High-Density Energy Storage in Light Si-Fe-Integrated Electrodes.

Abstract

The energy density of batteries represents a critical challenge in the current battery revolution. Traditional anodes use inactive copper foil current collectors, which significantly increase the weight of the entire electrode and reduce the overall energy density of the battery. To overcome this limitation, a Si-Fe self-supporting electrode with a three-dimensional axial mesh structure is fabricated on a polyacrylonitrile (PAN) substrate using electrospinning. As a flexible self-supporting electrode for a lithium-ion battery, replacing the traditional electrode greatly reduces the anode mass to achieve lighter weight and a higher specific energy density for the battery. Additionally, in the three-dimensional axial mesh PAN substrate, the porous main axes wrap the active material to facilitate Li⁺ transport, and the PAN carbon fiber mesh structure helps with electron transport, resulting in excellent conductivity and energy density. After cycling for 500 cycles at a current density of 0.5 A g^-1, the specific capacity based on the total electrode reached 436.3 mA h g^-1, with the coulomb efficiency remaining above 99.5%. The integrated electrode minimizes the influence of binders, conductive agents, and current collectors, significantly reducing side reactions at the electrode-electrolyte interface. This easy-to-manufacture innovative structure holds promise for the future development of lithium-ion battery anodes.