You are asking my question and I would love to hear what experts in battery have to say.  

Hi Bhavana and Abdulmenan,

Half cells are used as a platform for exploring the properties of a single electrode material (i.e. Bhavana's nanofibers). Using a lithium metal counter electrode (which also acts  as a pseudo reference) with substantial excess capacity relative the the material being studied is the most common practice. In this regard, the selected mass loading of the carbon nanofibers is a bit arbitrary because the Li counter electrode should always have excess capacity, but insufficient loading can introduce significant variability and error. 

In terms of practical loading amounts, most electrodes are normally coated as a slurry on a current collector foil (Al for cathodes, Cu for anodes) typically tens of microns thick). In my experience common loading amounts for thin film electrodes are somewhere in the range of 1 to 25 mg/cm^2. A lot of the factors involved in these tests are dictated by your cell infrastructure (i.e. coin cells, cylinder, pouch cells etc.) as some geometries are more sensitive to electrode thickness than others. The most important challenges in these experiments are taking accurate measurements of the electrode mass loading, closing enough cells to make sure the statistical variability in capacity is reasonable, and determining voltage limits for formation and cycling (more of a cathode issue).

Good luck! 

Thank you Dr. Marshall Schroeder for detailed answer. It is really helpful.

Thank you Dr. Schroeder and I appreciate your time to enlightening us.   I am working on anode materials (transition metals and oxides) and testing in half cells.  Thickness effect is huge and affecting capacity in a big way.  I do get good stable capacity for up to 0.4 mg/cm2.   But I wan to go higher but for a higher loading, capacity drops fast.  I can not able to get around a thickness.  Do you have any suggestions?  

My guess would be that your films are not conductive enough to retain high capacity with thicker films. This effect is probably even more noticeable at higher currents. You may have already tried this, but one common way to overcome this issue is to integrate a conductive additive (i.e. carbon black) to provide electron percolation networks through thicker films). However, this could be challenging depending on your electrode fabrication method and does result in some "inactive material", lowering the specific capacity of your electrode. Alternatively, you may be able to dope the anode material with other metals/oxides but this will most likely change the electrochemical behavior of your system.

Dr. Schroeder response is great.

You should also think of additional effect that may dictate your cell performances once changing to high loading of your working electrode (i.e the oxide you use).

If you exceed a certain loading the capacity drop is not necessarily due to problem on your electrode of interest, but possibly due to issues related to the lithium anode. More specifically, once you exceed a certain trash-hold of close to 1mA/cm2 of Li - you will enhance the tendency of Li do form dendrites upon cycling. Once you formed dendrites on your Li metal, issues that are related to electrolyte consumption and cell drying will take place.

So, if possible, try to use Li anode which enable you to pull currents that are bellow the trashhold for dendrtite formation. Or use other electrode as Li ion source ( Olivine e.g.).

I think the parameter of Li mass is less crucial than projected surface area of your Li anode in your half cell (Provided you hold huge excess of Li on your anode) 

I would like thank all of you for your thoughtful and detailed responses.  I have already added CB to improve the conductivity of the thicker film.  And i am adding CB through an aqueous or organic formulation.  But still facing similar problem.  What is the right amount of CB and what is the best way to introduce into an iron oxide anode? I have also read an article that mention adding too much of the conductive additives are not so good.  

With regard to to lithium source, i am testing anode in half cells using pure lithium foil as counter/reference electrode.