Study On Interface Optimization And Electrochemical Performance Of Li And Zn Metal Anode

There is an urgent need for developing advanced secondary batteries with high energy density,high-security,long lifespan and low-cost to meet the ever-growing energy demands.Among various secondary batteries,rechargeable lithium-metal batteries（LMBs）and zinc-metal batteries（ZMBs）are two most competitive and promising candidates.The former is considered as the"ultimate goal"of power batteries due to their extremely high energy density,and the latter is expected to be applied in the field of large-scale energy storage due to their high-safety,low-cost,and relatively high energy density.Nevertheless,both LMBs and ZMBs suffered from uncontrolled dendrite growth and unstable interface,which seriously impedes their further applications.In this thesis,series of modified Li or Zn anodes with high coulombic efficiency（CE）and long lifespan were constructed to solve these above-mentioned issues by regulating interfacial electric field,ion distribution,and stress from the perspective of optimizing the host–metal and metal–electrolyte interface.The main research contents and conclusions are as follows:（1）Aiming to solve the problems of uneven Li deposition and uncontrolled dendrite growth caused by poor lithium affinity of carbon nanofibers,in situ introduction uniform lithiophilic Co₃O₄nanocrystal on the nanofiber surface by coordination and calcination can effectively induce the uniform nucleation and regulate deposition of Li metal on nanofibers.Additionally,the 3D flexible conductive framework can effectively homogenize the Li-ion flux,further suppress dendrite growth and volume expansion of Li anode.As a result,the modified electrode can stably cycle for 400 cycles with an average CE of 99.1%at 1 m A cm^-2and 1 m Ah cm^-2.Even under harsh conditions of low N/P ratio（2.3）,full cells paired with high mass loading Li Fi PO₄(14 mg cm^-2)can also operate stably and preserve a remarkable capacity retention of86.6%over 440 cycles.（2）Aiming to improve the poor thermodynamic stability and non-uniform Li-ion flux of Li anode in high-voltage LMBs,a Li NO₃-modified conductivity gradient host（LNO-CGH）was prepared by electrospinning and calcination to control the deposition behavior of Li within carbonate electrolyte.The dielectric top layer can steadily release NO₃^-,which could alter the interfacial chemistry and improve the thermodynamic stability of Li anode.The conductivity gradient structure can endow a bottom-up Li deposition manner.Benefiting from this creative design,the LNO-CGH host manifests a well-maintained CE of 97.7%over 200 cycles in carbonate electrolyte.Under the condition of 2.3 N/P ratio,the high-voltage LMB with LNO-CGH@Li anode and Li Ni_0.8Co_0.1Mn_0.1O₂cathodes can work stably for over 60cycles with 72.9%capacity retention.（3）Aiming to address dendrites and uneven deposition of Zn,a series of inorganic ferroelectric interfacial layers(such as:Ba Ti O₃and Ba_0.8Sr_0.2Ti O₃)were prepared by the doctor blade coating method,which effectively manipulate the Zn deposition behavior.Under an external electric field,these ferroelectric particles can be polarized as oriented dipoles,guiding Zn²⁺migrating in an orderly manner,thereby inducing dendrite-free deposition of Zn metal.As a result,the lifespan of modified Zn anodes is extended by more than 10 times.Moreover,the assembled Ba Ti O₃-Zn||Mn O₂pouch cell can operate stably for 150cycles with 87.9%capacity retention at 600 m A g^-1.（4）Aiming to stabilize the Zn anode under draconian deep-discharging,an elastic and anti-corrosive artificial interlayer（PSN）is introduced by drop-casting.PSN is composed of polyacrylonitrile（PAN）matrix and amorphous Si₃N₄nanoparticles,in which PAN can effectively block the electrolyte corrosions,and amorphous Si₃N₄nanoparticles with high dielectric constant endow homogeneous Zn deposition through favorable interfacial polarization.Accordingly,the lifespan of PSN-Zn is extended by more than 16 times.Even under draconian deep-discharging（60%）and high current density(10 m Ah cm^-2),the PSN-Zn symmetric cell also delivers a remarkable cycle stability（250 h）.When matching PSN-Zn with different-types cathodes(Ba_0.26V₂O₅·0.92H₂O and Mn O₂),full cells can deliver significantly superior electrochemical performance.There are 92 pictures,5 tables and 211 references.