Electrochemical-Mechanical Analysis of Printed Silver Electrodes in a Microfluidic Device

Abstract

Nanoparticulate printed silver is a core material to flexible, printed circuits. Some commercial silvers are of a sufficient purity that one may consider their use in electrochemical power sources and sensors. We establish an iterative rapid prototyping and measuring method, printing electrodes, annealing them under temperature conditions from 210 to 280°C, and cycling them in a microfluidic cell such that the electrolyte becomes the shearing medium. Electrode strength is quantified by the breakage due to generation of gas-phase oxygen at the electrode. This oxygen generation assisted breaking is found to be a function of the amount of oxygen generation only, independent of current density and electrolyte flow rate. Silver cured at 280°C for 60 min had highest strength and required an average of 241.8 mC/mm 2 at electrode rupture; curing at 280°C for 20 min required only 203.8 mC/mm 2 for failure. Silver strength is quantified as an oxidant storage medium in the forms Ag 2 O and AgO and as a printed reference electrode. Ag and AgO have higher shear strength compared to Ag 2 O. Thus, shear strength of silver oxide electrodes at potentials of 0.15-0.55 V against a printed silver reference depends on the oxidation state.As the technology in the electronic industry advances, the next generation of sensor and wireless nodes will be physically flexible 1,2 and less than subcentimeter square in dimension. 3 These devices will require a power source, which is self-contained and has low maintenance, 4,5 and has high energy density while conforming to the stringent physical properties of the devices. Direct write printing 6-8 techniques can be used to print miniature power sources on sensor and wireless nodes. Direct write technique has a distinct advantage over the traditional lithographic technique, which involves series of deposition, lithographic etching, and masking steps. 9 In contrast, direct write printing is inexpensive and rapid and allows for significantly thicker electrodes, allowing the areal energy density when compared to "lith and etch" methods.In general, failure of any battery during operation may be attributed, in part, to the mechanical fatigue, leading to an isolation of active materials and therefore lost capacity. Batteries printed on a flexible substrate experience an additional stress due to the bending motion of the substrate. 10 Thus, a technique is required to examine the mechanical integrity of a battery in situ, so both mechanical and electrochemical performances can be correlated to processing parameters. Printed batteries need to be tested for the optimum ink composition, postprinting processing conditions, operating conditions, and response to external stress before they can be used on flexible sensors and wireless tags.Microfluidic devices have been used to study electrochemical systems. [11][12][13][14] In this work we demonstrate a microfluidic setup to test the performance of printed batteries. The shear imposed by a flowing electrolyte can be correlated with the state of charge and cha...

Fabrication of High‐Performance Flexible Alkaline Batteries by Implementing Multiwalled Carbon Nanotubes and Copolymer Separator

“…[1][2][3][4][5][6] Hence efforts are underway to make different fl exible power sources including primary batteries, rechargeable batteries, and supercapacitors. [ 2,5,[7][8][9][10][11] Commercially available printing methods such as dispensing [ 12,13 ] and stencil printing [ 14 ] are also being used to deposit electrode materials. [ 2,5,[7][8][9][10][11] Commercially available printing methods such as dispensing [ 12,13 ] and stencil printing [ 14 ] are also being used to deposit electrode materials.…”

“…[ 1,2,[5][6][7][8] There is much research activity in adopting conventional batteries such as zinc-carbon and lithium ion, but at the same time new materials such as those based on nanoparticle complexes are being developed for battery and supercapacitor electrodes. [ 2,5,[7][8][9][10][11] Commercially available printing methods such as dispensing [ 12,13 ] and stencil printing [ 14 ] are also being used to deposit electrode materials.…”

Printed batteries and conductive patterns in technical textiles

“…These include thin-film, flexible and stretchable batteries and capacitors, fabricated by using a variety of methods. [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] Inks for electrode productions can be deposited over large areas using blade 24) and dip coating, 30) or over small areas by different techniques such as stencil, 32) dispenser and screen printing. 26,29,33) The aim of an electrode thickness between 20 and 60 µm is described as an acceptable range for power capability and mechanical stress tolerance.…”

Recent Progress on Printed Flexible Batteries: Mechanical Challenges, Printing Technologies, and Future Prospects

“…Thefraction of the solvent in the ink is kept to am inimum to prevent sedimentation, and the active particles are ball milled to reduce the average particle size.D ispenser printing can be used to print inks over areas ranging from 100 mm 2 to 1m 2 by drawing patterns in the form of repeated lines or drops.D ispenser printing large electrodes is considerably slower as compared to other printing methods but it is advantageousf or printing electrodes with as mall footprint over ad efined location. Due to the non-contact nature of dispenser printing, the ink can be printed over uneven surfaces,w hichi sn ot possible with otherr oll-to-roll printing methods.D ispenser printing has been used to fabricate thermoelectric generator, [128][129][130] batteries [61,[63][64][65]128] and ceramic structures. [126,127] Reports on batteries fabricated using dispenser printing have predominately involved printing the active layers and polymer electrolyte on glass substrates with pre-patterned current collectors formed by lithography.…”

“…[52,[58][59][60] The term "printed battery" is used to describe ab attery for which at least one of the components is solution processed and deposited using ap rinter. [61][62][63][64][65][66][67][68][69] Then on-printed component (current collector or separator) serves as as upport for the printed components.T he mechanical characteristics of ap rinted battery depend on its architecture and design. Over the past couple of years,t here has been significantp rogress towards using printing-based processes to fabricate power sources.R esearchers have demonstrated full-cells using con-Tr aditional printing methods offer the advantage of well-matured technology,h igh accuracy of depositing inks over flexible substrates at high web speeds,and low cost of fabrication.…”