Effect of Crosslink Structure of Bridge Polycarboxylate Superplasticizers on Dispersion Ability

Bridge polycarboxylate superplasticizers（PCs） with crosslink structure were synthesized by using polyethyleneglycol di-acrylate（PEGdA）, replacing partial polyethyleneglycol mono-acrylate （PEGmA） as crosslinking agent. Structures of bridge PCs were analyzed by gel permeation chromatography, and dispersion ability was evaluated by cement paste dispersity variation on time and rheology test. The experimental results showed that, molecular weight（MW） of bridge PCs increased with increase of PEGdA proportion, and MW distribution curve changed from Gaussian to fiat like, which meant notable increase of highly crosslinked copolymer. Bridge PCs led to decreased initial cement paste dispersity and better dispersity retention due to slow releasing. Further research showed that, PEGdA proportion had slight effect on polymerization degree of backbone, MW distribution of backbone deviated from Gaussian distribution and shoulder peaks appeared on distribution curve when PEGdA increased.

Lithium bis(oxalate)borate crosslinked polymer electrolytes for high-performance lithium batteries

Solid electrolytes play a vital role in solid-state Li secondary batteries,which are promising high-energy storage devices for new-generation electric vehicles.Nevertheless,obtaining a suitable solid electrolyte by a simple and residue-free preparation process,resulting in a stable interface between electrolyte and electrode,is still a great challenge for practical applications.Herein,we report a self-crosslinked polymer electrolyte(SCPE)for high-performance lithium batteries,prepared by a one-step method based on 3-methoxysilyl-terminated polypropylene glycol(SPPG,a liquid oligomer).It is worth noting that lithium bis(oxalate)borate(Li BOB)can react with SPPG to form a crosslinked structure via a curing reaction.This self-formed polymer electrolyte exhibits excellent properties,including high roomtemperature ionic conductivity(2.6×10^(-4) S cm^(-1)),wide electrochemical window(4.7 V),and high Li ion transference number(0.65).The excellent cycling stability(500 cycles,83%)further highlights the improved interfacial stability after the in situ formation of SCPE on the electrode surface.Moreover,this self-formation strategy enhances the safety of the battery under mechanical deformation.Therefore,the present self-crosslinked polymer electrolyte shows great potential for applications in high-performance lithium batteries.

Carbon dots crosslinked gel polymer electrolytes for dendrite-free and long-cycle lithium metal batteries

Lithium metal batteries(LMBs)with extremely high energy densities have several advantages among energy storage equipment.However,the uncontrolled growth of dendrites and the flammable liquid electrolytes(LEs)often cause safety accidents.All solid-state batteries seem to be the ultimate choice,but solvent-free electrolytes usually fail in terms of conductivity at room temperature.Therefore,gel polymer electrolytes(GPEs)with a simple manufacturing process and high ionic conductivity are considered as the most competitive candidates to resolve the present difficulties.Herein,we design a polymeric network structure via esterification and amidation reactions between polyethylene glycol(PEG)and carbon dots(CDs).After incorporation with polyvinylidene fluoride and some LEs,the as-prepared PEG-CDs composite electrolytes(PCCEs)show a high ionic conductivity of 5.5 mS/cm and an ion transference number of 0.71 at room temperature,as well as good flexibility and thermostability.When the PCCEs are assembled with lithium metal anodes and LiFePO4 or LiCoO2 cathodes,both the cycling stability and the retention rate of these LMBs show excellent performance at room temperature.