The Application Of Polymers In The Design Of High Specific Energy Battery Electrode Structure

Sulfur(1672 mAh g^-1),silicon(4200 mAh g^-1),etc.are considered to be the most promising secondary lithium battery materials and have received widespread attention.However,the problems caused by the nature of these materials affect their electrochemical performance,thus limiting the use of these materials.The sulfur cathode is affected by the"shuttle effect"and silicon undergoes a huge volume expansion?300%?during charging and discharging,which will cause irreversible loss of active material and seriously affect the battery life.Polymer materials play an important role in multiple components of the battery,provide cohesion for the particles in the electrode and their adhesion to the metal current collector,and provide structural support and adhesion for energy storage devices.Therefore,the strategy of using functional polymers to solve key problems in high specific capacity electrode materials shows great potential.In this paper,the structure of the electrode is designed using polymer characteristics,and the following work is done to solve the key problems that limit the development of high energy density secondary batteries:?1?In response to the"shuttle effect"in the sulfur cathode,we were inspired by the affinity membrane chromatographic separation method and designed a built-in electrode for the affinity chromatography membrane.Using the gelation of sodium alginate,the electrode was realized using the crosslinking method In-situ construction and layer number regulation of the inner affinity membrane.At the same time,sodium alginate has a strong adsorption force to polysulfide,so that the polymer film formed by cross-linking of sodium alginate has both physical and chemical double blocking ability.This structure can take into account both the suppression of the polysulfide shuttle and the ion transmission ability without causing a large ohmic polarization.Thanks to the affinity membrane adsorption of polysulfides and the design of the electrode structure,the electrode can effectively improve the electrochemical stability of lithium-sulfur batteries.On the other hand,part of the sodium alginate in the electrode was changed from a binder to a polymer film covering the electrode,which changed the bonding method of the traditional sulfur electrode and achieved a breakthrough in load.?2?Aiming at the problems of serious volume expansion and poor conductivity of silicon anodes,a high-elasticity current collector was prepared by chemical deposition using the high elasticity of styrene-butadiene rubber.The design of the electrode structure was realized by chemical deposition method:Ni particles were not only deposited on the electrode surface to obtain a fitted current collector,but also Ni particles were also deposited inside the electrode,constructing a three-dimensional conductive network,which was conducive to improving the conductivity of the electrode.The addition of styrene-butadiene rubber can protect the electrode structure from damage when the current collector undergoes volume expansion,and"lock"the active substance firmly in the electrode.