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1、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 c
2、ostly，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
3、 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
4、,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
5、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 vol
6、tage 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 ca
7、pacity 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,C
8、o)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 current
9、s .,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 cycl
10、e 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 reten
11、tion 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. Effe
12、ct 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, go
13、od 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
14、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 c
15、onductivity,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+,
16、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
