Integrated Electrode Design And Electrochemical Performance Study Of Lithium/sodium Ion Batterie

In order to break through the shackles of the poor conductivity and unstable cycles of the conversion anode materials,the integrated electrodes for lithium-ion and sodium-ion batteries with high conductivity,high dispersion and high areal capacity were constructed by regulating the morphology and structure of flexible substrates and active materials.Their electrochemical performance,charge storage mechanisms,morphology evolutions of active materials were systematically analyzed.It is expected to provide meaningful instructions for designing high energy lithium/sodium ions batteries.（1）The SnO₂nanostructures were synthesized directly on the porous copper tube textile substrate to construct integrated electrode via a typical hydrothermal method,and their morphology dependent charge storage mechanisms and the solid phase diffusion process of lithium ions were systematically studied.As a result,the interlaced SnO₂nanosheets on the textile substrate（SnO₂NS@TS）with high surface area and abundant pores could obviously boost effective charge transfer,ion diffusion and enhanced surface capacitive behaviors.Therefore,the superior lithium-ion storage capacity could be easily achieved in single and multilayered electrodes,exhibiting excellent flexibility.（2）To further improve the mass-loading and disperstiveness of active materials,the tin disulfide（SnS₂）nanoparticles with tunable sizes were successfully synthesized on the carbon nanotubes supported by porous copper tube textiles via hydrothermal method.As an integrated electrode,the effects of SnS₂ particle size on charge storage mechanism,ion diffusion and morphology evolution of active materials was further investigated.It can be concluded that the smaller SnS₂ particles enable to expose more abundant grain boundaries and surface atoms,generating enhanced surface capacitive behaviors and effective solid phase diffusions process of sodium ions,presenting superior sodium ion storage capacity.（3）In order to further increase the mass-loading of active materials and optimize their interface bonding with conductive substrates,the nanoporous Ni₃S₂/Ni-Mn alloy was fabricated by vulcanization and annealing treatment using chemical dealloying Ni₃₀Mn₇₀ alloy as self-sacrifice template and flexible substrate.Morphology and structure analyses reveal that the tunable pore structures,enhanced interface bonding,nickel doping together with oxygen and sulfur vacancies synergistically boost sodium ion/electron transfer and alleviate the volume change during long-term cycle.Therefore,the integrated electrode delivers high reversible capacity of 2.13 mA h cm^-2 at 2.0 mA cm^-2 after 120 cycles,exhibiting excellent sodium ion storage performance.（4）The integrated Ni（Co）₃S₂/MnS electrode with Ni,Co co-doping and sulfide vacancies were fabricated by vulcanization and annealing treatment based on chemical dealloyed Ni₂₀Co₁₀Mn₇₀ alloy.As a result,the integrated electrodes deliver high reversible capacity of 4.19 mA h cm^-2at 2.0 mA cm^-2 and 2.59 mA h cm^-2 at 5.0 mA cm^-2 after 200 cycles.The kinetics analyses reveal that the robust interface bonding between active materials and alloy ligaments,nickel-cobalt co-doping and sulfur vacancies synergistically promote the rapid charge transfer and diffusion of sodium ions,thereby realizing the desirable electrochemical performances.