High safety and high energy-density sodium-ion batteries require the promising polyanionic insertion-type cathode possessing fast dis-/charging capability,yet persistent challenges remain in the kinetic optimization t...High safety and high energy-density sodium-ion batteries require the promising polyanionic insertion-type cathode possessing fast dis-/charging capability,yet persistent challenges remain in the kinetic optimization to accelerate their intrinsically low Na^(+)diffusivity.Exampled by the representative Na_(3)V_(2)(PO_(4))O_(2)F(NVPOF)with considerable theoretical energy density,structural distortion results in a one-dimensional sluggish Nat diffusion out of the two-dimensional Na pathway provided structurally.Previous endeavors with Na site or transition-metal site regulation successfully optimize the Na^(+)diffusion energy barrier of the available one-dimensional path.However,these substituted elements with non-equivalent valances or sizes further elevate the energy barrier of the other unavailable Na^(+)diffusion path.Herein,by defining the independently accessible Na^(+)diffusion pathways in the crystallographic structure as Na^(+) diffusion degree of freedom(df_([Na^(+)])),we demonstrate broadening df_([Na^(+)])to two in NVPOF by a mild perturb at the dangling site can fundamentally revise the Na diffusion behaviour.As demonstrated by in-situ synchrotron,various spectroscopic techniques,and density functional theory(DFT)modeling,this mild perturb equalizes the Na^(+) diffusion energy barriers along a and b directions and enables two-dimensional Nat transportation.The as-prepared NvPOF depicts an altered solid-solution phase transition,higher disorder in the framework and dramatically enhanced Na diffusivity,which leads to unprecedentedly high sodium storage properties in half cell(68.6 mAh g^(-1) at 100 C;103.3 mAh g^(-1) after 1300 cycles at 20 C;1 C=130 mA g^(-1))and full cell(313.8 Wh kg^(-1)@4063.5 W kg^(-1);113.9 Wh kg^(-1)@16,397.2 W kg^(-1)).This study enlightens the valuable role of broadening df_([Na^(+)])in fundamentally maximizing the polyanionic insertion-type performance.展开更多
基金supported by the National Natural Science Foundation of China(52272091)Agency for Science,Technology and Research(A*STAR)through Low Carbon Energy Research Finding Initiative(LCERFI01-0033|U2102d2006)+3 种基金A*STAR MTC programmatic project(M23L9b0052)Indonesia-NTU Singapore Institute of Research for Sustainability and Innovation(INSPIRASI)(6635/E3/KL.02.02/2023)Singapore NRF Singapore-China flagship program(023740-00001)Natural Science Foundation of Jiangxi Province(20232ACB214001).
文摘High safety and high energy-density sodium-ion batteries require the promising polyanionic insertion-type cathode possessing fast dis-/charging capability,yet persistent challenges remain in the kinetic optimization to accelerate their intrinsically low Na^(+)diffusivity.Exampled by the representative Na_(3)V_(2)(PO_(4))O_(2)F(NVPOF)with considerable theoretical energy density,structural distortion results in a one-dimensional sluggish Nat diffusion out of the two-dimensional Na pathway provided structurally.Previous endeavors with Na site or transition-metal site regulation successfully optimize the Na^(+)diffusion energy barrier of the available one-dimensional path.However,these substituted elements with non-equivalent valances or sizes further elevate the energy barrier of the other unavailable Na^(+)diffusion path.Herein,by defining the independently accessible Na^(+)diffusion pathways in the crystallographic structure as Na^(+) diffusion degree of freedom(df_([Na^(+)])),we demonstrate broadening df_([Na^(+)])to two in NVPOF by a mild perturb at the dangling site can fundamentally revise the Na diffusion behaviour.As demonstrated by in-situ synchrotron,various spectroscopic techniques,and density functional theory(DFT)modeling,this mild perturb equalizes the Na^(+) diffusion energy barriers along a and b directions and enables two-dimensional Nat transportation.The as-prepared NvPOF depicts an altered solid-solution phase transition,higher disorder in the framework and dramatically enhanced Na diffusivity,which leads to unprecedentedly high sodium storage properties in half cell(68.6 mAh g^(-1) at 100 C;103.3 mAh g^(-1) after 1300 cycles at 20 C;1 C=130 mA g^(-1))and full cell(313.8 Wh kg^(-1)@4063.5 W kg^(-1);113.9 Wh kg^(-1)@16,397.2 W kg^(-1)).This study enlightens the valuable role of broadening df_([Na^(+)])in fundamentally maximizing the polyanionic insertion-type performance.
