| Lithium ion battery has become a hotspot of energy application because of its advantages of high potential,no pollution and high specific capacity.However,the low specific capacity of commercial carbon anode materials restricts their further development.The sn-based cathode material has a theoretical mass ratio of up to 997 mAh g-1,which is double that of the traditional carbon anode material,and a volume ratio of up to 7200 mAh cm-3.It has a good prospect for industrialization,and has become an important direction for the research and development of new cathode materials for lithium ion batteries.In this paper,the following four composite film materials were prepared and their properties were studied.:?1?Sn-Cu composite film.The sputtering power of the Sn target is controlled to be constant,and the power of the Cu target is continuously adjusted.The film prepared by the magnetron sputtering method has a dense and uniform composition distribution and no accumulation agglomeration.It was found that the Sn target 40 W and the Cu target 25 W are the optimal sputtering power.The resulting film material was improved in cycle performance as well as rate performance.0.2 C current density after 100 cycles,the capacity retention rate was 52.1%;the capacity retention rate at 1 C was 82.8%,and the charge specific capacity was 540 mAh g-1.This indicates that the composite film material can maintain a small volume change even under the condition of large-rate current density charge and discharge,and the charge capacity is 582 mAh g-1 when returning to a current density of 0.2 C.?2?Sn-Ni composite film.A series of tests on the prepared film materials showed that the addition of Ni improved the properties of the material.Among them,the Sn-Ni?40 W-80W?group has a capacity retention rate of 45.6%and 213 mAh g-1 after 150 cycles,which significantly improves the cycle stability of pure Sn materials.The power of Ni should not be too high,and the excessive sputtering power will result in excessive loss of specific capacity of the material.It is most suitable to set the sputtering power of the Ni target to 80 W.?3?Sn-Ti composite film.Exploring the influence of sputtering power and sputtering time on the composite film material,it was found that the sputtering power of the Ti target is too high and the deposition time is too long,which will reduce the specific capacity of the film material.With the Sn target DC 40 W and the Ti target 60 W RF sputtering for 5 min,the cycle performance and rate performance of the composites obtained were significantly improved.After 50 weeks of cycling,the specific capacity of 700 mAh g-1 can still be maintained,and the capacity retention rate is nearly 100%;the capacity retention rate at 1C can reach 91%and the charging capacity is 600 mAh g-1,indicating composite film material.In the case of large-rate current density charge and discharge,a small volume change can be maintained,and the charge capacity is 707 mAh g-1 when returning to a current density of 0.2C.In the process of charging and discharging,the phenomenon of detachment and pulverization of the Sn material is improved,and the structure is basically intact.?4?Sn-Al-Ti ternary composite film.The Sn-Al-Ti ternary composite film material has a charge capacity of 840 mAh g-1 for the first week,and the first charge and discharge efficiency is 91.2%.It can still charge 600 mAh g-1 at 6000 mAh g-1 charge or discharge current.Specific capacity,returning to 0.2 C current density after 6 weeks of 20 C high current density charge and discharge cycle,the charge specific capacity can still reach 610mAh g-1,and the charge ratio of 694 mAh g-1 can be maintained after 120 weeks of cycling.The rate is 82%. |
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