Formation isn’t just a process step. It decides whether lithium ions move cleanly through the system or get slowed, trapped, or consumed along the way.
So instead of explaining formation like a textbook, we’re going to follow a single Li⁺ as it moves through the cell and show two realities at every step:
what success looks like
what failure actually feels like inside the system
Because most battery problems aren’t theoretical. They are transport problems in disguise.
Lithium ion from cathode to electrolyte
Success: Ion is dry, and all of a sudden, it gets soaked in a sweet, carbonate electrolyte. It remains stationary as the soaking lasts for 24 hours. It feels an abrupt pull - some may say electric - out of its olivine bed. Ion is dragged out to shore and released into a vast pool of electrolyte. Somewhere, an electron feels a similar pull, and mimics the ion’s travel plans through a drier pathway.
Duress: Ion is dry, but sees nearby ions in their olivine beds abruptly drenched in electrolyte. Ion experiences partial electrolyte wetting, but is unable to decide whether it should give in and leave its olivine structure. It deliberates for some time before deciding on following the pathway, though at a sluggish pace and may take some detours.
Explanation:
Conventional li-ion cells are injected with electrolyte and allowed to soak for a 12-24 hour rest before commencing formation to ensure sufficient wetting and robust SEI formation
External power source creates an electric potential, forcing ion out of LFP structure = endothermic driving force pushing from low energy cathode state to high energy anode state
Cathode is getting oxidized during the first charge, losing electrons
Voltage of battery = difference in chemical potential of lithium between materials, this barrier or difference must be overcome in order to store energy
