鋰離子正極三劍客之一:鈷酸鋰
1,LiCoO2的一種合成方法
??????????????????????900℃
2Co3O4+3Li2Co3+1/2O2?———?6LiCoO2+3CO2?↑
??????????????????????8hr
2,LiCoO2的結(jié)構(gòu)對鋰離子電池循環(huán)性能影響
???LiCoO2屬于α-NaFeO2型結(jié)構(gòu),它具有二維層狀結(jié)構(gòu),適宜鋰離子的脫嵌。LiCoO2中含有微量Fe,Ni等,當(dāng)Li+有序化/無序化轉(zhuǎn)變時,Fe,Ni等雜質(zhì)將取代Co晶格上的Co原子,則層狀結(jié)構(gòu)變壞,影響也LiCoO2的充放電性能.
???LiCoO2粒度大小對首次放電容量影響不大,而粒度分布越寬,其循環(huán)性越差;當(dāng)D50(粒度尺寸)=5.19μm且集中粒度分布在3-8μm時,LiCoO2達(dá)到最佳的放電容量及循環(huán)性.
???當(dāng)粒度分布較寬時,LiCoO2多孔電極孔隙度則差,影響其對電解液的毛細(xì)作用,使其阻抗較大;另外,當(dāng)充至極限電位時,大顆粒LiCoO2表面Li+會過脫嵌而破壞層狀結(jié)構(gòu).這兩種原因使粒度分布寬的LiCoO2循環(huán)性差.
3,德國MERCK公司LiCoO2的規(guī)格:
???形態(tài):Lithium?Cobalt?Oxide?
???顏色:黑色粉末(Black?Powder)
???Particle?Size:D50≈36μm
???Specific?Surface?Area:2m2/g(BET)
???Tap?Density:2Kg/l
???Specific?Capacity:min?130mAh/g(3?Cycle,3.3--4.3?vs.?Li)
???Cell?Design:
???Cell?Type?:Button?Cell?(Dia.?20mm)
???????Anode?:Lithium?Metal
???????Electrolyte:?Liquid?Battery?Electrolyte?,EC:DMC=50:50?wt%,1M?LiPF6
???????Cathode:???Active?Powder?:?Carbon?Black?:?PTFE=85:10:5?mix
???????Cathode?Current?Collector:?Aluminium?Foil
???????Test?Conditions:?Charge?:C/7;?Discharge?:?D/7
???????Potential?Range;?3.3—4.3V?vs.Li