Effect of microstructure on low temperature electrochemical properties of LiFePO4/C cathode material

Abstract The low-temperature electrochemical performance of Li-ion batteries is mainly determined by the choice of cathode material, as evident from a comparison of the low-temperature electrochemical performance of the 18650 batteries with the LiMn 2 O 4 , LiNi 1/3 Co 1/3 Mn 1/3 O 2 , and LiFePO 4 /C as the cathode, respectively, at −20 °C. LiFePO 4 /C materials with different morphologies and microstructures were prepared by different methods. The samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), galvanostatic charge–discharge measurements and EIS. The low-temperature performance of the samples and those of the coin cells utilizing the materials as cathodes were measured. The results indicate that the microstructure of LiFePO 4 /C is a key factor determining the low-temperature performance of LiFePO 4 /C. A new type of LiFePO 4 /C with a pomegranate-like spherical structure composed of smaller spherical particles is reported, which shows good process-ability and superior low-temperature performance. The composite has a uniform particle size and carbon network, which delivers a discharge capacity of 89.3 mA h g −1 at −20 °C at a discharge rate of 0.5 C, with capacity retention rate of 58.7%. The 18650 batteries were prepared with pomegranate-like spherical structure LiFePO 4 /C composite which delivers a discharge capacity of 1603.7, 1563.8, 1572.28, 1598.0, 1580.1, 1504.2, and 1405.4 mA h at 0.5 C, 1 C, 2 C, 5 C, 10 C, 15 C, and 20 C, under 25 °C, respectively. Moreover, the batteries also exhibit good low-temperature performance with capacity of 1127.2 mA h at −20 °C at a discharge rate of 1 C, which is the 72.1% of the same discharge rate at 25 °C. Otherwise, the 18650 batteries also exhibit excellent cycling performance and the capacity maintains 83.4% at −20 °C after 100 cycles. The superior low-temperature performance of the LiFePO 4 /C composite material may be attributed to its uniform carbon network and fine primary particles.

[1]  J. Janek,et al.  Nanostructured and nanoporous LiFePO4 and LiNi0.5Mn1.5O4-δ as cathode materials for lithium-ion batteries , 2014 .

[2]  Chengyun Wang,et al.  Effect of Mn2+-doping in LiFePO4 and the low temperature electrochemical performances , 2011 .

[3]  Y. Lai,et al.  Limiting factors for low-temperature performance of electrolytes in LiFePO4/Li and graphite/Li half cells , 2012 .

[4]  Xiaozhen Liao,et al.  Low-temperature performance of LiFePO4/C cathode in a quaternary carbonate-based electrolyte , 2008 .

[5]  Zhong-Min Su,et al.  Optimized LiFePO4–Polyacene Cathode Material for Lithium‐Ion Batteries , 2006 .

[6]  John B. Goodenough,et al.  Effect of Structure on the Fe3 + / Fe2 + Redox Couple in Iron Phosphates , 1997 .

[7]  Kang Xu,et al.  Electrochemical impedance study on the low temperature of Li-ion batteries , 2004 .

[8]  Guangchuan Liang,et al.  The cycling performance of LiFePO4/C cathode materials , 2009 .

[9]  P. Prosini,et al.  Improved electrochemical performance of a LiFePO4-based composite cathode , 2001 .

[10]  Pier Paolo Prosini,et al.  Determination of the chemical diffusion coefficient of lithium in LiFePO4 , 2002 .

[11]  Yu Zhou,et al.  Effect of carbon coating on low temperature electrochemical performance of LiFePO4/C by using polystyrene sphere as carbon source , 2011 .

[12]  K. S. Nanjundaswamy,et al.  Phospho‐olivines as Positive‐Electrode Materials for Rechargeable Lithium Batteries , 1997 .

[13]  Haizhu Sun,et al.  Polyvinylpyrrolidone (PVP) assisted synthesized nano-LiFePO4/C composite with enhanced low temperature performance , 2013 .

[14]  Ping He,et al.  Olivine LiFePO4: development and future , 2011 .

[15]  Kang Xu,et al.  Low temperature performance of graphite electrode in Li-ion cells , 2002 .

[16]  G. Cui,et al.  A facile method of preparing mixed conducting LiFePO4/graphene composites for lithium-ion batteries , 2010 .

[17]  X. Sun,et al.  Understanding and recent development of carbon coating on LiFePO4 cathode materials for lithium-ion batteries , 2012 .

[18]  Yu‐Guo Guo,et al.  Solvothermal Synthesis of LiFePO4 Hierarchically Dumbbell-Like Microstructures by Nanoplate Self-Assembly and Their Application as a Cathode Material in Lithium-Ion Batteries , 2009 .

[19]  P. Bruce,et al.  Nanomaterials for rechargeable lithium batteries. , 2008, Angewandte Chemie.

[20]  Su Jin Kim,et al.  Carbon coating on lithium iron phosphate (LiFePO4): Comparison between continuous supercritical hydrothermal method and solid-state method , 2012 .

[21]  Ke-ning Sun,et al.  Facile synthesis of nanocrystalline LiFePO4/graphene composite as cathode material for high power lithium ion batteries , 2014 .

[22]  Xiao‐Qing Yang,et al.  Comparative studies on C-coated and uncoated LiFePO4 cycling at various rates and temperatures using synchrotron based in situ X-ray diffraction , 2011 .

[23]  Danna Qian,et al.  Recent progress in cathode materials research for advanced lithium ion batteries , 2012 .

[24]  G. Lindbergh,et al.  Electrochemical investigation of LiMn2O4 cathodes in gel electrolyte at various temperatures , 2002 .

[25]  Yet-Ming Chiang,et al.  Electronically conductive phospho-olivines as lithium storage electrodes , 2002, Nature materials.

[26]  F. E. Little,et al.  Low-Temperature Characterization of Lithium-Ion Carbon Anodes via Microperturbation Measurement , 2002 .

[27]  Chusheng Chen,et al.  A comparative study on the low-temperature performance of LiFePO4/C and Li3V2(PO4)(3)/C cathodes for lithium-ion batteries , 2011 .

[28]  Huang Zhang,et al.  Effects of carbon coating and metal ions doping on low temperature electrochemical properties of LiFePO4 cathode material , 2012 .

[29]  Kang Xu,et al.  A new approach toward improved low temperature performance of Li-ion battery , 2002 .

[30]  Li Lu,et al.  Site-dependent electrochemical performance of Mg doped LiFePO4 , 2014 .

[31]  J. Goodenough.  Challenges for Rechargeable Li Batteries , 2010 .

[32]  H. Pan,et al.  Structure optimization and the structural factors for the discharge rate performance of LiFePO4/C cathode materials , 2010 .

[33]  L. Lei,et al.  Electrochemical performance of LiFePO4/C synthesized by solid state reaction using different lithium and iron sources , 2011 .

[34]  G. Liang,et al.  Delithiation kinetics study of carbon coated and carbon free LiFePO4 , 2014 .

[35]  Hong Wang,et al.  Preparation and characterization of Na-doped LiFePO4/C composites as cathode materials for lithium-ion batteries , 2010 .

[36]  Hongyu Chen,et al.  Synthesis and properties of Co-doped LiFePO4 as cathode material via a hydrothermal route for lithium-ion batteries , 2012 .

[37]  F. Gao,et al.  Kinetic behavior of LiFePO4/C cathode material for lithium-ion batteries , 2008 .

[38]  Kang Xu,et al.  The low temperature performance of Li-ion batteries , 2003 .

[39]  Yongan Huang,et al.  Enhanced high rate and low-temperature performances of mesoporous LiFePO4/Ketjen Black nanocomposite cathode material , 2013 .

[40]  Lixia Yuan,et al.  Development and challenges of LiFePO4 cathode material for lithium-ion batteries , 2011 .

[41]  Jeffrey W. Fergus,et al.  Recent developments in cathode materials for lithium ion batteries , 2010 .