Physical and Electrochemical Characterization of LiCo0.8M0.2O2 （M=Ni,Zr） Cathode Films for All-solid-state Rechargeable Thin-film Lithium Batteries

LiCo0.8M0.2O2 （M=Ni,Zr） films were fabricated by radio frequency sputtering deposition combined with conventional annealing methods. The strtuctures of the films were characterized with X-ray diffraction （XRD）, Raman spectroscopy and scarming electron microscopy （SEM） techniques. It was shown that the 700 ℃- annealed LiCo0.8M0.2O2 has an α-NaFeO2 like layered structure. All-solid-state thin-film batteries （TFBs） were fabrieated with these films as the cathode and their eleetroctemical performances were evaluated. It was found that doping of electrochemically active Ni and inactive Zr has different effects on the structural and elcctrochemical properties of the LiCoO2 cathode films. Ni doping increases the discharge capacity of the film while Zr doping improves its cycling stability.

Analysis of delamination in thin film electrodes under galvanostatic and potentiostatic operations with Li-ion diffusion from edge

Progressive delamination driven by Li-ion diffusion in elastic disk-like thin film electrodes of Li-ion batteries is modeled based on the cohesive model. Axisymmetric diffusion model is considered under both galvanostatic and potentiostatic operations. The effect of edge diffusion on the delamination process is evaluated. It is found that the diffusion from edge leads to an earlier delamination initiation. The edge effect is significant for active disks with a small aspect ratio, but negligible for the case of large aspect ratio. The edge diffusion is weaker in the potentiostatic operation than in the galvanostatic operation.

Self-standing oxygen-deficient a-MoO_(3-x)nanoflake arrays as 3D cathode for advanced all-solid-state thin film lithium batteries

Compared with the planar two-dimensional(2D)all-solid-state thin film batteries(TFBs),threedimensional(3D)all-solid-state TFBs with interdigitated contact between electrode and electrolyte possess great advantage in achieving both high energy and power densities.Herein,we report a facile fabrication of vertically aligned oxygen-deficient a-MoO3-x nanoflake arrays(3D MO_(x))using metal Mo target by direct current(DC)magnetron sputtering.By utilizing the 3D MO_(x)cathode,amorphous lithium phosphorus oxynitride solid electrolyte,and lithium thin film anode,3D solid-state TFBs have been successfully fabricated,exhibiting high specific capacity(266 mAh g^(-1)at 50 mA g^(-1)),good rate performance(110 mAh g^(-1)at 1000mA g^(-1)),and excellent cycle performance(92.7%capacity retention after 1000 cycles)in comparison with the 2D TFBs using the planar MO_(x)thin film as cathode.The superior electrochemical performance of the 3D TFBs can be attributed to the 3D architecture of the cathode,maximizing the cathode/electrolyte interface while retaining the short Lit diffusion length.The charge/discharge measurements of the 3D MO_(x)cathode in liquid electrolyte,however,exhibit fast capacity fading,demonstrating the advantage of using transition metal oxide as cathode in solid-state batteries.

Decorating carbon nanofibers with Mo_2C nanoparticles towards hierarchically porous and highly catalytic cathode for high-performance Li-O_2 batteries

A facile synthesis of the hierarchically porous cathode with Mo2C nanoparticles through the electrospinning technique and heat treatment is proposed. The carbonization temperature of the precursors is the key factor for the formation of M02C nanoparticles on the carbon nanofibers （MCNFs）. Compared with the Mo2N nanoparticles embedded into N-doped carbon nanofibers film （MNNFs） and N-doped carbon nanofibers film （NFs）, the battery with MCNFs cathode is capable of operation with a high-capacity （10,509 mAhg-1 at 100 mAg-l）, a much reduced discharge-charge voltage gap, and a long-term life （124 cycles at 200 mA g-1 with a specific capacity limit of 500 mAh g -1）. These excellent performances are derived from the synergy of the following advantageous factors： （1） the hierarchically self-standing and binder-free structure of MCNFs could ensure the high diffusion flux of Li＋ and O2 as well as avoid clogging of the discharge product, bulk Li202; （2） the well dispersed M02C nanoparticles not only afford rich active sites, but also facilitate the electronic transfer for catalysis.