A novel LiFePO4/graphene/carbon composite as a performance-improved cathode material for lithium-ion batteries

Su, Chang; Bu, Xidan; Xu, Lihuan; Liu, Junlei; Zhang, Cheng

doi:10.1016/j.electacta.2012.01.014

Cited by 136 publications

(82 citation statements)

References 28 publications

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“…Graphene increases electronic conductivity but, if present in high percentage as in LNMO/RGO electrodes, can also hinder Li + ion migration since its two-dimensional structure can occlude some Li + paths in LNMO composites, thereby forcing Li + to increase the path length to reach the electrochemical reaction site. 7,10,23 Figure 2 compares the voltage profiles of LNMO/C65 and LNMO/C65/RGO electrodes at different C-rates. While quite similar at the lowest C-rate, electrode polarization at high C-rate evinces clear differences.…”

Section: Resultsmentioning

confidence: 99%

Reduced Graphene Oxide in Cathode Formulations Based on LiNi_0.5Mn_1.5O₄

Arbizzani

Col

Giorgio

et al. 2015

J. Electrochem. Soc.

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We investigated the electrochemical properties of composite cathodes obtained by mixing LiNi 0.5 Mn 1.5 O 4 (LNMO), reduced graphene oxide (RGO) and carbon black (C65). Electrochemical electrode characterization was carried out in ethylene carbonate: dimethyl carbonate and 1 M LiPF 6 by galvanostatic charge/discharge cycles up to 4.8 V vs. Li + /Li and impedance spectroscopy. We demonstrate that RGO improves the electrode/electrolyte interface stability at high potentials and, consequently, the cycling stability of LNMO cathodes in the presence of C65 with 92% capacity retention after 100 cycles at 1 C. The reciprocal effect of RGO and C65 is also beneficial for rate capability, which retained a specific capacity of 75 mAh g −1 at 10 C. The electric contact between particles is promoted by C65 s conductive percolating network; RGO enhances the electrical conductivity of the composite electrode and hinders undesirable reactions between LNMO and the electrolyte. Despite RGO's lower electronic resistivity with respect to C65, the addition of RGO alone to LNMO is not sufficient to assure good performance. The mixing procedure without C65 promotes the agglomeration of graphene nanosheets rather than their distribution among LNMO particles and aggregates, limiting the electron and Li + transport in the cathode material. The appealing properties of graphene have attracted great attention in several research fields. Its superior electric conductivity, chemical stability and high flexibility make it of great interest as electrode material and additive in energy storage and conversion systems. [13][14][15][16][17][18][19] For example, the addition of graphene to lithium metal phosphates, which display low electrical conductivity (near 10 −9 -10 −7 S cm −1 ), boosts electronic conductivity, enhances microstructure via the formation of a three-dimensional network that shortens the lithium ion diffusion distance, and improves morphology by hindering grain growth.Directly adding graphene during conventional or non-conventional syntheses is often pursued. Graphene oxide (GO) is usually added to the precursors of the cathode materials so that the synthesis of the latter and GO reduction occur simultaneously during pyrolysis under reducing atmosphere.1 LiN 0.5 Mn 1.5 O 4 (LNMO)/graphene composites have recently been developed [20][21][22] by suspending mildly oxidized graphene and LNMO in ethanol to obtain graphene-wrapped LNMO. Graphene acts as a protective layer that minimizes the Mn 2+ dissolution in electrolyte and limits the unwanted parasitic electrode reactions, which affect both capacity and coulombic efficiency.Large-size battery production needs bulk syntheses of cathode materials and viable, inexpensive methods of preparing the composite electrode with graphene. Simple mixing of cathode composite components that include graphene might be a preferable, albeit nonoptimal, procedure. We thus investigated several mixing procedures for LNMO-based composites with reduced graphene oxide (RGO) and carbon black. The results o...

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Section: Resultsmentioning

confidence: 99%

Reduced Graphene Oxide in Cathode Formulations Based on LiNi_0.5Mn_1.5O₄

Arbizzani

Col

Giorgio

et al. 2015

J. Electrochem. Soc.

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“…Consequently, Li + ions can easily intercalate and exfoliate, resulting in high electron conductivity and electrochemical performance. A similar situation also happens with other composite such as LiFePO 4 /graphene [62,63], LiMn 2 O 4 /graphene [64,65], and LiMn 1−x FexPO 4 /graphene [38]. Thus it can be concluded that electronconducting graphene networks are formed, resulting in huge improvements in the electronic conductivity and electrochemical properties of the materials.…”

Section: Li-ion Storagementioning

confidence: 67%

Graphene as Sensitizer

Mat-Teridi

Ibrahim

Ahmad‐Ludin

et al. 2015

Graphene‐based Energy Devices

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“…particles, which has limited the high-rate performance of LiFePO 4 /C. Hence, network structure constructed by one dimensional (1D) (carbon nanotube) [31], 2D (graphene) [32][33][34] and 3D (porous structure of carbon) [32,[35][36][37][38] nano materials was favored recently for good interconnection (1D or 2D contacts) among adjacent LiFePO 4 particles, which can form continuous conductive paths of the network (shown in Fig. 2b) and enhance the electrical conductivity of LiFePO 4 /C composites.…”

Section: Characterizationmentioning

confidence: 99%