Yan Weibin,Liu Ying,Qiu Jiazhen,Tan Feipeng,Liang Jiahui,Cai Xinze,Dai Chunlong,Zhao Jiangqi,Lin Zifeng
The energy industry has taken notice of zinc-iodine (Zn-I 2 ) batteries for their high safety, low cost, and attractive energy density. However, the shuttling of I 3 − by-products at cathode electrode and dendrite issues at Zn metal anode result in short cycle lifespan. Here, a tripartite synergistic optimization strategy is proposed, involving a MXene cathode host, a n - butanol electrolyte additive, and the in-situ solid electrolyte interface (SEI) protection. The MXene possesses catalytic ability to enhance the reaction kinetics and reduce I 3 − by-products. Meanwhile, the partially dissolved n - butanol additive can work synergistically with MXene to inhibit the shuttling of I 3 − . Besides, the n - butanol and I − in the electrolyte can synergistically improve the solvation structure of Zn 2+ . Moreover, an organic-inorganic hybrid SEI is in situ generated on the surface of the Zn anode, which induces stable non-dendritic zinc deposition. As a result, the fabricated batteries exhibit a high capacity of 0.30 mAh cm −2 and a superior energy density of 0.34 mWh cm −2 at a high specific current of 5 A g −1 across 30,000 cycles, with a minimal capacity decay of 0.0004% per cycle. This work offers a promising strategy for the subsequent research to comprehensively improve battery performance.
Wei Yang,Qiankun Han,Wenshi Li,Maosheng Wu,Jing Yao,Man Zhao,Xianmao Lu
Redox-enhanced electrochemical capacitors (redox ECs) are promising energy-storage devices with the potential to deliver both high power and energy performances, although overcoming the severe self-discharge remains a great challenge due to the shuttle effect of redox species such as I − /I 3 − ions introduced in the electrolytes for gaining additional capacities. Herein, we propose a cation-initiated self-assembly process of Ti 3 C 2 T x MXene nanosheets onto glass fiber membranes to form Janus separators that can mitigate the shuttling of I − /I 3 − ions in iodine-based redox ECs. The interlayer spacing of the MXene films can be controlled by selecting different cations such as imidazolium (C 4 mim + ), Mg 2+ , and Al 3+ , therefore the resulting Janus separators exhibit tailored nanochannels for ion sieving. Both molecular dynamic (MD) simulations and electrochemical tests indicate that C 4 mim + -intercalated MXene Janus separators (C 4 mim + -MXene) can block the diffusion of I 3 − ions while allowing the pass of other electrolyte ions. As a result, self-discharge caused by the shuttle effect can be much reduced in C 4 mim + -MXene-based redox ECs, which deliver voltage and energy retentions substantially higher than that of the cells using glass fiber membrane separators (voltage retention: 70% vs. 10%, energy retention: 51% vs. 6.5%) after 24-h open-circuit test.
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