Match capacities more closely (balanced N/P ratio) to fix this

Do you start with a charged or discharged state at assembly? Do the anode, cathode and electrolyte match this state at assembly?

Filip Ponsaerts, hello,

I started with a charge.

Do the anode, cathode, and electrolyte match this state at assembly? (What is the meaning)

I seem to have been unclear.

Before you start with any charging or discharging, is the anode, cathode and electrolyte in a charged or uncharged state?

As you talk about Na-ion battery, for instance in uncharged state the anode will contain Na+ ions, electrolyte must be able to carry Na ions, and the cathode must be in a state able to receive/absorb or intercalate na ions.

Filip Ponsaerts, thank you for clarifying the question. they were in an uncharged state.

Ok, so next, what is the expected OCV based on anode and cathode composition? How did you calculate this?

Filip Ponsaerts, I didn't calculate it, I just used the voltage range of the cathode (1-3.2)V. OCP of half Cell Cathode was 2.6V, and the anode was ~2.7V

I don't quite understand your answer. If it's really 2.6 and 2.7 then your OCP will be neglectable 2.7-2.6=0.1V OCV???

Filip Ponsaerts, yes, it was negligible. When I assembled the full cell, the OCP was ~ 0.09V

You'll have to change your anode-cathode-electrolyte combination...

Filip Ponsaerts, should I assemble the cathode in the discharge state and the anode in the charge state to get the OCP difference?

For OCV the battery needs to have some charge.

Either you build it in charged state, or you need to charge it (at least some).

But to be able to charge it, you need to know the voltage you are aiming at.

Applying a charging voltage to low will not work, charging with a voltage to high might trigger side reactions. You also need to know the voltage drops that will occur in your battery while charging. (overvoltage needed for the processes at cathode and anode, the resistance at the separator,...

It sounds like you're experiencing issues with your Na-ion coin cell, specifically low or no capacity and a low open-circuit potential (OCP). Here are some possible reasons and solutions:

​​Possible Issues & Solutions:​​

• ​ ​No Na⁺ in cathode → Cannot release Na⁺ during charging.​​
• ​ ​No Na⁺ in anode → Cannot store Na⁺ during discharge.​​

​Result:​​ The cell shows ​​no capacity​​ and a ​​low OCP (

Mengfan Pei thank you