Analyses of the Calendaring Process for Performance Optimization of Li-Ion Battery Cathode

Charles F Oladimeji,Mark H Weatherspoon,Pedro L Moss

doi:10.1155/2016/7395060

Charles F Oladimeji, Mark H Weatherspoon + Show 1 more

Open Access

https://doi.org/10.1155/2016/7395060

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Abstract

Olivine structure LiFePO4(LFP) was synthesized via solid state processes, using Li2CO3, NH4H2PO4, and FeC2O4·H2O and C12H22O11as precursor materials. The effects of calendaring are analyzed in terms of electrochemical performance, cycle life, surface morphology, and ac impedance analysis. The resulting LFP electrode was divided into calendared and uncalendared samples. Under electrochemical impedance testing, the calendared and uncalendared electrodes exhibited a charge transfer resistance of 157.8 Ω and 182.4 Ω, respectively. The calendared electrode also exhibited a higher discharge capacity of about 130 mAh/g at0.1Ccompared to a discharge capacity of 120 mAh/g at0.1Cfor the uncalendared electrode.

Highlights

Lithium-ion batteries have an unmatchable combination of high-power and high-energy density and are expected to play a prominent role as larger-scale energy storage for renewable energy sources, aerospace application, grid-electric storage, and the main energy supply for hybrid/electric vehicles
Since the introduction of lithium iron phosphate as cathode material for lithium-ion batteries, lots of effort has gone into improving the electrochemical performance of this material
Over the years many techniques such as carbothermal reduction [1], doping [2], particle size reduction [3, 4], and mechanochemical activation [5] have been developed to enhance the electrochemical performance of this cathode material

Summary

Introduction

Lithium-ion batteries have an unmatchable combination of high-power and high-energy density and are expected to play a prominent role as larger-scale energy storage for renewable energy sources (e.g., wind, solar, and geothermal), aerospace application, grid-electric storage, and the main energy supply for hybrid/electric vehicles. Over the years many techniques such as carbothermal reduction [1], doping [2], particle size reduction [3, 4], and mechanochemical activation [5] have been developed to enhance the electrochemical performance of this cathode material Synthesis methods such as polyol [6], spray pyrolysis [7], solvothermal [8], and sol gel [9] have been successfully used to synthesize electrodes with very good performance at high rates due to high process and parameter control. Electron transport in lithium-ion battery structure is a key factor in the overall battery performance; the calendaring of the electrodes has become an important step in the battery fabrication process and is carried out after the coating and drying stage of fabrication, Figure 1 In this process the electrodes are compacted to improve the volumetric energy density and rate performance of the electrodes. Surface morphology, capacity fade, electrochemical impedance behavior, and rate capability are analyzed for both calendared and uncalendared electrodes

Experimental

Results and Discussion

Conclusion