Metal Foam-based Anode Materials For Lithium And Sodium Ion Batteries

Conversion type anode materials for Lithium and sodium ion battery are of great research value owing to their high theoretical capacity,abundance in nature,low cost,facile fabrication and environmental friendliness.However,they suffer from low electronic conductivity and large volume variation upon cycling,leading to unsatisfactory electrochemical performance.In this dissertation,three-dimensional porous metal foams were used as conductive substrates to in-situ growing active electrode materials,and their electrochemical performances as binder-free anodes of lithium and sodium-ion battery were studied.The porous structure of the foam metal is beneficial to enhance the contact and reaction between active material and electrolyte,and effectively buffer the volume variation of active material during the cycle;the good contact between active material and electric substrate is helpful to improve the overall conductivity of the electrode and enhance the structure stability upon cycling.The main contents of this dissertation are as follows:（1）NiO nanoflakes are successfully grown on Ni foam via electrochemical corrosion and subsequent sintering,which shows excellent electrochemical performance as binder-free anode for sodium-ion battery.The NiO/Ni electrode delivers initial charge/discharge capacities of 616/1395 m Ah g^-1 at a specific current of 300 m A g^-1,maintaining of 491/501 m Ah g^-1 after 100 cycles.When matching with a Na₃V₂（PO₄）₃cathode,the full cell delivers charge/discharge capacities of 102/108 m Ah g^-1 after 50cycles at a specific current of 200 m A g^-1.（2）Ni₃S₂ nanoarrays directly growing on Ni foam are fabricated via an electrochemical corrosion method,which shows excellent electrochemical performance as freestanding electrode for sodium ion batteries.The Ni₃S₂/Ni electrode delivers ultra-stable cycling with charge/discharge capacities of344.2/350.6 m Ah g^-1 after 200 cycles at 150 m A g^-1.After 70 cycles from 150 to3000 m A g^-1,the discharge capacity can remain at 427 m Ah g^-1 when the specific current returns to 150 m A g^-1.When matching with Na₃V₂（PO₄）₃ cathode,the full cell delivers discharge capacity of 347.8 m Ah g^-1 after 180 cycles at a specific current of 200 m A g^-1.（3）CuS nanosheets are grown on Ni foam via an electrochemical corrosion method,which shows prominent electrochemical performance as freestanding electrode for Li-ion batteries.The CuS/Cu electrode delivers no capacity fading at a specific current of 500 m A g^-1,showing charge/discharge capacities of 367/577 m Ah g^-1 in the initial cycle and834/845 m Ah g^-1 after 500 cycles.After 50 cycles at various specific current from 100 to1500 m A g^-1,the CuS/Cu electrode can still exhibit no capacity fading over 300 cycles at2000 m A g^-1,delivering discharge capacity of 414 m Ah g^-1.（4）Cu₃P nanoparticles are successfully grown on Cu foam by gas-solid reaction,which shows excellent electrochemical performance as binder-free anode for lithium ion batteries.The Cu₃P/Cu-C electrode delivers charge/discharge capacities of 399.1/778 m Ah g^-1 in the first cycle and 377.6/379.3 m Ah g^-1 after 600 cycles at a specific current of 150m A g^-1.After 250 cycles at various specific current ranging from 150 to 2000 m A g^-1,the charge/discharge capacities can remain at 437.3 and 440 m Ah g^-1when the specific current returns to 150 m A g^-1.