Optimization of lithium content in LiFePO 4 for superior electrochemical performance: the role of impurities.

Autor: Halankar KK; Chemistry Division, Bhabha Atomic Research Centre Mumbai-400085 India bpmandal@barc.gov.in aktyagi@barc.gov.in +91-22-25505151 +91-22-25592274., Mandal BP; Chemistry Division, Bhabha Atomic Research Centre Mumbai-400085 India bpmandal@barc.gov.in aktyagi@barc.gov.in +91-22-25505151 +91-22-25592274.; Homi Bhabha National Institute Mumbai-400085 India., Jangid MK; High Temperature and Energy Materials Laboratory, Department of Metallurgical Engineering and Materials Science, IIT Bombay Mumbai-400076 India., Mukhopadhyay A; High Temperature and Energy Materials Laboratory, Department of Metallurgical Engineering and Materials Science, IIT Bombay Mumbai-400076 India., Meena SS; Solid State Physics Division, Bhabha Atomic Research Centre Mumbai-400085 India., Acharya R; Radiochemistry Division, Bhabha Atomic Research Centre Mumbai-400085 India.; Homi Bhabha National Institute Mumbai-400085 India., Tyagi AK; Chemistry Division, Bhabha Atomic Research Centre Mumbai-400085 India bpmandal@barc.gov.in aktyagi@barc.gov.in +91-22-25505151 +91-22-25592274.; Homi Bhabha National Institute Mumbai-400085 India.
Jazyk: angličtina
Zdroj: RSC advances [RSC Adv] 2018 Jan 03; Vol. 8 (2), pp. 1140-1147. Date of Electronic Publication: 2018 Jan 03 (Print Publication: 2018).
DOI: 10.1039/c7ra10112k
Abstrakt: Carbon coated Li x FePO 4 samples with systematically varying Li-content ( x = 1, 1.02, 1.05, 1.10) have been synthesized via a sol-gel route. The Li : Fe ratios for the as-synthesized samples is found to vary from ∼0.96 : 1 to 1.16 : 1 as determined by the proton induced gamma emission (PIGE) technique (for Li) and ICP-OES (for Fe). According to Mössbauer spectroscopy, sample Li 1.05 FePO 4 has the highest content ( i.e. , ∼91.5%) of the actual electroactive phase ( viz. , crystalline LiFePO 4 ), followed by samples Li 1.02 FePO 4 , Li 1.1 FePO 4 and LiFePO 4 ; with the remaining content being primarily Fe-containing impurities, including a conducting FeP phase in samples Li 1.02 FePO 4 and Li 1.05 FePO 4 . Electrodes based on sample Li 1.05 FePO 4 show the best electrochemical performance in all aspects, retaining ∼150 mA h g -1 after 100 charge/discharge cycles at C/2, followed by sample Li 1.02 FePO 4 (∼140 mA h g -1 ), LiFePO 4 (∼120 mA h g -1 ) and Li 1.10 FePO 4 (∼115 mA h g -1 ). Furthermore, the electrodes based on sample Li 1.05 FePO 4 retain ∼107 mA h g -1 even at a high current density of 5C. Impedance spectra indicate that electrodes based on sample Li 1.05 FePO 4 possess the least charge transfer resistance, plausibly having influence from the compositional aspects. This low charge transfer resistance is partially responsible for the superior electrochemical behavior of that specific composition.
Competing Interests: There are no conflicts of interest.
(This journal is © The Royal Society of Chemistry.)
Databáze: MEDLINE
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