Transition Metal Oxide Crystals:Structural Modification And Lithium Storage Performance

The growing energy crisis and environmental pollution have urged the rapid development of the new energy technologies and secondary power source.As the most potential secondary power supply,lithium-ion battery is moving toward higher energy and better safety performance.Among them,the battery materials have become the key to the development of new lithium-ion battery.Transition-metal oxides have a critical role to play in achieving this change in the way we store energy.LiCoO2 is still the most wildly used as cathode material due to its advantages such as energy density,C-rate capacity and long cycle life.Now,the key to extensive application is to improve the structural stability and energy storage property of LiCoO2 at high cut-off voltage.LiNi0.80Co0.15Al0.05O2 is utilized in EVs by reason of its high reversible capacity and safety performance,but the poor storage property has limited large scale applications.Thus,it is pressing to explore the changing of the energy storage process at the interface.In addition,ZnMn2O4,as one of the most popular anode materials,has becoming a hotspot for the electrode materials.The contents in this paper are as follows:1.An oxalate precursor strategy to prepare Al-doped LiCoO2 cathode materials:Al-doped CoC2O4 was prepared to synthesis the Al-doped and Al/Na-doped LiCoO2 materials.Compared to the different LiCoO2 prepared by the same calcining procedure,the Al-doped LiCoO2 have the smaller grains,higher voltage platform and cycling stability.Especially,the Li-Co-Al-O prepared by oxalate precursor have more stable discharge median voltage and better cycling and rate property than the sample synthesised by Al2O3 solid method.For the Al/Na-doped LiCoO2 electrodes,the Na+extends the layer distance and improves the capacity.It is certain that the sample of Li0.998Na0.002Co0.995Al0.005O2 has the best cycling capacity by the cycling measurement at 1 C.2.The interface structure and electrochemical property of LiNi0.8Co0.15Al0.05O2(NCA)materials at the process of storage:The effects of exposure temperature,humidity and time for the NCA are studied systematically in this paper.The results indicate that the NiO layer and unformed mixed materials(LiOH/Li2CO3)are observed at the surface of the NCA by exposuring 1day and remarkable affected by the temperature,can increase with the prolong of time.After exposure,the content of Ni2+increased in the NCA stuff,leading to increasing of the disorder of Li/Ni,and then inducing the decay of cycling capability.3.The structural evolution and electrochemical properties of the Zn-Mn-O disposed in alkaline solution:The ZnO-MnO materials were synthesized by the thermal decomposition of as-prepared(ZnMn)C2O4 mediums.The phase,structure,morphology of the process 'ZnO-MnO?Mn3O4?ZnMn2O4?ZnMn2O4-MnO2' were comprehensively studied.ZnMn2O4 electrodes display an outstanding discharge capacity of 995 mAh g-1 at 3 C during 0.01 V to 3.0 V after 200 cycles,which have the best cycling and rate performance among all the samples.