锂离子电池用LiMn_2O_4/石墨烯复合材料的性能
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摘要
采用Hummers法制备少层氧化石墨烯(GO),再通过喷雾干燥高温固相原位还原法制备锰酸锂(LiMn_2O_4)/石墨烯复合正极材料。通过SEM、透射电镜(TEM)、XRD及电化学测试等方法,研究材料的结构和电化学性能。石墨烯能包覆LiMn_2O_4纳米颗粒团,并连接在纳米颗粒之间,减少LiMn_2O_4颗粒与电解液直接接触,形成纳米级的导电网络,提高LiMn_2O_4的循环性能和高倍率性能。在3. 0～4. 3 V充放电,LiMn_2O_4/石墨烯复合材料在0. 5 C倍率下的放电比容量为133. 0 m Ah/g,比Li LiMn_2O_4高11. 2 m Ah/g; LiMn_2O_4/石墨烯复合材料在1. 0 C倍率下循环100次,放电比容量由128. 7 m Ah/g衰减到127. 8 m Ah/g,容量保持率为99. 3%; 5. 0 C倍率下的放电比容量达到110. 9 m Ah/g,是0. 5 C时的83. 3%。
Micro layers of graphite oxide( GO) was prepared by Hummers method. Lithium manganese oxide( LiMn_2O_4)/graphene composite was prepared by spray drying high temperature solid situ reduction method. The structure and electrochemical performance of LiMn_2O_4/graphene composite materials were investigated systematically. Images of SEM and transmission electron microscopy( TEM) showed that graphene could effectively cover the surface of LiMn_2O_4 cluster nanoparticles and connect them between nanoparticles to reduce the direct contact between LiMn_2O_4 particles and electrolyte and to form a nanoscale conductive network,thus improved greatly cycling performance and high rate capacity of LiMn_2O_4. In particular,the discharge specific capacity of LiMn_2O_4/graphene composite reached 133. 0 m Ah/g at 0. 5 C in 3. 0-4. 3 V,compared with LiMn_2O_4,whose capacity was improved 11. 2 m Ah/g. After 100. 0 cycles at 1. 0 C,the capacity of LiMn_2O_4/graphene composite decreased from 128. 7 m Ah/g to 127. 8 m Ah/g,which was 99. 3% of the initial discharge specific capacity. When the discharge rate increased to 5. 0 C,the specific discharge capacity of graphene/LiMn_2O_4 battery was 110. 9 m Ah/g,which was 83. 3 % of the one at 0. 5 C.
Micro layers of graphite oxide( GO) was prepared by Hummers method. Lithium manganese oxide( LiMn_2O_4)/graphene composite was prepared by spray drying high temperature solid situ reduction method. The structure and electrochemical performance of LiMn_2O_4/graphene composite materials were investigated systematically. Images of SEM and transmission electron microscopy( TEM) showed that graphene could effectively cover the surface of LiMn_2O_4 cluster nanoparticles and connect them between nanoparticles to reduce the direct contact between LiMn_2O_4 particles and electrolyte and to form a nanoscale conductive network,thus improved greatly cycling performance and high rate capacity of LiMn_2O_4. In particular,the discharge specific capacity of LiMn_2O_4/graphene composite reached 133. 0 m Ah/g at 0. 5 C in 3. 0-4. 3 V,compared with LiMn_2O_4,whose capacity was improved 11. 2 m Ah/g. After 100. 0 cycles at 1. 0 C,the capacity of LiMn_2O_4/graphene composite decreased from 128. 7 m Ah/g to 127. 8 m Ah/g,which was 99. 3% of the initial discharge specific capacity. When the discharge rate increased to 5. 0 C,the specific discharge capacity of graphene/LiMn_2O_4 battery was 110. 9 m Ah/g,which was 83. 3 % of the one at 0. 5 C.
引文
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[3]邓凌峰,彭辉艳,覃昱焜,等.碳纳米管与石墨烯协同改性天然石墨及其电化学性能[J].材料工程,2017,45(4):121-127.
[4]GE Q,WANG D,LI F,et al. Enhanced cycling stability of spinel Li Mn2O4,cathode by incorporating graphene sheets[J]. Russ J Electrochem,2015,51(2):125-133.
[5]ZHU X,HOANG T K A,CHEN P,et al. Novel carbon materials in the cathode formulation for high rate rechargeable hybrid aqueous batteries[J]. Energies,2017,10(11):1 844.
[6]JIANG R,CUI C,MA H. Using graphene nanosheets as a conductive additive to enhance the rate performance of spinel Li Mn2O4cathode material[J]. Physical Chemistry Chemical Physics Pccp,2013,15(17):6 406-6 415.
[7]LUO X D,YIN Y Z,YUAN M,et al. High performance composites of spinel Li Mn2O4/3DG for lithium ion batteries[J]. Rsc Advances,2018,8(2):877-884.
[8]JABER-ANSARI L,PUNTAMBEKAR K P,KIM S,et al. Suppressing manganese dissolution from lithium manganese oxide spinel cathodes with single-layer graphene[J]. Advanced Energy Mate-rials,2015,5(17).
[9]崔永丽,徐坤,袁铮,等.石墨烯/尖晶石Li Mn2O4纳米复合材料制备及电化学性能[J].无机化学学报,2013,29(1):50-56.
[10]LUO X D,YIN Y Z,YUAN M,et al. High performance composites of spinel Li Mn2O4/3DG for lithium ion batteries[J]. Rsc Advances,2018,8(2):877-884.