Improved cycle performance of LiMn2O4cathode material for aqueous rechargeable lithium battery by LaF3coating
Qing Zhu a,b,Shuai Zheng a,Xuwu Lu a,Yi Wan b,Quanqi Chen a,*,Jianwen Yang a,
Ling-zhi Zhang a,Zhouguang Lu b,**
a College of Chemistry and Bioengineering,Guilin University of Technology,Guilin541004,China
b Department of Materials Science&Engineering,South University of Science and Technology of China,Shenzhen518055,China
a r t i c l e i n f o
Received in revised form
Accepted11September2015 Available online14September2015
Aqueous rechargeable lithium battery (ARLB)
Cathode a b s t r a c t
LaF3-coated LiMn2O4composites were prepared by a simple co-precipitation method using pristine LiMn2O4,La(NO3)3$6H2O,NH4F and polyvinyl pyrrolidone(PVP)as raw materials and the physical and electrochemical properties of the composites were investigated.The results indicate that LaF3coating is beneﬁcial to improving the electrochemical performance of LiMn2O4used as a cathode material for aqueous rechargeable lithium battery(ARLB)in1mol/L LiNO3solution.The optimal LaF3-coated LiMn2O4 composite(L-3-LMO)containing3wt%LaF3exhibits much improved electrochemical performance as compared with the pristine LiMn2O4.When galvanostatically charged and discharged at2C (296mA gÀ1),L-3-LMO displays initial discharge capacity of118.4mAh gÀ1and capacity retention of 99.7%after50cycles,while the pristine LiMn2O4presents initial discharge capacity of109.2mAh gÀ1and capacity retention of89.4%.Even at high current density of10C,L-3-LMO delivers discharge capacity of 109.5mAh gÀ1and the capacity remains107.9mAh gÀ1after100cycles,while the highest discharge capacity of pristine LiMn2O4is only101.6mAh gÀ1and the capacity is as low as86.3mAh gÀ1after100 cycles.The effects of LaF3coating on Liþdiffusion coefﬁcient,dissolution of manganese ion of electro-active materials are also investigated.
©2015Elsevier B.V.All rights reserved.
Since commercialized by Sony in1991,non-aqueous lithium-ion battery has been attractive for its high energy density and long cycle life and widely used to power portable electronic equipments such as laptop,camera and cellar phone.However,itsﬂammable organic electrolytes limit its large-scale applications in energy storage systems due to potential safety issues resulting from the ﬂammable solvents and lower power density originating from the lower conductivity of organic electrolytes[2e5].While its coun-terpart,aqueous rechargeable lithium battery(ARLB)containing aqueous electrolyte,has similar mechanism of energy storage and conversion[4,6],and recently has been regarded as one kind of the most competitive storage systems due to its safety,high power density,environmental friendliness and low cost since it was proposed by Dahn in1994.Unfortunately,the cycle perfor-mance of ARLB is much inferior to that of non-aqueous lithium battery with the same electrodes,and it was usually attributed to the dissolution of electroactive materials and side reactions in aqueous electrolytes.
Compared with other studied cathode materials for ARLBs such as LiNiO2,LiNi0.8Co0.2O2,LiCoO2[10,11],LiCo1/3Ni1/3Mn1/3O2 ,Li1.2Co0.3Mn0.5O2,Li1.05Cr0.10Mn1.85O4,LiFePO4 [15e17],LiFe0.6Mn0.4PO4,LiFe0.5Mn0.5PO4,LiFe1Àx V x PO4 ,Li3V2(PO4)3and LiMnPO4,the spinel LiMn2O4 recently has been regarded as one of the most promising cathodes because of its high energy density,low cost,safety,environmental affability and high rate capability.But the dissolution of Mn ion into the electrolyte and structural distortion result in poor cycle life,so the cycling performance could be improved by changing the morphology and size of LiMn2O4[23e29].But the effects of surface modiﬁcation on the electrochemical performance of LiMn2O4 cathode for ARLBs have been rarely studied.Previous reports have shown that the LaF3coating can greatly improve the cycle perfor-mance of LiMn2O4as a cathode material for non-aqueous lithium-
E-mail addresses:quanqi.chen@http://www.360docs.net/doc/info-1e91662ec1c708a1294a44f5.html ,quanqi.chen@http://www.360docs.net/doc/info-1e91662ec1c708a1294a44f5.html (Q.Chen), luzg@http://www.360docs.net/doc/info-1e91662ec1c708a1294a44f5.html (Z.
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Journal of Alloys and Compounds654(2016)384e391