Reduced Volume Change Research Articles

Proton Intercalation into an Open‐Tunnel Bronze Phase with Near‐Zero Volume Change

AbstractManaging safety and supply‐chain risks associated with lithium‐ion batteries (LIBs) is an urgent task for sustainable development. Aqueous proton batteries are attractive alternatives to LIBs because using water and protons addresses these two risks. However, most host materials undergo large volume changes upon H+ intercalation, which induces intraparticle cracking to accelerates parasitic reactions. Herein, we report that Mo3Nb2O14 bronze exhibits reversible H+ intercalation (200 mAh g−1) with a Coulombic efficiency of 99.7 % owing to near‐zero volume change and solid‐solution‐type phase transition. Combination of experimental and theoretical analyses clarifies that rotation and shrinkage of open tunnels, which consist of flexible corner‐sharing Mo/NbOn polyhedra, relieve local structural distortions upon H+ intercalation to suppress intraparticle cracking. The prototype full cell of an aqueous proton battery with a Mo3Nb2O14 anode operates stably over 1000 charge/discharge cycles. This study reveals the importance of implementing distortion‐relieving voids in host materials to reduce volume change upon charge/discharge.

Proton Intercalation into an Open-Tunnel Bronze Phase with Near-Zero Volume Change.

Managing safety and supply-chain risks associated with lithium-ion batteries (LIBs) is an urgent task for sustainable development. Aqueous proton batteries are attractive alternatives to LIBs because using water and protons addresses these two risks. However, most host materials undergo large volume changes upon H+ intercalation, which induces intraparticle cracking to accelerates parasitic reactions. Herein, we report that Mo3Nb2O14 bronze exhibits reversible H+ intercalation (200 mAh g-1) with a Coulombic efficiency of 99.7% owing to near-zero volume change and solid-solution-type phase transition. Combination of experimental and theoretical analyses clarifies that rotation and shrinkage of open tunnels, which consist of flexible corner-sharing Mo/NbOn polyhedra, relieve local structural distortions upon H+ intercalation to suppress intraparticle cracking. The prototype full cell of an aqueous proton battery with a Mo3Nb2O14 anode operates stably over 1000 charge/discharge cycles. This study reveals the importance of implementing distortion-relieving voids in host materials to reduce volume change upon charge/discharge.

MOF-Derived Bimetallic Selenide CoNiSe2 Nanododecahedrons Encapsulated in Porous Carbon Matrix as Advanced Anodes for Lithium-Ion Batteries.

Transition metal selenides have received considerable attention as promising candidates for lithium-ion battery (LIB) anode materials due to their high theoretical capacity and safety characteristics. However, their commercial viability is hampered by insufficient conductivity and volumetric fluctuations during cycling. To address these issues, we have utilized bimetallic metal-organic frameworks to fabricate CoNiSe2/C nanodecahedral composites with a high specific surface area, abundant pore structures, and a surface-coated layer of the carbon-based matrix. The optimized material, CoNiSe2/C-700, exhibited impressive Li+ storage performance with an initial discharge specific capacity of 2125.5 mA h g-1 at 0.1 A g-1 and a Coulombic efficiency of 98% over cycles. Even after 1000 cycles at 1.0 A g-1, a reversible discharge specific capacity of 549.9 mA h g-1 was achieved. The research highlights the synergistic effect of bimetallic selenides, well-defined nanodecahedral structures, stable carbon networks, and the formation of smaller particles during initial cycling, all of which contribute to improved electronic performance, reduced volume change, increased Li+ storage active sites, and shorter Li+ diffusion paths. In addition, the pseudocapacitance behavior contributes significantly to the high energy storage of Li+. These features facilitate rapid charge transfer and help maintain a stable solid-electrolyte interphase layer, which ultimately leads to an excellent electrochemical performance. This work provides a viable approach for fabricating bimetallic selenides as anode materials for high-performance LIBs through architectural engineering and compositional tailoring.

Co–MnO/C nanoparticles derived from MOFs with improved conductivity and reduced volume change for lithium-ion batteries

The specific capacity tested at 100 and 1000 mA g−1 can still reach 1414 and 772 mA h g−1, respectively, after about 300 cycles.

Mo-doped NiCo-LDH nanoflower derived from ZIF-67 nanosheet arrays for high-performance supercapacitors

Layered double hydroxides (LDHs) have gained utmost concern as anode materials for supercapacitors considering their high theoretical specific capacitances, short ion channels and good electrochemical properties. However, their practical application is hindered by low conductivity and limited performance in terms of charge storage. In this study, the researcher successfully synthesized Mo-doped NiCo-LDH nanoflower structures through a straightforward hydrothermal reaction and calcination utilizing lamellar ZIF-67 as a precursor. By adjusting the Mo doping concentration, the researcher was able to maintain the unique multilevel nanoflower-like structure of NiCo-LDH. Furthermore, the inclusion of Mo as a dopant introduced an amorphous phase and effectively modulated the electronic structure of NiCo-LDH, resulting in accelerating charge storage kinetics and reduced volume change. The 0.075 Mo-doped NiCo-LDH exhibited a specific capacitance of 1368.4C g−1 at 1 A g−1, with the capacity retention of 88.4 % at 10 A g−1. Additionally, the assembled asymmetric supercapacitor constructed with 0.075 Mo-doped NiCo-LDH@C//RGO achieved an energy density of 52.2 Wh kg−1 with a power density of 799.3 W kg−1. This study provides valuable insights into the rational doping of Mo elements for the controlled synthesis of supercapacitor electrode materials.

High Energy Density Sulfur‐Rich MoS6‐Based Nanocomposite for Room Temperature All‐Solid‐State Lithium Metal Batteries

AbstractThe all‐solid‐state lithium–sulfur battery is considered to be a promising energy device due to high energy density and excellent safety. However, sulfur suffers from its insulating nature and large volume changes. Employing transition‐metal sulfide cathodes is an attractive alternative. Herein, a high energy density sulfur‐rich MoS6‐based nanocomposite is designed, where MoS6 nanospheres are homogenously anchored on carbon nanotubes (CNTs) by a wet‐chemical method, providing improved electronic conductivity and reduced volume changes. In addition, a nanosized Li7P3S11 electrolyte is in situ coated on the surface of MoS6‐CNT20 to realize intimate interface contact and form nanoscale electronic/ionic transportation networks. The resultant MoS6‐CNT20@15%Li7P3S11 composite shows high electronic conductivity (1.7 × 10−1 S cm−1) and ionic conductivity (6.7 × 10−4 S cm−1), which are eight and three orders of magnitude improved compared to those of MoS6. The Li/Li6PS5Cl/MoS6‐CNT20@15%Li7P3S11 battery exhibits an initial discharge capacity of 1034.32 mAh g−1 at 0.1 A g−1. In addition, an ultrahigh reversible energy density of 1640 Wh kg−1 for the active material can be realized, which is the highest among all transition‐metal sulfide cathodes. Moreover, it shows a reversible capacity of 550.00 mAh g−1 at 0.5 A g−1 after 1000 cycles, demonstrating that the sulfur‐rich MoS6‐based nanocomposite is a promising highenergy density cathode material for next‐generation all‐solid‐state lithium batteries.

Flowers Like α-MoO3/CNTs/PANI Nanocomposites as Anode Materials for High-Performance Lithium Storage.

Lithium-ion batteries (LIBs) have been explored to meet the current energy demands; however, the development of satisfactory anode materials is a bottleneck for the enhancement of the electrochemical performance of LIBs. Molybdenum trioxide (MoO3) is a promising anode material for lithium-ion batteries due to its high theoretical capacity of 1117 mAhg-1 along with low toxicity and cost; however, it suffers from low conductivity and volume expansion, which limits its implementation as the anode. These problems can be overcome by adopting several strategies such as carbon nanomaterial incorporation and polyaniline (PANI) coating. Co-precipitation method was used to synthesize α-MoO3, and multi-walled CNTs (MWCNTs) were introduced into the active material. Moreover, these materials were uniformly coated with PANI using in situ chemical polymerization. The electrochemical performance was evaluated by galvanostatic charge/discharge, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). XRD analysis revealed the presence of orthorhombic crystal phase in all the synthesized samples. MWCNTs enhanced the conductivity of the active material, reduced volume changes and increased contact area. MoO3-(CNT)12% exhibited high discharge capacities of 1382 mAhg-1 and 961 mAhg-1 at current densities of 50 mAg-1 and 100 mAg-1, respectively. Moreover, PANI coating enhanced cyclic stability, prevented side reactions and increased electronic/ionic transport. The good capacities due to MWCNTS and the good cyclic stability due to PANI make these materials appropriate for application as the anode in LIBs.

Soil stabilization by reinforcing natural and synthetic fibers – A state of the art review

Expansive clays are present in many places across the world. They have an intrinsic volume change that causes fractures, differential settlements, heaves, and damage to the overlaying structures due to seasonal moisture variations. One of the most common treatments for expansive clay subgrades is fly ash (FA) stabilization. It also serves as a possible method for adequately disposing of FA. The inclusion of fibers further enhances the geotechnical properties of soil with FA. The objective of this review article is to examine how different natural and synthetic fibers affect the geotechnical properties of soil. Only peer-reviewed journals and proceedings papers were selected for review. Review of studies suggests that reinforcing soil with fibers is an effective, low-cost soil stabilizing technique with various geotechnical and environmental benefits. Review of the literature revealed that fly ash (FA) at various percentages raises the California Bearing Ratio (CBR) value up to 80–110%. Further, the inclusion of geofibres boosts the CBR values further by 40–50%. In terms of unconfined compressive strength, there has been a substantial improvement reported. The use of geofibres also reduced volume change in the soil (up to 94.4%). This review study will assist geotechnical engineers in stabilizing expansive soils using natural and synthetic fibers and researchers to perform future research.

Single-crystalline Mn-based oxide as a high-rate and long-life cathode material for potassium-ion battery

Mn-based oxides are promising cathode materials for potassium-ion batteries due to their high theoretical capacity and abundant raw materials. However, the anisotropic properties of their conventional polycrystalline structures lead to insufficient rate capability and cycle life. Here, a single-crystal Mn-based layered oxide, P3′-type K0.35Mn0.8Fe0.1Cu0.1O2 (KMFCO), is designed and synthesized through a bimetallic co-induction effect and used as a cathode for potassium-ion battery. Benefiting from a unique single-crystal structure that is devoid of grain boundaries, it achieves a higher K+ transport rate and a reduced volume change during the K+ intercalation/deintercalation process. Accordingly, the single-crystal P3′-type KMFCO delivers superior rate capability (52.9 ​mAh ​g−1 at 1000 ​mA ​g−1) and excellent cycling stability (91.1% capacity retention after 500 cycles at 500 ​mA ​g−1). A full cell assembled with the P3′-type KMFCO cathode and a graphite anode also exhibits a high reversible capacity (81.2 ​mAh ​g−1 at 100 ​mA ​g−1) and excellent cycling performance (97% capacity retention after 300 cycles). The strategy of developing single-crystal materials may offer a new pathway for maintaining structural stability and improving the rate capability of layered manganese oxide cathodes and beyond.

Microsized Gray Tin as a High-Rate and Long-Life Anode Material for Advanced Sodium-Ion Batteries.

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 situ formation of amorphous Sn, as supported by in situ XRD, 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-1 after 3500 cycles at 2 A g-1 or ∼464 mAh g-1 at 4 A g-1 in a rate test. The results indicate the promising potential of α-Sn in SIBs.

Structural engineering of CoMoO3 nanosheets on cage-like carbon nanoflakes toward enhanced lithium storage performance

Bimetal oxides possess high electronic conductivity and multiple electrochemically active sites owing to their stepwise electrochemical reactions compared with the single metal oxides. However, bimetal oxides still suffer from the severe volume changes upon lithium insertion/delithiation processes, thus leading to poor cycle stability. Herein, we demonstrate the growth of novel CoMoO3 nanosheets on the cage-like carbon nanoflakes (c-CNFs) through a facile in-situ thermal decomposition strategy. The phase and morphology structures of CoMoO3 can be readily controlled by adjusting the sintering temperature under the argon atmosphere, changing from 0D CoMoO4 nanoparticles@c-CNFs (350 ℃, denoted as CoMoO4 @C) to 0D CoMoO4 nanoparticles and 2D CoMoO3 nanosheets co-existed nanohybrids@c-CNFs (450 ℃, denoted as CoMoOx @C) and 2D CoMoO3 nanosheets@c-CNFs (550 ℃, denoted as CoMoO3 @C). When examined as anode materials for LIBs, the CoMoO3 @C electrode exhibited excellent lithium storage performance. The superior performance of the CoMoO3 @C electrode could be attributed to the novel CoMoO3 nanosheet structure combined with the reduced volume change from well-fitted CoMoO3 @c-CNFs, which delivered a reversible capacity of ~706 mA h/g for 360 cycles at 500 mA/g, higher than that of the CoMoO4 @C and CoMoOx @C electrodes.

Stabilization of Multicationic Redox Chemistry in Polyanionic Cathode by Increasing Entropy.

Polyanionic compounds have large compositional flexibility, which creates a growing interest in exploring the property limits of electrode materials of rechargeable batteries. The realization of multisodium storage in the polyanionic electrodes can significantly improve capacity of the materials, but it often causes irreversible capacity loss and crystal phase evolution, especially under high‐voltage operation, which remain important challenges for their application. Herein, it is shown that the multisodium storage in the polyanionic cathode can be enhanced and stabilized by increasing the entropy of the polyanionic host structure. The obtained polyanionic Na3.4Fe0.4Mn0.4V0.4Cr0.4Ti0.4(PO4)3 cathode exhibits multicationic redox property to achieve high capacity with good reversibility under the high voltage of 4.5 V (vs Na/Na+). Exploring the underlying mechanism through operando characterizations, a stable trigonal phase with reduced volume change during the multisodium storage process is disclosed. Besides, the enhanced performance of the HE material also derives from the synergistic effect of the diverse TM species with suitable molarity. These results reveal the effectiveness of high‐entropy concept in expediting high‐performance polyanionic cathodes discovery.

Selective wet oxidation of AlAsSb alloys on GaAs

In this paper, the oxidation of thin low-Sb-containing AlAsSb layers quasi-lattice matched on GaAs substrates is studied in detail since, compared to AlGaAs, these alloys had the prospects of being laterally oxidized at a faster rate, at lower process temperatures, and with a reduced volume change. Combining monitoring data of the oxidation kinetics and anisotropy with atomic-force-microscopy surface measurements enables us to establish the optimal composition range and process parameters that lead to nearly isotropic and Sb-segregation-free oxidations. The study also shows that strain plays a central role in triggering the detrimental Sb segregation.

Ten Thousand-Cycle Ultrafast Energy Storage of Wadsley-Roth Phase Fe-Nb Oxides with a Desolvation Promoting Interfacial Layer.

Developing advanced electrode materials with enhanced charge-transfer kinetics is the key to realizing fast energy storage technologies. Commonly used modification strategies, such as nanoengineering and carbon coating, are mainly focused on electron transfer and bulk Li+ diffusion. Nonetheless, the desolvation behavior, which is considered as the rate-limiting process for charge-storage, is rarely studied. Herein, we designed a nitridation layer on the surface of Wadsley-Roth phase FeNb11O29 (FNO-x@N) to act as a desolvation promoter. Theoretical calculations demonstrate that the adsorption and desolvation of solvated Li+ is efficiently improved at FNO-x@N/electrolyte interphase, leading to the reduced desolvation energy barrier. Moreover, the nitridation layer can also help to prevent solvent cointercalation during Li+ insertion, leading to advantageous shrinkage of block area and reduced volume change of lattice cell during cycling. Consequently, FNO-x@N exhibits a high-rate capacity of 129.7 mAh g-1 with negligible capacity decay for 10 000 cycles.

Inhibited intracrystalline cracks and enhanced electrochemical properties of NCM811 cathode materials coated by EPS

The formation of micro-cracks in Ni-rich LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode particles is an extremely important factor affecting the electrochemical characteristics after long-term cycling. Generally, cracks can be divided into intergranular crack and intracrystalline crack according to their positions. Coating has been confirmed as a highly effective strategy to relieve intergranular cracks. However, the intracrystalline cracks of primary-like particles have rarely been studied. In this work, ethoxy functional polysiloxane (EPS) was directly coated on the surface of original NCM811 by tetraethyl orthosilicate (TEOS) hydrolytic polycondensation method without any additives. Then, the microstructure, micromorphology, surface state and electrochemical properties were investigated in detail by XRD, SEM, TEM, CV and EIS. The results displayed that the micro-cracks of primary-like particles were effectively suppressed under appropriate EPS coating. Accordingly, excellent capacity retention of 95.6% (100 cycles, 1C) and rate performance (144.6 mA h/g, 5C) were obtained. These improved mechanical and electrochemical properties are considered to be related to the EPS stress buffer layer, suppressed oxygen vacancies, inhibited phase transition and reduced volume change.

The Effect of Sisal Juice Extract Admixture on Compressive and Flexural Strength of Cement Concrete

The characteristics of concrete are influenced by the ratio of water to cementitious materials (w/c) used in the mixture. An increase in paste quality will yield higher compressive and flexural strength, lower permeability, increased resistance to weathering, improve the bond between concrete and reinforcement, reduced volume change from drying and wetting, and reduced shrinkage cracking tendencies. Admixtures are used to improve the properties of concrete or mortar. The current study investigates the effect of Sisal Juice Extract (SJE) as an admixture on concrete durability. SJE contains unrefined minerals which can be used as organic retarders to increase the rate of strength development at an early age. A total of 84 concrete cubes were produced in 7 sets of 12 samples each. One set was the control mix which had zero SJE content. The remaining sets had varying dosages of SJ namely 5%, 10%, 15%, 20%, 25%, and 30%. Twelve beam specimens were also cast and subjected to the three-point flexural test. To establish the effect on strength of concrete, compressive strength was tested at 7, 14, 28, and 56 days while flexural strength was tested at 28 days. The highest compressive strength was achieved at 5% dosage beyond which a decrease in strength occurred for all the higher dosages.

Enablement of long-lifespan lithium metal battery via building 3D LixGey alloy framework

Li metal battery (LMB) is a commonly used chemical battery with excellent application potential in high-energy storage devices. However, several limitations impede the practical application of LMB, such as the uneven deposition of Li+, uncontrolled growth of dendrites and severe side reactions. Herein, we report a lithiophilic Li22Ge5 alloy framework which is fabricated by reacting Li with GeO2 particles. Li22Ge5 alloy framework can serve as a stable Li “host”, provide a fast transport channel for Li+ and reduce volume change. Furthermore, it guides Li+ to deposit at the bottom to prevent a loose structure below the deposited Li layer and suppress the growth of Li dendrites with repeated cycling. Based on the galvanostatic measurements, the symmetric cells with the 3D GeO2-Li electrode exhibit long cycling life at a current density of 1 mA cm−2 with fixed capacity of 1 mA h cm−2 over 1100 h. When GeO2-Li electrode used in the full cells, the coulombic efficiency (CE) of GeO2-Li/ LiFePO4 is 98.53% at 1 C after 200 cycles. Moreover, this work demonstrates that Li22Ge5 acting as a lithiophilic material is an effective method to guide the uniform deposition of Li+ and reduce volume change for Li metal battery.

Revealing the structure design of alloyed based electrodes for alkali metal ion batteries with in situ TEM

With the guidance of in situ TEM, the high energy density alloyed based anode materials can be realized optimization structure design, thus obtaining excellent electrochemical performances in storing metal ions. Alloyed based anode materials with high theoretical specific capacity and low reaction potential are considered to be highly potential high-energy density anode materials for alkali metal ion batteries (AMIBs). Thus, the design of alloyed based materials with high electrochemical performance has attracted great attention. Among the numerous characterization methods for guiding electrode materials design, in situ transmission electron microscopy (TEM) gradually plays an irreplaceable role due to its high temporal and spatial resolution in directly observing the change of morphology, crystal structure and element evolutions. Herein, we reviewed the two current research hotspots and mainly focused on the structure design of alloyed based electrode material under the guidance of in situ TEM. Specifically, various nanostructure designs of alloyed based electrode materials with guidance of in situ TEM were employed to solve the key scientific issues of the violent volume change during alloying/dealloying processes for enhanced electrochemical performances. Mainly through introducing buffer space in the electrode material to reduce volume change to improve structural stability, including porous structure (0D), nanotube structure (1D), simple hollow structure, yolk-shell structure and some hybrid hollow structures (3D). Furthermore, the direct guidance of in situ TEM is expected for creating new opportunities to next-generation electrode material design for AMIBs.

(Invited) High Coulombic Efficiency Electrolyte Enables Li||Span Batteries with Superior Cycling Performance

Lithium metal is being extensively studied as an anode to replace graphite due to its high capacity and the low electrochemical potential.Current research focus is to mitigate lithium dendrite growth and to increase coulomb efficiency during electrochemical cycling by using various surface coatings and electrolyte additives.1 , 2 In addition, a 3D host can be beneficial due to the reduced volume change.3 While sulfur or metal oxide intercalation cathodes can both in principle achieve full-cell energy densities of 500 Wh kg-1, sulfur-based cathodes are particularly appealing due to their low cost, abundant supply, and high storage capacity. Among these, the SPAN (sulfurized polyacrylonitrile) cathode is particularly promising due to the physical confinement of the small molecular sulfur in the conductive polymer network which provides a high specific capacity of > 550 mAh g-1 and an average discharge potential of ~ 1.8 V. We have recently focused on designing novel electrolyte solution chemistry that enables Li||SPAN batteries with superior cycling performance.In the first example, we designed a high-concentration, ether-based electrolyte with LiTFSI and LiNO3 as the co-salts. In addition to providing excellent protection for lithium metal anodes by forming the solid electrolyte interface (SEI), the electrolyte promotes the formation of a crystalline cathode electrolyte interface (CEI) on the SPAN surface composed of LiF and LiNO2. The CEI effectively prevents the formation of soluble polysulfide species and enables stable cycling of the Li||SPAN battery. The benefit of having effective CEI and SEI layers is also demonstrated in Li||SPAN cells with limited lithium supply, which exhibit lithium cycling efficiency values consistent with or exceeding Li||Cu test results, reaching 99.5%. The development of electrolyte chemistries to enable the formation of effective CEI layers is a promising approach to long-life lithium metal batteries.In another example, we formulated a highly concentrated salt/ether electrolyte diluted in a fluorinated ether, which realized an average lithium coulombic efficiency of 99.37% at 0.5 mA cm−2 and 1 mAh cm−2 for more than 900 cycles. This electrolyte also maintained a record coulombic efficiency of 98.7% at 10 mA cm−2, indicative of its ability to provide fast-charging with high cathode loadings. Morphological studies reveal dense, dendrite free Li depositions after prolonged cycling, while surface analyses confirmed the formation of a robust LiF-rich SEI layer on the cycled Li surface. Moreover, this ether-based electrolyte is highly compatible with the SPAN cathode, where the constructed Li||SPAN cell exhibited reversible cathode capacity of 579 mAh g-1 and no capacity decay after 1200 cycles. A cell where a high areal loading SPAN electrode (3.5 mAh cm−2) is paired with only one-fold excess Li was constructed and cycled at 1.75 mA cm−2, maintaining a coulombic efficiency of 99.30% for the lithium metal. This study provides a path to enable high energy density Li||SPAN battery with stable cycling. Acknowledgements This work was supported by the Office of Vehicle Technologies of the U.S. Department of Energy through the Advanced Battery Materials Research Program (Battery 500 Consortium) under Contract DE-EE0007764. Part of the work used the UCSD-MTI Battery Fabrication Facility and the UCSD-Arbin Battery Testing Facility. H. Liu, X. Wang, H. Zhou, H.-D. Lim, X. Xing, Q. Yan, Y. S. Meng and P. Liu, ACS Applied Energy Materials, 2018, DOI: 10.1021/acsaem.8b00348.H. Liu, H. Zhou, B.-S. Lee, X. Xing, M. Gonzalez and P. Liu, Acs Applied Materials & Interfaces, 2017, 9, 30635-30642.H. Liu, X. Yue, X. Xing, Q. Yan, J. Huang, V. Petrova, H. Zhou and P. Liu, Energy Storage Materials, 2018, DOI: https://doi.org/10.1016/j.ensm.2018.09.021.

Mechanochemical reactions of MnO2 and graphite nanosheets as a durable zinc ion battery cathode

Manganese dioxide has been recognized as the ideal cathode for the aqueous zinc ion batteries (ZIBs). Nevertheless, the poor conductivity and infinite relative volume changes limit its further practical applications. Herein, we developed a promising cathode design by ball milling of electrolytic manganese dioxide (MnO2) in the presence of graphite nanosheets. MnO2/graphite hybrids with the increase of contact surface and interfacial interaction are beneficial to construct an interfacial 3D conductive network and improve the inherent stability, which achieve the minimum volume change. As expected, the rate and cycling performance of MnO2/graphite hybrids (230 mAh g−1 at 0.1 A g−1, 80 mAh g−1 at 1 A g−1, 80.8% after 1000 cycles at 1 A g−1) are better than that of MnO2 (113 mAh g−1 at 0.1 A g−1, 24 mAh g−1 at 1 A g−1, 51.2% after 1000 cycles at 1.0 A g−1). The reduced volume change during charging/discharging can be observed via in situ optical observations. Furthermore, the Zn ion battery delivers higher energy density of 247 Wh kg−1 at 0.27 kW kg−1 and higher power density of 11.78 kW kg−1 at 78 Wh kg−1. Our work demonstrates the successful and large-scale conversion of industrial electrolytic manganese dioxide into a high-performance cathode of ZIBs.