Effect Of Self-healing Polysiloxane On Energy Storage Characteristics Of Lithium-sulfur Batteries

The theoretical specific energy of lithium-sulfur batteries is 2600 Wh/kg.Compared with other lithium-ion batteries,its advantages are high energy density,low cost,and low environmental pollution.However,there are still some deficiencies in lithium-sulfur batteries,such as the safety problems caused by the dendrite of the negative materials,the capacity loss caused by the volume expansion of the cathode materials,etc.These problems severely restrict the practical application of lithium-sulfur batteries.In order to solve the lithium dendrite problem of lithium negative electrode and the volume expansion problem of sulfur positive electrode in the process of charge and discharge of lithium-sulfur battery,the lithium branch was inhibited by introducing the self-healing polysiloxane into the solid electrolyte phase interface film(SEI film)of the negative electrode.Crystal,while using self-healing polysiloxane as a binder to relieve the sulfur loss caused by the volume expansion of the positive electrode sulfur.Firstly,during the lithium deposition process,an in-situ generation method was used to deposit the SEI film on the surface of the copper foil containing the self-healing polysiloxane coating,resulting in a stable lithium metal anode.The self-healing polysiloxane network enables the generated SEI layer to readily adapt to changes in volume during lithium deposition and self-repair after lithium dendrite piercing,thereby inhibiting the production of lithium dendrites and reducing the disadvantages of electrodes and electrolytes.reaction.The resulting lithium negative electrode has good cycle stability.When this electrode was applied to a Li/Li Fe PO4 battery,the discharge capacity remained 99% and the Coulomb efficiency reached 99.5% after 300 cycles.Next,the self-healing polysiloxane was used as a binder instead of the traditional PVDF binder to solve the volume expansion problem of sulfur in the lithium-sulfur battery cathode material.Since polysiloxane has excellent tensile properties and self-healing properties,it can adapt to the volume change of the positive electrode active material during the charge-discharge cycle of the lithium-sulfur battery,ensuring the positive electrode active material during the charge-discharge cycle and the current collector.Good contact avoids exfoliation of active substances,thereby inhibiting polysulfide shuttle effects and reducing capacity loss.After charging and discharging the battery obtained by using the self-healing polysiloxane as a binder 100 times,the specific discharge capacity was still 820 m Ah/g,indicating that the self-healing polysiloxane was used as a binder instead of the conventional PVDF adhesive.It is feasible to solve the problem of the volume expansion of sulfur in lithium-sulfur battery cathode materials.