Lithium iron phosphate with high-rate capability synthesized through hydrothermal reaction in glucose solution

Liang, Guangchuan; Wang, Li; Ou, Xiuqin; Zhao, Xing; Xu, Shuqin

doi:10.1016/j.jpowsour.2008.02.056

Cited by 58 publications

(28 citation statements)

References 23 publications

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“…13 C carbon coating.-The syntheses of LFP with and without carbon coating were carried out by applying a hydrothermal method similar to Liang et al 24 Lithium iron phosphate without carbon coating (further referred to as "LFP_uncoated") was synthesized using a reaction mixture of 75 mmol lithium hydroxide monohydrate (LiOH · H 2 O, 99.95%, Sigma-Aldrich, Germany), 25 • C for 6 h in a 100 ml Teflon-lined steel autoclave (Berghof BR-100, Germany). For purification, the solid product was centrifuged (Eppendorf Centrifuge 5810 R, Germany) and redispersed in H 2 O two times.…”

Section: Synthesis Of Lifepo 4 (Lfp) With Isotopically Labeledmentioning

confidence: 99%

Carbon Coating Stability on High-Voltage Cathode Materials in H₂O-Free and H₂O-Containing Electrolyte

Metzger

Sicklinger

Haering

et al. 2015

J. Electrochem. Soc.

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Carbon coatings on cathode materials with low electrical conductivity like phospho-olivines LiMPO 4 (M = 3d-transition metal) are known to improve their performance in Li-ion batteries. However, at high potentials and in the presence of water, the stability of carbon coatings on high-voltage materials (e.g., LiCoPO 4 ) may be limited due to the anodic oxidation of carbon. In this work, we describe the synthesis of LiFePO 4 (LFP) with an isotopically labeled 13 C carbon coating (characterized by Raman spectroscopy, electrical conductivity, and charge/discharge rate capability tests) as a model compound to study the anodic stability of carbon coated cathode materials in ethylene carbonate-based electrolytes. We characterize the degradation of the 13 C carbon coating by On-line Electrochemical Mass Spectrometry (OEMS) through the 13 CO 2 and 13 CO signals in order to differentiate the anodic oxidation of the coating ( 13 C) from the oxidation of electrolyte, conductive carbon, and binder (all 12 C) in the electrode. The oxidation of the carbon coating takes place at potentials ≥ 4.75 V for electrolyte without H 2 O (< 20 ppm) and ≥ 4.5 V for electrolyte with 4000 ppm H 2 O, and it is strongly enhanced for H 2 O-containing electrolyte. The extent of carbon coating oxidation over 100 h at 4.8 and 5.0 V vs. Li/Li + (25 • C) is projected on the basis of our OEMS data, suggesting that carbon coatings have insufficient stability at such high cathodic potentials. Furthermore, our results prove the in situ formation of H 2 O during the anodic decomposition of ethylene carbonate-containing electrolyte. The H 2 O formation is monitored via the detection of gaseous POF 3 , which is formed from the reaction of Li-ion batteries are extensively investigated as energy storage devices for electric vehicles (EVs) due to their high energy density and reasonable life time.1 In order to make EVs competitive with gasoline or diesel cars, and to eventually reduce CO 2 emissions by the electrification of personal mobility, many fundamental challenges still need to be overcome. In contrast to NMC and other layered oxides, phospho-olivines like LFP and LCP suffer from very poor electrical conductivity which limits their rate capability, i.e., their performance at high charge/discharge rates. 7 In the case of LFP, its poor electrical conductivity can be overcome by using small primary particles (0.1-0.5 μm) in combination with an electrically conductive very thin carbon coating (thickness 1-2 nm) 8 applied to the primary particles using different kinds of precursors.7,9 While uncoated LFP samples either show very poor rate capability or low capacity at rates as low as 0.1 C, 10-12 Lou et al. 13 showed that carbon coated LFP can reach 116 mAh/g LFP at high rates of 10 C (theoretical capacity: 170 mAh/g LFP ).3 Even when the current is increased to 30 C, the discharge capacity can still reach 75 mAh/g LFP , and in the 100 th cycle the capacity loss is only 2.3%. 14 presented a carbon coated LFP which is able to reach discharge capacities of 1...

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Section: Synthesis Of Lifepo 4 (Lfp) With Isotopically Labeledmentioning

confidence: 99%

Carbon Coating Stability on High-Voltage Cathode Materials in H₂O-Free and H₂O-Containing Electrolyte

Metzger

Sicklinger

Haering

et al. 2015

J. Electrochem. Soc.

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“…[20,21]. Many sources of carbon, such as ascorbic acid [20], lactose [21], sucrose [22], glucose [23], carbon nanotube [24], and graphene [25], were recognized as suitable ones for this purpose. However, the carbon source must be inexpensive, the amount used must be optimized, and the carbon coating must be uniform, in order to guarantee an excellent conducting network on the LiFePO 4 particles [26,27].…”

Section: Introductionmentioning

confidence: 99%

Improvement of electrochemical and electrical properties of LiFePO4 coated with citric acid

Talebi‐Esfandarani

Savadogo

2015

Rare Met.

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LiFePO 4 was synthesized using hydrothermal method and coated with different amounts of citric acid as carbon source. The samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), surface area measurement-Brunauer-Emmett-Teller (BET), discharge capability, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The results show that the quality and thickness of the carbon coating on the surface of LiFePO 4 particles are very important. The optimum carbon content (about 30 wt%) can lead to a more uniform carbon distribution. Electrochemical results show that the samples containing 20 wt%, 30 wt%, 40 wt%, and 50 wt% carbon deliver a discharge capacity of 105, 167, 151, and 112 mAhÁg -1 , respectively, at the rate of 0.1C. The increase of carbon content leads to the decrease of discharge capacity of LiFePO 4 /C, owing to the fact that excess carbon delays the diffusion of Li ? through the carbon layers during charge/discharge procedure. The LiFePO 4 /C with low carbon content exhibits poor electrochemical performance because of its low electrical conductivity. Therefore, the amount of carbon must be optimized in order to achieve excellent electrochemical performance of LiFePO 4 /C for its application in a lithium ion battery.

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“…LiFePO 4 is usually prepared by solid-state carbon thermal reduction, sol-gel method, hydrothermal method, co-precipitation, and rheological phase method [5][6][7][8][9]. Rheological phase method is favorable to synthesize small pure products and well-distributed particles.…”

Section: Introductionmentioning

confidence: 99%

Oxalic acid-assisted preparation of LiFePO4/C cathode material for lithium-ion batteries

Dou

Kang

Wumaier

et al. 2011

J Solid State Electrochem

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LiFePO 4 /C composite is synthesized by oxalic acid-assisted rheological phase method. Fe 2 O 3 and LiH 2 PO 4 are chosen as the starting materials, sucrose as carbon sources, and oxalic acid as the additive. The crystalline structure and morphology of the products are characterized by X-ray diffraction and field emission scanning electron microscopy. The charge-discharge kinetics of LiFePO 4 electrode is investigated using cyclic voltammetry and electrochemical impedance spectroscopy. It is found that the introduction of appropriate amount of oxalic acid leads to smaller particle sizes, more homogeneous size distribution, and some Fe 2 P produced in the final products, resulting in reduced polarization, impedance, and improved Li + ion diffusion coefficient. The best cell performance is delivered by the sample with R=1.5 (R of the molar ratio of oxalic acid to LiH 2 PO 4 ). Its discharge capacity is 154 mAh g −1 at 0.2 C rate and 120 mAh g −1 at 5.0 C rate. At the same time, it exhibits an excellent cycling stability; no obvious decrease even after 1,000 cycles at 1.0 C rate.

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Lithium iron phosphate with high-rate capability synthesized through hydrothermal reaction in glucose solution

Cited by 58 publications

References 23 publications

Carbon Coating Stability on High-Voltage Cathode Materials in H₂O-Free and H₂O-Containing Electrolyte

Carbon Coating Stability on High-Voltage Cathode Materials in H₂O-Free and H₂O-Containing Electrolyte

Improvement of electrochemical and electrical properties of LiFePO4 coated with citric acid

Oxalic acid-assisted preparation of LiFePO4/C cathode material for lithium-ion batteries

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Lithium iron phosphate with high-rate capability synthesized through hydrothermal reaction in glucose solution

Cited by 58 publications

References 23 publications

Carbon Coating Stability on High-Voltage Cathode Materials in H2O-Free and H2O-Containing Electrolyte

Carbon Coating Stability on High-Voltage Cathode Materials in H2O-Free and H2O-Containing Electrolyte

Improvement of electrochemical and electrical properties of LiFePO4 coated with citric acid

Oxalic acid-assisted preparation of LiFePO4/C cathode material for lithium-ion batteries

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Product

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Carbon Coating Stability on High-Voltage Cathode Materials in H₂O-Free and H₂O-Containing Electrolyte

Carbon Coating Stability on High-Voltage Cathode Materials in H₂O-Free and H₂O-Containing Electrolyte