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The utilization of MnO2/Mn2+chemistry in near-neutral pH acetate aqueous electrolytes provides an opportunity to achieve a higher energy density (theoretical capacity 616 mA h/g, discharge platform >1.5 V). However, this Zn-MnO2aqueous battery suffers from inevitable “dead Mn” and proton corrosion. In this study, we discover that the diffusion of the cathode reaction intermediate Mn3+is intrinsic for the generation of “dead Mn”, and the accumulation of “dead Mn” increases the H+which shuttles to the anode, inducing serious corrosion. A pH-neutral hydrogel ion-anchored strategy is proposed here not only to restrict the diffusion of Mn3+but also to suppress the proton transference. This hydrogel ion anchor is designed by deprotonating a series of monomers undergoing in situ free radical polymerization at the cathode interface. The anionic monomer with a moderate binding energy to manganese ions is screened to anchor Mn3+, which enhances the reversibility of the MnO2/Mn2+reaction. Simultaneously, a substantial amount of anionic groups and hydrophilic functional groups in the hydrogel effectively constrains the proton shuttle to corrode the anode. Consequently, the Zn/MnO2battery achieves exceptional cyclic stability of the MnO2/Mn2+reaction, sustaining 8500 cycles even at a relatively low current density and discharge current density of 1 mA/cm2. Our findings highlight the importance of anchoring Mn3+at the cathode interface and offer valuable insights for advancing practical applications of MnO2/Mn2+reactions.

Vanadium oxide has been extensively studied as a host of zinc ion intercalation but still suffers from low conductivity, dissolution, and byproduct accumulation during cycling. Here, we hydrothermally synthesize the VO2@MXene Ti3C2(MV) composite and find that in the MV//3 M Zn(CF3SO3)2//Zn system, the double hydroxide Zn12(CF3SO3)9(OH)15·nH2O (ZCOH) uniformly covers VO2during the charging process and dissolves reversibly during the discharge process. In situ X-ray diffraction of the MV combined with in situ pH measurements reveals that ZCOH acts as a pH buffer during cycling, which is beneficial to the cycling stability of batteries. And the theoretical calculation indicates that the decomposition energy required by ZCOH on the MV surface is lower than that on pure VO2, which is more conducive to ZCOH dissolution. The coin battery exhibits high-rate performance of 65.1% capacity retention at a current density of 15 A g–1(compared to 0.6 A g–1) and a long cycling life of 20,000 cycles with a capacity retention of 80.7%. For a 22.4 mA h soft-packaged battery, its capacity remains at 72.1% after 2000 cycles. This work demonstrates the active role of ZCOH in the electrochemical process of VO2and provides a new perspective for exploiting this mechanism to develop high-performance aqueous zinc-ion battery vanadium oxide cathode materials.

Owing to their high volumetric capacity, reasonably low redox potential, and budget friendliness, manganese metal batteries (MnMBs) are excellent candidates for batteries with a high energy-to-price ratio. However, since there is no suitable electrolyte ensuring reversible Mn plating/stripping due to the low redox potential of the Mn2+/Mn redox couple and the strong interaction between charge-dense Mn2+ions and solvents, the development of MnMBs has been largely constrained. Herein, a halogen-mediated non-aqueous electrolyte (HM-NAE) is developed to enable highly reversible Mn plating/stripping. Benefiting from this halogen-mediated mechanism, the asymmetric Mn cell can cycle stably more than 1,000 h with a Coulombic efficiency close to 100%. Moreover, a Mn|HM-NAE|Mo6S8full cell with high electrochemical performances is constructed and fully understood. This work offers a new avenue to the development of rechargeable, non-aqueous MnMB through electrolyte engineering, which can also shed light on other multivalent metal batteries and electroplating industry.

The stable and dimer-like Sn-Bi@C heterostructures with phase boundaries can facilitate the charge transportation and buffer the intrinsic stress, which can enhance the sodium storage properties.

Cu as the cathode of aqueous batteries faces serious side reactions. Here, Na2EDTA is introduced to the catholyte, greatly suppressing the formation of by-products and improving the electrochemical performance of Cu//Zn.

Vapor-phase-etching hard-template (VEHT) method can directly fabricate a series of tubular materials. TiO2−xtubes were used as model to illustrate their structure evolution mechanism of Rayleigh instability by in-situ TEM and good Na+storage performances.

Sodium-ion batteries (SIBs) are developed to address the serious concern about the limited resources of lithium. To achieve high energy density, anode materials with a large specific capacity and a low operation voltage are highly desirable. Herein, microsized particles of gray Sn (α-Sn) are explored as an anode material of SIBs for the first time. The distinct structure of α-Sn endows it the reduced volume change, the improved interaction with polymer binders and the in situformation of amorphous Sn, as supported by in situXRD, TEM and DFT calculations. Therefore, α-Sn exhibits an excellent electrochemical performance, much better than β-Sn widely used before. Even microsized particles of α-Sn without any treatments deliver a capacity of ∼451 mAh g–1after 3500 cycles at 2 A g–1or ∼464 mAh g–1at 4 A g–1in a rate test. The results indicate the promising potential of α-Sn in SIBs.

The shuttle effect of polysulfides and Li2S sluggish nucleation are the major problems hampering the further development of lithium–sulfur batteries. The reasonable design for sulfur host materials with catalytic function has been an effective strategy for promoting polysulfide conversion. Compared with other types of transition metal compounds, transition metal borides with high conductivity and catalytic capability are more suitable as sulfur host materials. Herein, a niobium diboride (NbB2) nanoparticle with abundant and high-efficiency catalytic sites has been synthesized by facile solid-phase reaction. The NbB2with both high conductivity and catalytic nature could regulate 3D-nucleation and growth of Li2S, decrease the reaction energy barrier, and accelerate the transformation of polysulfides. Thus, the NbB2cathode could retain a high capacity of 1014 mAh g–1after 100 cycles. In addition, the high initial specific capacities of 703/609 mAh g–1are also achieved at 5 C/10 C and could run for 1000/1300 cycles within a low decay rate of 0.057%/0.051%. Even with a high sulfur loading up to 16.5 mg cm–2, an initial areal capacity of 17 mAh cm–2could be achieved at 0.1 C. This work demonstrates a successful method for enhancing the kinetics of polysulfide conversion and directing Li2S nucleation.

With the advantages of a high theoretical capacity, proper working voltage, and abundant reserves, silicon (Si) is regarded as a promising anode for lithium-ion batteries. However, huge volume expansion and low electronic conductivity impede the commercialization of Si anodes. We devised a one-step, vacuum-assisted reactive carbon coating technique to controllably produce micrometer-sized nanoporous silicon confined by homogeneous N-doped carbon nanosheet frameworks (NPSi@NCNFs), achieved by the solid state reaction of a commercial bulk precursor and the subsequent evaporation of byproducts. The graphitization degree, C and N contents of the carbon shell, as well as the porosity of Si can be regulated by adjusting the synthetic conditions. A rational structure can mitigate volume expansion to maintain structural integrity, enhance electronic conductivity to facilitate charge transport, and serve as a protected layer to stabilize the solid electrolyte interphase. The NPSi@NCNF anode enables a stable cycling performance with 95.68% capacity retention for 4000 cycles at 5 A g–1. Furthermore, a flexible 2D/3D architecture is designed by conjugating NPSi@NCNFs with MXene. Lithiophilic NPSi@NCNFs homogenize Li nucleation and growth, evidenced by structural evolutions of MXene@NPSi@NCNF deposited Li. The application potential of NPSi@NCNFs and MXene@NPSi@NCNFs is estimated via assembling full cells with LiNi0.8Co0.1Mn0.1O2and LiNi0.5Mn1.5O4cathodes. This work offers a method for the rational design of alloy-based materials for advanced energy storage.

An integrated hybrid architecture composed of ultrathin Cu3P nanoparticles confined in porous carbon nanosheets (Cu3P ⊂ NPCSs) is synthesized by a self-designed self-templating strategy. Benefiting from the unique structural advantages, the two-dimensional hybrid electrode indicates excellent electrochemical performance as an anode material for potassium-ion batteries.

•Black phosphorus is prepared at large scale by reducing PCl5with metallic Al in melt AlCl3at 270 °C.•Through gradient centrifugation, gram-scale black phophorus quantum dots can be obtained.•The as-prepared black phosphorus used as anode for lithium ion battery exhibits a high specific capacity of 1610 mAh g−1with cycle life up to 1000 cycles.

Constructing SiOx-based composite materials with fast reaction kinetics and high stability is crucial but challenging for high-performance lithium-ion batteries. Herein, we developed the N-doped Ti3C2TxMXene ultrathin sheet (NTS)-coupled SiOxnanoparticles using a melamine-assisted ball milling and annealing procedure. The principle of melamine in exfoliating MXene was demonstrated by contrast experiments and theoretical calculations. The strong interfacial interactions between SiOxand the NTS (Si−O−Ti bond) can effectively enhance the electron transfer and ensure electrode stability. Moreover, the NTS with rich surface groups endowed the composite with a pseudocapacitive behavior, beneficial for fast lithium storage. As a result, the composite delivered a long lifespan (∼700 mA h g−1over 800 cycles at 1.0 A g−1) and a superior rate performance (596.4 mA h g−1at 5 A g−1). More importantly, the composite in half and full cells exhibited high areal capacity and good cycling stability at high mass loadings, revealing a promising application prospect.

The superior surface electron energy levels of WP2NWs facilitate the proton-coupled charge transfer dynamics between the adsorbed N2and WP2, leading to superior NRR catalytic activity.

Rechargeable zinc (Zn)-ion batteries are regarded as highly prospective candidates for next-generation renewable and safe energy storage systems. However, the uncontrolled dendrite growth of the Zn anode impedes their practical application. Here, a scalable and controllable approach is developed for converting commercial titanium (Ti) foil to 3D porous Ti, which retains good resistance to corrosion, high electrical conductivity, and excellent mechanical properties. Benefiting from a spontaneous ultrathin zincophilic titanium dioxide (TiO2) interfacial layer and continuous 3D structure, the 3D porous Ti can act as an effective host to achieve a 3D Ti/Zn metal anode. By ensuring homogeneous nucleation, uniform current distribution, and volume change accommodation, the dendritic growth of 3D Ti/Zn metal anode is effectively inhibited with stable Zn plating/stripping up to 2000 h with low polarization. When conjugated with a 3D sulfur-doped Ti3C2TxMXene@MnO2nanotube cathode, a high rate and stable Zn cell is achieved with 95.46% capacity retention after 500 cycles at a high rate of 5 A g–1. This work may also be interesting for researches in porous metals and other battery systems.

Silicon has been considered as the most promising anode candidate for next-generation lithium-ion batteries. However, the fast capacity decay caused by huge volume expansion and low electronic conductivity limit the electrochemical performance. Herein, atomic distributed, air-stable, layer-by-layer-assembled Si/C (L-Si/C) is designed and in situconstructed from commercial micron-sized layered CaSi2alloy with the greenhouse gas CO2. The inner structure of Si as well as the content and graphitization of C can be regulated by simply adjusting the reaction conditions. The rationally designed layered structure can enhance electronic conductivity and mitigate volume change without disrupting the carbon layer or destroying the solid electrolyte interface. Moreover, the single-layer Si and C can enhance lithium-ion transport in active materials. With these advantages, L-Si/C anode delivers an 82.85% capacity retention even after 3200 cycles and superior rate performance. The battery-capacitance dual-model mechanism is certified viaquantitative kinetics measurement. Besides, the self-standing architecture is designed viaassembling L-Si/C and MXene. Lithiophilic L-Si/C can guide homogeneous Li deposition with alleviated volume change. With the MXene/L-Si/C host for lithium–metal batteries, an ultralong life span up to 500 h in a carbonate-based electrolyte is achieved. A full cell with a high-energy 5 V LiNi0.5Mn1.5O4cathode is constructed to verify the practicality of L-Si/C and MXene/L-Si/C. The rational design of a special layer structure may propose a strategy for other materials and energy storage systems.

Nanostructured anode materials have attracted significant attention for lithium-ion batteries (LIBs) due to their high specific capacity. However, their practical application is hindered by the rather low areal capacity in the ultrathin electrode (∼1 mg cm–2). Herein, we propose a new strategy of an all-conductive electrode to fabricate a flexible and free-standing vanadium nitride@N-doped carbon/graphene (VN@C/G) thick electrode. Due to the free-standing structure and absence of any nonconductive components in the electrode, the obtained thick electrode displays excellent cycling performances. With the high mass loading of 5 mg cm–2, VN based electrodes achieve a reversible capacity of 2.6 mAh cm–2after 200 cycles. Moreover, the all-conductive electrode allows an ultrahigh areal capacity of 7 mAh cm–2with a high mass loading of 18.3 mg cm–2, which is comparable to state-of-the-art graphite anodes (4 mAh cm–2). Theoretical calculations prove the metallic conductivity of VN, which allows fast charge transport in the thick electrode. This strategy of fabricating all-conductive electrodes shows great potentials to achieve high areal capacity in practical lithium-ion batteries.

Two-dimensional carbon architectures are attracting tremendous interests for various promising applications due to their outstanding electronic and mechanical properties, although it is a great challenge to rationally devise facile and operative methodologies to engineer their structural traits owing to complex synthetic processes. Herein, for the first time, we fabricate two-dimensional carbon nanoribbons via direct thermal exfoliation of one-dimensional Ni-based metal–organic framework (MOF) nanorods, in which interconnected graphitic carbon nanocages are self-assembled into a belt-like superstructure with carbon-encapsulated Ni nanoparticles immobilized on the surface. Due to the unparalleled structural superiority, the MOF-derived carbon nanobelts exhibit excellent catalytic performances in electrocatalytic hydrogen evolution. Importantly, the practical synthetic strategy may trigger the rapid development of carbon-based superstructures in many frontier fields.

Lithium metal anodes are considered as promising candidates for next-generation high-energy-density batteries. However, the dendrite formation of Li metal anodes during charge–discharge results in some serious issues. Herein, we show a simple way to flatten the Li metal deposition surface on Ag-modified Cu foil using a spherical island model. In this model, Ag nuclei induce the deposition of Li atoms with low nucleation potentials at the initial heterogeneous nucleation stage. Then, Li homogeneously grows around the spherical islands and these regular islands overlap each other and form a flat Li surface. On the bare Cu foil surface, the Li growth behavior is random, and the deposition surface is porous and covered with dendrites. Stable long-term plating/stripping of a symmetric battery over 800 h at 1 mA cm–2was achieved. Moreover, the super flat Li structure can be achieved by constructing islands into a three-dimensional (3D) current collector using the spherical island model. Benefiting from the spherical island model, Li||LiFePO4and Li||O2batteries with this 3D anode structure can obtain a stable performance.

High-performance cathodes are essential for all kinds of rechargeable batteries, and vanadium pentoxide (V2O5) has wide applications as a cathode in various batteries because of its high theoretical capacity, abundant reserves, and high safety performances. However, the irreversible phase transitions and sluggish ion diffusion limit its advancements. Herein, morphology-tunable micron-sized nanoporous V2O5arrays are synthesized from V2CTxMXene by a one-step annealing process. The component and structure of the V2CTxMXene are simply controlled by regulating the reaction time. The effects of annealing conditions on crystallinity, microstructure, and electrochemical performance of V2O5are further probed. The rationally designed V2O5possesses special porous architecture, 2D structure, and pseudocapacitive effect, which ensures high ion accessibility, excellent structure stability, and fast charge transport. As a consequence, the optimal V2O5cathode for gel zinc-ion batteries exhibits high capacity (358.7 mA h g–1at 200 mA g–1after 400 cycles), superior rate performance (250.4 mA h g–1at 8000 mA g–1), and stable long-term cyclability (279 mA h g–1at 2000 mA g–1over 3500 cycles). The zinc storage enhancing mechanism is assessed by quantitative kinetics analysis. Furthermore, the V2O5cathode also delivers an improved potassium storage performance. This work may provide a universal avenue to fabricate high-performance electrodes from MXene-based materials for next generation battery systems.

The past few decades have witnessed the unprecedented success of the commercialized LiCoO2layered cathode in consumer electronics, but it still faces the poor rate capability and cycling performance because of its hexagonal layered α-NaFeO2structure and the high energy of electrochemically active crystal planes. In a bid to address these problems, we report the delicate design and synthesis of hierarchical fusiform LiCoO2microrods constructed by directionally assembled nanoplatelets along the [001] direction via a self-template route (PAHF-LCO). Remarkably, it is the first time that almost all the exposed surfaces of layered cathodes are dominated by the consistent {010} facets, which enable the express channels of Li+diffusion to penetrate throughout the entire fusiform microrods. The as-obtained PAHF-LCO cathode material delivers specific capacities of 113 and 106 mA h g–1at 10 and 20 C after 200 cycles, respectively. Even under the high rate of 50 C, the discharge capacity initializes around 105 mA h g–1and ends around 80 mA h g–1after 200 cycles. The improvement mechanisms to the high-rate performance through crystal habit tuning have also been unraveled. The enhanced electrochemical performance can be attributed to the hierarchical fusiform structure as well as the coordinated crystal orientation of {010} facets.

Vanadium-based compounds with an open framework structure have become the subject of much recent investigation into aqueous zinc-ion batteries (AZIBs) due to high specific capacity. However, there are some issues with vanadium dissolution from a cathode framework as well as the generation of byproducts during discharge that should not be ignored, which could cause severe capacity deterioration and inadequate cycle life. Herein, we report several barium vanadate nanobelt cathodes constructed of two sorts of architectures, i.e., Ba1.2V6O16·3H2O and BaV6O16·3H2O (V3O8-type) and BaxV2O5·nH2O (V2O5-type), which are controllably synthesized by tuning the amount of barium precursor. Benefiting from the robust architecture, layered BaxV3O8-type nanobelts (Ba1.2V6O16·3H2O) exhibit superior rate capability and long-term cyclability owing to fast zinc-ion kinetics, enabled by efficiently suppressing cathode dissolution as well as greatly eliminating the generation of byproduct Zn4SO4(OH)6·xH2O, which provides a reasonable strategy to engineer cathode materials with robust architectures to improve the electrochemical performance of AZIBs.

Li metal has been regarded as one of the most promising anode candidates for high-energy rechargeable lithium batteries. Nevertheless, the practical applications of the Li anode have been hampered because of its low Coulombic efficiency and safety hazards. Here, acid-treated g-C3N4with O- and N-containing groups are coated on Li foil through a facile physical pressing method. The O- and N-containing groups cooperate to rearrange the concentration of Li ions and enhance the Li ion transfer. Hence, the cycle and rate performances of acid-treated g-C3N4-coated Li electrodes are greatly improved in symmetric cells, which show cycling stability over 400 h at 1 mA cm–2in ester-based electrolytes and over 2100 h in ether-based electrolytes. As for the Li//LiFePO4full cells, there is a high capacity retention of 80% over 400 cycles at 1 C. The full cells of Li//S in ether-based electrolytes also exhibit a capacity of 520 mA h g–1after 400 cycles at 1 C.

N-Doped carbon-encapsulated SiOxand Co nanoparticles are synthesized by the calcination of ZIF-67-coated SiOxnanoparticles. This composite exhibits good electrochemical conductivity and superior accommodation to volume change from N-doped carbon and Co with SiOxnanoparticles, exhibiting improved cycle and rate performances for lithium storage. It retains a capacity of 1044 mA h g–1over 150 cycles at 1.5 A g–1, outperforming those without Co or N-doped carbon. It well confirms the contributions of Co- and N-doped carbon to the electrochemical properties of SiOx. Even after 350 cycles at 1.0 A g–1, this composite nonetheless delivers a capacity of 900 mA h g–1. If it is coupled with LiFePO4, the full cells show a stable cycling, indicating the promising application of this composite.

Owing to its distinctive structure and properties, 2D silicon (2DSi) has been widely applied in hydrogen storage, sensors, electronic device, catalysis, electrochemical energy storage, etc. However, scalable and low-cost fabrication of high-quality 2DSi remains a great challenge. In this work, a physical vacuum distillation method is designed to obtain high-quality 2DSi from a bulk layered calcium–silicon alloy. With this method, the lower boiling point calcium metal is evaporated to construct 2DSi and can be further recycled. The effect of vacuum conditions on morphology, components, and electrochemical properties is further explored. As an anode for lithium-ion batteries, the 2DSi delivers a stable cyclability of 835 mAh g–1after 3000 cycles at 5000 mA g–1(0.003025% capacity decay per cycle). The electrochemical performance enhancing mechanism is also probed. In addition, a 2D/2D flexible and binder-free paper by combining 2DSi with 2D MXene is constructed. As a lithiophilic nuclear agent for lithium metal anodes, the 2DSi can efficiently suppress the Li dendrite growth and reduce nucleation barriers, achieving a high Coulombic efficiency (98% at 1 mA cm–2, 97% at 2 mA cm–2) around 600 cycles and a long lifespan of 1000 h. The crystal growth difference of lithium metal on Cu foil and 2DSi is studied. This work may provide a pathway for green, low-cost, and scalable synthesis of 2D materials.

Proposing a one-step pyrolysis strategy to fabricate a novel bilayer-shelled N, O-doped hollow porous carbon microspheres (NOHPC) anode.The optimized NOHPC anode displays a high K-storage capacity of 325.9 mAh g−1at 0.1 A g−1and excellent rate performance (201.1 mAh g−1at 5 A g−1after 6000 cycles).The assembled NOHPC//hollow porous activated carbon microspheres (HPAC) potassium ion hybrid capacitors deliver a high energy density of 90.1 Wh kg−1at a power density of 939.6 W kg−1even over 6000 cycles.

Dendrite growth of metal anodes is one of the key hindrances for both secondary aqueous metal batteries and nonaqueous metal batteries. In this work, a freestanding Ti3C2TxMXene@Zn paper is designed as both zinc metal anode and lithium metal anode host to address the issue. The binder-free Ti3C2TxMXene@Zn paper exhibits merits of good mechanical flexibility, high electronic conductivity, hydrophilicity, and lithiophilicity. The crystal growth mechanism of Zn metal on common Zn foil and Ti3C2TxMXene@Zn composite is also studied. It is found that the Ti3C2TxMXene@Zn paper can effectively suppress the dendrite growth of Zn, enabling reversible and fast Zn plating/stripping kinetics in an aqueous electrolyte. Moreover, the Ti3C2TxMXene@Zn paper can be used as a 3D host for a lithium metal anode. In this host, Zn is utilized as a nucleation agent to suppress the Li dendrite growth. The freestanding Ti3C2TxMXene@Zn@Li anode exhibits superior reversibility with high Coulombic efficiency (97.69% over 600 cycles at 1.0 mA cm–2) and low polarization compared with the Cu@Li anode. These findings may be useful for the design of dendrite-free metal-based energy storage systems.

The exploration of high-performance anode materials is imperative for the development of sodium-ion batteries (SIBs). Herein, a molten-salt-assisted approach is developed to prepare crystallized Zn2GeO4clusters constructed by interconnected nanorods, and the Na-ion storage mechanism is studied systemically through in situ X-ray diffraction, ex situ X-ray photoelectron spectroscopy, and high-resolution transmission microscopy associated with galvanostatic intermittent titration technique. The Zn2GeO4anode undergoes conversion reactions followed by the alloying reaction. The large channel in the Zn2GeO4crystal structure ensures insertion of sodium ions. The amorphous transformation during the initial discharge process increases the active site for the fast electrochemical reaction. As the anode for SIBs, the Zn2GeO4cluster exhibits good rate capability with a capacity retention of 111.1 mA h g–1at 20 A g–1in half cells and 118.9 mA h g–1at 2 A g–1in full cells, associated with a capacity of 184.2 mA h g–1at 0.5 A g–1after 500 cycles. The ex situ scanning electron microscopy images of the electrode material disclose that the hierarchical structure can accommodate the volume variation of Zn2GeO4during discharge/charge cycling, facilitating long cycling stability. The investigation of Zn2GeO4provides new insight for the development of high-rate anode materials for SIBs.

SiOxcoating is an effective strategy to prolong the cycling stability of Si-based anodes due to the robust interaction between Si and the SiOxlayer. However, the SiOxlayer-protected Si anode is limited by the relatively low initial Coulombic efficiency and sluggish Li+diffusion ability induced by the SiOxlayer. Herein, we present the preparation of selectively prelithiated Si@SiOx(Si@Li2SiO3) anode by using a facile strategy to resolve the above issues. As the anode for lithium ion batteries, Si@Li2SiO3exhibits a high initial Coulombic efficiency (ICE) of 89.1%, an excellent rate performance (959 mA h g–1at 30 A g–1), and a superior capacity retention (3215 mA h g–1). The full cell with LiFePO4cathode and Si@Li2SiO3anodes is successfully assembled, disclosing a high ICE of 91.1% and excellent long cycling stability. The superior electrochemical performance of Si@Li2SiO3can be attributed to the coating layer, which can strengthen the integrity of the electrode, decrease irreversible reactions, and provide efficient Li+diffusion channels.

Graphene-like N,S-codoped bio-carbon nanosheets (GNSCS) were prepared by a facile and environment-friendly NaCl non-aqueous ionic liquid route to house sulfur for lithium-sulfur battery. The natural nori powder was calcined at 900°C for 3 h under Ar, in which NaCl non-aqueous ionic liquid can exfoliate carbon aggregates into nanosheets. The structural characterization of GNSCS by a series of techniques demonstrates the graphene-like feature. When evaluated as the matrix for sulfur cathode, GNSCS/S exhibits more prominent cycling stability and rate capability. A discharge capacity of 548 mA h g−1at a current density of 1.6 A g−1after 400 cycles was delivered with a capacity fade rate of only 0.13% per cycle and an initial Coulombic efficiency (CE) as high as 99.7%. When increasing the areal sulfur loading up to 3 mg cm−2, the discharge capacity can still be retained at 647 mA h g−1after more than 100 cycles with a low capacity degradation of only ~0.30% per cycle. The features of N/S dual-doping and the graphene-like structure are propitious to the electron transportation, lithium-ion diffusion and more active sites for chemically adsorbing polysulfides. It is anticipated that other functional biochar carbon can also be attained viathe low-cost, sustainable and green method. 本论文通过结构设计利用简单方法成功制备了一种二维N,S共掺杂类石墨烯纳米片复合结构, 即利用NaCl非离子液体的剥离作用 使生物质剥离得到二维片层类石墨烯结构. 这种新的非离子液体剥离技术较其他的碳材料剥离技术具有环境友好性、 低成本、 安全无毒 性等优势, 有利于实现量化制备锂硫电池电极材料. 该材料采用大自然中广泛存在的紫菜作为原料, 其内部富含的氨基酸为原位掺杂N,S元素提供了可能性. 二维结构的纳米片能够提供有效的导电性和电解液浸润性的网络结构, 同时还能够有效地降低电池在充放电循环过 程中导致的体积膨胀效应, 最终实现一种高机械性能、 优异电化学活性的电极在锂硫电池储能领域中的应用.

A novel electrolyte additive[?](trifluoroethoxy)pentafluorocyclotriphosphazene (TFPN) is synthesized and tested as flame retardant additives for lithium metal batteries. Flame test reveals that 5 wt% TFPN addition can enable electrolyte non-flammable. Moreover, it is found that TFPN addition could form a LiF-rich solid electrolyte layer (SEI) on lithium metal and suppress the growth of lithium dendrites. With 5 wt% TFPN added electrolyte, the Ni-rich LiNi0.8Co0.1Mn0.1O2 (NCM811)/Li full cells show a high reversible capacity and a much improved capacity retention. These results suggest that TFPN may be used as a promising multifunctional additive for lithium metal batteries. These findings may also be useful for the design of other nonaqueous batteries.

Potassium-ion batteries are now regarded as powerful competitors to lithium-ion batteries due to their merits of low-cost and abundant resource contrasted with state-of-art lithium ion batteries. However, the extremely flammable electrolytes may cause severe safety issues. Herein, we report an intrinsic non-flammable trimethyl phosphate-based potassium ion battery electrolyte. The problem of its poor electrochemical compatibility with graphite electrode is successful settled by using concentrated salt electrolyte. Graphite anode with high concentrated potassium bis(fluorosulfonyl)imide (KFSI)/trimethyl phosphate (TMP) electrolyte demonstrates high Coulombic efficiency and stable cyclability after 80 cycles. The performance enhancement mechanism is further probed via X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Raman spectroscopy, and scanning electron microscopy (SEM). The flame-retarding character of the concentrated electrolyte with stable electrochemical performance paves the way toward low cost and highly safe potassium ion batteries.

Potassium-ion batteries (KIBs) are considered favorable candidates for post-lithium-ion batteries, a quality attributed to their low cost, abundance as a resource, and high working potential (−2.93 V for K+/K). Owning to its relatively low potassiation potential and high theoretical capacity, antimony (Sb) is one of the most favorable anodes for KIBs. However, the large volume changes during K–Sb alloying and dealloying causes fast capacity degradation. In this report, nanoporous Sb (NP-Sb) is fabricated by an environmentally friendly vacuum-distillation method. The NP-Sb is formed viaevaporating low-boiling-point zinc (Zn). The byproduct Zn can be recycled. It is further found that the morphology and porosity can be controlled by adjusting Zn–Sb composition and distillation temperature. The nanoporous structure can accommodate volume expansion and accelerate ion transport. The NP-Sb anode delivers an improved electrochemical performance. These results suggest that the vacuum-distillation method may provide a direction for the green, large-scale, and tunable fabrication of nanoporous materials.

Sodium ion batteries are one of most promising alternatives to lithium ion batteries for large-scale energy storage, due to the high abundance and low cost of sodium in the earth. However, the lack of advanced electrode materials greatly affects their applications. Here, layered-structure SbPO4is explored as an anode material for sodium ion batteries in terms of SbPO4nanorods on reduced graphene oxide (SbPO4/rGO). In situtransmission electron microscopy images reveal the preferential expansion along the transverse direction of the nanorods upon the first discharging, which arises from the reduction of SbPO4to Sb and the subsequent alloying of Sb as supported by in situX-ray diffraction and selected area electron diffraction patterns. SbPO4/rGO exhibits a capacity retention of 99% after 100 cycles at 0.5 A g–1both in half cells and in full cells. Its specific capacity at 5 A g–1is 214 mA h g–1in half cells or 134 mA h g–1in full cells. Moreover, the energy density of the full cells at 1.2 kW kg–1totalis still 99.8 W h kg–1total, very promising as an advanced electrode material.

Despite the fact that metal-based compounds have been extensively used as sulfur cathode additives, large variations in electrochemical performance have been commonly observed from one material to another, which cannot be simply explained by the adsorption capability. Herein, we have systematically studied the kinetic behaviors of Li-S chemistry on Co-based compounds with fixed metal cation and varied non-metal anions, and deciphered the intrinsic modulation essence of the anions. Among the Co-based compounds, CoP exhibits the lowest overpotential for polysulfide transformation. Even at 40.0 C, S@CoP/rGO still delivers a high capacity of 417.3 mA hr g−1and an unprecedented power density of 137.3 kW kg−1, representing the best rate performance. DFT analysis reveals that the performance variations mainly originate from the shift of p band centers, which modulate the interfacial electron transfer dynamics. This work could unlock the potential of band engineering for Li-S batteries and beyond.

Metal-organic frameworks (MOFs)-derived metal chalcogenides/carbon, has been developed as promising anode materials for lithium/sodium ion batteries. However, they are not explored for potassium-ion batteries yet. Here, ZIF-67 is employed as a self-sacrificed template to synthesize Co0.85Se nanoparticles in N-doped carbon as an anode material for potassium-ion batteries. In this composite, N-doped carbon enhances the electron conductivity, cushions the volume change and inhibits the aggregation of Co0.85Se upon cycling. Meanwhile, mesoporous structure shortens the diffusion distance of potassium ions, as well as increases the contact between electrolyte and electrode. These features endow this composite superior performances. It delivers a specific capacity of 114.7 mA h g−1at 1000 mA g−1after 250 cycles. At 2.0 A g−1, the specific capacity still maintains at 110.7 mA h g−1. The electrochemical performances of full cells based on Co0.85Se@NC as an anode material are also investigated. The result greatly spurs the exploration of metal chalcogenides as anode materials for potassium ion batteries.

The common sulfur/carbon (S/C) composite cathodes in lithium sulfur batteries suffer gradual capacity fading over long-term cycling incurred by the poor physical confinement of sulfur in a nonpolar carbon host. In this work, these issues are significantly relieved by introducing polar SnO2or SnS2species into the S/C composite. SnO2- or SnS2-stabilized sulfur in porous carbon composites (SnO2/S/C and SnS2/S/C) have been obtained through a baked-in-salt or sealed-in-vessel approach at 245 °C, starting from metallic tin (mp 231.89 °C), excess sulfur, and porous carbon. Both of the in situ-formed SnO2and SnS2in the two composites could ensure chemical interaction with lithium polysulfide (LiPS) intermediates proven by theoretical calculation. Compared to SnO2/S/C, the SnS2/S/C sample affords a more appropriate binding effect and shows lower charge transfer resistance, which is important for the efficient redox reaction of the adsorbed LiPS intermediates during cycling. When used as cathodes for Li–S batteries, the SnS2/S/C composite with sulfur loading of 78 wt % exhibits superior electrochemical performance. It delivers reversible capacities of 780 mAh g–1after 300 cycles at 0.5 C. When further coupled with a Ge/C anode, the full cell also shows good cycling stability and efficiency.

A molten salt metallothermic reduction strategy is developed for preparing phosphorus (P) or phosphides controllably at low temperature, which is simple, energy-saving, and easy to scale up. Typically, synthesis of spongelike porous amorphous P (a-P) is realized through reduction of PCl5with Zn (or Al) at 50 °C assisted by AlCl3. It is demonstrated that an adduct salt PCl5·AlCl3composed of PCl4+and AlCl4–ions with a low melting point below 50 °C is formed from covalent salts PCl5and AlCl3. This system is also suitable for producing nanostructured phosphides by adding corresponding transition-metal (Co, Fe, and Cu) chlorides even at 50 °C. As a Li storage anode, the as-prepared a-P exhibits a capacity of 1605 mA h g–1at 0.2 C, a good rate capability of 1283 mA h g–1at 10 C, and a long-term cycling stability of 1082 mA h g–1after 200 cycles. Additionally, the Na-/K-ion storage performance is investigated systematically.

Lithium–sulfur batteries are the most promising candidates for advanced electrochemical energy storage systems benefiting from their high energy density and low cost of sulfur. Improving the conductivity of sulfur cathode and stabilizing the polysulfide shuttle are the key factors for obtaining high-performance lithium–sulfur batteries. Herein, metallic and polar TiB2nanomaterials are applied for the first time as sulfur hosts. The 70S/TiB2composite exhibits a long-term cycling stability up to 500 cycles at the current density of 1 C. It is worth noting that even when the sulfur areal mass loading is up to 3.9 mg cm–2, a stable capacity of 837 mA h g–1can be still maintained after 100 cycles. The outstanding electrochemical performance can be attributed to the strong anchoring effect of TiB2to lithium polysulfides, which is confirmed by the X-ray photoelectron spectroscopy analyses and theoretical calculations with a favorable surface-passivated chemistry. The study presented here will shed a new light for metal borides as hosts to improve the cycling life of lithium–sulfur batteries and provide a deep comprehension of the instinct interaction evolution at a molecular level, which is invaluable in the material rational fabrication for future high-performance Li–S batteries.

Nickle sulfides as promising anode materials for sodium-ion batteries have attracted tremendous attention owing to their large specific capacity and good electrical conductivity. However, the relative large volume changes during the sodiation/desodiation process usually result in a fast capacity decay, poor cycling stability, and sluggish electrode kinetics which hinder their practical applications. Herein, NiS1.03porous hollow spheres (NiS1.03PHSs) and porous NiS1.03hollow cages (NiS1.03PHCs) with high yield are designed and selectively fabricated viaa simple solvothermal and subsequent annealing approach. The obtained NiS1.03PHSs display long-term cycling stability (127 mAh g–1after 6000 cycles at 8 A g–1) and excellent rate performance (605 mAh g–1at 1 A g–1and 175 mAh g–1at 15 A g–1). NiS1.03PHCs also show high rate capability and outstanding cycling stability. In addition, the analyses results of in situand ex situXRD patterns and HRTEM images reveal the reversible Na-ion conversion mechanism of NiS1.03. It is also worth noting that the NiS1.03PHSs//FeFe(CN)6full cell is successfully assembled and exhibits an initial reversible capacity of 460 mAh g–1at 0.5 A g–1, which further evidence that NiS1.03is a kind of prospective anode material for SIBs.

Silicon is considered as one of the most favorable anode materials for next-generation lithium-ion batteries. Nanoporous silicon is synthesized viaa green, facile, and controllable vacuum distillation method from the commercial Mg2Si alloy. Nanoporous silicon is formed by the evaporation of low boiling point Mg. In this method, the magnesium metal from the Mg2Si alloy can be recycled. The pore sizes of nanoporous silicon can be secured by adjusting the distillated temperature and time. The optimized nanoporous silicon (800 °C, 0.5 h) delivers a discharge capacity of 2034 mA h g–1at 200 mA g–1for 100 cycles, a cycling stability with more than 1180 mA h g–1even after 400 cycles at 1000 mA g–1, and a rate capability of 855 mA h g–1at 5000 mA g–1. The electrochemical properties might be ascribed to its porous structure, which may accommodate large volume change during the cycling process. These results suggest that the green, scalable, and controllable approach may offer a pathway for the commercialization of high-performance Si anodes. This method may also be extended to construct other nanoporous materials.

Lithium metal has been considered as the most ideal anode in lithium based batteries due to its high specific theoretical capacity and lowest working potential. Nevertheless, the growth of dendritic or mossy Li, the crush of solid electrolyte interface (SEI) layer and the successive reactions between the fresh Li metal and electrolytes hinder the commercialization of Li metal anode. In this paper, we utilize an environmental–friendly and low–cost one–step facile vacuum distillation approach to fabricate the 3D porous Cu current collector from commercial brass foil (Cu–Zn alloy) for Li metal anodes. The continuous porous 3D Cu skeleton is obtained after the vacuum distillated the low boiling point Zn (907 °C) component. The voids of the 3D porous copper can be easily regulated by adjusting the distillation temperature and time. As a current collector, the as–prepared 3D porous copper can inhibit the growth of Li dendrite and mitigate the huge volume change of Li metal anode during cycling process, resulting in stable SEI layer and electrode structure. As a result, the 3D porous Cu current collector can achieve a steady Coulumbic efficiency after 120 cycles at 0.52 mA cm−2and for more than 80 cycles at 1.04 mA cm−2with much reduced polarization. A long lifespan of 800 h is attained in the symmetric Li|Li@Cu battery, and it also indicates the potential for practical application when the Li@Cu|Li(NiCoMn)O2full battery is built. More promisingly, such a vacuum distillation method is plain and simple to be combined with current commercial technique of Li metal anode manufacture using a Cu current collector, exhibiting great potentials to accelerate the commercialization lithium metal based (such as Lithium–sulfur and Lithium–air) batteries and the development of high–energy lithium–ion batteries.

Transition-metal sulfides/selenides are explored as advanced electrode materials for nonaqueous sodium-ion capacitors, using FeS2–xSexas an example. A solid solution of S/Se in FeS2–xSexallows it to combine the high capacity of FeS2and the good diffusion kinetics of FeSe2together, thereby exhibiting excellent cycle stability (∼220 mA h g–1after 6000 cycles at 2 A g–1) and superior rate capability (∼210 mA h g–1at 40 A g–1) within 0.8–3.0 V. These results are much better than those of FeS2and FeSe2, confirming the advantages of S/Se solid solution, as supported by EIS spectra, DFT calculations, and electronic conductivity. As FeS2–xSexis paired with the activated carbon (AC) as Na-ion capacitors, this device is also better than sodium-ion batteries of FeS2–xSex//Na3V2(PO4)3and sodium-ion capacitors of metal oxides//AC, particularly at high rates. These results open a new door for the applications of sulfides/selenides in another device of electrochemical energy storage.

Generally, Ge-based anodes are prepared by metallothermic reduction of GeO2with Mg at 650 °C. Herein, a molten-salt system is developed a low-temperature metallothermic reduction of GeO2to prepare nanostructured Ge based anode materials. Typically, mesoporous hollow Ge microspheres are prepared by reduction of GeO2with metallic Mg in molten ZnCl2(mp 292) at 350 °C. Monodispersed Ge particles are synthesized through reduction of GeO2with Mg in molten AlCl3(mp 192 °C) at 250 °C. The meso-porous Ge anode delivers the reversible capacity of 1291 mA h g–1at 0.2 C after 150 cycles with a retention of 97.3%, 1217 mA h g–1at 0.8 C after 400 cycles with a retention of 91.9%, and superior rate capability with a capacity of 673 mA h g–1even at 10 C. Then, the reaction mechanism and full-cell performance of as-prepared Ge anodes are studied systemically.

The insulating and dissoluble features of sulfur and polysulfide intermediates significantly hinder the cycling performance and coulombic efficiency of Li–S batteries. We herein design fully integrated hierarchical double-shelled Co9S8@CNT hollow nanospheres as a sulfur host, where each shell owns a tri-layer sandwich structure and six functional layers are constructed in total. Uniquely, the hierarchical structures integrate the beneficial functions of electrical conductivity, ion diffusion, polysulfide immobilization and polysulfide redox kinetics. The Co9S8@CNT/S delivers a reversible specific capacity of 1415 mA h g−1at 0.2C, which is very close to the theoretical capacity of sulfur. Moreover, even at a high rate of 10C, an unprecedented capacity of 676.7 mA h g−1can still be achieved, which represents the best rate capability among the ever-reported sulfur cathodes with similar sulfur content. More importantly, the Co9S8@CNT/S also displays a high coulombic efficiency of nearly 100% and an excellent cycling performance for up to 1000 cycles with a capacity fading rate of only 0.0448% per cycle. Even at the loading amount of 5.5 mg cm−2, the areal capacity can still reach 4.3 mA h cm−2. The concept to rationally integrate distinct components into fully functional units could provide valuable insights for the development of Li–S batteries and beyond.

Flower-like assembly of ultrathin nanosheets composed of anatase and bronze TiO2embedded in carbon is successfully synthesized by a simple solvothermal reaction, followed with a high-temperature annealing. As an anode material in sodium-ion batteries, this composite exhibits outstanding electrochemical performances. It delivers a reversible capacity of 120 mA h g–1over 6000 cycles at 10 C. Even at 100 C, there is still a capacity of 104 mA h g–1. Besides carbon matrix and hierarchical structure, abundant interfaces between anatase and bronze greatly enhance the performance by offering additional sites for reversible Na+storage and improving the charge-transfer kinetics. The interface enhancements are confirmed by discharge/charge profiles, rate performances, electrochemical impedance spectra, and first-principle calculations. These results offer a new pathway to upgrade the performances of anode materials in sodium-ion batteries.

Aqueous zinc-ion batteries (ZIBs) has been regarded as a promising energy storage system for large-scale application due to the advantages of low cost and high safety. However, the growth of Zn dendrite, hydrogen evolution and passivation issues induce the poor electrochemical performance of ZIBs. Herein, a Na3Zr2Si2PO12(NZSP) protection layer with high ionic conductivity of 2.94 mS/cm on Zn metal anode was fabricated by drop casting approach. The protection layer prevents Zn dendrites formation, hydrogen evolution as well as passivation, and facilitates a fast Zn2+transport. As a result, the symmetric cells based on NZSP-coated Zn show a stable cycling over 1360 h at 0.5 mA/cm2with 0.5 mAh/cm2and 1000 h even at a high current density of 5 mA/cm2with 2 mAh/cm2. Moreover, the full cells combined with V2O5-based cathode displays high capacities and high rate capability. This work offers a facile and effective approach to stabilizing Zn metal anode for enhanced ZIBs.

Si-containing graphite-based composites are considered as promising high-capacity anodes for lithium-ion batteries (LIBs). Here, a controllable and scalable self-assembly strategy is developed to produce micro-nanostructured graphite/Si/reduced graphene oxides composite (SGG). The self-assembly procedure is realized by the hydrogen bond interaction between acylamino-modified graphite and graphene oxides (GO); Si nanoparticles are in situ embedded between graphite and GO sheets uniformly. This architecture is able to overcome the incompatibility between Si nanoparticles and microsized graphite. Accordingly, the as-prepared SGG anode (Si 8 wt %) delivers a reversible Li-storage capacity of 572 mAh g–1at 0.2 C, 502.2 mAh g–1after 600 cycles at 0.8 C with a retention of 92%, and a capacity retention of 64% even at 10 C. The impressive electrochemical properties are ascribed to the stable architecture and three-dimensional conductive network constructed by graphite and graphene sheets, which can accommodate the huge volume change of Si, keep the conductive contact and structural integrity, and suppress side reactions with electrolyte. Additionally, the full-cell (LiFePO4cathode/SGG anode) delivers a specific capacity of 550 mAh g–1with a working potential beyond 3.0 V.

We report an activation-free approach for fabricating ultramicroporous carbon as an accommodation of sulfur molecules for Li–S and Na–S batteries applications in carbonate-based electrolyte. Because of the high specific surface area of 967 m2g–1, as well as 51.8% of the pore volume is contributed by ultramicropore with pore size less than 0.7 nm, sulfur cathode exhibits superior electrochemical behavior in carbonate-based electrolyte with a capacity of 507.9 mA h g–1after 500 cycles at 2 Cin Li–S batteries and 392 mA h g–1after 200 cycles at 1 Cin Na–S batteries, respectively.

Metal boride, carbide, and nitride materials are useful owing to their wide variety of interesting chemical and physical properties. However, the synthesis of these materials with nano or mesoscale sizes is challenging due to the usually required high temperatures and long reaction durations. To our knowledge, the exploration of a number of simultaneous chemical reactions through rapid synthesis still remains a great challenge. In this study, a general route for the reduction and transformation of metal oxides into related metal boride (TiB2, MoB2, DyB4, ErB4, YB4, LaB6, CeB6, SmB6, EuB6), carbide (SiC, TiC, VC, WC, W2C, ZrC, MoC, NbC), and nitride (TiN, VN, BN, AlN, CrN, MgSiN2) nanocrystals were achieved at 150 °C. Here, the exothermic reaction of metal magnesium hydrolysis is utilized to assist the reaction in sealed stainless steel autoclaves. In situ temperature monitoring showed that the inside temperature increased quickly from 139 to 902 °C at the initial stage. The obtained products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), and high-resolution TEM techniques. The low reaction temperature and cheap raw materials make it possible for large-scale synthesis of those nanomaterials.