Suppressing Fe–Li Antisite Defects in LiFePO₄/Carbon Hybrid Microtube to Enhance the Lithium Ion Storage

Abstract

ethanol) were found to play an important role in reducing the concentration of Fe-Li antisite defects. However, the concentration of Fe-Li antisite defects reduced is still limited (higher than 0.99%), which cannot improve the rate performance of LIB efficiently. [9,10] Herein, we report on the synthesis of an ideal crystalline LFP/carbon hybrid microtube (LFP/CMT) with the lowest Fe-Li antisite defects reported (<0.3%) to boost the lithium ion storage. The key concept for suppressing the Fe-Li antisite defects is through the use of the strong chelation interaction with Fe 3+ and absorbs interaction with Li + of alginate. This is able to efficiently control the prior occupancy of Fe at the beginning of the crystal formation, thus reduce the concentration of Fe-Li antisite defects in subsequent pyrolysis process and produce well-crystallized LFP nanoparticles (NPs). Meantime, the carbohydrate framework of alginate fiber was converted to highly porous carbonaceous hybrid microtube (CMT) after pyrolysis in nitrogen (N 2 ) atmosphere, in which the LFP NPs with low Fe-Li antisite defects are embedded. This can highly enhance the electrical conductivity of the LFP NPs. As a consequence, the LFP/CMT displays superior discharge capacity of 165 mAh g −1 at 0.5 C, excellent capacity retention of 91% after 1000 cycle numbers, and outstanding rate capacity of 99.7 mAh g −1 at 100 C.Protonated alginate fiber [11][12][13] was used to prepare the LFP electrodes with low Fe-Li antisite defects (see details in Supporting Information). The protonated alginate fiber was soaked into the mixed aqueous solutions of ferric nitrate nonahydrate (Fe(NO 3 ) 3 ·9H 2 O), ammonium dihydrogen phosphate (NH 4 H 2 PO 4 ), and lithium nitrate (LiNO 3 ) to form yellow Li-Fe-P-alginate fibers. The reduction of Fe-Li antisite defects is achieved by unique "egg-box" structure in alginate macromolecule. As shown in Scheme 1b, the Fe 3+ was immobilized into "egg-box" via coordination with G blocks in alginate, and the PO 4 3− was adsorbed by the Fe 3+ cations. As described in Figure S1 of the Supporting Information, the diffraction peak at 2θ = 21.18° was observed from the X-ray diffraction (XRD) pattern of Fe-P-alginate fiber, ascribed to a typical "egg-box" structure in G-rich Fe-alginate junction zones. [14,15] However, the monovalent Li + ions can only be adsorbed by the carboxyl (M block) via the electrostatic force. [16,17] The diffraction peaks at 2θ = 38.05° and 44.22° are ascribed to Fe-rich Li-alginate junction zones (see Figure S1, Supporting Information). [16] Obviously, the unexpected Fe-Li mixing could be avoided at the initial ion-exchange stage.The Li-Fe-P-alginate fibers were calcined at different temperatures (350-850 °C) in N 2 atmosphere to obtain a series of porous LFP/CMT with low concentration of Fe-Li antisite Olive structured LiFePO 4 (LFP) is a good candidate for lithiumion battery (LIB) cathode material due to its high theoretical capacity of 170 mAh g −1 , high electrochemical potential, good thermal stability, environmenta...

Biomimetic taro leaf-like films decorated on wood surfaces using soft lithography for superparamagnetic and superhydrophobic performance

“…4e), it had been formerly reported that Fe 2p3/2 for Fe 3 O 4 did not have a satellite peak. The peak positions of Fe 2p3/2 and Fe 2p1/2 were 710.6 and 723.9 eV, respectively, and the energy separation between the two Fe 2p3/2 and Fe 2p1/2 peaks was 13.3 eV [34]. The relative binding energies of the Fe 2?…”

LiFePO4 Particles Embedded in Fast Bifunctional Conductor rGO&C@Li3V2(PO4)3 Nanosheets as Cathodes for High‐Performance Li‐Ion Hybrid Capacitors

“…Therefore, the final product of LFP particles trapped in fast bifunctional conductor rGO&C@ LVP nanosheets was obtained, denoted as LFV-GC. [20] The peaks of Fe2p, V2p, O1s, P2p, C1s, and N1s can be clearly observed from the survey spectrum (note that the weak signal of Li1s is difficult to detect due to the overlap with the much larger Fe3p peak) ( Figure S2a, Supporting Information). The phase purity and crystal structure of the final product were examined by X-ray diffraction (XRD).…”

“…[3,4] As the bridge that links batteries and capacitors, Li-ion capacitors emerge with different storage mechanisms at both ends, filling the gap between batteries and supercapacitors in energy storage systems, especially for organic electrolyte systems, which could efficiently extend the electrochemical window for high energy density. [19][20][21] Another cathode material for Li-ion batteries, monoclinic Li 3 V 2 (PO 4 ) 3 (LVP) as a lithium super ion conductor with large 3D open frameworks, is also used to modify LFP, resulting in enhanced electrochemical performances for its much higher Li-ion diffusivity and working potentials. [8][9][10] Nevertheless, the limited diffusion kinetics of Li + along the preferential [010] channel and the poor electronic conductivity are primary problems impeding its applications in EVs; [11][12][13] therefore, efficient strategies are necessary to facilitate Li + migration and electron transfer.…”

Double‐Helix Structure in Carrageenan–Metal Hydrogels: A General Approach to Porous Metal Sulfides/Carbon Aerogels with Excellent Sodium‐Ion Storage

“…Figure 3a shows the CV curves of FeS/CA in the first five cycles.T he first scan CV curve shows four reductive peaks at 0.01, 0.35, 0.82, and 1.15 V. Four oxidation peaks are found at 0.09, 1.38, 1.59, and 2.16 V. In the subsequent four charge/discharge process,t he reductive peaks at 0.82 and 1.15 Vshift to 0.78 and 0.93 Vowing to the formation of solidelectrolyte-interphase (SEI) film on the electrode surface in the first cycle,w hich leads to irreversible capacity loss.T he reductive/oxidation peaks at 0.01 and 0.09 Vc orrespond to interference of Na + insertion/extraction to porous carbon. [10] The subsequent four CV curves show stable reductive/oxidation peaks,i ndicating the FeS/CA exhibits good stability toward sodiation/desodiation. [23] Thet hree oxidation peaks at 1.38, 1.59, and 2.16 Vdemonstrate conversion of Na 2 Sand Fe to FeS.…”

“…[4][5][6][7][8] However,t he existed MS nanostructures usually have poor electrochemical performance in energystorage and conversion devices owing to their unstable structure and unsatisfactory electronic conductivity. [10][11][12][13] In particular, the nextgeneration of SIBs are believed to have the potential to replace LIBs,o wing to the low cost and natural abundant sodium resources. [10][11][12][13] In particular, the nextgeneration of SIBs are believed to have the potential to replace LIBs,o wing to the low cost and natural abundant sodium resources.…”