A Yolk–Shell‐Structured FePO₄ Cathode for High‐Rate and Long‐Cycling Sodium‐Ion Batteries

Abstract

Amorphous iron phosphate (FePO4) has attracted enormous attention as a promising cathode material for sodium‐ion batteries (SIBs) because of its high theoretical specific capacity and superior electrochemical reversibility. Nevertheless, the low rate performance and rapid capacity decline seriously hamper its implementation in SIBs. Herein, we demonstrate a sagacious multi‐step templating approach to skillfully craft amorphous FePO4 yolk–shell nanospheres with mesoporous nanoyolks supported inside the robust porous outer nanoshells. Their unique architecture and large surface area enable these amorphous FePO4 yolk–shell nanospheres to manifest remarkable sodium storage properties with high reversible capacity, outstanding rate performance, and ultralong cycle life.

Dual‐Strategy of Cation‐Doping and Nanoengineering Enables Fast and Stable Sodium‐Ion Storage in a Novel Fe/Mn‐Based Layered Oxide Cathode

“…[5,6] Given that cathode is the crucial element dominating the cost and electrochemical performance of batteries, great efforts should be devoted to exploring advanced cathode materials with high redox potential, high capacity, and rapid sodium-ion mobility. [7,8] Among the various reported cathode candidates, such as transition metal oxides (TMOs), [9][10][11][12][13][14][15][16] polyanion-type compounds, [17][18][19][20][21][22] Prussian blue analogs, [23] and organic salts, [24] layered TMOs have gained considerable attention on account of their high theoretical capacities and special 2D structural merits. [9,13,25] Typically, the layered TMOs can be mainly divided into two polymorphs: P2 type (P: prismatic) and O3 type (O: octahedral) in accordance with the coordination environment of Na ions, where the "2" or "3" means the number of transition metal layers in a single cell unit.…”

A binary PMMA/PVDF blend film modified substrate enables a superior lithium metal anode for lithium batteries

“…The Li/Li symmetric cell tests were carried out to evaluate Li plating/stripping performance during long cycling. Noteworthily, 4 mAh/cm 2 Li was pre-deposited on modified Cu or bare Cu at 1.0 mA/cm 2 (labelled as modified Cu@Li or bare Cu@Li), and the symmetric cells were assembled with two identical electrodes. As shown in Figure 4a, cycling at a current density of 1.0 mA/cm 2 with a fixed capacity of 1.0 mAh/cm 2 , the cell with bare Cu@Li electrode presents higher voltage overpotential due to the continuous consumption of electrolyte and the accumulation of dead lithium [29] .…”

“…Developments in consumer electronics and electric vehicles have recently heightened the need for rechargeable batteries with high energy density and long cycling life [1,2] . Compared with graphite anode of commercial lithium ion batteries, lithium metal anode has been attracting considerable interest for its high theoretical specific capacity (3860 mAh g -1 ) and the lowest redox potential (-3.04 V vs. SHE) [3] .…”

Anchoring ultrafine CoP and CoSb nanoparticles into rich N-doped carbon nanofibers for efficient potassium storage

“…Nevertheless, when potassium ions are intercalated/deintercalated, transition metal compounds often generate a large volume expansion (>80% for CoP), which could cause the collapse and powdering of the material structures. There are three common strategies to diminish the impact of volume expansion: designing hollow structures [16], reducing particle size [17], and coating carbon materials [18,19]. But it is worth mentioning that although the hollow structure could provide extra buffering space for volume expansion, it would substantially reduce the volume energy density [20].…”