A high-performance lithium anode based on N-doped composite graphene

Lithium(Li)metal is the most promising electrode for next-gene ration rechargeable batteries.In order to push the commercialization of the lithium metal batteries,a kind of nitrogen(N)-doped composite graphene(NCG)adopted as the Li plating host was prepared to regulate Li metal nucleation and suppress dendrite growth.Furthermore,a new kind of sandwich-type composite lithium metal(STCL)electrode was developed to improve its application.The STCL electrode can be used as convenient as a piece of Li foil but no dendrite growth.In a symmetric battery,the STCL electrode cycled for more than 4500 h with the overpotential of less than 40 mV.And due to the creative design,the STCL promises the Li-S battery with a prolonged cycling lifespan.

Electrochemical properties of high-loading sulfur–carbon materials prepared by in situ generation method

A high sulfur content sulfur–carbon composite was synthesized via in situ generation method in aqueous solution.When the sulfur loading is up to 90%,the electrode still exhibits good cycling performance with a reversible capacity of about 623 mAh·g^(-1)after 100 cycles.To further commercialize the Li–S battery,understanding the capacity degradation mechanism is very essential,especially with a high sulfur loading electrode.To achieve this goal,the electrochemical performance of the high sulfur loading electrode was studied,and the structure change of the electrode after cycling was also examined by ex situ scanning electron microscopy(SEM)and other techniques.The result shows that the Li_(2)S_(2)and Li_(2)S inhomogeneous precipitation contributes to the majority capacity fading of the high sulfur loading Li–S cells.

Self-healing alginate-carboxymethyl chitosan porous scaffold as an effective binder for silicon anodes in lithium-ion batteries

Polymer binder plays a pivotal role in electrochemical performance of high-capacity silicon(Si)anode that usually suffers from severe capacity fading due to enormous substantial volume change of Si during cycling.In an effort to find efficient polymer binder that could mitigate such capacity fading,alginate-carboxymethyl chitosan(Alg-C-chitosan)composite polymer was investigated as a low-cost watersoluble binder for silicon anodes in lithium-ion batteries.The electrostatic interaction between carboxylate(-COO-)of Alg and protonated amines(-NH3+)of C-chitosan forms a selfhealing porous scaffold structure.Synergistic effect on the enhanced porous scaffold structure and self-healing electrostatic interaction of Alg-C-chitosan binder effectively can tolerate the tremendous volume change of Si and maintain an integrated electrode structure during cycling process.The Si nanopowder electrodes with Alg-C-chitosan composite binder exhibit an excellent cycling stability,with a capacity of750 mAh·g-1 remaining after 100 th cycling.In addition,an extraordinary areal capacity of 3.76 mAh·cm-2 is achieved for Si-based anodes with Alg-C-chitosan binder.

Electrochemical preparation of silicon nanowires from porous Ni/SiO2 blocks in molten CaCl2

Silicon nanowires(SiNWs)with diameter distributions ranging from 80 to 350 nm were prepared by electrochemical reduction of Ni/SiO2 in molten CaCl2.The effect of the content of nickel additives on the morphology of produced silicon was investigated.Large quantities of SiNWs are obtained by the electrochemical reduction of Ni/SiO2 blocks with SiO2 to Ni molar ratio of 20 and 10.Nickel additives repress the growth of irregular branches and promote longitudinal growth of SiNWs.Wire morphologies and surfaces are influenced by the electrolysis temperature.SiNWs become thicker with the increase of the electrolysis temperature.The optimum temperature to prepare single crystal SiNWs with high aspect ratio and extraordinary surface quality seems to be 1173 K.The amorphous layer of the silicon nanowire is thinner compared to the SiNWs obtained from the pure SiO2 pellets.The produced SiNWs show a photoluminescence emission peak at about 758 nm at room temperature.This work demonstrates the potentiality for the electrochemical reduction process to obtain large quantities of SiNWs with high quality.