Meaning
Electrochemical process that occurs when sodium ions begin to group and form metallic nuclei on the anode surface or within hard carbon pores during charging. Controlling sodium cluster nucleation is necessary to prevent dendrite growth and ensure safe battery operation. This nucleation process is influenced by the local current density and the chemical composition of the anode, which together determine the energy barrier required for stable phase transition.
Pore Storage
Sodium atoms aggregate within the closed pores of hard carbon during the low voltage plateau region. The pore storage of the anode relies on this localized cluster formation to achieve high energy densities. This storage mechanism is unique to the electrochemical behavior of sodium in hard carbon.
Dendrite Prevention
High charging rates can cause cluster formation on the outer surface of the electrode rather than inside the pores. The dendrite prevention of the cell requires careful management of the charging protocol and the electrode microstructure. Surface cluster formation can lead to separator penetration and internal short circuits.
Sourcing Metric
Anode materials are tested to determine their nucleation overpotential and cluster distribution profiles. The sourcing metric of the hard carbon dictates its compatibility with fast charging applications. Procuring materials with low nucleation overpotentials improves the high rate performance of the cells.
