Failure Mechanism And Performance Optimization Of Aqueous Zinc Ion Battery Under Wide Temperature Conditions

Rechargeable aqueous Zn ion batteries（ZIBs）play an important role in electrochemical energy storage owing to their low manufacturing cost,high safety,and high theoretical capacity of Zn metal anode.As the demands for energy storage/conversion continue to soar and more special applications emerge,aqueous ZIBs are urged to function under a wide temperature range.In some use cases,such as subsurface/subsea exploration and grid storage,which requires periodic and recurring exposures to subzero temperatures or elevated temperatures,the performance of aqueous ZIBs may be constrained and thus the aqueous ZIBs fail to perform optimally.Therefore,it is of great scientific and practical significance to develop aqueous ZIBs under wide temperature conditions.However,the excellent electrochemical performance of aqueous ZIBs under a broad range of temperature conditions still confronts significant obstacles in theory and technology aspect.Herein,this research focuses on"failure mechanism"and"performance optimization"of aqueous ZIBs under wide temperatures.The following summarizes the major contents and results:（Ⅰ）In the first work,the failure mechanism of aqueous ZIBs is systematically investigated with thermodynamic and kinetic perspectives.Firstly,the relationships between"operating temperature","current density"and"cell life"are analyzed through electrochemical testing and mathematical modeling.The fundamental law is summarized that high/subzero temperatures and high current density could diminish the cell life.Meanwhile,the ultra-long cycle stability of the Zn metal anode is disclosed at 0°C and 10 m A cm^-2.Furthermore,the nucleation and growth behaviors of Zn metal anodes is explored under a wide range of temperatures.A series of ex-situ material characterization techniques demonstrate that low temperature and current density can induce a smaller and dense nucleus,and high temperature and current density induce a larger and sparse nucleus.Moreover,the kinetic behavior of Zn²⁺transport and mitigating at different current densities under wide temperature conditions is derived from electrochemical tests.Low temperatures could lead to sluggish kinetic processes,while high temperatures could accelerate the rate of Zn²⁺transport.However,simultaneously increased parasitic reactions could lead to unstable electrode/electrolyte interphase,which accelerate cell aging.This research sheds light in the understanding of the thermodynamic and kinetics of ZIBs at various temperatures and can offer inspiration for the design of aqueous ZIBs under wide temperature conditions.（Ⅱ）In the second work,the high cyclic stability of ZIBs under wide temperature conditions（-20 to 80°C）is achieved through modulating electrolyte chemistry.The grievous Zn dendrite growth at low temperatures and severe parasitic reactions of Zn metal anode at high temperatures can be solved by introducing a multi-hydroxyl polymer（polyethylene glycol,PEG）cosolvent.At subzero temperatures,PEG molecules adsorbed on the Zn surface would inducs uniform deposition of Zn²⁺,which inhibit dendrite growth.Meanwhile,the interactions between PEG and H₂O molecules would diminishe the activity of free water by perturbing hydrogen bonds,which suppress the parasitic reactions of Zn anode at elevated temperatures.As a result,Zn||Zn symmetric cells achieve an ultralong-term cycling life of over 1000 h at 0.2 m A cm^-2at-20°C or at1 m A cm^-2at 20°C,and exhibit an ultrahigh cumulative cycling capacity（CCC）of over1500 m Ah cm^-2at 60°C,which is superior to the previously reported ZIBs.Moreover,the Zn||PANI@V₂O₅full batteries also exhibit excellent electrochemical performance from-20°C to 80°C,suggesting great potential for practical applications.（Ⅲ）In the third work,a high-rate aqueous ZIBs under wide temperature conditions is achieved through interfacial stabilization strategy.The double-salt cosolvent aqueous electrolyte was prepared by adding 2-methyltetrahydrofuran（2-Me THF）/H₂O cosolvent with the 1:1 volume ratio of 0.8 M Zn（OTf）₂and 0.2 M Zn（Cl O₄）₂mixed zinc salt.2-Me THF and Cl O₄^-as hydrogen-bond modulator could perturb the hydrogen bonding networks between water molecules in electrolyte,significantly expand the operation temperature window of batteries.Meanwhile,superior kinetics capability of ions transportation across a broad range of temperatures are promoted by the low viscosity of electrolyte.Furthermore,the Zn²⁺solvation structure is tailored with effectively promoted reductive decomposition of organic solvents and anions,resulting in the formation of a stable and Zn F₂-rich organic/inorganic hybrid interphase on Zn mteal anode.The detrimental Zn dendrites growth at subzero temperatures and notorious parasitic reactions at elevated temperatures of the Zn metal anode were largely suppressed through this interface,and thus the cycling stability of aqueous high-rate ZIBs at wide temperatures are greatly improved.Consequently,Zn||Zn symmetric cells achieve a stable cycling at 10 m A cm^-2under-20℃or 60℃,and have an excellent CCC up to 2250 m Ah cm^-2at 20℃.This superior kinetics and high CCC reach a record level among the reported aqueous ZIBs.Moreover,the high-rate Zn||PANI@V₂O₅full batteries also exhibit excellent application prospects from-20℃to 80℃.