A revised half-cell test method that can measure ICE and real capacity of hard carbon more precisely is introduced to lay the foundation for full-cell design.
Unfortunately, owing to the potential of constant voltage or low current discharge stage is close to the sodium deposition potential, there is a risk of sodium plating on hard carbon anode, making the sodiation capacity from half-cell test is difficult to be fully employed in full-cell system.
In light of this, this work proposes an improved half-cell test strategy that fits the dQ/dV curve of the desodiation process of hard carbon at over-sodiated states, allowing for a more accurate determination of the available capacity of the hard carbon.
However, current half-cell test method for assessing the available specific capacity of hard carbon faces challenges. Typically, the constant voltage or low current discharge strategy is typically adopted at the end of the discharge process to minimize the influence of polarization.
Another currently urgent issue is that most of the investigations on electrolyte optimization for SIBs are carried out in a half-cell system and the conclusion might be unsuitable for the sodium-matched full-cell, due to the huge difference between the Na BCC -metal counter electrode and a real cathode 51,57,63,64 as discussed previously.
The anode/electrolyte interface behavior, and by extension, the overall cell performance of sodium-ion batteries is determined by a complex interaction of processes that occur at all components of the electrochemical cell across a wide range of size- and timescales.