3D cross-linked POSS-containing borate single ion conductor organic-inorganic hybrid gel electrolytes for dendrite-free lithium metal batteries

Abstract

At present, lithium (Li) metal has become the most promising anode for the next generation of batteries due to its excellent theoretical capacity and low electrochemical potential. Nevertheless, low lithium-ion transference numbers and poor stability between conventional electrolytes and electrodes limit its development. In this work, a novel three-dimensional cross-linked hybrid borate single ion conductor polymer electrolyte (POSS-BSICP) was constructed by coupling of novel synthesized lithium bis-allylmalonate borate (LiBAMB), poly (ethylene glycol) diacrylate (PEGDA) and vinyl-containing caged poly(sesquisiloxane) (MAPOSS) in the presence of pentaerythritol tetrakis(mercaptoacetate) (PETMP) as cross-linker and PVDF-HFP as support materials through UV-thermal Dual-Curing procedures. As expected, the lithium-ion transference number and electrochemical stability of the hybrid electrolyte membranes improve with the incorporation of MAPOSS. The tLi+ is up to 0.82 and the electrochemical window reaches 5.50 V. The Li/Li cell assembled with the POSS-containing single ion conductor gel polymer electrolytes can be subjected to stripping/plating cycles without short circuit over 2700 h at 0.1 mA cm−2, the peak of the SiO bond at 102.3 eV in the Si 2p spectrum confirms that the POSS participate in the formation of SEI, indicating that the incorporation of MAPOSS could increase the compatibility between the electrolytes and electrode. The Li|POSS-BSICP|LiFePO4 cell exhibits excellent cycle performance with a capacity retention over 90 % after 170 cycles and 82.0 % after 290 cycles at 0.1 C.