Electrochemical properties of LiNi_(0.5)Mn_(1.3)Ti_(0.2)O_4/Li_4Ti_5O_(12)cells

Spinel compounds LiNi0.5Mn1.3Ti0.2O4（LNMTO） and Li4Ti5O12 （LTO） were synthesized by different methods. The particle sizes of LNMTO and LTO are 0.5-2 and 0.5-0.8 μm, respectively. The LNMTO/LTO cell exhibits better electrochemical properties at both a low current rate of 0.2C and a high current rate of 1C. When the specific capacity was determined based on the mass of the LNMTO cathode, the LNMTO/LTO cell delivered 137 mA.h.g-1 at 0.2C and 118.2 mA-h-g-l at 1C, and the corresponding capacity retentions after 30 cycles are 88.5% and 92.4%, respectively.

In situ sol-gel synthesis of Ti2Nb10O29/C nanoparticles with enhanced pseudocapacitive contribution for a high-rate lithium-ion battery

Ti2Nb10O29/C nanoparticles with a carbon content of 13 wt%and a mean size of 50 nm were fabricated through a convenient and effective in situ sol-gel process.The small grain size and carbon modification can improve the pseudocapacitive effect of the Ti2Nb10O29/C nanoparticles,leading to excellent rate capacity,especially at high current rate.Specifically,the discharge capacity of the Ti2Nb10O29/C electrode is 258.3,236.0,216.6,184.5 and161.5 mAh·g-1 at different current densities of 1C,5C,10C,20C and 30C.Nevertheless,the discharge capacity of the Ti2Nb10O29 electrode is 244.9 mAh·g-1 at 1C,which is rapidly reduced to 89.7 mAh·g-1 at 30C.In addition,the small size and carbon layer of the Ti2Nb10O29/C nanoparticles can supply abundant active sites for Li+storage as well as enhance the electronic conductivity and Li+diffusion,endowing these nanoparticles with a high discharge capacity and excellent cycle performance.

Ionic liquid-induced ultrathin and uniform N-doped carbon-wrapped T-Nb_(2)O_(5) microsphere anode for high-performance lithium-ion battery

Orthorhombic-phase Nb_(2)O_(5)(T-Nb_(2)O_(5)) has been widely investigated as an intercalation anode material for Li-ion batteries due to the larger interplanar lattice spacing and high safety.However,its applications are limited by the intrinsic low electric conductivity.Herein,an ultrathin N-doped carbon-coating layer was constructed on porous T-Nb_(2)O_(5) microspheres uniformly via a convenient thermal treatment method with ionic liquid as a carbon precursor.The synthesized T-Nb_(2)O_(5)@N-C exhibits significantly enhanced rate capability(155.5 mAh·g^(-1) at 20 C) than initial T-Nb_(2)O_(5)(110.2 mAh·g^(-1) at 20C).Besides,T-Nb_(2)O_(5)@N-C shows ultralong cycle life,with only a 0.02% decrease in the capacity per cycle at a high current density of 10 C.The corresponding electrochemical tests show that the preferable rate capability of T-Nb_(2)O_(5)@N-C electrode is attributed to the increased electronic conductivity and pseudocapacitance contribution induced by ultrathin surface N-doped carbon layer.On the other hand,the mesoporous structure of T-Nb_(2)O_(5)@N-C ensures fast Li+ diffusion dynamics and electrolyte penetration.Furthermore,T-Nb_(2)O_(5)@N-C also performs well in a LiNi_(0.5)Mn_(0.3)Co_(0.2)O_(4) llT-Nb_(2)O_(5)@N-C full cell.This work provides a facile method to construct integrated anode materials for potential applications in lithium-ion batteries.