Hello, curious researcher friend Snehal Kadam! Let's dive into your questions about supercapacitor electrode materials and their practical applicability in portable electronics.

1) When determining the suitability of your electrode material for practical energy storage applications in portable electronics, there aren't rigid standards or value limits that universally define its applicability. The decision should be based on several factors, including the specific requirements of your target application, such as voltage, energy density, power density, and size constraints. The specific capacitance, specific power, and specific energy of your prepared electrode should be evaluated against these requirements. It's also important to consider factors like cycle life, stability, and environmental concerns.

2) Exploring the relationship between crystal structure and energy storage performance is a vital aspect of materials science, especially for supercapacitors. While comprehensive literature might be somewhat limited, here are some general tips to help you in your search:

a) Search for Review Articles: Sometimes, review articles provide a good overview of the current state of research in a particular area, including the impact of crystal structure on supercapacitor performance. They can be a valuable source of information and can direct you to primary research papers.

b) Patent Databases: Patents often contain detailed information about materials and their applications. You can explore patent databases for insights into the crystal structure of materials used in supercapacitors.

c) Collaborate and Network: Reach out to experts in the field, attend conferences, and engage in discussions with fellow researchers. They might provide insights, references, or guidance on where to find relevant literature.

d) Consult Your Institution's Library Services: University libraries often have access to a wide range of academic journals, research databases, and interlibrary loan services that can help you access hard-to-find literature.

e) Explore Beyond Academic Databases: Sometimes, relevant information can be found in industry reports, technical documents, or white papers. Expanding your search to non-academic sources can yield valuable insights.

Remember that research often involves creative problem-solving and perseverance. Don't be discouraged if you Snehal Kadam can't find a specific paper or answer right away. Keep exploring various sources and don't hesitate to seek guidance from mentors and peers. Best of luck with your research, and keep those questions coming!

Thank you so much for your valuable guidance and encourangement@Kaushik Shandilya. I will definitely explore the various sources.

1) Is there any standards or value limit for specific capacitance, specific power, and specific energy of prepared electrode to decide suitable practical applications in portable electronics?

GZC: There is a limit on specific capacitance.

For EDL capacitance, it is the charge density allowed at the specific accessible interface (SAI) by ions that is truly accessible to ions. This understanding is often correlated with the specific surface area (SSA) of a porous or powdery material determined by the adsorption of small gas molecules such as those used in BET analysis. The empirical rule is that the EDL capacitance, Cdl, is usually up to 40 uF/cm2 or for carbon based materials which can be converted to the specific capacitance of the material if its SSA (m2/g) is known by the following equation:

Csp = SSA * Cdl (1)

However, because the SAI is often smaller than SSA under commonly applied conditions in electrochemical experiments, equation (1) predicts the maximum value of the specific capacitance.

For pseudocapacitive materials, the maximum specific capacitance is the reversible specific charge capacity (Qsp) divided by the so called capacitive potential range (CPR) in which the CV retains the rectangular shape.

Csp = Qsp / CPR (2)

I shall mention that equation (2) has often been distorted by many authors by replacing CPR with the potential range, deltaE = E2 - E1 of the CV which is peak-shaped. Peak-shaped CVs are featuring battery-like behaviour or Nernstian storage mechanism which should never be used for capacitance analysis.

For true capacitive materials, which exclude any that shows peak shaped or non-rectangular CVs, the maximum specific energy is simply derived from the maximum specific capacitance and voltage of the cell. For a symmetrical cell, the cell performance can be derived from that of the electrode, such as

Ccell,sp = Csp / 4 (3)

However, it is not simple for an asymmetrical cell. The following two rules must be followed: (1) the charge stored in or released from the positrode and negatrode must be equal, and (2) the current passing through the two electrode must equal.

There is not a theoretical limit for power density or specific power, but it is determined by how the material, electrode and cell are designed and manufactured. However, in terms of physics of power source, the following equation is well known for the maximum power.

Pcell, max = U2/(4*ESR) (4)

U is the cell voltage at work, and ESR the internal resistance of the cell. In practice, because both U and ESR are dependent on the materials used and the design and manufacture of the electrodes and the cell, and there is always an external load whose impedance cannot be a single constant value as that of a simple resistor , equation (4) is not practically very useful.

2) I am searching continuously for reference papers on how the crystal structure of developed electrode material affects energy storage performance, especially for supercapacitors. But didn't get satisfactory literature.

GZC: There may be such a relationship but it is not very meaningful for capacitive charge storage because the effect of nanostructures, either external or internal, is far greater than that from bulk crystallinity.