Investigation On The Safety Performances Of Ceramic Fiber Separator For Lithium-ion Batteries

In this article,the safety performance of lithium ion battery with ceramic fiber separator was studied from three aspects.Firstly,the possibility of used ceramic fiber products as raw materials in lithium ion battery was explored.Secondly,the laminated soft-packed lithium ion batteries with different separators were assembled.Through the contrast experiments,the capacity,rate performance,cycle properties and AC impedance analysis of cells were researched.Finally,through acupuncture,high temperature performance and overcharge tests,the safety mechanism of cell with ceramic fiber separator was included.The physical and chemical properties of the ceramic fiber separator were discussed in this article.Through SEM characterization,thermal shrinkage test,absorption rate test,membrane conductivity test and electrochemical stability test,the differences between PE separator,ceramic fiber separator and ceramic coated separator were compared.The results show that:the ceramic fiber separator possesses three-dimensional network structure,excellent electrochemical stability and thermal stability.The absorption rate is 382.5%and the lithium ionic conductivity is 14.79×10^-3S/cm,which is twice to other separators.The three types of batteries,which adopting the PE separator,the ceramic coated separator and the ceramic fiber separator,were prepared by using graphite carbon material as the negative electrode and LiNi_0.5Co_0.2Mn_0.3O₂ as the cathode.The electrochemical properties of cells were studied.The results show that:the cell with ceramic fiber separator is better than the other two types on electrochemical performance.At 0.2C,it reaches95.61%of the design capacity during the first discharge process.At 0.5C/0.5C and 1C/1C,the capacity retention rates are respectively 98.31%and 92.23%after 100 cycles.The internal resistance of stable SEI film is only 1.58?after activation.The interface performance between electrode,separator and electric liquid is improved,because of the special properties of the ceramic fiber.The high security mechanism of battery system with ceramic fiber was explored and security of three kinds of cells was tested.By comparison,the safety performance of lithium ion battery with ceramic fiber separator is excellent even after cycle life test.At the acupuncture experiment,the temperature increases of cells with ceramic fiber separator,ceramic coated separator and PE separator were 10°C,20°C and 70°C respectively.Voltage change trend of the cell with ceramic fiber separator changes similar to the low rate discharge.During the overcharge experiment,the ceramic fiber cell's heat generation rate is similar to heat conduction rate and thermal contraction of ceramic fiber separator isn't exist.During the high temperature storage experiment,there is no thermal runaway through the test.In summary,the cell with ceramic fiber separator passed the security test and possessed excellent safety performance.