Non-desolvation Zn^(2+)storage mechanism enables MoS_(2)anode with enhanced interfacial charge-transfer kinetics for low temperature zinc-ion batteries

The emerging rocking-chair aqueous zinc-ion battery(AZIB)configuration provides a promising approach for realizing their practical applications by avoiding the critical drawbacks of Zn metal anodes including unsatisfactory Coulombic efficiency and low Zn utilization.Therefore,exploiting appropriate insertion-type anodes with fast charge-transfer kinetics is of great importance,and many modifications focusing on the improvement of electron transport and bulk Zn^(2+)diffusion have been proposed.However,the interfacial Zn^(2+)transfer determined by the desolvation process actually dominates the kinetics of overall battery reactions,which is mainly overlooked.Herein,the interlayer structure of Mo S_(2)is rationally co-intercalated with water and ethylene glycol(EG)molecules(Mo S2@EG),giving rise to a fast non-desolvation Zn^(2+)storage mechanism,which is verified by the extraordinarily smaller activation energy of interfacial Zn^(2+)transfer(4.66 k J mol^(-1))compared with that of pristine Mo S_(2)(56.78 k J mol^(-1)).Furthermore,the results of theoretical calculations,in-situ Raman and ex-situ characterizations also indicate the enhanced structural integrity of Mo S2@EG during cycling due to the enlarged interlayer spacing and charge screening effect induced by interlaminar EG molecules.Consequently,the Mo S_(2)@EG anode enables excellent cycling stability of both high-energy-density Mo_S2@EG||PVO(polyaniline intercalated V_(2)O_(5))and high-voltage Mo S2@EG||Na_(3)V_(2)(PO_(4))_2O_(2)F(NVPF)full batteries with neglectable capacity decay at-20℃.

Stabilizing layered superlattice MoSe_(2) anodes by the rational solvation structure design for low-temperature aqueous zinc-ion batteries

Aqueous zinc-ion batteries(AZIBs)have attracted widespread attention due to their intrinsic merits of low cost and high safety.However,the poor thermodynamic stability of Zn metal in aqueous electrolytes inevitably cause Zn dendrites growth and interface parasitic side reactions,resulting in unsatisfactory cycling stability and low Zn utilization.Replacing Zn anode with intercalation-type anodes have emerged as a promising alternative strategy to overcome the above issues but the lack of appropriate anode materials is becoming the bottleneck.Herein,the interlayer structure of MoSe_(2) anode is preintercalated with long-chain polyvinyl pyrrolidone(PVP),constructing a periodically stacked p-MoSe_(2)superlattice to activate the reversible Zn^(2+) storage performance(203 mAh g^(−1)at 0.2 A g^(−1)).To further improve the stability of the superlattice structure during cycling,the electrolyte is also rationally designed by adding 1,4-Butyrolactone(γ-GBL)additive into 3 M Zn(CF_(3)SO_(3))_(2),in whichγ-GBL replaces the H2O in Zn^(2+) solvation sheath.The preferential solvation ofγ-GBL with Zn^(2+)effectively reduces the water activity and helps to achieve an ultra-long lifespan of 12,000 cycles for p-MoSe_(2).More importantly,the reconstructed solvation structure enables the operation of p-MoSe_(2)||ZnxNVPF(Na3V2(PO4)2O_(2)F)AZIBs at an ultra-low temperature of−40°C,which is expected to promote the practical applications of AZIBs.