近期，我院研究生李靜（第一作者），教師蘇超（通訊作者）等的研究成果“Zincophilic, Green, Non-Toxic Additives Modulate Lean-Water Inner Helmholtz Layer for Enhanced Stability of Zinc Anodes”在《Energy & Environmental Materials》（IF=14.1）上發(fā)表。
論文簡(jiǎn)介如下：
傳統(tǒng)水系電解液中，游離水分子優(yōu)先吸附在鋅負(fù)極表面，形成內(nèi)亥姆霍茲平面（IHP）。富水的IHP通常會(huì)誘發(fā)無(wú)法控制的鋅枝晶、析氫反應(yīng)和腐蝕問(wèn)題，從而嚴(yán)重影響鋅負(fù)極的循環(huán)壽命。本研究通過(guò)采用綠色無(wú)毒的二丙二醇二甲醚（DMM）作為電解液添加劑來(lái)重塑IHP。DMM具有親鋅性，能優(yōu)先吸附在鋅負(fù)極表面，占據(jù)IHP。同時(shí)，DMM含有兩個(gè)疏水甲基，可以排斥去溶劑化后殘留的游離水分子，構(gòu)建一個(gè)貧水IHP，隔絕水分子與鋅負(fù)極持續(xù)接觸。石英微晶天平可以準(zhǔn)確地反映 DMM分子在鋅負(fù)極表面的吸附行為，實(shí)現(xiàn)了吸附型添加劑從定性分析到定量分析的飛躍。采用DMM添加劑電解液的Zn//Zn對(duì)稱電池在0.5 mA cm-2、0.5 mAh cm-2的條件下，循環(huán)壽命穩(wěn)定在2500 h以上。此外，使用 DMM添加劑電解液的Zn//PANI全電池在1 A g-1電流密度下可循環(huán)使用1000次，且容量保持率達(dá)90%。
In conventional aqueous electrolytes, free water molecules are preferentially adsorbed on the surface of the zinc anode, forming an inner Helmholtz plane (IHP).Water-rich IHPs typically induce uncontrollable zinc dendrites, hydrogen evolution reaction, and corrosion problems that can severely impact the cycle life of zinc anodes. The present study reengineers IHP by employing the green, non-toxic dipropylene glycol dimethyl ether (DMM) as an electrolyte additive.Experimental and computational results show that DMM is zincophilic and can preferentially adsorb on the surface of zinc anode to occupy the IHP. Meanwhile, DMM contains two hydrophobic methyl groups, which can repel free water molecules remaining after desolvation to construct a water-poor IHP and isolate the water molecules from continuous contact with the zinc anode. The quartz crystal microbalance with dissipation test intuitively and accurately reflected the adsorption behavior of DMM on the surface of zinc anode, and realized the leap from qualitative analysis to quantitative analysis. The Zn//Zn symmetric cell with DMM electrolyte have a stable cycle life of over 2500 h at 0.5 mA cm-2, 0.5 mAh cm-2. In addition, Zn//PANI full battery with DMM electrolyte can be cycled 1,000 times with 90% capacity retention under 1 A g-1.
Design strategy of DMM additive for reconstructing a lean-water IHP. In the conventional zinc salt solution, free water molecules in the electrolyte occupy the IHP, leading to severe zinc dendrites and side reactions such as HER and corrosion. The introduction of DMM molecules can quickly occupy the IHP, and Zn2+ can be uniformly deposited on the surface of the zinc anode through electrostatic interactions. At the same time, the hydrophobic methyl group can isolate the direct contact between the free water molecules and the zinc anode surface and inhibit the interfacial side reactions.
