Study On The Application Of Room Temperature Liquid Metal In Lithium Ion Battery Anode Materials

With the rapid development of power batteries,consumer electronics,and energy storage systems,consumers have put forward higher requirements for the energy density and power density of lithium-ion batteries.The lower specific capacity limits the further development of graphite materials,and alloy anode materials are expected to become the next generation of high-power density lithium-ion battery anode materials due to their higher theoretical capacity.Among them,Ga-based liquid metal has higher theoretical capacity and unique self-healing properties,which has attracted wide attention from researchers.However,Ga-based liquid metal has good fluidity and is easily oxidized,accompanied by a certain volume expansion,which limits the further application of Ga-based liquid metal in anode materials.Researchers mainly limit the fluidity of liquid metals and buffer volume expansion by introducing various carbonbased materials,but this is difficult to integrate well with the current commercial homogenization coating process.Therefore,on the basis of matching with industrial production process,this paper further discusses the possibility of gallium-based liquid metal in the application of anode materials by limiting the fluidity of gallium-based liquid metal.The main contents of this paper are divided into the following two parts :(1)GaInSn / Graphite composites prepared by mechanical stirring method show good self-healing properties by preventing the flow and agglomeration of GaInSn particles through the sponge-like carbon phase formed by conductive agent and binder.The first lithium insertion capacity of the sample prepared at 20000 r / min can reach more than 400 m Ah / g,and the first effect is more than 80 %.During the chargedischarge cycle,it shows a more obvious Ga / Sn deintercalation reaction process,but its GaInSn particle coating effect is poor,and the capacity attenuation during the cycle is greater.The sample prepared at 2000 r / min has a good carbon coating effect,and there is almost no capacity decay after 100 cycles at a current density of 0.1C,showing good cycle stability.(2)The GaInSn-based semi-solid composites were prepared by planetary stirring method.By introducing graphite,copper powder,silicon powder and other particles during the oxidation process,the viscosity was improved and the wetting effect was improved.The charge-discharge cycle of GaInSn-based semi-solid composites is mainly the process of Ga / Sn deintercalation and lithium insertion,and there is a significant capacity decay.Due to the introduction of active materials,GaInSn +Graphite(316 m Ah / g)and GaInSn + Si(410 m Ah / g)samples showed higher initial lithium intercalation capacity.Due to the formation of Cu Ga2 phase in GaInSn + Cu samples,the Ga concentration decreased,the initial lithium intercalation capacity was low(183 m Ah / g),and the electrochemical reaction rate decreased significantly.During the first lithium insertion process of the GaInSn + Graphite sample,only the part of the surface electrolyte penetration participates in the lithium insertion reaction.The volume change causes the material to crack,the electrolyte penetrates inward,the electrochemical reaction proceeds layer by layer,and the SEI film continues to crack and grow,resulting in continuous attenuation of capacity.Secondly,the self-healing function of GaInSn liquid metal can only achieve liquid-solid conversion in a small size range.The GaInSn semi-solid material at the crack is restored to a small sphere after delithiation and gradually separated from the current collector.