Conductive polymer film supporting LiFePO4 as composite cathode for lithium ion batteries

Abstract

h i g h l i g h t s < Free-standing PEDOTeLiFePO 4 composites for lithium ion batteries by dynamic three phase interline electropolymerization. < PEDOTeLiFePO 4 serves as current collector, binder and carbon filler free functional electrodes. < LiFePO 4 mass fraction of 33.5 wt.% in the composite film confirmed by TGA analysis. < The cathode discharge capacity of the PEDOTeLiFePO 4 composite film is 75 mAh g À1 at C/10. a b s t r a c tFree-standing poly(3,4-ethylenedioxythiophene) (PEDOT)eLiFePO 4 composite films were successfully prepared by dynamic three phase interline electropolymerization (D3PIE). These films were used without further modification as the positive electrode in standard lithium ion batteries. As such, this new process eliminates all electrochemically inactive materials (carbon, polymer binder and current collector) used in conventional composite cathodes. The PEDOTeLiFePO 4 composite film offers a discharge capacity of 75 mAh g À1 at the C/10 rate and high capacity retention at the C/2 rate. When reporting this value to the relative amount of LiFePO 4 in the PEDOT-LiFePO 4 composite film, the discharge capacity reached 160 mAh g À1 , close to the theoretical maximum value (170 mAh g À1 ). As such, this approach yield highly functional hybrid free-standing conductive polymer/active material composite cathode with controllable size and structure.

Nanostructured conductive polymers for advanced energy storage

“…50 Conductive polymers are commonly used as modification materials to enhance the performance of other cathode and anode materials. For example, Co 3 O 4 anodes suffer from poor rate capabilities due to their low intrinsic electronic conductivity.…”

“…9a). 50 The PEDOT-LiFePO 4 film shows high conductivity, flexibility and porosity and achieves high electrochemical performance with a discharge capacity of B160 mA h g À1 at the C/10 rate. The conductive polymer PEDOT:PSS could also be applied on sulfur particles to effectively trap the polysulfides and minimize the dissolution of polysulfides.…”

New functional conducting poly-3,4-ethylenedioxythiopene:polystyrene sulfonate/carboxymethylcellulose binder for improvement of capacity of LiFePO4-based cathode materials

“…Additional improvement of the electrochemical properties of LFP-based cathode materials with the use of conducting polymer coatings [9][10][11][12][13][14][15][16][17][18][19][20], and in particular, poly-3,4-ethylenedioxythiopene [12,[13][14][15] was proposed.…”

“…Tel/fax: +7 (812) 4286900, E-mail address: vkondratiev@mail.ru 2 LFP/PEDOT or LFP/PEDOT:PSS composites, however, large amounts either of carbon additives and inactive binders or conducting polymer were needed to produce mechanically stable electrodes with good electrochemical performance. Therefore, the values of capacities of LFP/PEDOT referred to the total weight of the composite electrodes including LFP and additives are relatively low (75-130 mAh g -1 at 0.1 C) [13][14][15]17].…”

LiFePO 4 particle conductive composite strategies for improving cathode rate capability

“…However, perfect surface coatings and desired mixtures are often very difficult to achieve and the powerperformance enhancement of these electrode materials is still limited. More recently, the use of conductive polymers such as poly(3,4-ethylenedioxythiophene) (PEDOT) is especially attractive in terms of the improvement of the mechanical flexibility, the option to be coated under mild processing conditions compared to carbon coating, improvement of Li-ion transport, and for its dual role as conductive and binder additive [11][12][13] . In these cathodes, the synthesis procedure is key for the final stoichiometry and microsctructure that largely influence the physico-chemical properties of the material.…”