Continuous Pyrolysis versus Chemical Pre-Sodiation in Hard Carbon Yields
Continuous pyrolysis delivers lower manufacturing costs and stable hard carbon yields, whereas chemical pre-sodiation boosts efficiency at higher scrap and reagent expenses.
Sodium Dendrites
Meaning
Metallic growths represent the uneven accumulation of sodium atoms on an anode surface during charging. These needle-like structures can pierce the separator and create a path for electricity to flow directly between the electrodes. Because sodium dendrites cause internal short circuits, they are a primary safety concern for sodium-ion battery technology.
Their formation is often linked to high charging speeds or cold temperatures.
Interface Stability
Smooth deposition of ions is required to prevent the initiation of a spike. If the surface of the anode has defects or if the electrolyte does not wet the surface properly, the ions will cluster in one spot. When sodium dendrites start to grow, they create a localized high electric field that attracts more ions.
This self-reinforcing process leads to rapid growth across the gap.
Short Circuit
Failure occurs when the metallic bridge makes contact with the cathode. This event releases the stored energy of the battery as heat, which can lead to fire or explosion. Since sodium dendrites are often very thin, the first contact might only cause a small drop in voltage.
Over time, these small shorts can grow into a major failure.
Current Density
Limits on how much power can be pushed into a cell are set to avoid the conditions that favor growth. Fast charging forces ions to move quicker than they can spread out on the anode surface. Controlling the current density is the most effective way to prevent sodium dendrites in existing battery designs.