Initial Efficiency Research Articles

Long-Lifespan 522 Wh kg-1 Lithium Metal Pouch Cell Enabled by Compound Additives Engineering.

Matching high-voltage cathodes with lithium metal anodes represents the most viable technological approach for developing secondary batteries with ultra-high energy density exceeding 500 Wh kg-1. Nevertheless, the instability of electrolyte/electrode interface film and commercial electrolytes with cut-off voltage above 4.3 V is still a major concern. Herein, we present that excellent cycling stability with an ultra-high cut-off voltage of up to 5.0 V can be obtained by using three-component additives containing fluoroethylene carbonate (FEC), hexadecyl trimethylammonium chloride (CTAC), and tri(pentafluorophenyl)borane (TPFPB). Excellent ionic conductivity, robust interfacial films on both electrodes, and long-lasting uniform Li+ regulation ability can be obtained in the modifying electrolyte. Consequently, using a high plating/stripping capacity of 3 mAh cm-2 under the current density of 1 mA cm-2, lithium symmetric cells demonstrate stable cycling performance exceeding 800 hours. Meanwhile, the 7.3 Ah-class Li[NixCoyMn1-x-y]O2 (x=0.83, NCM83)|Li pouch cells are assembled, which show a high energy density of 522 Wh kg-1 and present excellent stability over 178 cycles with a high initial coulombic efficiency (CE) of 98.0 %.

Engineering Spacer Conjugation for Efficient and Stable 2D/3D Perovskite Solar Cells and Modules

Incorporating 2D perovskite in 3D perovskite absorber holds great potential to improve the stability and efficiency of perovskite solar cells (PSCs). However, the bulky‐cation‐based 2D structures often exhibit poor charge transport and are prone to formation of charge‐extraction barrier that impedes efficient device operation. We address these issues by introducing aromatic spacers with enhanced molecular conjugation. Among our tested aromatic spacers, the pyrenylbutanamine (PyBA) spacer was shown to endow 2D perovskites with superior charge transport properties and efficient charge extraction from the bulk perovskite in 2D/3D PSCs, due to the highest degree of conjugation. As a result, we achieved a power conversion efficiency of up to 25.3% in a 0.16‐cm2 single cell and 21.0% in a 24.8‐cm2 module. Moreover, the incorporated PyBA substantially raised the resistance of 2D/3D PSCs against moisture and ion migration, resulting in enhanced environmental, thermal, and operational stability. Notably, the PyBA‐based devices retained over 90% of their initial efficiency after 2000 hours at 25 ℃ and 80% relative humidity, or 1000 hours at 85 ℃ and 85% humidity, or 3000 hours of operation under continuous 1‐Sun illumination at 40 ℃, showcasing their enhanced stability compared to previously reported 2D/3D PSCs.

Three-Dimensional (3D) Fluoride Molecular Glue to Improve the SnO2/Perovskite Interface for Efficient Perovskite Solar Cells.

Aiming at numerous defects at SnO2/perovskite interface and lattice mismatch in perovskite solar cells (PSCs), we design a kind of three-dimensional (3D) molecular glue (KBF4-TFMSA), which is derived from strong intramolecular hydrogen bonding interaction between potassium tetrafluoroborate (KBF4) and trifluoromethane-sulfonamide (TFMSA). A remarkable efficiency of 25.8 % with negligible hysteresis and a stabilized power output of 25.0 % have been achieved, in addition, 24.57 % certified efficiency of 1 cm2 device is also obtained. Further investigation reveals that this KBF4-TFMSA can interact with oxygen vacancies and under-coordinated Sn(IV) from the SnO2, in the meantime, FA+ (NH2-C=NH2 +) and K+ cations can be well fixed by hydrogen bonding interaction between FA+ and BF4 -, and electrostatic attraction between sulfonyl oxygen and K+ ions, respectively. Thereby, FAPbI3 crystal grain sizes are increased, interfacial defects are significantly reduced while carrier extraction/ transportation is facilitated, leading to better cell performance and excellent stabilities. Non-encapsulated devices can maintain 91 % of their initial efficiency under maximum-power-point (MPP) tracking while continuous illumination (~100 mW cm-2) for 1000 h, and retain 91 % of the initial efficiency after 1000 h "double 60" damp-heat stability testing (60 °C and 60 %RH (RH, relatively humidity)).

Engineering Spacer Conjugation for Efficient and Stable 2D/3D Perovskite Solar Cells and Modules.

Incorporating 2D perovskite in 3D perovskite absorber holds great potential to improve the stability and efficiency of perovskite solar cells (PSCs). However, the bulky-cation-based 2D structures often exhibit poor charge transport and are prone to formation of charge-extraction barrier that impedes efficient device operation. We address these issues by introducing aromatic spacers with enhanced molecular conjugation. Among our tested aromatic spacers, the pyrenylbutanamine (PyBA) spacer was shown to endow 2D perovskites with superior charge transport properties and efficient charge extraction from the bulk perovskite in 2D/3D PSCs, due to the highest degree of conjugation. As a result, we achieved a power conversion efficiency of up to 25.3% in a 0.16-cm2 single cell and 21.0% in a 24.8-cm2 module. Moreover, the incorporated PyBA substantially raised the resistance of 2D/3D PSCs against moisture and ion migration, resulting in enhanced environmental, thermal, and operational stability. Notably, the PyBA-based devices retained over 90% of their initial efficiency after 2000 hours at 25 ℃ and 80% relative humidity, or 1000 hours at 85 ℃ and 85% humidity, or 3000 hours of operation under continuous 1-Sun illumination at 40 ℃, showcasing their enhanced stability compared to previously reported 2D/3D PSCs.

Enhanced charge carrier transport and defects mitigation of passivation layer for efficient perovskite solar cells

Surface passivation has been developed as an effective strategy to reduce trap-state density and suppress non-radiation recombination process in perovskite solar cells. However, passivation agents usually own poor conductivity and hold negative impact on the charge carrier transport in device. Here, we report a binary and synergistical post-treatment method by blending 4-tert-butyl-benzylammonium iodide with phenylpropylammonium iodide and spin-coating on perovskite surface to form passivation layer. The binary and synergistical post-treated films show enhanced crystallinity and improved molecular packing as well as better energy band alignment, benefiting for the hole extraction and transfer. Moreover, the surface defects are further passivated compared with unary passivation. Based on the strategy, a record-certified quasi-steady power conversion efficiency of 26.0% perovskite solar cells is achieved. The devices could maintain 81% of initial efficiency after 450 h maximum power point tracking.

Li-Fe-Cl Families as Novel Solid Electrolytes for All-Solid-State Batteries.

The halides have attracted much attention as novel solid electrolytes because of their easy synthesis, high electrochemical stability, and high ionic conductivities. However, the reported halides for solid electrolytes are still understudied compared with the oxides and sulfides. Here, we studied the Li-Fe-Cl phases that include Li2FeCl4 and Li6FeCl8. Using the self-doping approach, a maximum ionic conductivity of 2.0 × 10-4 S cm-1 at 50 °C was achieved for Li1.8Fe1.1Cl4. It was improved by 3 orders of magnitude compared with that of Li2FeCl4 (8.27 × 10-7 S cm-1 at 50 °C). For the Li|Li1.8Fe1.1Cl4|Li half-cell, it cycled for 2000 h at 50 °C under a current density of 0.01 mA cm-2, indicating an acceptable compatibility between Li2FeCl4 and Li. Finally, an all-solid-state battery was successfully assembled with Li1.8Fe1.1Cl4@LFP as the cathode, Li1.8Fe1.1Cl4 as the electrolyte, and a Li sheet as the anode. The initial specific charge capacity of the battery was 76.36 mAh g-1 at 0.1C and 50 °C. The initial Coulombic efficiency was 73.06%. This study suggests Li2FeCl4 as a new solid electrolyte, and the introduction of Li vacancies into the Li site is an efficient way to improve the electrochemical properties of halides.

Improving the electrochemical performance of lithium-rich manganese-based cathode materials by Na₂S₂O₈ surface treatment

Lithium-rich manganese-based cathode materials are well-regarded for their high specific capacity and notable voltage thresholds, making them attractive for advanced energy storage applications. However, their widespread commercialization is hindered by challenges in cycle performance, including suboptimal initial Coulombic efficiency, inadequate cycle stability, and constrained rate capability. To address these issues, this paper introduces a novel modification strategy using Na₂S₂O₈ to chemically delithiate the surface of the materials. This modification strategy dramatically enhances the initial Coulombic efficiency. The results demonstrate that the initial Coulombic efficiency of the two pre-activated samples improved to 84.6 % and 102.2 %, respectively. At the same time, the Na₂S₂O₈-treated samples exhibit a higher maximum discharge capacity at a 0.2 C rate, reaching 211.1 mAh g⁻¹ and 201.3 mAh g⁻¹, which notably surpasses the untreated sample's capacity of 188.7 mAh g⁻¹. Additionally, the treated samples exhibit improved cycling and rate performance, with capacity retention of 81.2 % and 63.5 %, respectively. After 60 cycles, these figures continue to be superior to those of the untreated material, which stands at 57.3 %. The results demonstrate that Na₂S₂O₈ treatment leads to the in situ formation of spinel phases on the material surface, thereby enhances the cycling stability and rate capability of the cathode material. Compared to traditional surface treatment methods, Na₂S₂O₈ solution treatment can induce more profound structural evolution without necessitating high-temperature calcination, thus reducing the demands on process conditions and equipment and offering greater process controllability. Moreover, this surface modification strategy paves the way for applying spinel coatings on other substrates with similar structures.

Unveiling the Microscopic Origin of Ultrahigh Initial Coulombic Efficiency of High-Entropy Metal-Organic Frameworks for Sodium Storage.

The initial irreversible capacity loss during the first charging process largely reduces the affordable energy and power density of sodium storage devices, and developing advanced materials is the efficient way to solve this problem, which is fraught with challenges. Herein, inspired by theoretical calculations and the high-entropy concept, a series of fewer layers of high-entropy metal-organic frameworks (FLHE-MOFs) are successfully fabricated, delivering an ultrahigh initial Coulombic efficiency (ICE) of 86.1% and excellent cycling performance, which is far more than that of the other electrode materials (generally <70%). Greatly, the storage behavior of high-, medium-, and low-entropy MOFs is clarified by theoretical calculations and in-/ex-situ characterization, revealing that Co and Fe species can provide substantial sodium storage sites and largely enhance the charge transfer rate, whereas high-entropy effect can enable structural reversibility. Sodium ion capacitors constructed with FLHE-MOFs as the anode can provide an ultrahigh energy density of 121.8 W h kg-1 (200 W kg-1) and an extremely long-term cycle lifespan. This work not only breaks the limitation of MOF materials with poor performance for sodium storage but also provides an effective strategy for the fabrication and application of high-performance MOF-based anode materials with high ICE, in which this idea may also be applied in other fields.

Study on the enhancement of device performance by the action of carbonohydrazide at the buried bottom interface of inverted mesoporous perovskite solar cells

The interface of perovskite solar cells (PSCs) significantly influences their efficiency and stability. Researchers tend to pay more attention to the upper surface of the perovskite absorber layer and conduct relatively less research on the bottom buried interface, mainly because the bottom of the perovskite film is challenging to peel off, which increases the difficulty of the characterization of the observation and analysis. Defects at the bottom interface make it more challenging to optimize the treatment than the upper surface. For inverted PSCs, the interface located in direct contact between the light absorption layer of perovskite and the hole transport layer is the buried interface. The buried interface is the direct interface for transporting charge carriers of PSCs and is also the center of non-radiative compound enrichment. The defect density is higher than the defect density of perovskite film crystal. Due to the DMSO initially left in the commonly used perovskite precursor solution during the film formation process, evaporation during the annealing and crystallization process creates vacancy holes at the bottom of the perovskite layer film. These holes and crystal boundaries tend to produce many non-radiative recombinations. These holes are also the sites of photodecomposition, leading to reduced efficiency and stability in PSCs, ultimately impacting the overall performance of PSCs. The work adds an Al2O3 mesoporous layer on top of the hole transport layer (HTL), which reduces the direct contact area between PTAA and perovskite film. In the perovskite precursor solution, we incorporate a solid additive called Carbonohydrazide (CBH), this substance replaces some of the DMSO and fills in the voids at the bottom of the perovskite film that is left when the DMSO evaporates. This process helps to reduce non-radiative recombination and photodegradation caused by the voids at the bottom of the perovskite, leading to an improvement in the efficiency and stability of the cell. The optimization of the buried bottom interface has improved the cell’s average efficiency from 17.6 % to 19.7 %, an 11.9 % increase. The aperture area of the devices in this work is 0.048 cm2, and the photoelectric conversion efficiency of our device still reaches 80.64 % of the initial efficiency after 600 h of continuous heating in a glove box with a nitrogen atmosphere, maintaining a test temperature of 60 °C.

Fabrication of gradient band tin oxide electron transport layer using self-separated dual-quantum dots for perovskite solar cells

Constructing a gradient band structure electron transport layer (ETL) and thereby enhancing the performance and stability of perovskite solar cells are an effective approach. Leveraging two types of quantum dots (QDs) with different masses, namely GQDs and Au QDs, along with tin oxide (SnO2) colloidal particles, we successfully prepared an ETL with a gradient band structure. Perovskite solar cells fabricated based on this gradient band ETL achieved a power conversion efficiency (PCE) of 22.2%, whereas those prepared with a conventional SnO2 ETL yielded only 19.6% efficiency. Furthermore, under continuous AM 1.5 G and 45°C temperature illumination for 1000 hours, the cells retained 91% of their initial efficiency. Further investigation revealed that the construction of this gradient band structure effectively compensated for the defects of the SnO2, thereby improving its electrical properties. Additionally, it enhanced the transport and separate ability of charge carriers in the ETL, reducing recombination probabilities. This work provides a simple and effective method for constructing gradient band structures, which not only enhances the performance of perovskite solar cells but also holds promise for other photovoltaic conversion devices.

Reducing defects in hard carbon graphite domain: Employing a fully dynamic bonding with a multi-crosslinked biomass-based binder for enhanced sodium ion storage

Binders are crucial for maintaining the integrity of an electrode and are confronted with the imperative for multifunctionality. Herein, we have developed and synthesized an entirely biomass-based water-soluble binder with outstanding adhesion, conductivity, flowability, and dispersibility for the hard carbon (HC) anode. Specifically, MXene (Ti3C2Tx) reduces the amount of HC graphite domain imperfections, the cross-linked carboxymethyl chitosan (CCS) chain facilitates Na+ movement, and the amphiphilic nature of lignosulfonate (LS) enhances the distribution of active material. As a result, the HC anode achieves an initial coulombic efficiency (ICE) of 88 % and high-capacity retention of 110 % after 100 cycles. This work promotes the progress of green energy in parallel with the promotion of the high-value utilization of biomass.

Near-surface reconstruction strategy stabilizing high-voltage redox reactions in single crystal Li-rich Mn-based oxides

Li-rich Mn-based oxides (LRMO) greatly increase its output energy density due to its additional oxygen redox activity. However, the inherent oxygen loss and irreversible phase transition induce low initial coulombic efficiency and serious voltage decay, further seriously impeding its industrial application. Herein, a near-surface in-situ reconstruction strategy has been proposed, which constructs the oxygen vacancies and spinel phase coating on the surface of single-crystal Li-rich Mn-based oxide (SC-LRMO) concurrently to improve Li+ storage performance via the oxalic acid induction method. Intensive exploration based on structure characterizations demonstrates that such a near-surface in-situ reconstruction strategy not only accelerates the transmission of Li+, but also stabilizes high-voltage redox reactions by trapping the escaping On− within the newly formed spinel phase coating. Impressively, the modified sample exhibit 91.1% capacity retention ratio after 300 cycles, superior to the SC-LRMO (74.5% capacity retention ratio after 300 cycles). Additionally, even at a high cut-off voltage of 5 V, the acid etched sample exhibits significantly enhanced cycling stability, delivering 200 mAh g−1 with a 94% capacity retention ratio after 300 cycles. This surface self-reconstruction strategy provides profound insights into regulating the surface structure of LRMO for high-energy-density lithium-ion batteries.

High temperature induced abundant closed nanopores for hard carbon as high-performance sodium-ion batteries anodes

Hard carbon (HC) stands out as the preeminent anode material for sodium-ion batteries (SIBs) which are deployed in expansive energy storage infrastructures. Herein, the large enough graphene nanosheets interlayer and abundant nanopores with a diameter of ∼2.1 nm induced by adjusting the pyrolysis temperature in the thermosetting phenolic resin-derived hard carbon matrix to augment the performance of the sodium ion storage. The presence of sufficiently large carbon interlayers has been proven to provide active sites for reversible adsorption, enabling effective storage of sodium ions in the high-voltage slope region, while also promoting rapid Na+ transport. Meanwhile, forming abundant closed nanopores with larger sizes helps sodium ion storage in the low-voltage plateau region. In the optimized samples, the formation of sufficient long graphene nanosheets with a perfect crystal lattice, which further shrinks to form enclosed nanopores, effectively reduces defective sites and specific surface area. Additionally, the appropriate content of C-O and C=O functional groups contributes to an exceptional initial Coulombic efficiency (ICE) of up to 93%. Simultaneously, the optimized sample HC-1500 contributes to a remarkable plateau capacity of 294 mAh g-1 during the charging process (high reversible capacity of 403 mAh g-1 at 0.1 C). Moreover, based on the microstructure evolution and Na storage behavior of hard carbon, an “adsorption (27%) – filling (73%)” sodium storage mechanism that the sodium storage as a quasi-metallic sodium state is demonstrated. Consequently, this study will offer valuable insights for the development of hard carbon anodes tailored for high-energy practical SIBs, while also advancing the understanding of sodium storage mechanisms.

Reversible silicon anodes enabled by fluorinated inorganic-organic hybrid coating

Silicon anodes deliver batteries with energy densities much higher than those based on today’s dominant graphite anodes. However, they commonly exhibit huge volume variations and unfavorable interface stability, causing a gradually diminishing capacity on extended cycling. Most Si-based batteries consisting Si/C composites in industry can only use a very limited amount of Si (<30 % by weight). Exploiting molecular layer deposition (MLD) technique, a fluorine-rich flexible inorganic–organic hybrid alucone (AlFHQ) shell is controllably deposited onto Si electrodes. Employing ex situ XPS and AFM, the AlFHQ film presents reversible electrochemical evolutions in terms of composition and morphology. The interactions the between Li+ and −O−2,3,5,6-fluorobenzene functional groups help to construct a mechanically-chemically robust LiF-rich hybrid solid electrolyte interphase (SEI) on Si anode, delivering enhanced interfacial stability and integrity of electrode. An optimized coating thickness (≈5 nm) for interfacial stabilization and Li+ transport kinetics is demonstrated, namely, Si@AlFHQ-20. The reported fluorine-rich hybrid modification technique endows (a), stable cycling of Si anode (≈3.8 mAh cm−2) with an ultrahigh initial Coulombic efficiency (ICE) of 92.3 %; (b), enhanced rate capability of 1468 mAh/g at 2.0 A g−1 and good cycling performance; and (c), overall cell (Si@AlFHQ-20//LiCoO2@Al2O3) operational stability for more than 100 cycles under stringent cathode conditions (2.68 mAh cm−2, high cutoff voltage at 4.55 V).

Realizing interfacial coupled electron/ion transport through reducing the interfacial oxygen density of carbon skeletons for high-performance lithium metal anodes

Lithium plating/stripping occurs at the anode/electrolyte interface which involves the flow of electrons from the current collector and the migration of lithium ions from the solid-electrolyte interphase (SEI). The dual continuous rapid transport of interfacial electron/ion is required for homogeneous Li deposition. Herein, we propose a strategy to improve the Li metal anode performance by rationally regulating the interfacial electron density and Li ion transport through the SEI film. This key technique involves decreasing the interfacial oxygen density of biomass-derived carbon host by regulating the arrangement of the celluloses precursor fibrils. The higher specific surface area and lower interfacial oxygen density decrease the local current density and ensure the formation of thin and even SEI film, which stabilized Li+ transfer through the Li/electrolyte interface. Moreover, the improved graphitization and the interconnected conducting network enhance the surface electronegativity of carbon and enable uninterruptible electron conduction. The result is continuous and rapid coupled interfacial electron/ion transport at the anode/electrolyte reaction interface, which facilitates uniform Li deposition and improves Li anode performance. The Li/C anode shows a high initial Coulombic efficiency of 98% and a long-term lifespan of over 150 cycles at a practical low N/P (negative-to-positive) ratio of 1.44 in full cells.

Manufacturing lithium-ion anodes from silicon recovered from end-of-life solar panels

With the rapid growth of solar energy, the recycling or re-use of used solar panels has become a key issue. Recycling high-value photovoltaic silicon from solar cells is an important step towards achieving “carbon neutrality.” In this paper, an efficient and high-value recycling strategy is employed to convert recycled silicon from discarded solar cells into lithium-ion anode materials. In this case, the recycled PV silicon is etched with hydrofluoric acid (HF) to create a porous silicon structure. This structure is designed to withstand the expansion stress of the electrodes. After surface modification with citric acid and carbon nanotubes to enhance the electrical conductivity of the recycled silicon and buffer the electrode from stress expansion during lithium storage and release, lithium difluorooxalate borate was added to pre-treat the surface of the recycled photovoltaic silicon through heat treatment. This process creates a robust and fast lithium-ion conductive interface enriched with LiF, Li2C2O4, LiBO2, and Li2B4O7. Density Functional Theory (DFT) calculations were performed to investigate the electronic structure of the synthesized materials, revealing their remarkable electronic conductivity and atomic bonding characteristics. When used as an anode for Li-ion batteries, W-pSi@C/CNTs exhibited high initial coulombic efficiency with stable cycling, demonstrating a capacity of 2040 mAh/g at 0.2 A/g for 200 cycles. In addition, this high-value recycling will help promote the development of renewable energy in an economically and environmentally sustainable manner.

Facile synthesis of GexSiO(1-x) alloys as a superior anode enables high-energy lithium-ion batteries

The large-scale development of low-cost silicon monoxide (SiO) anode is limited due to its low initial Coulombic efficiency (ICE) and poor cycle stability. Herein, the GexSiO(1-x) (0<x<1) composite anode has been facile synthesized by introducing germanium (Ge) atoms disrupted the structure of SiO matrix, which exhibits superior lithium storage performance. In particular, the optimized Ge0.5SiO0.5 electrode with nanoscale dispersion shows a high ICE of 80.2 % and a reversible capacity of 673.9 mAh g−1 after 100 cycles. To evaluate the effect of the Ge addition on the electrochemical properties, the lithium storage behaviors and structural evolution of the GexSiO(1-x) electrodes are investigated systematically. The in-situ electrochemical dilatometry reveals that the Ge0.5SiO0.5 electrode displays a better reversible thickness variation during cycling process. Density functional theory (DFT) calculation demonstrates that the SiGe domain can accommodate the volume expansion of Si and Ge domains. Moreover, the relationships between the electrochemical performance and morphology evolution demonstrate that the disordered structure and nanoscale distribution of Ge0.5SiO0.5 electrodes are the main reasons for improving ICE and cycle stability. This work provides a commercially available synthetic route for the design of advanced anode materials for large-scale energy storage applications.

Innovative Design of anode materials for Li-ion batteries: Bismuth oxide/sodium bismuth molybdate nanocomposites

Novel bismuth oxide/sodium bismuth molybdate nanocomposites (NCs), Bi2O3@NaBi(MoO4)2, were developed successfully via simple methods. Advanced analyses revealed that the NCs were composed of Bi2O3 and NaBi(MoO4)2 particles at the nanoscale, below 10 nm, in a combination of amorphous and crystalline forms. In this work, these NCs were utilized as lithium-ion battery anode materials for the first time, demonstrating exceptional electrochemical performances, including high capacity, superior capacity retention, high coulombic efficiency, excellent rate capacity, and pseudo-capacitance behavior. For instance, Bi2O3@NaBi(MoO4)2 NCs prepared at 1 h and 3 h of reaction time delivered a reversible charge capacity of 1052 and 1034 mAh g−1 after 200 cycles at current densities of 0.1 A g−1 with a capacity retention of 110 and 129 %, respectively. Notably, all the NCs anodes exhibited an excellent initial coulombic efficiency of above 80 %. Materials characterizations and electrochemical analysis revealed that the improved electrochemical properties of the NCs were attributed to their unique architectures, which featured nanostructures, molybdate components, and a small amount of amorphous phase. In addition, the significant capacity increase could be due to the electrochemical milling effect, the in situ formation of metallic particles, and the role of Mo metal in the NCs anodes as the catalysts for Li2O decomposition during cycling. It concluded that Bi2O3@NaBi(MoO4)2 NCs have great potential as advanced anodes for Li-ion storages.

Single-step pyrolysis of Stipa Tenacissima fibers to hard carbon: A potential route for sodium-ion battery anodes

Hard Carbon (HC) has emerged as a viable candidate for the negative electrode material in sodium-ion batteries (SIBs). This study focuses on the development of a novel HC-negative electrode derived from the pyrolysis of Stipa tenacissima fibers (STF). Prior to pyrolysis, STF underwent a hot water wash pre-treatment, and various pyrolysis temperatures (800 °C, 1000 °C, and 1300 °C) were investigated to elucidate their influence on HC properties and performance. Structural analysis revealed significant differences in the HC structure, highlighting a direct correlation between capacity improvement and the size of accessible micropores for sodium insertion. Composite electrodes were assembled and evaluated in non-aqueous sodium half-cells to assess HC's performance. Notably, increasing the pyrolysis temperature resulted in higher reversible capacity (RC). Specifically, HC prepared at 1300 °C exhibited an RC of 270 mAh g−1, initial coulombic efficiency (ICE) of approximately 60 %, and exceptional reversibility with 99 % capacity retention after 90 cycles at a 25 mA g−1 of current density (CD). These results surpassed those obtained with HC prepared at 800 °C and 1000 °C. Moreover, this study explores the biological, biochemical, biophysical, and structural advantages conferred by STF, making it a promising component in SIBs, with the ultimate goal of establishing long-lasting, high-performance battery systems.

Aromatic carboxyl acid regulated nanoparticle deposition and passivation of tin oxide for high performance perovskite solar cells

The composition and nano particle agglomeration of hydrolyzed species in chemical bath deposition (CBD) plays a key role in obtaining efficient SnO2 film for high performance perovskite solar cells (PSCs). In this work, the aromatic acids with varied carboxyl groups were investigated to regulate the nano particle deposition and passivate the buried SnO2/perovskite interface. The quasi in-situ dynamic light scattering and Zeta potential results indicated that the nano particle agglomeration with trimesic acid (TMA) was significantly refined throughout the whole deposition process. The TMA-SnO2 achieved an ideal energy band alignment with perovskite and released the internal residual strain, promoting the growth and crystallization of the perovskite film due to the corrdination of carboxyl groups. As a result, the interface defects were effectively passivated with enhanced efficiency and stability. The small area device based on TMA-SnO2 obtained an efficiency of 25.07 %. The devices with an enlarged area of 1.4 cm2 and the 5x5 cm2 mini-module (active area 10.054 cm2) showed impressive PCEs of 23.93 % and 22.40 %, respectively. Furthermore, the unencapsulated devices exhibit enhanced long-term stability, maintaining 80 % and 90 % of the initial efficiencies under 80 ± 5°C thermal annealing in nitrogen for 1176 h and in air condition for 3224 h, respectively.