High Initial Capacity Research Articles

Flexible CNT-Interpenetrating Hierarchically Porous Sulfurized Polyacrylonitrile (CIHP-SPAN) Electrodes for High-Rate Lithium-Sulfur (Li-S) Batteries.

Sulfurized polyacrylonitrile (SPAN) is a promising cathode material for lithium-sulfur batteries owing to its reversible solid-solid conversion for high-energy-density batteries. However, the sluggish reaction kinetics of SPAN cathodes significantly limit their output capacity, especially at high cycling rates. Herein, a CNT-interpenetrating hierarchically porous SPAN electrode is developed by a simple phase-separation method. Flexible self-supporting SPAN cathodes with fast electron/ion pathways are synthesized without additional binders, and exceptional high-rate cycling performances are obtained even with substantial sulfur loading. For batteries assembled with this special cathode, an impressive initial discharge capacity of 1090 mAh g-1 and a retained capacity of 800 mAh g-1 are obtained after 1000 cycles at 1 C with a sulfur loading of 1.5 mg cm-2. Furthermore, by incorporating V2O5 anchored carbon fiber as an interlayer with adsorption and catalysis function, a high initial capacity of 614.8 mAh g-1 and a notable sustained capacity of 500 mAh g-1 after 500 cycles at 5 C are achieved, with an ultralow decay rate of 0.037% per cycle with a sulfur loading of 1.5 mg cm-2. The feasible construction of flexible SPAN electrodes with enhanced cycling performance enlists the current processing as a promising strategy for novel high-rate lithium-sulfur batteries and other emerging battery electrodes.

Enhancing ammonium-ion storage in Mo-doped VO2 (B) nanobelt-bundles anode for aqueous ammonium-ion batteries.

The recent surge in interest in aqueous ammonium ion rechargeable batteries (AAIBs) has been fueled by their eco-friendliness, efficiency, safety, and sustainability. However, finding the optimal anode material for effective ammonium ion (NH4+) storage remains a nascent and significant challenge. The research presented here focuses on the enhancement of aqueous ammonium rechargeable batteries by incorporating Mo atoms into VO2 (B) (denote as MVO), a material that has shown promise as an anode for NH4+ storage. The introduction of Mo ions was found to optimize the electronic structure and morphology of pristine VO2 (B) (label as PVO), resulting in the transformation of its nanobelts into thin nanobelt-bundles. This alteration exposes more active sites and increases oxygen vacancies, which in turn improve the conductivity and diffusion rate of NH4+ ions, thereby enhancing the overall electrochemical performance of the material. The MVO material demonstrates a high initial capacity of 283.5 mA h g-1 at 0.3 A g-1, and maintained 86.7% of its capacity after 4500 cycles, indicating excellent long-term stability. To further validate the practical application, a full cell was garnered utilizing MVO as the anode and Cu3[Fe(CN)6]2 (CuHCF) as the cathode. The resulting AAIB displays remarkable cycling stability, with 81.5% capacity preservation after 1000 cycles and large energy density of 57.9 W h kg-1. The study reveals that the doping of Mo ions can significantly improve both the stability and NH4+ storage capacity of PVO, offering a promising new direction for the exploitation of efficacious and sustainable NH4+ host materials for rechargeable batteries.

Impeding polysulfide diffusion strategies in lithium-sulfur batteries using 3D porous carbon nanosheets integrated by cathode and functional separator

Lithium-sulfur(Li-S) batteries show high theoretical capacity and energy density compared to lithium-ion batteries(LIBs), which are one of the candidates for next-generation energy storage systems. However, rapid capacity fading caused by polysulfide shuttling effects remains critical issue for the commercial development in the Li-S batteries. Therefore, we aimed to derive 3D porous carbon nanosheets(C900) through the simple carbonization of organic salts as base materials for application as both sulfur host and functional separator. C900 had 3D vertically aligned and hierarchical carbon nanosheet structure with a high specific surface area and large pore volume, which was benefits for sulfur hosts because of the efficient electrolyte diffusion pathways and high mass loading of sulfur. Furthermore, nitrogen doped C900(NC900) can be improved chemical reactions with lithium polysulfides. Subsequently, an integrated electrode composed of a cathode with C900 and functional separator with NC900, respectively, was found to be highly efficient in restraining the shuttle effect via multimodal capturing effects. Consequently, all-integrated electrode composed of S-C900 and NC900@PP delivered a high initial specific capacity of 1453mAh·g-1 at 0.1C and achieved cycle stability with 64% capacity retention after 300cycles at 0.5C. This work suggests a potential carbon material design for bi-functional materials in a high-performance Li-S batteries.

A three-dimensional Ge@C anode with a hollow and micro/nano structure for high-capacity lithium-ion battery

Aiming at the key issues of low intrinsic conductivity and large volume expansion during the cycling existed in high-capacity Ge anode material system, a micro/nano structured Ge@C hybrid material was designed and prepared through a facile and controllable method. The as-prepared micron conductive cage with a dodecahedral structure is composed of interconnected ultra-thin walled Ge nanotubes encapsulated in the porous N-containing carbon network, which can not only reserve more buffer space for the volume expansion of Ge and assist in building a stable SEI film during the cycling, improves the conductivity and stability of the material, but also provide a rich and penetrating channel for the transmission of ions, realizing high dynamics. When applied to the anode of lithium-ion battery, the three-dimensional micro/nano structured germanium-based hybrid material (Ge-3D@C) delivers a high initial specific capacity of 1500 mAh g−1 at 0.2 A g−1, and after 350 cycles, it can still maintain a high reversible specific capacity of 1147 mAh g−1. Even at high current densities of 1 A g−1 and 2 A g−1, high reversible specific capacities of 752 and 631 mAh g−1 can still be obtained. Importantly, the rational design can be used to prepare Ge hybrids doped with other metals or metal oxides, as well as different structures, by adjusting the layer materials and the types of germanates, so as to adapt to different application environments.

Constructing heterojunction on N-doped porous carbon nanofibers for Li-S batteries: Effect of built-in electric field on efficient catalytic transformation kinetics

In this study, the CoP-Co2P heterojunction nanoparticles embedded in N-doping porous carbon nanofibers (CoP-Co2P/NPCNFs) are designed and prepared. The highly conductive grid of NPCNFs can physically confining lithium polysulfide (LiPS) and provide facilitated channels for Li+ transport. Furthermore, due to the spontaneous built-in electric field (BIEF) based on at the formed heterogeneous interfaces of CoP-Co2P, the heterojunction can significantly catalyze bi-directional conversion of LiPS and chemically adsorb LiPS which confirmed by the DFT calculations, suppressing the “shuttle effect” of LiPS. Thus, the Li-S batteries with the CoP-Co2P/NPCNFs modified separators exhibit a high initial specific capacity of 1322.86 mAh g−1 at 1 mA cm−2 and stable 695 cycles with a low decay rate (0.069 %). More importantly, the assembled pouch cell also can run with ultra-low specific capacity decay rate. Additionally, the pouch battery can also be applied to the operation of fans, temperature and humidity meters, mobile phone charging, etc.

Transformer enables ion transport behavior evolution and conductivity regulation for solid electrolyte

Ab initio molecular dynamics (AIMD) is an important technique for studying ion transport within solid electrolyte and interface effects between electrode and electrolyte, which is particularly critical for the rational design of new energy materials. However, AIMD is limited by the high-cost density functional theory (DFT) solution process and is unable to reach the time scale of the entire dynamic simulation, resulting in time-consuming AIMD calculations and a considerable scarcity of AIMD-based conductor data. Here, we propose a sequence relational large model based on transformer (T-AIMD) to infer ion diffusion from mean square displacement sequence data and hybrid multi-source material descriptor. T-AIMD successfully learns the whole long-range atomic diffusion to predict the ionic conductivity (σ) of any ion in any crystal structure to find fast-ion conductors, thus reducing the cost of AIMD simulation by a factor of 100. Using T-AIMD, we built the largest database of mixed ion conductors, and the σ of representative solid electrolytes has been successfully validated in previous battery experiments. Further, the manufactured solid-state battery with the predicted promising electrolyte exhibits almost no obvious capacity decay after 50 cycles with a high initial specific capacity of 1270 mAh g−1, which is promising to help devices work in extreme environments while guaranteeing battery life. By speeding up the prediction time of AIMD, the proposed T-AIMD opens the door for scientists to explore the atomic and molecular behaviors of other molecules/materials on long time scales, and will ultimately benefit the exploration of other key scientific questions in the energy field.

Single‐Atom Cobalt Catalyst Boosting Reaction Kinetics in Li–Organosulfur Battery

AbstractOrganosulfur compounds are regarded as a kind of prospective cathode materials for lithium batteries due to their high theoretical specific capacity. However, they still suffer from the issues of sluggish redox kinetics and low utilization. The rational design of the cathode host for effectively confining active materials and accelerating the sluggish sulfur kinetics is an effective strategy. Herein, the study synthesizes an atomic‐scale single‐atom cobalt catalyst and interweave it with CNTs to fabricate an ideal host material (donated as CoSANC@CNTs) for the cathode in Li–PTS batteries. Electrochemical measurements reveal that CoSANC not only efficiently accelerates the redox kinetics in the whole reaction process but also shows excellent adsorption capacity, which is corroborated by the theoretical calculation results as well. As excepted, the Li–PTS battery equipped with CoSANC@CNTs electrode delivers an outstanding long cycling stability with a high initial specific capacity of 550.2 mAh g−1 and a slow capacity decay rate of 0.05% per cycle over 700 cycles at 1 C. Even under a high PTS loading of 8.6 mg cm−2, the PTS/CoSANC@CNTs cathode is still maintained with an excellent capacity retention of 91.1% at 0.1 C after 50 cycles.

Rapid Joule heating-induced welding of silicon and graphene for enhanced lithium-ion battery anodes

In the pursuit of enhanced energy storage solutions, the application of silicon-based anode materials faces significant hurdles, primarily stemming from the rapid capacity degradation during battery cycles. This study introduces a novel and efficient method for fabricating Si/graphene composites (F-Si@rGO), enhancing the performance and longevity of silicon-based anodes. Utilizing ultra-high-speed thermal treatment, this technique controls the thermal interaction between carbon and silicon phases, leading to the formation of silicon carbide “riveting points” that firmly anchor silicon nanoparticles within the graphene matrix. This novel method effectively minimizes the problems of phase segregation, which are caused by varying degrees of wettability alteration in the two phases during conventional heat treatments, and guarantees a robust integration of graphene and silicon. This integration results in homogeneous charging and outstanding structural stability of the composites, over extended cycles of use. The resulting Si/graphene composites exhibit exceptional electrochemical performance, achieving a high initial capacity of 1141.3 mAh g−1 at 1C and maintaining a capacity of 894.95 mAh g−1 after 1000 cycles with minimal degradation (0.0216 % per cycle). This synthesis method, notable for its speed and scalability, offers a potential advancement in battery material technology, suggesting a path towards more resilient and efficient energy storage solutions.

Electrolyte-Enabled High-Voltage Operation of a Low-Nickel, Low-Cobalt Layered Oxide Cathode for High Energy Density Lithium-Ion Batteries.

The lithium-ion battery industry acknowledges the need to reduce expensive metals, such as cobalt and nickel, due to supply chain challenges. However, doing so can drastically reduce the overall battery energy density, attenuating the driving range for electric vehicles. Cycling to higher voltages can increase the capacity and energy density but will consequently exacerbate cell degradation due to the instability at high voltages. Herein, an advanced localized high-concentration electrolyte (LHCE) is utilized to enable long-term cycling of a low-Ni, low-Co layered oxide cathode LiNi0.60Mn0.31Co0.07Al0.02O2 (NMCA) in full cells with graphite or graphite-silicon anodes at 4.5V (≈4.6 vs Li+/Li). NMCA cells with the LHCE deliver a high initial capacity of 194mAhg-1 at C/10 rate along with 73% capacity retention after 400 cycles compared to 49% retention in a baseline carbonate electrolyte. This is facilitated by reduced impedance growth, active material loss, and gas evolution with the NMCA cathode. These improvements are attributed to the formation of robust, inorganic-rich interphase layers on both the cathode and anode throughout cycling, which are induced by a favorable salt decomposition in the LHCE. This study demonstrates the efficacy of electrolytes toward facilitating the operation of high-energy-density, long-life, and cost-effective cathodes.

Enhancing the cycling stability of full-concentration-gradient Ni-rich layered cathodes via in-situ Zr doping

Full-concentration-gradient (FCG) Ni-rich layered cathodes suffers from severe structural deterioration caused by the high-Ni content in the cores of the particles. Herein, an in-situ doping strategy is proposed to remove the structural deterioration in the cores of the particles, and a Zr-doped FCG LiNi0.80-xZrxCo0.05Mn0.15O2 (FNCMZ) cathode is successfully prepared. In-situ doping achieved a gradient distribution of Zr inside the particles, and induced the Li+/Ni2+mixing into an order structure. The order structure and Zr–O strong bonds reduced the degree of lattice contraction in the cores of the particles during the H2–H3 phase transition. Density functional theory calculations further proved that Zr doping and the order structure improved the electronic conductivity and structural stability of the cathodes. The improvement of structural stability and ion/electron migration environment enhanced the cycling stability and thermal stability of the FCG cathodes. Therefore, The FNCMZ0.2 cathode (doped with 0.2 mol% Zr) exhibited a high initial discharge specific capacity (181.7 mAh/g) with excellent capacity retention (91.9 %) after 200 cycles (1 C, 2.7–4.3 V). Even at a high cutoff voltage (4.5 V) and high temperature (50 °C), the capacity retention remained high at 83.7 % and 85.2 %, respectively, after 200 cycles. Overall, in-situ Zr doping effectively resolves structural deterioration in the cores of the particles and improves the electrochemical properties of FCG Ni-rich layered cathodes.

High‐Density and Freestanding Porous Carbon Film for Compact Sodium‐Ion Storage

AbstractPorous carbon materials are often difficult to achieve high density while possessing high porosity, which limits their application in compact energy storage. Here, a design of freestanding porous‐yet‐dense carbon films with a tunable density (1.08–1.33 g cm−3) and porosity (specific surface area of 0–423.8 m2 g−1) is presented through an assembly of porous carbon nanosheet with graphene oxide under vacuum filtration. The typical freestanding carbon films simultaneously deliver a high density of 1.08 g cm−3 and a high specific surface area of 423.8 m2 g−1 when the porous carbon nanosheet content is 75 wt.%. As anode materials for sodium‐ion batteries, the optimized freestanding carbon films deliver high volumetric capacity (270 mAh cm−3 at 20 mA g−1), high initial capacity efficiency (81 %) and superior long‐term cycling stability (1300 cycles with a capacity decay rate of 0.012 % per cycle). This study provides a promising direction for creating freestanding electrodes that meet both high‐porosity and high‐density requirements for compact sodium‐ion batteries.

In-situ coating strategy to synthesize ultra-soft sulfide solid-state electrolytes for dendrite-free lithium metal batteries

High energy density lithium metal batteries play a crucial role in future energy storage. High ionic conductivity argyrodite-type Li5.5PS4.5Cl1.5 is a promising candidate for future lithium metal all-solid-state batteries. However, under cold pressing conditions, the combination of high electronic conductivity and high porosity significantly accelerates the growth of lithium dendrites, resulting in low capacity and a short lifespan. In this study, we combined a simple wet ball milling and in-situ polymerization process to fabricate a polyvinylene carbonate-coated sulfide composite solid electrolyte. The ultra-soft particle, when cold-pressed without binders, completed a tightly packed and void-free internal structure. This electrolyte, combined with a stable LiF-rich interface layer on lithium metal, held a higher critical current density of 2.0 mA cm−2 than 0.65 mA cm−2 of uncoated argyrodite and a 2000-hour stable cycle at 0.5 mA cm−2 in lithium symmetric cells. The unique coating structure also mitigated the chemomechanical failure between electrolyte and electrode, preventing the rapid increase of interface impedance and achieving a high initial capacity of 173.5 mAh g−1 without a short circuit for 300 cycles in LiNi0.6Co0.2Mn0.2O2//Li cells.

High-Entropy Alloy Electrocatalysts Bidirectionally Promote Lithium Polysulfide Conversions for Long-Cycle-Life Lithium-Sulfur Batteries.

High-entropy alloys (HEAs) have attracted considerable attention, owing to their exceptional characteristics and high configurational entropy. Recent findings demonstrated that incorporating HEAs into sulfur cathodes can alleviate the shuttling effect of lithium polysulfides (LiPSs) and accelerate their redox reactions. Herein, we synthesized nano Pt0.25Cu0.25Fe0.15Co0.15Ni0.2 HEAs on hollow carbons (HCs; denoted as HEA/HC) by a facile pyrolysis strategy. The HEA/HC nanostructures were further integrated into hypha carbon nanobelts (HCNBs). The solid-solution phase formed by the uniform mixture of the five metal elements, i.e., Pt0.25Cu0.25Fe0.15Co0.15Ni0.2 HEAs, gave rise to a strong interaction between neighboring atoms in different metals, resulting in their adsorption energy transformation across a wide, multipeak, and nearly continuous spectrum. Meanwhile, the HEAs exhibited numerous active sites on their surface, which is beneficial to catalyzing the cascade conversion of LiPSs. Combining density functional theory (DFT) calculations with detailed experimental investigations, the prepared HEAs bidirectionally catalyze the cascade reactions of LiPSs and boost their conversion reaction rates. S/HEA@HC/HCNB cathodes achieved a low 0.034% decay rate for 2000 cycles at 1.0 C. Notably, the S/HEA@HC/HCNB cathode delivered a high initial areal capacity of 10.2 mAh cm-2 with a sulfur loading of 9 mg cm-2 at 0.1 C. The assembled pouch cell exhibited a capacity of 1077.9 mAh g-1 at the first discharge at 0.1 C. The capacity declined to 71.3% after 43 cycles at 0.1 C. In this work, we propose to utilize HEAs as catalysts not only to improve the cycling stability of lithium-sulfur batteries, but also to promote HEAs in energy storage applications.

Facile Fabrication of Large-Area CuO Flakes for Sodium-Ion Energy Storage Applications.

CuO is recognized as a promising anode material for sodium-ion batteries because of its impressive theoretical capacity of 674 mAh g-1, derived from its multiple electron transfer capabilities. However, its practical application is hindered by slow reaction kinetics and rapid capacity loss caused by side reactions during discharge/charge cycles. In this work, we introduce an innovative approach to fabricating large-area CuO and CuO@Al2O3 flakes through a combination of magnetron sputtering, thermal oxidation, and atomic layer deposition techniques. The resultant 2D CuO flakes demonstrate excellent electrochemical properties with a high initial reversible specific capacity of 487 mAh g-1 and good cycling stability, which are attributable to their unique architectures and superior structural durability. Furthermore, when these CuO flakes are coated with an ultrathin Al2O3 layer, the integration of the 2D structures with outer nanocoating leads to significantly enhanced electrochemical properties. Notably, even after 70 rate testing cycles, the CuO@Al2O3 materials maintain a high capacity of 525 mAh g-1 at a current density of 50 mA g-1. Remarkably, at a higher current density of 2000 mA g-1, these materials still achieve a capacity of 220 mAh g-1. Moreover, after 200 cycles at a current density of 200 mA g-1, a high charge capacity of 319 mAh g-1 is sustained. In addition, a full cell consisting of a CuO@Al2O3 anode and a NaNi1/3Fe1/3Mn1/3O2 cathode is investigated, showcasing remarkable cycling performance. Our findings underscore the potential of these innovative flake-like architectures as electrode materials in high-performance sodium-ion batteries, paving the way for advancements in energy storage technologies.

Carbon coated and oxygen vacancies incorporated Wadsley-Roth phase molybdenum niobium oxide for high-performance lithium-ion storage

Nb-based oxides with Wadsley-Roth shear structure have been aroused extensive research interest as promising anode for Li-ion batteries, due to the multi-electron redox, safe working voltage and open structural framework. However, the low intrinsic electronic conductivity limits their further practical applications. Herein, the lithium storage performances of MoNb6O18 with Wadsley-Roth shear structure are optimized by carbon coating and oxygen vacancies (VO-MNO@C), which synthesized with freeze-drying and subsequently heat treatment. As expected, the VO-MNO@C electrode demonstrates a high initial reversible capacity of 259.6 mAh/g at 0.2C and the capacity retention rate of 85.7 % after 200 cycles at 1C. Moreover, the reversible of Mo6+/Mo5+ and Mo5+/Mo4+ redox reaction can be effectively improved. In situ X-ray diffraction (XRD) and ex situ X-ray photoelectron spectroscopy (XPS) characterization indicate that VO-MNO@C undergoes a solid-solution structural evolution disclosing the stepwise reaction of Mo5+/Mo6+, Mo4+/Mo5+, Nb4+/Nb5+ and Nb3+/Nb4+ redox couples with a small volume variation of 5.7 %. Also, the full cell based on commercial LiMn2O4 cathode and VO-MNO@C anode displays an operating voltage about 2.4 V with the high energy density of 681.4 Wh/kg (calculated with the mass of anode). This work will offer more insights for the development of Wadsley-Roth shear structure anode materials with excellent Li-ion storage properties.

One-Step Molten-Salt-Assisted Approach for Direct Preparation and Regeneration of LiNi0.6Co0.2Mn0.2O2 Cathode.

Single-crystal lithium-nickel-manganese-cobalt-oxide (SC-NMC) is attracting increasing attention due to its excellent structural stability. However, its practical production faces challenges associated with complex precursor preparation processes and severe lithium-nickel cation mixing at high temperatures, which restricts its widespread application. Here, a molten-salt-assisted method is proposed using low-melting-point carbonates. This method obviates the necessity for precursor processes and simplified the synthetic procedure for SC-NMC down to a single isothermal sintering step. Multiple characterizations indicate that the acquired SC-LiNi0.6Mn0.2Co0.2O2 (SC-622) exhibits favorable structural capability against intra-granular fracture and suppressive Li+/Ni2+ cation mixing. Consequently, the SC-622 exhibits superior electrochemical performance with a high initial specific capacity (174 mAhg-1 at 0.1C, 3.0-4.3V) and excellent capacity retention (87.5% after 300 cycles at 1C). Moreover, this molten-salt-assisted method exhibits its effectiveness in directly regenerating SC-622 from spent NMC materials. The recovered material delivered a capacity of 125.4 mAhg-1 and retained 99.4% of the initial capacity after 250 cycles at 1 C. This work highlights the importance of understanding the process-structure-property relationships and can broadly guide the synthesis of other SC Ni-rich cathode materials.

Stable room-temperature sodium-sulfur battery enabled by pre-sodium activated carbon cloth anode and nonflammable localized high-concentration electrolyte

Room-temperature (RT) sodium-sulfur (Na–S) battery is a promising energy storage technology with low-cost, high-energy-density and environmental-friendliness. However, the current RT Na–S battery suffers from various problems, such as poor cycling stability and poor electrolyte-electrode compatibility caused by polysulfide shuttling and active Na-metal anode. Here, a nonflammable localized high-concentration electrolyte (LHCE) (sodium bis(trifluoromethanesulfonyl)imide salt, sulfolane solvent and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether diluent in a molar ratio of 1:2:2), and a pre-sodium activated carbon cloth (NaACC) anode, are combined to enable stable and high-safety RT Na–S battery. In LHCE, the shuttle effect of polysulfide is greatly alleviated, a stable anions-derived NaF-rich cathode electrolyte interphase is formed, and a solid-solid conversion mechanism of a solid S8-solid Na2Sn (1 ≤ n ≤ 3) is achieved. Meanwhile, the Na dendrites and side reactions between electrolyte and anode are effectively inhibited by using NaACC anode. Therefore, under the synergistic effect of electrolyte regulation and negative electrode structure optimization, although using a low N/P ratio of 1.7, the RT Na–S battery also delivers a high initial capacity of 1220.8 mAh g−1, good rate capability and stable cycling performance with a high average Coulombic efficiency of 99.1 %. The capacity still remains at 704.5 mAh g−1 after 100 cycles. This innovative combination of LHCE and NaACC anode in Na–S batteries provides a new idea for further achieving stable RT Na–S batteries with long-cycle-life and high-safety.

Solid-state lithium batteries composed of hematite and oxide electrolyte

As Li-ion battery anode materials, two types of hematite (Fe2O3(big), Fe2O3(ultrafine)) were evaluated by using liquid electrolyte and oxide-based solid electrolyte. Although the anode using Fe2O3(ultrafine) with larger specific surface area showed a high initial reversible capacity in the liquid-electrolyte cell, there was a steep capacity decay in the cycling test. In the solid-electrolyte cell, we obtained very low reversible capacities of 40 mA h g−1 for the anode using Fe2O3(big) with smaller specific surface area. In contrast, the capacity of Fe2O3(ultrafine) anode was as high as 400 mA h g−1 at the 20th cycle. This is the first demonstration of charge–discharge reactions for Fe2O3 anode in oxide-based solid-state batteries. The Fe2O3(ultrafine) particles were dispersed relatively uniformly between solid electrolyte in the active layer, suggesting that the contact area between Fe2O3 and solid electrolyte becomes large. Consequently, Fe2O3(ultrafine) could benefit from larger contact area delivering the suitable reaction site for Li+ to improve the anode performance.

Conformally reactive interphase enables excellent kinetics and cyclability in quasi-solid-state sodium metal battery

The rational design of flexible and robust anode-electrolyte interface is of great significance for extending the cycle life and improving the kinetics performance for sodium metal batteries (SMBs). Herein, a conformally reactive solid-electrolyte interphase (SEI) is constructed through a spontaneous absorption-oligomerization strategy in a quasi-solid-state polymer electrolyte (QSE-T). The polymeric network in the QSE-T system ensures a stable environment with high Na+ transfer number to suppress Na dendrite growth and chemical corrosion. Simultaneously, the reactive SEI is consisted of inorganic NaF and low crosslinked O-B-O and O-B-F segments derived from the 4-trifluoromethylphenylboronic acid (TFPBA) additive, which exhibits lower Na+ diffusion-barriers, and accommodates the ever-changing quasi-solid interface during cycling. Consequently, the NVP||QSE-T||Na cells exhibit ultra-stable cycling performance and high rate capability, with a high initial capacity of 95.1 mAh g−1 at a high rate of 5 C and a capacity retention rate of 86.6 % after 12,000 cycles.

High-rate lithium-ion battery performance of a ternary sea urchin-shaped CoNiO2@NiP6Mo18/CNTs composites

Bimetallic oxides are attractive anode materials for lithium-ion batteries (LIBs) due to their large theoretical capacity. However, the low conductivity, short cycle life, and poor rate capability are the bottlenecks for their further applications. To overcome above issues, the basket-like polymolybdate (NiP6Mo18) and carbon nanotubes (CNTs) were uniformly embedded on the urchin-shaped CoNiO2 nanospheres to yield a ternary composites CoNiO2@NiP6Mo18/CNTs via electrostatic adsorption. The multi-level morphology of urchin spinules accelerates the diffusion rate of Li+; CNT improves the conductivity and enhances cycle stability of the material; and heteropoly acid contributes more redox activity centres. Thus, CoNiO2@NiP6Mo18/CNTs as an anode of LIBs exhibits a high initial capacity (1396.7 mA h g−1 at 0.1 A g−1), long-term cycling stability (750.2 mA h g−1 after 300 cycles), and rate performance (450.3 mA h g−1 at 2 A g−1), which are superior to reported metallic oxides anode of LIBs. The density functional theory (DFT) and kinetic mechanism suggest that CoNiO2@NiP6Mo18/CNTs delivers an outstanding pseudocapacitance and rapid Li+ diffusion behaviors, which is due to the rich surface area of the urchin-like CoNiO2 with the uniform embeddedness of NiP6Mo18 and CNTs. This study provides a new idea for optimizing the performance of bimetallic oxides and developing high-rate lithium-ion battery composites.