3D Graphene Encapsulated Hollow CoSnO3 Nanoboxes as a High Initial Coulombic Efficiency and Lithium Storage Capacity Anode

An NIR-II-photoresponsive CoSnO3 nanozyme for mild photothermally augmented nanocatalytic cancer therapy

The main challenges of nanozyme-based tumor catalytic therapy (NCT) lie in the unsatisfactory catalytic activity accompanied by a complex tumor microenvironment (TME). A few nanozymes have been designed to possess both enzyme-like catalytic activities and photothermal properties; however, the previously reported nanozymes mainly utilize the inefficient and unsafe NIR-I laser, which has a low maximum permissible exposure limit and a limited penetration depth. Herein, we report for the first time an all-in-one strategy to realize mild NIR-II photothermally amplified NCT by synthesizing amorphous CoSnO3 nanocubes with efficient triple enzyme-like catalytic activities and photothermal conversion properties. The presence of Co2+ and Sn4+ endows CoSnO3 nanocubes with the triple enzyme-like catalytic activities, not only achieving enhanced reactive oxygen species (ROS) generation through the Co2+-mediated peroxidase-like catalytic reaction to generate ˙OH and Sn4+-mediated depletion of overexpressed GSH, but also realizing the catalytic decomposition of endogenous H2O2 for relieving tumor hypoxia. More importantly, the obtained CoSnO3 nanocubes with a high photothermal conversion efficiency of 82.1% at 1064 nm could achieve mild hyperthermia (43 °C), which further improves the triple enzyme-like catalytic activities of the CoSnO3 nanozyme. The synergetic therapeutic efficacy of the NIR-II-responsive CoSnO3 nanozyme through mild NIR-II PTT-enhanced NCT could realize all-in-one multimodal tumor therapy to completely eliminate tumors without recurrence. This study will open a new avenue to explore NIR-II-photoresponsive nanozymes for efficient tumor therapy.

Core-shell-structured Mn2SnO4@Void@C as a stable anode material for lithium-ion batteries with long cycle life

Owing to its high theoretical specific capacity, Mn₂SnO₄ has been regarded as a promising electrode material for lithium-ion batteries. However, in suffering from huge volume expansion and pulverization amidst the alloying/dealloying processes, it presents difficulties in applications as an anode material. Herein, a core-shell-structured Mn₂SnO₄@Void@C anode material was successfully synthesized using a layer-wise assembly and selective etching method. Tetraethyl silicate (TEOS) and resorcinol formaldehyde resin, serving, respectively, as sacrificial template (SiO₂) and carbon layer sources, were coated successively onto Mn₂SnO₄ particles. Adopting an alkali etching process, the SiO₂ template was removed, and a Mn₂SnO₄@Void@C was therewith constructed. As Mn₂SnO₄ is well wrapped by a carbon shell and there are enough voids therein, its volume expansion whilst cycling can be significantly buffered. Moreover, the porous structure in Mn₂SnO₄@Void@C can provide convenient channels for ion transport and alleviate volume changes. Mn₂SnO₄@Void@C exhibits upgraded capacity and long cycling stability, since its specific capacity is maintained at 783.1 mA h g^-1 at 100 mA g^-1 after 150 cycles and at 553.3 mA h g^-1 at 1000 mA g^-1 after 1000 cycles.

Fabrication of MnSe/SnSe@C heterostructures for high-performance Li/Na storage

Novel heterostructured MnSe/SnSe@C nanoboxes display excellent electrochemical performance.

Rod-like Ni0.5Co0.5C2O4·2H2O in-situ formed on rGO by an interface induced engineering: Extraordinary rate and cycle performance as an anode in lithium-ion and sodium-ion half/full cells

Transition metal oxalates have attracted wide attention due to the characteristics of the conversion reaction as anode materials in lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs), However, there are huge volume expansion and sluggish circulation dynamics during the reversible Li⁺ and Na⁺ insertion/extraction process, which would lead to unsatisfactory reversible capacity and stability. In order to solve these problems, a rod-like structure Ni_0.5Co_0.5C₂O₄·2H₂O is in-situ formed on the reduced graphene oxide layer (Ni_0.5Co_0.5C₂O₄·2H₂O/rGO) in a glycol-water mixture medium via an interface induced engineering strategy. Benefitting from the synergistic cooperation of nano-diameter rod-like structure and high conductive rGO networks, the experimental results show that the prepared Ni_0.5Co_0.5C₂O₄·2H₂O/rGO electrode has predominant rate performance and ultra-long cycle stability. For the LIBs, it not only exhibits an ultrahigh reversible capacity (1179.9 mA h g^-1 at 0.5 A g^-1 after 300 cycles), but also presents outstanding rate and cycling performance (646.5 mA h g^-1 at 5 A g^-1 after 1200 cycles). Besides, the Ni_0.5Co_0.5C₂O₄·2H₂O/rGO electrode displays remarkable sodium storage capacity of 221.6 mA h g^-1 after 100 cycles at 0.5 A g^-1. Further, the extraordinary electrochemical capability of Ni_0.5Co_0.5C₂O₄·2H₂O/rGO active material is also reflected in two full-cells, assembled using commercial LiCoO₂ as cathode for LIBs and commercial Na₃V₂(PO₄)₃ as cathode for SIBs, both of which can show wonderful specific capacity and cycling stability. It is found in in-situ Raman experiments that the reversible changes of oxalate peaks are monitored in a charge/discharge process, which is scientific evidence for the transform reaction mechanism of metal oxalates in LIBs. These findings not only provide important ideas for studying the charge/discharge storage mechanism but also give scientific basis for the design of high-performance electrode materials.

Synergistic Interactions of Different Electroactive Components for Superior Lithium Storage Performance

The fusion of different electroactive components of lithium-ion batteries (LIBs) sometimes brings exceptional electrochemical properties. We herein report the reduced graphene-oxide (rGO)-coated Zn₂SnO_4z@NiO nanofibers (ZSO@NiO@G NFs) formed by the synergistic fusion of three different electroactive components including ZnO, SnO₂, and NiO that exhibit exceptional electrochemical properties as negative electrodes for LIBs. The simple synthetic route comprised of electrospinning and calcination processes enables to form porous one-dimensional (1D) structured ZSO, which is the atomic combination between ZnO and SnO₂, exhibiting effective strain relaxation during battery operation. Furthermore, the catalytic effect of Ni converted from the surface-functional NiO nanolayer on ZSO significantly contributes to improved reversible capacity. Finally, rGO sheets formed on the surface of ZSO@NiO NFs enable to construct electrically conductive path as well as a stable SEI layer, resulting in excellent electrochemical performances. Especially, exceptional cycle lifespan of more than 1600 cycles with a high capacity (1060 mAh g^-1) at a high current density (1000 mA g^-1), which is the best result among mixed transition metal oxide (stannates, molybdates, cobaltates, ferrites, and manganates) negative electrodes for LIBs, is demonstrated.

Structural and chemical interplay between nano-active and encapsulation materials in a core–shell SnO2@MXene lithium ion anode system

Structural and chemical interplay between nano-active and encapsulation materials in a core–shell SnO₂@MXene lithium ion anode system was investigated in detail.

Multifunctionalities of Graphene for Exploiting a Facile Conversion Reaction Route of Perovskite CoSnO3 for Highly Reversible Na Ion Storage

Transition-metal oxides are promising anode materials for sodium ion batteries (SIBs) and have attracted a great deal of attention because of their natural abundance and high theoretical capacities. However, they suffer from low conductivity and large volumetric/structural variation during sodiation/desodiation processes, leading to unsatisfactory cycling stability and poor rate capability. This study proposes a novel conversion reaction using CoSnO₃ (CSO) nanocubes uniformly wrapped in graphene nanosheets, which are fabricated using a wet-chemical strategy followed by low-temperature heat treatment. This optimized composite exhibits durable cyclability and high rate capability, which can be attributed to the strong interaction between reduced graphene oxide and CSO through its surface oxygen moieties. It develops a facile conversion reaction route, thereby leading to SnO₂ formation during charging. This interactive phenomenon further contributes to improving the reaction kinetics and restraining the volume expansion during cycling. This study may provide a facile approach for addressing irreversible conversion of high-capacity oxide materials toward advanced SIBs.

Higher Than 90% Initial Coulombic Efficiency with Staghorn-Coral-Like 3D Porous LiFeO2- x as Anode Materials for Li-Ion Batteries

Transition metal oxides represent a promising class of anode materials for high-capacity lithium-ion batteries. However, low initial coulombic efficiency (ICE, <80%) still remains a crucial challenge for practical applications. Herein, a unique 3D Fe(II)-rich porous LiFeO_{2- x} comprising of staghorn-coral-like skeleton measuring ≈100 nm in diameter is demonstrated, which is readily prepared by reacting Fe₂ O₃ with LiH at 550 °C. When used as an anode material, the Fe(II)-rich LiFeO_{2- x} delivers the presently known highest ICE value of 90.2% with 1170 mAh g^-1 discharge capacity. The high ICE value can be ascribed to a fast conversion reaction of LiFeO_{2- x} upon lithiation/delithiation facilitated by the presence of Fe(II), which generates oxygen vacancies and makes electron transportation much easier, based on the experimental results and density functional theory (DFT) calculations.

3D Porous Self-Standing Sb Foam Anode with a Conformal Indium Layer for Enhanced Sodium Storage

Antimony (Sb) has been considered as a promising anode for sodium-ion batteries (SIBs) because of its high theoretical capacity and moderate working potential but suffers from the dramatic volume variations (∼250%), an unstable electrode/electrolyte interphase, active material exfoliation, and a continuously increased interphase impedance upon sodiation and desodiation processes. To address these issues, we report a unique three-dimensional (3D) porous self-standing foam electrode built from core-shelled Sb@In₂O₃ nanostructures via a continuous electrodepositing strategy coupled with surface chemical passivation. Such a hierarchical structure possesses a robust framework with rich voids and a dense protection layer (In₂O₃), which allow Sb nanoparticles to well accommodate their mechanical strain for efficiently avoiding electrode cracks and pulverization with a stable electrode/electrolyte interphase upon sodiation/desodiation processes. When evaluated as an anode for SIBs, the prepared nanoarchitectures exhibit a high first reversible capacity (641.3 mA h g^-1) and good cyclability (456.5 mA h g^-1 after 300 cycles at 300 mA g^-1), along with superior high rate capacity (348.9 mA h g^-1 even at 20 A g^-1) with a first Coulomb efficiency as high as 85.3%. This work could offer an efficient approach to improve alloying-based anode materials for promoting their practical applications.

Facile synthesis of novel tungsten-based hierarchical core-shell composite for ultrahigh volumetric lithium storage

The development of novel high volumetric capacity electrode materials is crucial to the application of lithium-ion batteries (LIBs) in miniaturized consumer electronics. In this work, a novel tungsten-based octahedron (CoWO₄/Co₃O₄) with unique hierarchical core-shell structure is successfully fabricated by simply calcinating a cyanide-metal framework precursor. Benefitting from the heavy element W, the CoWO₄/Co₃O₄ octahedrons show a high mass density of 5.18 g cm^-3. When applied as anode materials for LIBs, the CoWO₄/Co₃O₄ octahedrons exhibit an ultrahigh volumetric capacity (6226 mAh cm^-3 after 350 cycles at 0.4 A g^-1), superior rate capability (3165 mAh cm^-3 at 3.0 A g^-1) and outstanding long-term cycling performance (4703 mAh cm^-3 at 1.0 A g^-1 after 800 cycles). The extraordinary lithium storage performance can be ascribed to the unique hierarchical core-shell structure and the possible synergistic effect between W and Co, which provide more Li⁺ insertion sites and effectively buffer the volume variation during cycling. This work not only provides an ultrahigh volumetric lithium storage anode, but also gives a simple and general strategy for the synthesis of novel anode materials for high volumetric energy density LIBs.

Integrated Design of Hierarchical CoSnO3@NC@MnO@NC Nanobox as Anode Material for Enhanced Lithium Storage Performance

Transition-metal oxides (TMOs) are potential candidates for anode materials of lithium-ion batteries (LIBs) due to their high theoretical capacity (∼1000 mA h/g) and enhanced safety from suppressing the formation of lithium dendrites. However, the poor electron conductivity and the large volume expansion during lithiation/delithiation processes are still the main hurdles for the practical usage of TMOs as anode materials. In this work, the CoSnO3@NC@MnO@NC hierarchical nanobox (CNMN) is then proposed and fabricated to solve those issues. The as-prepared nanobox contains hollow cubic CoSnO3 as a core and dual N-doped carbon-"sandwiched" MnO particles as a shell. As anode materials of LIBs, the hollow and carbon interlayer structures effectively accommodate the volume expansion while dual active TMOs of CoSnO3 and MnO efficiently increase the specific capacity. Notably, the dual-layer structure of N-doped carbons plays a critical functional role in the incorporated composites, where the inner layer serves as a reaction substrate and a spatial barrier and the outer layer offers electron conductivity, enabling more effective involvement of active anode materials in lithium storage, as well as maintaining their high activity during lithium cycling. Subsequently, the as-prepared CNMN exhibits a high specific capacity of 1195 mA h/g after the 200th cycle at 0.1C and an excellent stable reversible capacity of about 876 mA h/g after the 300th cycle at 0.5C with only 0.07 mA h/g fade per cycle after 300 cycles. Even after a 250 times fast charging/discharging cycle both at 5C, it still retains a reversible capacity of 422.6 mA h/g. We ascribe the enhanced lithium storage performances to the novel hierarchical architectures achieved from the rational design.

Susceptible CoSnO3 nanoboxes with p-type response for triethylamine detection at low temperature

CoSnO₃ nanoboxes exhibit a p-type response to detect triethylamine at 100 °C with a limit of detection of 134 ppb.

SnS2 /Co3 S4 Hollow Nanocubes Anchored on S-Doped Graphene for Ultrafast and Stable Na-Ion Storage

SnS₂ has been widely studied as an anode material for sodium-ion batteries (SIBs) based on the high theoretical capacity and layered structure. Unfortunately, rapid capacity decay associated with volume variation during cycling limits practical application. Herein, SnS₂ /Co₃ S₄ hollow nanocubes anchored on S-doped graphene are synthesized for the first time via coprecipitation and hydrothermal methods. When applied as the anode for SIBs, the sample delivers a distinguished charge specific capacity of 1141.8 mAh g^-1 and there is no significant capacity decay (0.1 A g^-1 for 50 cycles). When the rate is increased to 0.5 A g^-1 , it presents 845.7 mAh g^-1 after cycling 100 times. Furthermore, the composite also exhibits an ultrafast sodium storage capability where 392.9 mAh g^-1 can be obtained at 10 A g^-1 and the charging time is less than 3 min. The outstanding electrochemical properties can be ascribed to the enhancement of conductivity for the addition of S-doped graphene and the existence of p-n junctions in the SnS₂ /Co₃ S₄ heterostructure. Moreover, the presence of mesopores between nanosheets can alleviate volume expansion during cycling as well as being beneficial for the migration of Na⁺ .

Three-dimensional porous Co3O4-CoO@GO composite combined with N-doped carbon for superior lithium storage

Transition metal oxides (TMOs) as anode materials have potential for lithium-ion batteries (LIBs). However, the poor rate capacity and cycle stability restrict its application. Herein, we demonstrate a facile one-step hydrothermal method to construct a three-dimensional porous conductive network structure, which consists of thin-layered graphene, ultrafine Co₃O₄-CoO nanoparticles and nitrogen-doped carbon. This unique structure can effectively prevent particle agglomeration and cracking caused by volume expansion, provide fast passage for lithium ion/electron transport during cycling and improve the electrical conductivity of the electrode. Moreover, the electrochemical kinetic analysis proves that this is a process dominated by pseudocapacitive behavior. Consequently, the N-C@Co₃O₄-CoO@GO hybrid electrode delivers an ultrahigh capacity of 1 273.1 mA h g^-1 at 0.1 A g^-1 and superior rate performance (725.1 mA h g^-1 at 5 A g^-1). Additionally, it exhibits a high reversible cycling capacity of 787.4 mA h g^-1 at 1 A g^-1 over 600 cycles and even maintains excellent cycling stability for a ultra-long cycles at 5 A g^-1. This work provides a feasible strategy for fabricating the N-C@Co₃O₄-CoO@GO composite as a promising high-performance TMOs anode for LIBs.

Enhancing Delithiation Reversibility of Li15Si4 Alloy of Silicon Nanoparticles-Carbon/Graphite Anode Materials for Stable-Cycling Lithium Ion Batteries by Restricting the Silicon Particle Size

Silicon nanoparticles (SiNPs) with a median size of 51 nm are prepared by the sand mill from waste silicon, and then carbon-interweaved SiNPs/graphite anode materials are designed. Because of the size of SiNPs is restricted below a critical fracture size of 150 nm as well as the rational decoration of carbon and graphite, fracture of SiNPs, and volume deformation of active materials are highly alleviated, leading to low impedance, enhanced electrochemical reaction kinetics, and good electronic connection between active materials and current collector. Furthermore, delithiation reversibility of the formed crystalline Li₁₅Si₄ alloy is enhanced. As a result, the anode with 10.5 wt % content of Si (including SiO_x) delivers a properly high initial reversible capacity of 505 mA h g^-1, high cycling stability with capacity retentions of 86.3%, and 91.5% at 0.1 and 1 A g^-1 after 500 cycles, respectively. After cycling at a series of higher current densities, the reversible capacity recovers to the original level completely (100% recovery) when the current density is set back to the original value, exhibiting outstanding rate performance. The results indicate that the silicon-carbon anode can achieve high cycling performances with enhanced delithiation reversibility of the formed crystalline Li₁₅Si₄ alloy by restricting size of SiNPs and decoration of carbon materials, which are discussed systematically. The SiNPs are recycled from waste Si, and synthetic strategy of anode materials is very facile, cost-effective, and nontoxic, which has potential for industrial production.

Porous Multicomponent Mn-Sn-Co Oxide Microspheres as Anodes for High-Performance Lithium-Ion Batteries

Porous multicomponent Mn-Sn-Co oxide microspheres (MnSnO3-MC400 and MnSnO3-MC500) have been fabricated using CoSn(OH)6 nanocubes as templates via controlling pyrolysis of a CoSn(OH)6/Mn0.5Co0.5CO3 precursor at different temperatures in N2. During the pyrolysis process of CoSn(OH)6/Mn0.5Co0.5CO3 from 400 to 500 °C, the part of (Co,Mn)(Co,Mn)2O4 converts into MnCo2O4 accompanied with structural transformation. The MnSnO3-MC400 and MnSnO3-MC500 microspheres as secondary nanomaterials consist of MnSnO3, MnCo2O4, and (Co,Mn)(Co,Mn)2O4. Benefiting from the advantages of multicomponent synergy and porous secondary nanomaterials, the MnSnO3-MC400 and MnSnO3-MC500 microspheres as anodes exhibit the specific capacities of 1030 and 750 mA h g-1 until 1000 cycles at 1 A g-1 without an obvious capacity decay, respectively.

Uniform Na+ Doping-Induced Defects in Li- and Mn-Rich Cathodes for High-Performance Lithium-Ion Batteries

The corrosion of Li- and Mn-rich (LMR) electrode materials occurring at the solid-liquid interface will lead to extra electrolyte consumption and transition metal ions dissolution, causing rapid voltage decay, capacity fading, and detrimental structure transformation. Herein, a novel strategy is introduced to suppress this corrosion by designing an Na+-doped LMR (Li1.2Ni0.13Co0.13Mn0.54O2) with abundant stacking faults, using sodium dodecyl sulfate as surfactant to ensure the uniform distribution of Na+ in deep grain lattices-not just surface-gathering or partially coated. The defective structure and deep distribution of Na+ are verified by Raman spectrum and high-resolution transmission electron microscopy of the as-prepared electrodes before and after 200 cycles. As a result, the modified LMR material shows a high reversible discharge specific capacity of 221.5 mAh g-1 at 0.5C rate (1C = 200 mA g-1) after 200 cycles, and the capacity retention is as high as 93.1% which is better than that of pristine-LMR (64.8%). This design of Na+ is uniformly doped and the resultanting induced defective structure provides an effective strategy to enhance electrochemical performance which should be extended to prepare other advanced cathodes for high performance lithium-ion batteries.

High Initial Reversible Capacity and Long Life of Ternary SnO2-Co-carbon Nanocomposite Anodes for Lithium-Ion Batteries

The two major limitations in the application of SnO₂ for lithium-ion battery (LIB) anodes are the large volume variations of SnO₂ during repeated lithiation/delithiation processes and a large irreversible capacity loss during the first cycle, which can lead to a rapid capacity fade and unsatisfactory initial Coulombic efficiency (ICE). To overcome these limitations, we developed composites of ultrafine SnO₂ nanoparticles and in situ formed Co(CoSn) nanocrystals embedded in an N-doped carbon matrix using a Co-based metal-organic framework (ZIF-67). The formed Co additives and structural advantages of the carbon-confined SnO₂/Co nanocomposite effectively inhibited Sn coarsening in the lithiated SnO₂ and mitigated its structural degradation while facilitating fast electronic transport and facile ionic diffusion. As a result, the electrodes demonstrated high ICE (82.2%), outstanding rate capability (~ 800 mAh g^-1 at a high current density of 5 A g^-1), and long-term cycling stability (~ 760 mAh g^-1 after 400 cycles at a current density of 0.5 A g^-1). This study will be helpful in developing high-performance Si (Sn)-based oxide, Sn/Sb-based sulfide, or selenide electrodes for LIBs. In addition, some metal organic frameworks similar to ZIF-67 can also be used as composite templates.

Constructing Heterointerface of Metal Atomic Layer and Amorphous Anode Material for High-Capacity and Fast Lithium Storage

Interfacial engineering plays an important role in tuning the intrinsic property of electrode materials for energy applications such as lithium-ion batteries (LIBs), which however is rarely realized to amorphous electrode materials, despite a set of characteristics of amorphous materials desirable for LIBs. Here, Au atomic cluster layer-interfaced amorphous porous CoSnO₃ nanocubes were fabricated by galvanic replacement and employed as a superior LIB anode, showing high reversible capacity (1615 mAh g^-1 at 0.2 A g^-1), good rate capability (1059 mAh g^-1 with a 61.3% capacity retention upon the dramatic current variation from 0.1 to 5 A g^-1), and excellent cycling stability. The amorphous nature, interconnected mesopores, and especially the thin Au atomic cluster layer on the surface/pore walls of CoSnO₃ nanocubes can not only improve electron transport and ion diffusion in the electrode and electrolyte but also release the volume strain. Most significantly, density functional theory calculations reveal that the CoSnO₃∥Au heterointerface can induce the atomic polarization of CoSnO₃ and lower Li ion diffusion barriers in CoSnO₃ near the heterointerface, endowing it with a significantly enhanced theoretical lithium storage capacity and outstanding rate capability. This study provides a model of a heterointerface for amorphous materials with desired properties for high-performance LIBs and future energy applications.

Low Interface Energies Tune the Electrochemical Reversibility of Tin Oxide Composite Nanoframes as Lithium-Ion Battery Anodes

The conversion reaction of lithia can push up the capacity limit of tin oxide-based anodes. However, the poor reversibility limits the practical applications of lithia in lithium-ion batteries. The latest reports indicate that the reversibility of lithia has been appropriately promoted by compositing tin oxide with transition metals. The underlying mechanism is not revealed. To design better anodes, we studied the nanostructured metal/Li₂O interfaces through atomic-scale modeling and proposed a porous nanoframe structure of Mn/Sn binary oxides. The first-principles calculation implied that because of a low interface energy of metal/Li₂O, Mn forms smaller particles in lithia than Sn. Ultrafine Mn nanoparticles surround Sn and suppress the coarsening of Sn particles. Such a composite design and the resultant interfaces significantly enhance the reversible Li-ion storage capabilities of tin oxides. The synthesized nanoframes of manganese tin oxides exhibit an initial capacity of 1620.6 mA h g^-1 at 0.05 A g^-1. Even after 1000 cycles, the nanoframe anode could deliver a capacity of 547.3 mA h g^-1 at 2 A g^-1. In general, we demonstrated a strategy of nanostructuring interfaces with low interface energy to enhance the Li-ion storage capability of binary tin oxides and revealed the mechanism of property enhancement, which might be applied to analyze other tin oxide composites.