Yusong Zhu

Composite of a nonwoven fabric with poly(vinylidene fluoride) as a gel membrane of high safety for lithium ion battery

A composite membrane of a nonwoven fabric with poly(vinylidene fluoride) exhibiting high safety (self-extinguishing), good mechanical property and low cost is reported. The ionic conductivity of the as-prepared gel membrane saturated with 1 mol l−1 LiPF6 electrolyte at ambient temperature can be up to 0.30 mS cm−1, higher than that of the corresponding well-used commercial separator (Celgard 2730), 0.21 mS cm−1. Moreover, the lithium ion transference in the gel membrane at room temperature is almost twice that in the commercial separator. Furthermore, the absorbed solvent is difficult to evaporate at elevated temperature. Its electrochemical performance is evaluated by using a LiFePO4 cathode. The obtained results suggest that this gel-type composite membrane is very attractive for large-capacity battery systems requiring high safety and low cost.

Aqueous rechargeable lithium batteries as an energy storage system of superfast charging

Due to the energy crisis within recent decades, renewable energies such as solar, wind and tide energies have received a lot of attention. However, these renewable energies are dependent on the time and season. Consequently, energy storage systems are needed to fully utilize these energies including their connection with smart grids. Aqueous rechargeable lithium batteries (ARLBs) may be an ideal energy storage system due to its excellent safety and reliability. However, since the introduction of ARLBs in 1994, the progress on improving their performance has been very limited. Recently, their rate performance, especially superfast charging performance, reversible capacity and cycling life of their electrode materials were markedly improved. The present work reviews the latest advances in the exploration of the electrode materials and the development of battery systems. Also the main challenges in this field are briefly commented on and discussed.

An Aqueous Rechargeable Lithium Battery Using Coated Li Metal as Anode

New energy industry including electric vehicles and large-scale energy storage in smart grids requires energy storage systems of good safety, high reliability, high energy density and low cost. Here a coated Li metal is used as anode for an aqueous rechargeable lithium battery (ARLB) combining LiMn2O4 as cathode and 0.5 mol l−1 Li2SO4 aqueous solution as electrolyte. Due to the “cross-over” effect of Li+ ions in the coating, this ARLB delivers an output voltage of about 4.0 V, a big breakthrough of the theoretic stable window of water, 1.229 V. Its cycling is very excellent with Coulomb efficiency of 100% except in the first cycle. Its energy density can be 446 Wh kg−1, about 80% higher than that for traditional lithium ion battery. Its power efficiency can be above 95%. Furthermore, its cost is low and safety is much reliable. It provides another chemistry for post lithium ion batteries.

An aqueous rechargeable lithium battery of excellent rate capability based on a nanocomposite of MoO3 coated with PPy and LiMn2O4

A nanocomposite of MoO3 coated with polypyrrole (PPy) was prepared as an anode material for ARLBs. When nanochain LiMn2O4 is used as the cathode, the ARLB can deliver an energy density of 45 Wh kg−1 at 350 W kg−1 and even maintain 38 Wh kg−1 at 6 kW kg−1 in 0.5 M Li2SO4 aqueous electrolyte, corresponding to an good rate capability. In addition, its cycling behavior is greatly improved compared with the virginal MoO3. Our findings provide valuable clues to improve the comprehensive performance of ARLBs for practical application. This unique performance demonstrates that this battery will be of great promise as a power source for large power devices such as power loading and the storage of solar and wind energies.

Preparation of carbon coated MoO2 nanobelts and their high performance as anode materials for lithium ion batteries

Carbon coated MoO2 nanobelts were successfully synthesized via a hydrothermal method followed by calcination under inert atmosphere, using α-MoO3 nanobelts as the precursor and self-template, ethanol as the reducer and glucose as the carbon source. Under the protection of polysaccharide resulting from glucose polycondensation, the 1-D morphology can be well retained during the reduction and carbonization processes. Tested as anode materials for lithium ion batteries, the carbon coated MoO2 nanobelts exhibit a reversible capacity of 769.3 mA h g−1 at a current density of 100 mA g−1 in the first cycle, and retain 80.2% of the capacity after 30 cycles. When the current density increases, this material shows high rate capability and good cycling performance.

A hybrid of V2O5 nanowires and MWCNTs coated with polypyrrole as an anode material for aqueous rechargeable lithium batteries with excellent cycling performance

A hybrid of V2O5 nanowires and MWCNTs coated with polypyrrole (PPy) was prepared as an anode material for ARLBs. The hybrid shows a good electrochemical reversibility since the PPy coating can effectively prevent the dissolution of the reduced vanadium ions.

A trilayer poly(vinylidene fluoride)/polyborate/poly(vinylidene fluoride) gel polymer electrolyte with good performance for lithium ion batteries

A composite membrane based on poly(vinylidene fluoride) (PVDF) and lithium polyacrylic acid oxalate borate (LiPAAOB) exhibiting high safety (self-extinguishing) and good mechanical property was prepared. The ionic conductivity of the gel polymer electrolyte (GPE) by saturating with 1 mol L−1 LiPF6 electrolyte at ambient temperature can be up to 0.35 mS cm−1, higher than that of the well-used commercial separator (Celgard 2730), 0.21 mS cm−1. The lithium ion transference in the GPE at room temperature is 0.58, twice that in the commercial separator (0.27). Moreover, the GPE presents a true shut-down behavior, which is quite different from the not-real shut-down behaviour of the commercial separators. Furthermore, the absorbed electrolyte solvent is difficult to evaporate at elevated temperature. Its electrochemical performance is evaluated by using LiFePO4 cathode. The obtained results suggest that this composite GPE is very attractive to large-capacity battery systems requiring high safety and low cost.

Nanostructured positive electrode materials for post-lithium ion batteries

Nanotechnology has opened up new frontiers in materials science and engineering in the past several decades. Considerable efforts on nanostructured electrode materials have been made in recent years to fulfill the future requirements of electrochemical energy storage. Compared to bulk materials, most of these nanostructured electrode materials improve the thermodynamic and kinetic properties of electrochemical reactions for achieving high energy and power densities. Here we briefly review the state-of-the-art research activities in the area of nanostructured positive electrode materials for post-lithium ion batteries, including Li–S batteries, Li–Se batteries, aqueous rechargeable lithium batteries, Li–O2 batteries, Na-ion batteries, Mg-ion batteries and Al-ion batteries. These future rechargeable battery systems may offer increased energy densities, reduced cost, and more environmental benignity. A particular focus is directed to the design principles of these nanostructured positive electrode materials and how nanostructuring influences electrochemical performance. Moreover, the recent achievements in nanostructured positive electrode materials for some of the latest emerging rechargeable batteries are also summarized, such as Zn-ion batteries, F- and Cl-ion batteries, Na–, K– and Al–S batteries, Na– and K–O2 batteries, Li–CO2 batteries, novel Zn–air batteries, and hybrid redox flow batteries. To facilitate further research and development, some future research trends and directions are finally discussed.

Cheap glass fiber mats as a matrix of gel polymer electrolytes for lithium ion batteries

Lithium ion batteries (LIBs) are going to play more important roles in electric vehicles and smart grids. The safety of the current LIBs of large capacity has been remaining a challenge due to the existence of large amounts of organic liquid electrolytes. Gel polymer electrolytes (GPEs) have been tried to replace the organic electrolyte to improve their safety. However, the application of GPEs is handicapped by their poor mechanical strength and high cost. Here, we report an economic gel-type composite membrane with high safety and good mechanical strength based on glass fiber mats, which are separator for lead-acid batteries. The gelled membrane exhibits high ionic conductivity (1.13 mS cm−1), high Li+ ion transference number (0.56) and wide electrochemical window. Its electrochemical performance is evaluated by LiFePO4 cathode with good cycling. The results show this gel-type composite membrane has great attraction to the large-capacity LIBs requiring high safety with low cost.

A Quasi-Solid-State Sodium-Ion Capacitor with High Energy Density

A quasi-solid-state sodium-ion capacitor is demonstrated with nanoporous disordered carbon and macroporous graphene as the negative and positive electrodes, respectively, using a sodium-ion-conducting gel polymer electrolyte. It can operate at a cell voltage as high as 4.2 V with an energy density of record high 168 W h kg(-1).