Electrolyte Design And Interface Investigation For High Performance Secondary Battery

The co-development of modern society and electronic technology has led to a growing demand for environmental protection,which has in turn promoted the development of various green energy sources.At present,renewable energy sources such as solar,tidal,and wind energy play an important role in the supply of electricity.However,they have certain disadvantages,such as intermittency and immobility,which limit their application in mobile devices.Scholars are focusing their research on resolving the storage of this discontinuous energy.Energy storage batteries have become one of the most important energy research directions today due to their high energy density,flexible usage scenarios,and low cost.Specifically,secondary metal batteries,such as lithium metal batteries and zinc-ion batteries,consist of four essential components:a metallic anode,a cathode,a separator,and an electrolyte.When storing external energy,these batteries undergo the formation of new compounds alongside the exchange of electrons and ions.The migration of ions through the electrolyte is governed by the ion solvation structure and the physicochemical properties of the solvent.The solvation structure of the ions and the composition of the electrolyte interface have a direct bearing on the growth pattern of the compounds,which subsequently impacts the battery’s reversibility and cyclability.The electrolyte serves as a conduit for the exchange of electrons and ions,and it influences the stability of the interface between the electrolyte and the electrode.This paper addresses the core issues of lithium-carbon dioxide batteries and zinc ion batteries by regulating the chemical environment at the interface through electrolyte design.The research is divided into three aspects:1.Modulating reaction pathways by designing solvated structuresThe development of conventional lithium-carbon dioxide batteries is constrained by the insulating properties of lithium carbonate.This work aims to modulate the reaction pathways of the products by using different lithium ions solvation structures.As a result,lithium-carbon dioxide batteries based on soluble products were designed and constructed.By introducing a low salt concentration of dimethyl sulfoxide electrolyte,the solvation energy of lithium ions increases,creating a lithium ion "unavailable" environment at the interface.This environment hinders ion exchange and enables preferential electron transfer,ultimately facilitating the conversion of carbon dioxide to the oxalate intermediate.Lithium-carbon dioxide batteries based on oxalate-like products have a reduced charging potential of 3.4 V and a cycle life of 260 hours.The grown soluble oxalate-like products were found to reversibly grow and decompose during cycling,as demonstrated by multiple characterizations and tests.This unique design and mechanism exploration are important references for the development of advanced lithium-carbon dioxide battery systems.2.Construction of a "trinity" system to regulate discharge productA "trinity" system was designed based on the knowledge of the product growth mechanism.The system is composed of carbon dioxide,2,2,6,6-tetramethylpiperidoxyl,and a reduced graphene oxide electrode.The study discovered that 2,2,6,6-tetramethylpiperidinium oxide,acting as a soluble mediator,can selectively bind with carbon dioxide molecules,leading to a reduction reaction at a potential higher than 2.80 V.The "trinity" reaction system enables the conversion of carbon dioxide to lithium oxalate while improving the kinetics and rechargeability of the battery.The designed lithium-carbon dioxide battery has a discharge plateau of up to 2.97 V and a round-trip efficiency of 97.1%.Furthermore,the interaction of the soluble mediator with carbon dioxide in the electrolyte converts the conventional solid-gasliquid interface into a more manageable two-phase reaction interface.This conversion enables the battery to function effectively in sudden carbon dioxide-deficient environments.The findings from this study hold substantial significance for the advancement of novel lithiumcarbon dioxide systems.3.Highly reversible zinc electrodes enabled by interfacial modulationIn neutral or mildly acidic conditions,the deposition and stripping processes within zincion batteries are frequently complicated by hydrogen evolution and the growth of zinc dendrites.The addition of methylsulfonylmethane(MSM)molecules as electrolyte additives for zinc ion batteries achieves co-regulation of the hydrogen bonding network and the zinc ion solvation structure.Furthermore,MSM molecules can selectively adsorb onto the electrode surface,thereby modulating the nucleation sites and deposition patterns of zinc ions.This approach reduces the content of reactive water molecules at the interface,improves the stability of the electrode/electrolyte interface,thereby preventing the onset of side reactions,including hydrogen evolution.The symmetric Zn‖Zn battery,which introduced the MSM additive,cycled stably for 150 days at a current density of 2 mA cm-2.The cumulative stripping capacity reached up to 3.7 Ah cm-2.The assembled Zn‖Cu half-batteries achieved 3100 cycles at a current density of 2 mA cm-2,with a coulombic efficiency of 99.8%.Various characterizations and tests have analyzed the deposition/stripping behavior of ions and the evolution of the interfacial environment.This study presents a novel research perspective for stabilizing the interfacial environment,providing valuable insights for the design of electrolytes in zinc ion batteries.