XXXX,Recent developments in cathode materials for lithium ion batteries,Review,1. Introduction,battery performance,electrode material,Lithium-ion batteries：widely utilized Future：light weight,small volume, high energy density, safety,2. Cathode materials,LiCoO2：-NaFeO2 structure，commonly used，more costly，less stable，rapid decrease； LiNiO2：-NaFeO2 structure，lower in cost, higher energy density, less stable，less ordered; LiMnO2：monoclinic structure，less ordered; Li(Ni1/3Mn1/3Co1/3)O2:commonly used, high capacity, good rate capability,higher charging voltage,rapid loss of capacity; LiMn2O4:spinel structure, lower cost and safer than LiCoO2, lower capacity,easy phase changes; V2O5、LiV3O8:low voltages LiFePO4:olivine structure,two-phase(FePO4 and LiFePO4), relatively constant voltage,low electronic conduction; LiMnPO4、LiCoPO4:higher open circuit voltages(4.1v,4.8v), lower capacities; Li(Mn,Fe,Co)PO4、Li3V2(PO4)3:high operating voltage，good performance at high discharge currents;,3. Cathode performance,Fig. 2. Plateau voltage and capacity (see Fig. 1) for LiFePO4 123,153162 and LiCoO2 163167 with a charging voltage of 4.2V and discharge current of 1C.,Fig. 3. Plateau voltage and capacity for LiFePO4 123,150,153,156,158161,168174 with a charging voltage of 4.2V and discharge current of 0.1C.,The operating voltage for LiCoO2 is higher than that for LiFePO4 ，LiFePO4 has a narrower voltage range.,A reduction in the discharge current increases the capacity of LiFePO4.,Fig. 4. Plateau voltage and capacity for Li(Ni1/3Mn1/3Co1/3)O2 ,LiCoO2, LiFePO4 , and LiMn2O4 with a charging voltage of 4.3V and discharge current of 1C.,Fig. 5. Plateau voltage and capacity (see Fig. 1) for Li(Ni1/3Mn1/3Co1/3)O2,LiMn2O4 and LiCoO2 with a charging voltage of 4.3V and discharge current of 0.1C.,The capacity of Li(Ni1/3Mn1/3Co1/3)O2 increases more than that of LiCoO2, suggesting that the kinetics of charge transfer and/or mass transport are slower in Li(Ni1/3Mn1/3Co1/3)O2 than in LiCoO2.,Fig. 6. Discharge capacity of LiCoO2 as a function of discharge rate.,Fig. 7. Discharge capacity of Li(Ni,Mn,Co)O2 and LiMn2O4 as a function of discharge rate.,The decrease in capacity with increasing discharge current is generally smaller for LiCoO2 than for Li(Ni,Mn,Co)O2.,Fig. 8. Discharge capacity of LiFePO4 as a function of discharge rate.,Fig. 9. Discharge capacity of LiFePO4 at high discharge currents .,Rapid decrease in capacity is for a cell with a polymer electrolyte, rather than a liquid LiPF6-based electrolyte, so the high current performance may be limited by the electrolyte rather than the electrode.,LiFePO4 can be used at high discharge currents.,Figs. 1012. Capacity after 1st/50th cycle and percent change in capacity after 50 cycles for LiFePO4 LiCoO2 Li(Ni,Mn,Co)O2 cathodes.,The decrease in capacity of LiFePO4 (1020%) after cycling is much smaller than that for LiCoO2 or Li(Ni,Mn,Co)O2(3040%).,4. Composite cathodes,Combination of two electrode materials,To improve capacity retention during cycling and performance at high discharge currents,adding LiFePO4 to LiCoO2, Li(Li0.17Mn0.58Ni0.25)O2 , Li(Ni0.5Mn0.3Co0.2)O2.,Coating particles of one cathode material with another active material,With a Co3O4 coating,the cycling and rate capability of LiMn2O4 has been improved.,5. Effect of doping,Dopant additions,Fe,Ru,LiNiO2、Li2MnO3、LiNi0.125Mn0.75Co0.125O2,LiMn2O4、LiFePO4、LiMn1.5Ni0.5O4、Li3V2(PO4)3,Cr,LiMn2O4、LiMn1.5Ni0.5O4、Li(Mn0.5Ni0.5)O2、V2O5、Li(Ni1/3Mn1/3Co1/3)O2 、 Li3V2(PO4)3,Zn、Al、Ti、Mg、La,Capacity、cycling、electrical conductivity,High voltages, high discharge current, good capacities are required.,6.Conclusions,Progress has been made by engineering the electrode composition, microstructure and morphology, but additional improvements are needed.,Niobium doped lithium titanate as a high rate anode material for Li-ion batteries,1 Introduction,2 Experimental,3 Results and discussion,4 Conclusions,1. Introduction,Lithium-ion batteries：widely utilized Future：light weight,small volume, high energy density, safety,As a anode material,Li4Ti5O12 is promising compared to the currently used graphite：zero strain material,safe, stable.,advantages,obstacles,Low electronic conductivity,which leads to its low rate capacity.,Solution,(1) improving the synthesis route to get nano-sized particles； (2) adding a second conductive phase into the Li4Ti5O12, such as metal powder and carbon ; (3) substituting Li or Ti by other metal cations, such as Cr3+, V5+, Mn4+, Fe3+, Al3+, Co3+, Ta5+, Cu2+;,No investigation was reported on the electrochemical characteristics of Nb-doped Li4Ti5O12 as an anode material.,Nb,2. Experimental,Cathode(+):Li4Ti4.95Nb0.05O12 (solgel method) CH3COOLi+Ti(OC4H9)4+Nb(OH)5,Anode(-):Lithium metal,Electrolyte:ethylene carbonate(EC) +dimethyl carbonate (DMC) (1:1 in volume) + LiPF6(1.0 mol/dm3),Separator:porous membrane of polypropylene,For comparison，Li4Ti5O12 were also prepared using similar method.,3