| Because of high energy density high voltage low self-discharge rate and long cycle- life the asecond lithium lion batteries are becoming more and more important in the field of batteries. The changes which were brought by the second lithium lion batteries are becoming more and more evident However because of the expensive cathode materials the development of the second lithium lion batteries are limited. Among the cathode materials LiCoO2 has good chararistics such as high energy density long cycle life the stability of its structure But it is very expensive, which cause the second lithium lion batteries that use LiCoO2 as cathode materials. Except of this cathode material, there are such cathode materials as LiMn2O4 and LiNiO2. LiMn2O4 is much cheaper than LiCoO2 and it is easy for us to prepare it. However its capacity is lower than that of LiCoO2 .Because of its structure the charge and discharge current was limited. And its cycle life is very poor. Though much work people have done to improve it ,we can not produce LiMn2O4 which can be used as cathode materials for second lithium batteries.LiNiO2 has higher capacity than LiCoO2 It has the same structure as LiCoO2 .So it has long cycle life and can be charged and discharged with high current. But the difficulty of preparing it cause it is not used as the cathode material for second lithium batteries, in this article our main work is to find cheaper cathode materials which has good chararistics instead of LiCoO2. First we study the preparation and chararistics of LiCoO2 and we found that: LiCoO2 1) The chararistics of LiCoO2 can be improved by the control of the time of the pre-handle and by the control of the temperature and by the control of the cooling rate The slow cooling rate can improve the stability of the structure of the LiCoO2.If the time is short the materials can not be mixed enough which is the reason that the LiCoO2 has poor chararistics. 2) The technology of the pre-handle can improve the real density and the mic-appearance of the LiCoO2 , and at the same time it can make work simple. 3) The scope of charge voltage is important for us to keep the stability of the LiCoO2 if the charged voltage is higher than 4.15 V its structure can be changed arid make its life become shorter. prepare LiCoO2 ich has long cycle life In order to look for the cathode material which can take the placc of LiCoO2 we study the preparetion and thechararistics of LiNixCol-x02. Atlast we found that: 1)The rate of Ni/Co is one of the most important elements for the preparetion of LiNixColxO2.The suitiful ra~te can add the lithium lion in the LiNixCol- x02.Usurally the lithium lion is added with the adding of the rate. 2)The suitiful choice of preparation route can produce good material. We favored the route which can lower the reaction time 3)Because there are many conditions which can influnce the poor lithium phenomenon so only adding the rate of Li/(Ni+Co) can not change the poor lithium of LiNixCol-x02. 4) Slow cooling rate can improve the mic-ppearance of LiNixCo]-x02 because slow cooling rate can help it react completely. 5)The scope of charge and discharge voltage have effect on the stability of LiNixCol-x02.Excel charge voltage can reduce its cycle life. The temperature is im... |
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