Preparation And Properties Of Epoxy Resin Based Self-healing Electrolute

Nowadays,the complex application environment requires lithium batteries to be self-healing to cope with the inevitable volume changes and breakage during use.However,only a small part of self-healing materials has been applied in lithium batteries because the introduction of self-healing components will affect the electrochemical performance.Developing a self-healing and recyclable electrolyte to pursue sustainable and long-life lithium batteries is still a great challenge.Epoxy resins have a high reactivity and can introduce functional groups into polymers relatively easily.In this paper,epoxy resins were chosen as the substrate,and electrolytes with excellent self-healing performance and electrochemical performance were prepared through a rational structural design.Firstly,a rigid epoxy resin DGEBA and a flexible epoxy resin PEGDGE were chosen as the substrates,2,2’-diaminodiphenyl disulfide 2-AFD containing disulfide bonds was used as the curing agent and polyethylene glycol PEG200 was used as the pore-forming agent.By adjusting the content of the pore-forming agent and the ratio of soft and hard segments in the polymer,the self-healing gel electrolytes were prepared with excellent performance.The electrolyte has an electrochemical stability window of 4.4 V,an ionic conductivity of 1.5×10^-3S cm^-1at room temperature and can heal itself in 2 h at room temperature.Secondly,the ionic liquid BMIM-TFSI was introduced and reacted with PEGDGE and 2-AFD to prepare an epoxy resin-based self-healing solid electrolyte,which has a doubly reversible cross-linked network.The electrolyte has an ionic conductivity up to 2.34×10^-4S cm^-1,a low migration activation energy of 0.0646 e V and an electrochemical stability window of 4.6V.The electrolyte has excellent self-healing properties and can be healed at room temperature for 30 min without any change in electrochemical properties after healing.In addition,the electrolyte has excellent lithium dendrite inhibition and can cycle stably for over 900 h at 0.5 m A/cm².The initial discharge specific capacity of LFP/electrolyte/Li is 139.5 m Ah g^-1when cycled at 0.1 C.After 100 cycles,the capacity retention is as high as 92.7%and the Coulomb efficiency is close to 100%.After charging and discharging at high current densities（0.5 C）,the capacity of the cell can be restored to93%of its original capacity.