The pursuit of high energy densities propels the design of next-generation nickel-based layered oxide cathodes. The utilization of low-cobalt, ultrahigh-nickel layered oxide cathodes, and the extension of operating voltages promise enhanced energy density. However, stability and safety face challenges associated with nickel content, including structural degradation, lattice oxygen evolution, and thermal instability. In this study, a promising strategy of Al and Nb dual-bulk-doping is presented in high-Ni cathode materials of LiNi0.96Co0.04O2 (NC) to stabilize the bulk structure, suppress oxygen release, and attain superior electrochemical performance at high voltages. The introduction of Al and Nb effectively raises the migration energy of Ni2+ into Li sites and stabilizes lattice oxygen through strengthened AlâO and NbâO bonds. Furthermore, the substitution of high-valence Nb ions reduces the charge depletion of lattice oxygen and induces an ordered microstructure. The Al and Nb dual-bulk-doping strategy mitigates strain and stress associated with the H2âH3 phase transition, reducing the generation and propagation of microcracks. The resulting Li(Ni0.96Co0.04)0.985Al0.01Nb0.005O2 (NCAN) cathode exhibits superior cycling stability, with a capacity retention of 77.8% after 300 cycles, even when operating at a high-voltage of 4.4 V, outperforming the NC (48.5%). This work provides a promising perspective for developing high-voltage and high-Ni cathode materials.
Lithium-sulfur (Li-S) batteries are one of the most promising high-energy density secondary batteries due to their high theoretical energy density of 2600 Wh kg-1. However, the sluggish kinetics and severe "shuttle effect" of polysulfides are the well-known barriers that hinder their practical applications. A carefully designed catalytic host of sulfur may be an effective strategy that not only accelerates the conversion of polysulfides but also limit their dissolution to mitigate the "shuttle effect." Herein, in situ surface-phosphided Ni0.96Co0.03Mn0.01O (p-NCMO) oxide microspheres are prepared via gas-phase phosphidation as a catalytic host of sulfur. The as-prepared unique heterostructured microspheres, with enriched surface-coated metal phosphide, exhibit superior synergistic effect of catalytic conversion and absorption of the otherwise soluble intermediate polysulfides. Correspondingly, the sulfur cathode exhibits excellent electrochemical performance, including a high initial discharge capacity (1162 mAh gs-1 at 0.1C), long cycling stability (491 mAh gs-1 after 1000 cycles at 1C), and excellent rate performance (565 mAh gs-1 at 5C). Importantly, the newly prepared sulfur cathode shows a high areal capacity of 4.0 mAh cm-2 and long cycle stability under harsh conditions (high sulfur loading of 5.3 mg cm-2 and lean electrolyte/sulfur ratio of 5.8 µL mg-1). This work proposes an effective strategy to develop the catalytic hosts of sulfur for achieving high-performance Li-S batteries via surface phosphidation.
OBJECTIVES: To study the intervention effect of narrative therapy on non-suicidal self-injury (NSSI), as well as anxiety and depression symptoms in adolescents with depressive disorder. METHODS: Sixty adolescents with depressive disorder and NSSI were randomly assigned to either the intervention group or the control group using coin flipping. The control group received conventional psychological support, while the intervention group received individual narrative therapy in addition to the conventional psychological support (twice a week, 60 minutes per session, for a total of 3 weeks). Assessment of treatment efficacy was conducted using the Adolescent Self-Harm Questionnaire, Children's Depression Inventory, and Children's Anxiety and Mood Scale before the intervention, at the end of the intervention, and one month after the intervention for both groups. RESULTS: A total of 26 adolescents in the intervention group and 29 adolescents in the control group completed the entire study. At the end of the intervention and one month after the intervention, the intervention group showed a significant reduction in the NSSI frequency score, NSSI level, anxiety score, and depression score compared to before the intervention (P<0.017). Moreover, at the end of the intervention and one month after the intervention, the intervention group exhibited significantly lower NSSI frequency score, NSSI severity score, NSSI level, anxiety score and depression score compared to the control group (P<0.05). CONCLUSIONS: Narrative therapy is effective in reducing NSSI frequency and alleviating NSSI severity, as well as anxiety and depression symptoms in adolescents with depressive disorder.
Depressive Disorder , Narrative Therapy , Self-Injurious Behavior , Child , Adolescent , Humans , Prospective Studies , Self-Injurious Behavior/therapy , Anxiety
Owing to the high energy density, ultrahigh-nickel (Ni > 0.9) layered oxides are used as promising cathode materials for next-generation Li-ion batteries. Unfortunately, the serious pulverization and rapid capacity fading during cycling limit the commercial viability of an ultrahigh-nickel oxide cathode. Herein, the introduction of Ga into LiNi0.96Co0.04O2 brings a radially aligned microstructural change of oxide microspheres during the lithiation of the Ni0.96Co0.04(OH)2 precursor. As expected, such radially aligned needle-like primary grains on microspheres have a positive influence to reduce the anisotropic volume change and suppress the formation of microcracks of Ga-induced Li(Ni0.96Co0.04)0.99Ga0.01O2 during cycling. Specifically, compared with irregular primary grains of LiNi0.96Co0.04O2, Ga-induced oxide presents a high initial discharge capacity of 227.9 mA h g-1 at 0.1C rate between 2.8 and 4.3 V. Especially, Ga-induced oxide delivers higher initial discharge capacities of 233.9 and 240.3 mA h g-1 with higher cutoff charge voltages of 4.4 and 4.5 V at 0.1C, respectively. Furthermore, a good capacity retention of 74.1% at 1 C rate is obtained after 300 cycles, which is almost 85% higher than that of the pristine sample, mainly due to the generation of microcracks of oxide microspheres during the long-term cycle. Therefore, the introduction of Ga into LiNi0.96Co0.04O2 is a feasible approach for improving the microstructure and cycling stability of the ultrahigh-Ni layered oxides.
Currently, ultrahigh-nickel layered oxide is one of the most promising cathodes for lithium-ion batteries, with the advantages of high theoretical capacity and low cost. However, some problems in ultrahigh-nickel layered oxides are more serious, such as irreversible structural transformation, particle cracking, and side reactions at the electrode/electrolyte interface, resulting in the fast decay of the discharge capacity and midpoint potential. In this work, La doping is introduced into ultrahigh-nickel layered LiNi0.9Co0.1O2 oxide to improve the cycle stability on both discharge capacity and midpoint potential. As demonstrated, La can be doped successfully into the subsurface of LiNi0.9Co0.1O2 oxide, and the morphology of the oxide microspheres is not changed obviously by La doping. Compared with the pristine sample, the La-doped sample presents improved electrochemical performance, especially good cycle stabilization on both discharge capacity and midpoint potential. In addition, after a long-term cycle, the La-doped sample still maintains a relatively complete spherical morphology. It means that the pillaring effect of La with a large radius is helpful in accommodating the volume change caused by the insertion/extraction of Li ions, thus easing the anisotropic stress accumulation and microcrack growth inside the microspheres of the La-doped sample.
A Li-rich Mn-based layered oxide cathode (LLO) is one of the most promising cathode materials for achieving high-energy lithium-ion batteries. Nevertheless, the intrinsic problems including sluggish kinetics, oxygen evolution, and structural degradation lead to unsatisfactory performance in rate capability, initial Coulombic efficiency, and stability of LLO. Herein, different from the current typical surface modification, an interfacial optimization of primary particles is proposed to improve the simultaneous transport of ions and electrons. The modified interfaces containing AlPO4 and carbon can effectively increase the Li+ diffusion coefficient and decrease the interfacial charge-transfer resistance, thereby achieving fast charge-transport kinetics. Moreover, the in situ high-temperature X-ray diffraction confirms that the modified interface can improve the thermal stability of LLO by inhibiting the lattice oxygen release on the surface of the delithiated cathode material. In addition, the chemical and visual analysis of the cathode-electrolyte interface (CEI) composition clarifies that a highly stable and conductive CEI film generated on the modified electrode can facilitate interfacial kinetic transmission during cycling. As a result, the optimized LLO cathode exhibits a high initial Coulombic efficiency of 87.3% at a 0.2C rate and maintains superior high-rate stability with a capacity retention of 88.2% after 300 cycles at a 5C high rate.
Lithium electrodes have gained increasing attention in recent years for their promising applications in high-energy-density secondary batteries. However, structural instability during cycling remains a considerable obstacle to development. In this study, a dimensionally stable Li-Mg/Cu composite electrode was fabricated. Cu foam as a plate grid can sustain the structure, and Li-Mg alloy as the active and lithophilic component can guide the uniform Li plating within the composite. Thus, Li-Mg/Cu electrode shows long-term stability in terms of dimensional change and surface morphology. This work provides a facile and practical way to fabricate composite Li electrodes with high dimensional stability for secondary batteries.
Ni-rich layered oxides as cathode materials deliver a higher capacity than those used currently, in hopes of improving the energy density of Li-ion batteries. However, the surface residual alkali and the interfacial parasitic reactions caused by the rich nickel bring a series of problems such as surface slurrying, structure deterioration, mechanical fracture, and capacity decay. Herein, different from the common surface coating strategies with inorganics, an organo-soluble acid modification approach is proposed to meet the challenges. For LiNi0.90Co0.07Mn0.03O2 (NCM90), decanoic acid can react with the residual lithium salts on the surface to form an organic lithium salt-dominant modification layer. During cycling, an organic lithium-involved cathode/electrolyte interface (CEI) layer is rapidly formed. Specially, the solubility of decanoic acid in the organic electrolyte makes the CEI layer keep strong interaction with NCM90, thin but effective. Consequently, the modified NCM90 exhibits notable performances in terms of structural stability, mechanical integrity, and capacity retention.
The standard potential of a lithium metal electrode versus the standard hydrogen electrode was calculated by constructing the thermodynamic cycle in a hypothetical electrochemical cell with a dual-phase electrolyte. It is demonstrated that the standard potential of the lithium metal electrode can fluctuate over 0.5 V in different organic solvents, and is correlated to the modified donor number by the entropy of fusion of the solvents.
Simultaneously harvesting, converting and storing solar energy in a single device represents an ideal technological approach for the next generation of power sources. Herein, we propose a device consisting of an integrated carbon-based perovskite solar cell module capable of harvesting solar energy (and converting it into electricity) and a rechargeable aqueous zinc metal cell. The electrochemical energy storage cell utilizes heterostructural Co2P-CoP-NiCoO2 nanometric arrays and zinc metal as the cathode and anode, respectively, and shows a capacity retention of approximately 78% after 25000 cycles at 32 A/g. In particular, the battery cathode and perovskite material of the solar cell are combined in a sandwich joint electrode unit. As a result, the device delivers a specific power of 54 kW/kg and specific energy of 366 Wh/kg at 32 A/g and 2 A/g, respectively. Moreover, benefiting from its narrow voltage range (1.40-1.90 V), the device demonstrates an efficiency of approximately 6%, which is stable for 200 photocharge and discharge cycles.
Lithium-sulfur batteries with high theoretical energy density have emerged as one of the most promising next-generation rechargeable batteries, while their discharge capacity and cycle stability are challenges mainly due to the shuttle effect of polysulfide intermediates. Employing an effective catalyst for the conversion of polysulfides in cathode reactions can promote the reaction kinetics to restrain the shuttle of polysulfides. Here, for the first time, La2MoO6 (LMO) as a catalyst is introduced into sulfur cathodes. To investigate the effect of La2MoO6, we prepare two different structures of La2MoO6/carbon nanofiber composites. One is carbon nanofiber-supported crystalline La2MoO6 nanoparticles (LMO@CNFs) and the other is amorphous La2MoO6 nanoparticles embedded in carbon nanofibers (LMO-in-CNFs). For sulfur electrodes with â¼73 wt % sulfur loading, LMO@CNFs/S and LMO-in-CNFs/S deliver initial gravimetric capacities of 1493.4 and 1246.7 mA h g-1, respectively, at a 0.1C rate, obviously higher than that of the control sample CNFs/S. Moreover, LMO@CNFs/S shows much better rate performance than LMO-in-CNFs/S, indicating strongly that La2MoO6 is a highly effective catalyst to promote kinetic conversion of polysulfides.
All-solid-state lithium-sulfur batteries (ASSLSBs) have become a promising candidate because of their high energy density and safety. To ensure the high utilization and electrochemical capacity of sulfur in all-solid-state batteries, both the electronic and ionic conductivities of the sulfur cathode should be as high as possible. In this work, an intercalation-conversion hybrid cathode is proposed by distributing sulfur evenly on electroactive niobium tungsten oxide (Nb18W16O93) and conductive carbon nanotubes (CNTs) for achieving high performance ASSLSBs. Herein, Nb18W16O93 shows good electrochemical lithium storage in the hybrid cathode, which could serve as an effective Li-ion/electron conductor for the conversion of sulfur in the discharge/charge processes to achieve a high utilization of sulfur. However, CNTs could further increase the electronic conductivity of the hybrid cathode by constructing good conductive frameworks and suppress the volumetric fluctuation during the interconversion of sulfur and Li2S. With this strategy, the S/Nb18W16O93/CNT cathode achieves a high sulfur utilization of 91% after one cycle activation with a high gravimetric capacity of 1526 mA h g-1. In addition, excellent rate performance is also obtained at 0.5 C with a reversible capacity of 1262 mA h g-1 after 1000 cycles. This work offers a new perspective to develop ASSLSBs.
The merits of Ni-rich layered oxide cathodes in specific capacity and material cost accelerate their practical applications in electric vehicles and grid energy storage. However, detrimental structural deterioration occurs inevitably during long-term cycling, leading to potential instability and capacity decay of the cathodes. In this work, we investigate the effect of the doped cation radius on the electrochemical performance and structural stability of Ni-rich cathode materials by doping with Mg and Ca ions in LiNi0.8Co0.1Mn0.1O2. The results reveal that an increase in the doping ion radius can enlarge the interlayer spacing but lead to the collapse of the layered structure if the ion radius is too large, which undermines the cycling stability of the cathode material. Compared with the Ca-doped sample and the pristine material, Mg-doped LiNi0.8Co0.1Mn0.1O2 presents improved structural stability and superior thermal stability due to the pillar and glue roles of medium-sized Mg ions in the lithium layer. The results of this study suggest that a suitable ionic radius of the dopant is critical for stabilizing the structure and improving the electrochemical properties of Ni-rich layered oxide cathode materials.
Glass-ceramic sulfide solid electrolytes like Li7P3S11 are practicable propellants for safe and high-performance all-solid-state lithium-sulfur batteries (ASSLSBs); however, the stability and conductivity issues remain unsatisfactory. Herein, we propose a congener substitution strategy to optimize Li7P3S11 as Li7P2.9Sb0.1S10.75O0.25 via chemical bond and structure regulation. Specifically, Li7P2.9Sb0.1S10.75O0.25 is obtained by a Sb2O5 dopant to achieve partial Sb/P and O/S substitution. Benefiting from the strengthened oxysulfide structural unit of POS33- and P2OS64- with bridging oxygen atoms and a distorted lattice configuration of the Sb-S tetrahedron, the Li7P2.9Sb0.1S10.75O0.25 electrolyte exhibits prominent chemical stability and high ionic conductivity. Besides the improved air stability, the ionic conductivity of Li7P2.9Sb0.1S10.75O0.25 could reach 1.61 × 10-3 S cm-1 at room temperature with a wide electrochemical window of up to 5 V (vs Li/Li+), as well as good stability against Li and Li-In alloy anodes. Consequently, the ASSLSB with the Li7P2.9Sb0.1S10.75O0.25 electrolyte shows high discharge capacities of 1374.4 mAh g-1 (0.05C, 50th cycle) at room temperature and 1365.4 mAh g-1 (0.1C, 100th cycle) at 60 °C. The battery also presents remarkable rate performance (1158.3 mAh g-1 at 1C) and high Coulombic efficiency (>99.8%). This work provides a feasible technical route for fabricating ASSLSBs.
The organic-inorganic hybrid perovskite solar cells present a rapid improvement on power conversion efficiency from 3.8% to 25.5% in the past decades. Owing to the tuneable bandgaps, low-cost, and ease of fabrication, perovskites become ideal candidate materials for fabricating tandem solar cells, especially for efficient and high-voltage monolithic two-terminal devices. In this review, an overview of recent advances in various monolithic perovskite-based tandem solar cells with a focus on the key challenges is provided. Subsequently, the recombination layer materials, construction of wide-bandgap perovskite layer, stability of narrow-bandgap, and current matching principle in tandems are highlighted in order to optimize the output voltage and conversion efficiency of tandem solar cells. Finally, the recent progress is summarized with a focus on potential applications of tandem solar cells for energy conversion and storage, including hydrogen production by water splitting, CO2 reduction, supercapacitors, and rechargeable batteries, benefiting from the adjustable output voltage of tandem solar cells. It is hoped that this work can offer a feasible strategy to explore more possibilities for fabricating new two-terminal tandem solar cells with high voltage and high conversion efficiency for energy conversion and storage.
Despite their high theoretical energy density, the application of lithium-sulfur batteries is seriously hindered by the polysulfide shuttle and sluggish kinetics, especially with high sulfur loading and under low electrolyte usage. Herein, to facilitate the conversion of lithium polysulfides, nickel-boron (Ni-B) alloy nanoparticles, dispersed uniformly on carbon nanotube microspheres (CNTMs), are used as sulfur hosts for lithium-sulfur batteries. It is demonstrated that Ni-B alloy nanoparticles can not only anchor polysulfides through Ni-S and B-S interactions but also exhibit high electrocatalytic capability toward the conversion of intermediate polysulfide species. In addition, the intertwined CNT microspheres provide an additional conductive scaffold in response to the fast electrochemical redox. The enhanced redox kinetics is beneficial to improve the specific capacity and cycling stability of the sulfur cathode, based on the fast conversion of lithium polysulfides and effective deposition of the final sulfide products. Conclusively, the S/Ni-B/CNTM composite delivers a high specific capacity (1112.7 mAh gs-1) along with good cycle performance under both high sulfur loading (8.3 mg cm-2) and a lean electrolyte (3 µL mgs-1). Consequently, this study opens up a path to design new sulfur hosts toward lithium-sulfur batteries.
Lithium-sulfur (Li-S) battery is one of the most promising next-generation rechargeable batteries. Lots of fundamental research has been done for the problems during cycling like capacity fading and columbic efficiency reducing owing to severe diffusion and migration of polysulfide intermediates. In the early stage, a wide variety of carbon materials are used as host materials for sulfur to enhance electrical conductivity and adsorb soluble polysulfides. Beyond carbon materials, metal based polar compounds are introduced as host materials for sulfur because of their strong catalytic activity and adsorption ability to suppress the shuttle effect. In addition, relatively high density of metal compounds is helpful for increasing volumetric energy density of Li-S batteries. This review focuses on crystalline multi-metal compounds as host materials in sulfur cathodes. The multi-metal compounds involve not only transition metal composite oxides with specific crystalline structures, binary metal chalcogenides, double or complex salts, but also the metal compounds doped or partially substituted by other metal ions. Generally, for the multi-metal compounds, microstructure and morphologies in micro-nano scale are very significant for mass transfer in electrodes; moreover, adsorption and catalytic ability for polysulfides make fast kinetics in the electrode processes.
The high-nickel layered oxides are potential candidate cathode materials of next-generation high energy lithium-ion batteries, in which higher nickel/lower cobalt strategy is effective for increasing specific capacity and reducing cost of cathode. Unfortunately, the fast decay of capacity/potential, and serious thermal concern are critical obstacles for the commercialization of high-nickel oxides due to structural instability. Herein, in order to improve the structure and thermal stability of high-nickel layered oxides, we demonstrate a feasible and simple strategy of the surface gradient doping with yttrium, without forming the hard interface between coating layer and bulk. As expected, after introducing yttrium, the surface gradient doping layer is formed tightly based on the oxidation induced segregation, leading to improved structure and thermal stability. Correspondingly, the good capacity retention and potential stability are obtained for the yttrium-doped sample, together with the superior thermal behavior. The excellent electrochemical performance of the yttrium-doped sample is primarily attributed to the strong yttrium-oxygen bonding and stable oxygen framework on the surface layer. Therefore, the surface manipulating strategy with the surface gradient doping is feasible and effective for improving the structure and thermal stability, as well as the capacity/potential stability during cycling for the high-Ni layered oxides.
Metallic lithium as an anode is an ultimate ideal for rechargeable lithium batteries with high energy density such as lithium-oxygen batteries and lithium-sulfur batteries. However, the excess reactivity and asymmetrical dissolution-deposition of the metallic lithium anode make it impossible to support a stable long charge-discharge cycling. To protect the metallic lithium anode, apparently it needs to adjust the dissolution and deposition of lithium ions, but more essentially, it should reasonably change the distribution and transport of electrons on the surface and interface of the metallic lithium. In this work, anodic aluminum oxide (AAO) membranes are used to build highly ordered channels on the lithium anode surface in which lithium ions can transfer in the channels and electrons can be transported by the lithiation reaction of alumina with an oxygen vacancy-involved process. As a result, the cyclic reaction actually is partially transferred to the AAO surface, and lithium deposition occurs there as a hemispherical appearance but not as dendrites. Meanwhile, the highly ordered characteristics provide a physical effect to make the deposited lithium hemispheres a uniform distribution on the AAO surface. The AAO-regulated lithium anodes could be widely used to improve the cycling performance for metal lithium batteries.
Lithium-sulfur (Li-S) batteries hold the promise of the next generation energy storage system beyond state-of-the-art lithium-ion batteries. Despite the attractive gravimetric energy density (WG ), the volumetric energy density (WV ) still remains a great challenge for the practical application, based on the primary requirement of Small and Light for Li-S batteries. This review highlights the importance of cathode density, sulfur content, electroactivity in achieving high energy densities. In the first part, key factors are analyzed in a model on negative/positive ratio, cathode design, and electrolyte/sulfur ratio, orientated toward energy densities of 700 Wh L-1 /500 Wh kg-1 . Subsequently, recent progresses on enhancing WV for coin/pouch cells are reviewed primarily on cathode. Especially, the "Three High One Low" (THOL) (high sulfur fraction, high sulfur loading, high density host, and low electrolyte quantity) is proposed as a feasible strategy for achieving high WV , taking high WG into consideration simultaneously. Meanwhile, host materials with desired catalytic activity should be paid more attention for fabricating high performance cathode. In the last part, key engineering technologies on manipulating the cathode porosity/density are discussed, including calendering and dry electrode coating. Finally, a future outlook is provided for enhancing both WV and WG of the Li-S batteries.
