Lithium battery, as one of the high capacity battery systems, has been a major challenge in the field of dendritic growth and instability of SEI film. There are a lot of research from the battery lab equipments, electrolyte, seperator and other directions to improve the safety of lithium metal batteries. There are many studies to enhance the safety of the battery through the strengthening of the seperator, and through the coating of ceramic materials to improve the seperator strength is one of the commonly used methods.
But the method still has some problems:
(1) coating the ceramic material can be directly in contact with the electrode material, the occurrence of electrochemical reaction;
(2) in order to improve the infiltration of ceramic materials on the electrolyte, usually coated on the seperator, the performance of complementary;
(3) During the charging and discharging process, the ceramic material may fall off from the seperator.
Recently, CuiYi research group through the preparation of nano-silica sandwich membrane method to extend the life of lithium metal batteries. Compared to a conventional sandwich seperator, the
seperator is characterized by:
(1) nano-silica as the middle layer, to prevent the occurrence of side effects;
(2) the accumulation of nano-silica particles can be lithium ions and electrolyte through the provision of adequate space;
(3) Silica is an insulating material, only in the lithium metal piercing the seperator can occur when the reaction to prevent the further growth of dendrites.
Figure 1. Schematic representation of nano-silica sandwich membrane and SEM image
The nano-silica sandwiched seperators were compared with Ordinary seperator, the nano-silica sandwich seperators and the PMMA sandwich seperators respectively. The results showed that the nano-silica sandwiched seperator could more effectively retard the growth of dendrites and enhance the safety of battery pilot production line.
Figure 2. (a) STEM of Lithium Insertion Silicon Dioxide (b) Li, (c)Si, (d)O Distribution of the EELS diagram. (e) Silicon dioxide nanoparticles discharge curve diagram. (f) Silicon dioxide nanoparticles CV curve diagram.
Figure 3. (a)Comparison of dendritic penetration of different seperators. (b)A nano-silica sandwich seperator improves the safety of the battery
In summary, the work through the design of nano-silica sandwich seperator, when dendrites pierced into the seperator, it can effectively slow down the further growth of dendrites to improve the safety of lithium metal batteries, make sense for lithium metal battery design guidance.
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