Bifunctional Conducting Polymer Coated CoP Core–Shell Nanowires on Carbon Paper as a Free‐Standing Anode for Sodium Ion Batteries

Abstract

This study proposes a conformal surface coating of conducting polymer for protecting 1D nanostructured electrode material, thereby enabling a free‐standing electrode without binder for sodium ion batteries. Here, polypyrrole (PPy), which is one of the representative conducting polymers, encapsulated cobalt phosphide (CoP) nanowires (NWs) grown on carbon paper (CP), finally realizes 1D core–shell CoP@PPy NWs/CP. The CoP core is connected to the PPy shell via strong chemical bonding, which can maintain a Co–PPy framework during charge/discharge. It also possesses bifunctional features that enhances the charge transfer and buffers the volume expansion. Consequently, 1D core–shell CoP@PPy NWs/CP demonstrates superb electrochemical performance, delivering a high areal capacity of 0.521 mA h cm−2 at 0.15 mA cm−2 after 100 cycles, and 0.443 mA h cm−2 at 1.5 mA cm−2 even after 1000 cycles. Even at a high current density of 3 mA cm−2, a significant areal discharge capacity reaching 0.285 mA h cm−2 is still maintained. The outstanding performance of the CoP@PPy NWs/CP free‐standing anode provides not only a novel insight into the modulated volume expansion of anode materials but also one of the most effective strategies for binder‐free and free‐standing electrodes with decent mechanical endurance for future secondary batteries.

Advanced Se3P4@C Anode with Exceptional Cycling Life for High Performance Potassium‐Ion Batteries

“…The peaks at 55.55 and 54.74 eV correspond to the Se 3d 3/2 and Se 3d 5/2 , respectively, implying the Se species exist as Se 2− ion . In Figure 2d, the peaks at 130.75 and 131.50 eV correspond to P 2p 3/2 and P 2p 1/2 …”

“…However, the R ct (charge transfer resistance) for the 20th cycle (36.23 Ω) is lower than that of the 1st cycle(58.44 Ω), suggesting that the Se 3 P 4 @C electrode can keep its structure to improve the reaction kinetics. To further discuss the diffusion kinetics of K + in the Se 3 P 4 @C electrode, galvanostatic intermittent titration technique (GITT) is employed (Figure S6, Supporting Information) . The diffusion coefficients can be further quantified by using the following equation: In this equation, τ is the relaxation time, n is the number of moles, V is the molar volume, S is the electrode/electrolyte contact area. can be calculated from the data in Figure S6, Supporting Information.…”

Co–B Nanoflakes as Multifunctional Bridges in ZnCo2O4 Micro‐/Nanospheres for Superior Lithium Storage with Boosted Kinetics and Stability

“…They both manifest a positive shift compared to that of ZCO (≈0.3 and 0.9 eV, respectively), revealing that the Co atoms in ZCO/Co-B are more electropositive, accompanying with redistribution of the electron density. [37,38] The B 1s characteristic peak at 187.7 eV is due to the interaction between B and Co. [34,39] According to the quantitative analysis, the Co/B atomic ratio in Co-B nanoflakes is estimated to be 1.1:1, indicating the chemical composition to be near CoB (the detailed calculation can be found on the bottom of Table S1 in the Supporting Information). The mass content of Co-B in ZCO/Co-B hybrid was further calculated to be 5.6 wt%, which is very close to the experimental value (6.3 wt%) by testing the weights of ZCO and ZCO/Co-B products before and after the solution reaction, respectively.…”

State-of-the-Art Electrode Materials for Sodium-Ion Batteries

“…CoP nanowires were formed by growing cobalt carbonate hydroxide hydrate Co(CO 3 ) 0.5 OH•0.11H 2 O on carbon paper substrate. Then, the CoP wires were coated with polypyrrole by a simple in-situ polymerization process [349]. The 5-nm thick polypyrrole coating layer was able to buffer the change of volume of the CoP nanowires (50 nm in diameter), and the carbon paper was used as a conductor.…”