Exfoliated multi-layered graphene anode with the broadened delithiation voltage plateau below 0.5 V

The commercial graphite(CG)is the conventional anode material for lithium ion batteries(LIBs)due to its low delithiation voltage plateau(below 0.5 V)and extraordinary durability.Nevertheless,the further promotion of energy density of LIBs is restricted by the limited capacity below 0.5 V of CG.Here,based on the supercritical CO2 exfoliation technique,the production of multi-layered graphene(MLG)is achieved from the pilot scale production line.The great merit of the exfoliated MLG anode is that the voltage plateau below 0.5 V is broadened obviously as compared to those of natural graphite and CG.Additionally,no obvious lithium dendrites are observed for MLG during the lithiation process.The large delithiation capacity under the low voltage plateau of MLG is mainly benefited from the combination of Li intercalation and boundary storage mechanism,which is further confirmed by the density functional theory calculations.The LiFePO4/MLG full cell can afford the satisfactory electrochemical property with respect to the capacity,energy density and ultralong cycling stability(90%capacity retention after 500 cycles at 2 C),significantly better than that of LiFePO4/CG.Besides,this developed technique not only dedicates to producing the high-performance anode for LIBs but also opens a door for the mass production of MLG in the industrial scale.

Porous carbon spheres anode with the stable output of low delithiation plateau and constant delithiation ratio for lithium ion hybrid capacitor

Porous carbon spheres derived from the facile hydrothermal treatment associated with the calcination process exhibit the good spherical morphology and unique porous structure.For the Li-based half-cell test,porous carbon spheres electrode not only exhibits larger reversible capacities and better compatibility as compared to the widely-used graphite,but also provides stable delithiation plateaus under different current density.Additionally,the delithiation ratio below 1 V almost accounts for a constant value(around 70%)with the increase of current density,evidencing that Li intercalation storage is the dominant model and Li insertion/extraction processes are propitious.The lithium ion hybrid capacitor configured with S-doped mesoporous graphene and porous carbon spheres as cathode and anode,delivers satisfied energy and power densities(up to 177 Wh kg^(−1) and 12,303 W kg^(−1),respectively)as well as long-term cyclability,which is superior to the corresponding S-doped mesoporous graphene//graphite and activated carbon//porous carbon spheres.In addition,the developed synthesis strategy is in favor of the realization of the scalable production of porous carbon spheres.

LITHIUM ORDERING IN CHEMICALLY DELITHIATED Li_xCoO_2

Chemical delithiated LixCoO2 （x=1, 0.7, 0.66 and 0.57） has been synthesized by using a strong oxidant, NaS2O8 .The structure investigations indicate that all the samples remain with hexagonal cells, which have expansion of c axis during Li extraction. Transmission electron microscopy （TEM） observations revealed the presence of superstructures arising from intercalated U-ordering corresponding to first-principle calculations. The measurements of the physical properties are also influenced by Li concentration.

Chemical Extraction Preparation of Delithiated Cathode Materials of Li-ion Battery

A method of conventional chemical reaction to prepare delithiated cathode materials of Li-ion battery was introduced. The cathode material of Li-ion battery was mixed with oxidizing agent Na2S2O8 in water solution, and the solution was stirred continuously to make the chemical reaction proceed sufficiently, then the reaction product was filtered and finally the insoluble delithiated cathode material was obtained. A series of tests were conducted to verify the composition, crystal structure and electrochemical property of the delithiated cathode materials were all desirable. This method overcomes the shortcomings of battery charging preparation and chemical extraction preparation employing other oxidizing agents.

锂离子电池BaLi_(2-x)Na_xTi_6O_(14)(0≤x≤2)负极材料的结构与电化学性能（英文）

本文采用简单的高温固相法制备了BaLi_(2-x)NaxTi_6O_(14)(0≤x≤2)系列化合物作为储锂材料.XRD Rietveld精确表明Bragg点与Ba Li2Ti6O14相对应,由于Na+的半径比Li+的半径大55%,因此Na+掺杂的BaLi_2-xNaxTi_6O_(14)化合物具有比纯Ba Li2Ti6O1 4更大的晶胞体积.SEM测试结果表明,BaLi_2-xNaxTi_6O_(14)(x=0,0.5,1)粉末呈相似的不规则的颗粒状,粒径大约在500到1000 nm之间.但是,BaLi_2-xNaxTi_6O_(14)(x=1.5,2)展示了棒状的形貌.循环伏安结果表明,钝化膜主要在第一次嵌锂过程时形成,BaLi_(2-x)NaxTi_6O_(14)(0≤x≤2)表面的SEI膜主要在第一次循环且电位在0.7 V以下时形成.相对于其他样品,Ba Li0.5Na1.5Ti6O14具有较高的可逆容量,较好的倍率性能和优异的循环性能.电流密度为50、100、150、200、250和300mAg-1时,Ba Li0.5Na1.5Ti6O14的脱锂容量分别为162.1、158.1、156.7、152.2、147.3和142 mAhg(-1).有趣的是,Ba Na2Ti6O14作为阳极也展示了可接受的电化学性能.Ba Li0.5Na1.5Ti6O14所提高的电化学性能可以归因于其最小的极化和最高的锂离子扩散系数.因具有优异的循环性能、简单的合成路线和宽的放电区间,Ba Li0.5Na1.5Ti6O14可作为锂离子电池负极候选材料.