reliable safety, low-valent silicon-based composites with small grain sizes are practicable anode materials for lithium-ion batteries. However, robust tetravalent silicon precursors make the synthesis hard to be green. Using biosilicification in water hyacinth (Eichhornia crassipes), it is found to be a superior natural precursor of low-valent silicon. The biogenic sub-nano (0.5 nm) siliceous dots composite (EC-SiOC) shows a reversible conversion mechanism between Si─O and C─O bonds, unlike previous lithium storage mechanisms associated with alloying reactions. Due to the homogeneous biogenic structure facilitating the solid-phase reaction, the normalized energy consumption of pyrolytic EC-SiOC is about 80% lower than the carbothermic reduction of silica, similar to molten salt electrolysis. Statistically, the sampling survey of EC-SiOC from different regions shows a high average capacity of 749.9 mAh g−1 under a current density of 100 mA g−1. This study reveals the great potential of biomass precursors for synthesizing Si─O─C materials.

In organic solar cells with very small energetic-offset (ΔELE − CT), the charge-transfer (CT) and local-exciton (LE) states strongly interact via electronic hybridization and thermal population effects, suppressing the non-radiative recombination. Here, we investigated the impact of these effects on charge generation and recombination. In the blends of PTO2:C8IC and PTO2:Y6 with very small, ultra-fast CT state formation was observed, and assigned to direct photoexcitation resulting from strong hybridization of the LE and CT states (i.e., LE-CT intermixed states). These states in turn accelerate the recombination of both CT and charge separated (CS) states. Moreover, they can be significantly weakened by an external-electric field, which enhanced the yield of CT and CS states but attenuated the emission of the device. This study highlights that excessive LE-CT hybridization due to very low , whilst enabling direct and ultrafast charge transfer and increasing the proportion of radiative versus non-radiative recombination rates, comes at the expense of accelerating recombination losses competing with exciton-to-charge conversion process, resulting in a loss of photocurrent generation.

The solar-only response nature limits the luminescent solar concentrators (LSCs) to solar harvesting rather than responding to other stimuli, which restricts the role of LSCs to energy supply in self-powered internet of things (IoT) systems, and the application potential of LSCs in self-powered devices has been seriously overlooked. In this work, LSCs with photovoltaic and piezoelectric features are proposed for the first time, extending the application scenario of LSCs to self-powered sensors with pressure responsiveness. The luminescent layer of perovskite-polymer composite film is prepared via in situ blade coating with the piezoelectric polymer matrix of poly(vinylidenefluoride-trifluoroethylene) (P(VDF-TrFE)). P(VDF-TrFE) possesses stronger DMF adsorption capacity and higher electroactive phase content than a conventional piezoelectric matrix of poly(vinylidene fluoride) (PVDF), which not only reduces the residual-solvent-induced defects in perovskite luminophores, but also brings a sensitive pressure response to LSCs. The dual-functional LSCs achieve a power conversion efficiency of 1.01% and a output piezoelectric voltage of 0.95 V can be obtained even at a low pressure of 0.16 kPa. A self-powered speed measurement system is demonstrated, and the actual speed measurement is carried out. Such dual-functional LSCs show great potential in self-powered electrical devices, which can be applied to low-energy-consumption IoT systems and other commercial smart home products.

The absence of liquid components in all-solid-state batteries (ASSBs) based on sulfide solid electrolytes (SSEs) significantly impacts manufacturing processes and performance, particularly concerning mechanical properties and evolution. SSE films play vital roles in this context. This review provides a comprehensive analysis of SSE film design strategies, emphasizing their significance in the cell assembly and operation of practical ASSBs. Essential SSE film components are examined, including SSEs, binders, and scaffold or substrate materials, and key characteristics related to ASSB assembly and operation are addressed, such as conduction properties, electrochemical stability, and mechanical properties. Various SSE films fabricated using different binders and scaffold or substrate materials are explored through slurry-casting or solvent-free methods, and ASSBs employing SSE films with diverse form factors and components are presented, emphasizing their ability to operate under low-pressure conditions. Additionally, the importance of establishing test protocols for assessing SSE film performance metrics is highlighted and strategies for enabling Li metal anodes are introduced. By deepening the understanding of the electrochemo-mechanical phenomena and engineering processes in ASSBs, it is anticipated that the gap between lab-scale research and practical goals can be bridged through design strategies that leverage the hybridization of various compositions and the immiscible nature of solid-state materials.

Aqueous redox flow batteries (RFBs) have attracted significant attention as energy storage systems by virtue of their inexpensive nature and long-lasting features. Although all-vanadium RFBs exhibit long lifetimes, the cost of vanadium resources fluctuates considerably, and is generally expensive. Iron–chromium RFBs take advantage of utilizing a low-cost and large abundance of iron and chromite ore; however, the redox chemistry of CrII/III generally involves strong Jahn–Teller effects. Herein, this work introduces a new Cr-based negolyte coordinated with strong-field ligands capable of mitigating strong Jahn–Teller effects, thereby facilitating low redox potential, high stability, and rapid kinetics. The balanced full-cell configuration features a stable lifetime of 500 cycles with energy density of 14 Wh L−1. With an excessive posolyte, the full-cell can attain a high energy density of 38.6 Wh L−1 as a single electron redox process. Consequently, the proposed system opens new avenues for the development of high-performance RFBs.

Oxygen Evolution Reaction

High-performance metal fluoride cathodes are crucial to design ultrahigh-capacity lithium metal batteries for taking part in the next-generation energy storage market. However, their insulating nature and sluggish reaction kinetics result in voltage hysteresis, low-rate capability, and rapid capacity degradation. Herein, a generalizable one-step melt synthesis approach is reported to construct hetero-packing nanostructures of FeF3@C-Asphalt nanocomposites, where ultrafine FeF3 nanoparticles are homogeneously covered by a high conductive carbon framework. By the electrochemical kinetics calculation and multiphysics simulations, this FeF3@C-Asphalt nanocomposites consist of ultrafine nanoparticles and a constrained carbon framework, offering a high tap density (1.8 g cm−3), significantly improved conductivity, and enhanced charge pathways, and thereby enabling the fast electron transport, rapid ion migration, depressed electrode internal stress, and mitigated volume expansion. As a result, the optimized FeF3@C-Asphalt cathode delivers a high capacity of 517 mAh g−1, high cyclic stability of 87.5% after 1000 cycles under 5 A g−1 (10 C), and excellent capacity retention of 77% from 0.5 A g−1 to 10 A g−1 (20 C, 250 mAh g−1). The work provides an easy-to-operate and low-cost approach to accomplish high cyclic stability metal fluoride-lithium batteries, which will guide the development of fast-charging ultrahigh-capacity cathode materials for the new energy industry.

All-polymer solar cells (all-PSCs) have promising potential for industrial production due to their superior stability. Recently, the widespread application of the polymerized small molecule acceptor (PSMA) has led to a surge in the efficiency of all-PSCs. However, the high efficiencies of these devices generally rely on the use of the highly volatile solvent, chloroform (CF). Furthermore, the molecular weights of PSMA are lower than polymer donors, yet their crystallinity is weaker than typical small molecules, making most PSMA-based all-PSCs suffer from low electron mobility. To improve device performance and facilitate large scale production of all-PSCs, it is necessary to enhance electron mobility and avoid the use of CF. This paper investigates the use of sequential processing (SqP) for active layer preparation using toluene as the solvent to address these issues. This work reports 18.1% efficient all-PSC devices, which is the highest efficiency of all-PSCs prepared using non-halogen solvents. This work systematically compares the conventional blend-casting method with the SqP method using PM6 as the donor and PY-V-γ and PJ1-γ as the acceptors, and compares the performance of binary and ternary blends in both methods. Finally, this work measures the device stability and finds that SqP can significantly improve the photostability of the device.

Potassium-Ion Batteries

The growth of lithium dendrites hinders the commercial applications of lithium-metal batteries. Electrolytes play a crucial role in influencing electrode/electrolyte interfacial chemistry. Traditional electrolytes adopt strongly solvating solvents to dissolve Li salts, creating an organic-rich solid electrolyte interface (SEI). The Li+ conductivity and mechanical strength of the organic-rich SEI are poor, so the derived SEI cannot effectively suppress the growth of Li dendrites. The weakly solvating electrolyte (WSE) system can realize an inorganic-rich SEI, demonstrating improved compatibility with the Li metal. However, the design rules for the WSE are not clear. Here, four kinds of “4S” (single salt and single solvent) WSE are designed to investigate interface chemistry. The SEI thickness, pore volume, and porosity are revealed via a reactive force field. The results show the heterocyclic and symmetric tetrahydropyran has the most suitable solvating power and the best interfacial stability in the lithium-metal battery system. This research provides a weakly solvating electrolyte design route for bridging the molecular thermodynamic and interfacial chemistry gap.

Aqueous organic redox flow batteries (AORFBs) are an emerging technology for fire safe grid energy storage systems with sustainable material feedstocks. Yet, designing organic redox molecules with the desired solubility, viscosity, permeability, formal potential, kinetics, and stability while remaining synthetically scalable is challenging. Herein, the adaptability is demonstrated of a single-step, high-yield hydrothermal reaction for nine viologen chloride salts. New empirical insights are gleaned into fundamental structure–property relationships for multiobjective optimization. A new asymmetric Dex-DiOH-Vi derivative showcases an enhanced solubility of 2.7 m with minimal tradeoff in membrane permeability. With a record viologen cycling volumetric capacity (67 Ah L−1 anolyte theoretical), Dex-DiOH-Vi exhibits 14-d of stable cycling performance in anolyte-limiting AORFB with no crossover or chemical degradation. This work highlights the importance of designing efficient synthetic approaches of organic redox species for molecular engineering high-performance flow battery electrolytes.

Nickel is a promising candidate as an alternative to ruthenium for an ammonia decomposition catalyst. However, the performance of Ni-based catalysts for ammonia decomposition is still not sufficient to achieve a good hydrogen production rate under low-temperature because the weak nitrogen affinity of Ni reduces the frequency of the ammonia decomposition reaction. Here, it is reported that Ni supported on barium titanium oxynitride (Ni/h-BaTiO3−xNy) with a hexagonal structure acts as a highly active and water-durable catalyst for ammonia decomposition. The operation temperature is reduced by over 140 °C when N3− ions are substituted onto the O2− sites of the BaTiO3 lattice, and the Ni/h-BaTiO3−xNy catalyst significantly outperforms conventional oxide-supported Ni catalysts for ammonia decomposition. Furthermore, the activity of Ni/h-BaTiO3−xNy remains unchanged after exposure to water. The 15NH3 decomposition reaction and Fourier transform-infrared spectroscopy (FT-IR) measurements reveal that lattice nitrogen vacancy sites on h-BaTiO3−xNy function as the active sites for ammonia decomposition. The ammonia decomposition activity of Ni/h-BaTiO3−xNy is also higher than that of the Ni/h-BaTiO3−xHy oxyhydride catalyst, making a contrast to the activity trend in ammonia synthesis.

All-Solid-State Batteries

Electrolytes

Popularly-used fluorination can effectively weaken Li+-solvent interaction to facilitate the desolvation process at low temperature; however, high fluorination degree sacrifices salt dissociation and ionic conductivity. Herein, functional fluorinations are well tuned with different amounts of F atoms to balance Li+-solvent binding energy and ion movement, which reveals the fluorination effect on the solvation behavior and low-temperature performance. Noteworthily, the moderately-fluorinated ethyl difluoroacetate (EDFA) successfully favors a lower binding energy than less-fluorinated ethyl fluoroacetateand superior salt dissociation more than highly-fluorinated ethyl trifluoroacetate, realizing the trade-off between weak affinity and sufficient ionic conductivity. The well-formulated EDFA-based electrolyte exhibits a unique solvation sheath and generates inorganic-rich solid electrolyte interphase with low resistance for smooth Li+ diffusion, which enables graphite anodes with excellent fast-charging capability (196 mAh g−1 at 6 C) and impressive low-temperature performance with a reversible capacity of 279 mAh g−1 under −40 °C. Subsequently, the wide electrochemical potential window of EDFA-based electrolyte endows the 1.2 Ah LiNi0.8Co0.1Mn0.1O2 (NCM811)||graphite pouch cells with a high reversible capacity retention of 58.3% at −30 °C and discharge capacity of 790 mAh at −40 °C. Such solvent molecules with a moderately-fluorinated strategy promise advanced electrolyte design for lithium-ion batteries operating under harsh conditions.

To expedite the commercialization of perovskite solar cells (PSCs), researchers are exploring the feasibility of employing nickel phthalocyanine (NiPc) as a hole transport material (HTM) due to its cost-effectiveness, excellent thermal stability, and suitability for solution coating. However, the low LUMO energy level of the NiPc may limit its ability to block photoelectrons generated in the perovskite layer from recombining with holes, which can reduce the overall efficiency of the solar cell. One solution is to use cascaded bilayers with HTMs that have relatively higher LUMO levels. In this study, a bilayer consisting of NiPc and poly(3-hexylthiophene) (P3HT) is employed as the HTM, where the P3HT exhibits vertical phase separation during the coating process. By optimizing the mixing amount of P3HT into the NiPc, a record power conversion efficiency of 23.11%, the highest reported for NiPc-based PSCs is achieved. Moreover, an excellent long-term stability is demonstrated by encapsulating the PSC in polyisobutylene, with the device retaining 90% of its initial efficiency after exposure to 85 °C and 85% relative humidity for 1000 h.

Ti3C2Tx MXene has shown remarkable potential for supercapacitors. However, its limited capacitance restrains the energy density. Here, a designed redox-electrolyte strategy boosted with electrode engineering for Ti3C2Tx MXene is demonstrated, by which a record-high specific capacitance of 788.4 F g−1 at 2 mV s−1 is achieved, accompanied by good rate capability and highly improved cyclic stability compared with the pristine MXene electrode. For the first time, redox additives with redox potentials falling in the Ti3C2Tx MXene's potential range and that can take full advantage of the characteristics of Ti3C2Tx MXene are investigated. CuSO4 and VOSO4 are screened as the hybrid redox additives; and it is revealed that copper and vanadium ions can bond with ═O terminals on the MXene surface and undergo redox reactions mainly via Cu2+/Cu+ and V3+/V2+. The electrode engineering significantly boosts the designed redox-electrolyte strategy by enhancing ion dynamics and increasing electrochemically active sites. High energy density of 80.9 Wh kg−1 at a power density of 376.0 W kg−1 and high cyclic stability and improved self-discharging behavior are obtained for the fabricated supercapacitor by applying this strategy. The strategy is also demonstrated for the performance improvement of MXene-based flexible supercapacitors with hydrogel electrolytes.

Rechargeable Zn-ion batteries (ZIBs), prospective candidates for broad-scale energy storage, still encounter many challenges such as hydrogen evolution corrosion, Zn dendrite growth, and capacity fading. Therefore, one specific strategy for tuning the internal structure of solid polymer electrolytes (SPEs) via organic additives is proposed to address these urgent bottlenecks simultaneously. With trimethyl phosphate (TMP) addition, the coordination environment of Zn2+ in SPEs is altered and exists as Zn2+(TMP)x(OTf−)y coordinated molecules. Meanwhile, the strong interaction between TMP and Zn enables the preferential growth of Zn(002) planes during electrodeposition, which is proved based on first-principles calculations, finite element simulations, and multiple in situ characterizations. Such excellent interfacial engineering in situ forms the solid electrolyte interface rich in Zn3(PO4)2 fast ion conductor and guarantees one ultra-long cycle life for more than 6000 h in a Zn|Zn symmetric cell at 0.1 mA cm−2. Moreover, the universality of TMP-modified SPEs shows 1000 times stable cycling of VO2(B)|Zn full cells at 1 A g−1 under 0 °C with 95.24% capacity retention, which satisfies potential applications of wide-ranging energy storage based on solid-state ZIBs.