Search

Although Mg–Li dual metal-ion batteries are proposed as a superior system that unite safety of Mg-batteries and performance of Li-ion based systems, its practical implantation is limited due to the lack of reliable high-performance cathodes. Herein, we report a high-performance Mg–Li dual metal-ion battery system based on highly pseudocapacitive hierarchical TiO2-B nanosheet assembled spheres (NS) cathode. This 2D cathode displayed exceptional pseudocapacitance (a maximum of 93%) specific capacity (303 mAh g −1 at 25 mA g−1), rate performance (210 mAh g −1 at 1 A g−1), consistent cycling (retain ∼100% capacity for 3000 cycles at 1 A g−1), Coulombic efficiency (nearly 100%) and fast-charging (∼12.1 min). These properties are remarkably dominant to the existing Mg-Li dual metal-ion battery cathodes. Spectroscopic and microscopic mechanistic studies confirmed negligible structural changes during charge-discharge cycles of the TiO2-B nanosheet assembled spheres electrodes. Exceptional electrochemical properties of the 2D electrode is ascribed to remarkable pseudocapacitive Mg–Li dual metal-ion diffusion via the numerous nanointerfaces of TiO2-B caused by its hierarchical microstrucrure. Large surface area, nanosheet morphology, mesoporous structure and ultrathin nature also acted as secondary factors facilitating improved electrode-electrolyte contact. Demonstrated approach of pseudocapacitive type Mg-Li dual metal-ion intercalation through hierarchical nanointerfaces may be further utilized for the designing of numerous top-notch electrode materials for futuristic Mg–Li dual metal-ion batteries. [ABSTRACT FROM AUTHOR]

Disordered carbon is the state of the art anode material for Na‐ion batteries due to their increased interlayer spacing and good electronic conductivity. However, its practical application is hindered by average specific capacity, poor rate performance, low coulombic efficiency and limited cycling stability. Herein, we report the superior pseudocapacitance enhanced Na‐ion storage of in situ surface functionalized carbon nanosheets. Anodes composed of ultrathin (~15 nm) carbon nanosheets demonstrated excellent reversible specific capacity (375 mAh/g at 25 mA/g), rate performance (150 mAh/g at 2 A/g), long‐term cycling performance (1000 cycles at 1 A/g) and coulombic efficiency (~100 %). Considerably higher pseudocapacitance (up to ~78 %) is also identified in this case compared to amorphous carbon particles. Spectroscopic and electrochemical studies proved Na‐ion intercalation in to the disordered carbon and pseudocapacitive storage driven by oxygen‐containing surface functional groups. Outstanding electrochemical performance is credited to the synergy between diffusion limited intercalation and pseudocapacitive surface Na‐ion storage. The demonstrated synthetic method of in situ functionalized carbon nanosheets is inexpensive and scalable. The strategy of functional group and morphology induced pseudocapacitive Na‐ion storage offer new prospects to design high‐performance Na‐ion battery electrodes. [ABSTRACT FROM AUTHOR]

Secondary lithium-ion batteries are restricted in large-scale applications including power grids and long driving electric vehicles owing to the low specific capacity of conventional intercalation anodes possessing sluggish Li-ion diffusion kinetics. Herein, we demonstrate an unusual pseudocapacitive lithium-ion storage on defective Co3O4 nanosheet anodes for high-performance rechargeable batteries. Cobalt-oxide nanosheets presented here composed of various defects including vacancies, dislocations and grain boundaries. Unique 2D holey microstructure enabled efficient charge transport as well as provided room for volume expansions associated with lithiation-delithiation process. These defective anodes exhibited outstanding pseudocapacitance (up to 87%), reversible capacities (1490 mAh gâ€"1 @ 25 mA gâ€"1), rate capability (592 mAh gâ€"1 @ 30 A gâ€"1), stable cycling (85% after 500 cycles @ 1 A gâ€"1) and columbic efficiency (∼100%). Exceptional Li-ion storage phenomena in defective Co3O4 nanosheets is accredited to the pseudocapacitive nature of conversion reaction resulting from ultrafast Li-ion diffusion through various crystal defects. The demonstrated approach of defect-induced pseudocapacitance can also be protracted for various low-cost and/or eco-friendly transition metal-oxides for next-generation rechargeable batteries. [ABSTRACT FROM AUTHOR]

Despite the proposed safety, performance, and cost advantages, practical implementation of Mg−Li hybrid batteries is limited due to the unavailability of reliable cathodes compatible with the dual‐ion system. Herein, a high‐performance Mg−Li dual ion battery based upon cobalt‐doped TiO2 cathode was developed. Extremely pseudocapacitance‐type Ti1‐xCoxO2‐y nanosheets consist of an optimum 3.57 % Co‐atoms. This defective cathode delivered exceptional pseudocapacitance (maximum of 93 %), specific capacities (386 mAh g−1 at 25 mA g−1), rate performance (191 mAh g−1 at 1 A g−1), cyclability (3000 cycles at 1 A g−1), and coulombic efficiency (≈100 %) and fast charging (≈11 min). This performance was superior to the TiO2‐based Mg−Li dual‐ion battery cathodes reported earlier. Mechanistic studies revealed dual‐ion intercalation pseudocapacitance with negligible structural changes. Excellent electrochemical performance of the cation‐doped TiO2 cathode was credited to the rapid pseudocapacitance‐type Mg/Li‐ion diffusion through the disorder generated by lattice distortions and oxygen vacancies. Ultrathin nature, large surface area, 2D morphology, and mesoporosity also contributed as secondary factors facilitating superior electrode‐electrolyte interfacial kinetics. The demonstrated method of pseudocapacitance‐type Mg−Li dual‐ion intercalation by introducing lattice distortions/oxygen vacancies through selective doping can be utilized for the development of several other potential electrodes for high‐performance Mg−Li dual‐ion batteries. [ABSTRACT FROM AUTHOR]

Although lithium-sulfur (Li-S) batteries are one of the promising candidates for nextgeneration energy storage, their practical implementation is limited by rapid capacity fading due to lithium polysulfide (LiPSs) formation and the low electronic conductivity of sulfur. Herein, we report a high-performance lithium-sulfur battery based on multidimensional cathode architecture consisting of nanosulfur, graphene nanoplatelets (2D) and multiwalled carbon nanotubes (1D). The ultrasonic synthesis method results in the generation of sulfur nanoparticles and their intercalation into the multilayered graphene nanoplatelets. The optimized multidimensional graphene-sulfur-CNT hybrid cathode (GNS58-CNT10) demonstrated a high specific capacity (1067 mAh g-1 @ 50 mA g-1), rate performance (539 @ 1 A g-1), coulombic efficiency (~95%) and cycling stability (726 mAh g-1 after 100 cycles @ 200 mA g-1) compared to the reference cathode. Superior electrochemical performances are credited to the encapsulation of nanosulfur between the individual layers of graphene nanoplatelets with high electronic conductivity, and effective polysulfide trapping byMWCNT bundles. [ABSTRACT FROM AUTHOR]

High-performance anodes for rechargeable Li-ion batteries are produced by nanostructuring of transition metal oxides on a conductive support. Here, we demonstrate a hybrid material of MnO2 directly grown onto fabrics of carbon nanotube fibres, which exhibits notable specific capacities over 1100 and 500 mA h g−1 at discharge current densities of 25 mA g−1 and 5 A g−1, respectively, with a coulombic efficiency of 97.5%. Combined with 97% capacity retention after 1500 cycles at a current density of 5 A g−1, both capacity and stability are significantly above literature data. Detailed investigations involving electrochemical and in situ synchrotron X-ray scattering studies reveal that during galvanostatic cycling, MnO2 undergoes an irreversible phase transition to LiMnO2, which stores lithium through an intercalation process, followed by a conversion mechanism and pseudocapacitive processes. This mechanism is further confirmed by Raman spectroscopy and X-ray photoelectron spectroscopy. The fraction of pseudocapacitive charge storage ranges from 27% to 83%, for current densities from 25 mA g−1 to 5 A g−1. The firm attachment of the active material to the built-in current collector makes the electrodes flexible and mechanically robust, and ensures that the low charge transfer resistance and the high electrode surface area remain after irreversible phase transition of the active material and extensive cycling. [ABSTRACT FROM AUTHOR]

Uniform colloidal building-blocks enable the creation of more stable, structurally sophisticated materials. Here we describe a simple polymer-mediated approach to generate grams of monodisperse, single-crystal α-Mn2O3 nanocrystals bound by {111} facets. The technique is inspired in part by biomineralization, where organisms use macromolecular matrices or compartments to trigger the oriented nucleation and growth of crystalline phases. Polyvinylpyrrolidone (PVP) behaves as a polymeric nano-reactor by coordinating to the manganese (Mn) precursor while recruiting the NOx oxidizing agent from solution to drive the co-precipitation of the manganese oxide. PVP also serves as a molecular template to guide the nucleation of trigonal bipyramids composed of Mn3O4. The porosity of the Mn3O4 particles indicates that they form non-classically via oriented attachment instead of atom-by-atom. The particles are further oxidized and transform into single-crystal α-Mn2O3 octahedra. This co-precipitation approach is advantageous because it can generate large amounts of monodisperse nanocrystals at low economic cost. α-Mn2O3 is an alternative lithium ion battery (LIB) anode material that is earth abundant and has ∼2.7 times higher capacity than conventional graphite anodes. We assembled the monodisperse α-Mn2O3 octahedra into LIB anodes to examine their performance in a realistic device. The α-Mn2O3 octahedra exhibit good rate performance, cycling stability, coulombic efficiency and morphology retention during extended lithiation–delithiation cycles compared to previous reports for this material. We attribute the improved electrochemical performance of the α-Mn2O3 octahedra to the lack of agglomeration in the uniformly distributed electrode and improved lithiation of single crystalline α-Mn2O3 nanoparticles. [ABSTRACT FROM AUTHOR]

Amorphous and turbostratic porous carbon spheres are synthesized through a template-free spray pyrolysis method. Anodes composed of these non-graphitic carbon spheres outperformed the commercial graphitic carbon anodes in rechargeable Li-ion batteries. A discharge capacity of 378 mA h g−1, which is equivalent to the theoretical limit of 372 mA h g−1, is achieved at a current density of 0.1 C (37.2 mA g−1). At a higher charge–discharge rate of 1 C, electrochemically most active turbostratic carbon spheres exhibited a reversible specific capacity of 270 mA h g−1, which is 4-fold higher compared to those of commercial graphitic carbon anodes. After 100 charge–discharge cycles at current densities of 0.1 C and 1 C, carbon spheres retained stable specific capacities of 365 and 250 mA h g−1, respectively. Spectroscopic and microscopic investigation of porous carbon anodes after 100 galvanostatic cycles illustrated an excellent structural stability of turbostratic carbon spheres during the lithiation–delithiation process. The notably higher electrochemical performance of carbon spheres is explained by their disordered crystal structure and porosity, which resulted in lower impedance and superior rate performance. This study demonstrates porous turbostratic carbon spheres having a higher charge potential and sloping profile as promising anodes for rechargeable Li-ion batteries. [ABSTRACT FROM AUTHOR]

An ordered network of interconnected tin oxide (SnO2) nanoparticles with a unique 3D architecture and an excellent lithium-ion (Li-ion) storage performance is derived for the first time through hydrolysis and thermal self-assembly of the solid alkoxide precursor. Mesoporous anodes composed of these ≈9 nm-sized SnO2 particles exhibit substantially higher specific capacities, rate performance, coulombic efficiency, and cycling stabilities compared with disordered nanoparticles and commercial SnO2. A discharge capacity of 778 mAh g-1, which is very close to the theoretical limit of 781 mAh g-1, is achieved at a current density of 0.1 C. Even at high rates of 2 C (1.5 A g-1) and 6 C (4.7 A g-1), these ordered SnO2 nanoparticles retain stable specific capacities of 430 and 300 mAh g-1, respectively, after 100 cycles. Interconnection between individual nanoparticles and structural integrity of the SnO2 electrodes are preserved through numerous charge-discharge process cycles. The significantly better electrochemical performance of ordered SnO2 nanoparticles with a tap density of 1.60 g cm-3 is attributed to the superior electrode/electrolyte contact, Li-ion diffusion, absence of particle agglomeration, and improved strain relaxation (due to tiny space available for the local expansion). This comprehensive study demonstrates the necessity of mesoporosity and interconnection between individual nanoparticles for improving the Li-ion storage electrochemical performance of SnO2 anodes. [ABSTRACT FROM AUTHOR]

A new method was developed to synthesize nanosheet-assembled TiO2–B microflowers for Li-ion batteries. Significantly higher electrochemical performance of these microflowers compared to other TiO2–B nanostructures was attributed to their hierarchical microstructure and exposed (1 1̅ 0) facets of the individual nanosheets. [ABSTRACT FROM AUTHOR]

A lithium–sulfur (Li–S) battery is one of the post‐lithium‐ion battery chemistry candidates due to the high theoretical capacity of the sulfur cathode (1672 mAh g−1). However, low electronic conductivity of sulfur and severe capacity fading during the charge–discharge process limit the commercial realization of Li–S batteries. The origin of capacity fading is mainly due to the polysulfide shuttling effect, resulting from the dissolution of sulfur in the electrolyte solution. Herein, atomic layer deposition (ALD) (6–8 Å thickness) of alumina is presented as a strategy to suppress capacity degradation on the 2D graphene–sulfur hybrid electrode. Low‐temperature ALD prevents sulfur sublimation from the composite electrode. Despite the insulating property of alumina, atomic layer coating maintains good electrical conductivity, thereby yielding lower charge transfer resistance. Alumina‐coated graphene–sulfur hybrid electrodes (AGS) exhibit a high specific capacity of 960 mAh g−1 at a current density of 50 mA g−1 and retain 519 mAh g−1 after 100 galvanostatic cycles. Superior electrochemical performance is credited to the combination of the high electronic conductivity of multilayered graphene platelets and low charge transfer resistance, resulting from effective polysulfide blocking by the atomic scale Al2O3 coating. [ABSTRACT FROM AUTHOR]

An ordered 3D network of interconnected SnO2 nanoparticles is reported by Vilas G. Pol and co‐workers in article number 1401289. Superior Li‐ion storage of these ordered SnO2 nanoparticles is attributed to the enhanced electrode/electrolyte contact, Li‐ion diffusion, the absence of particle agglomeration, and improved strain relaxation. This work proves the necessity of mesoporosity and interconnected microstructure for stable electrochemical performance of SnO2 anodes. [ABSTRACT FROM AUTHOR]