Prelithiation Methods Compared

HypSi™ is 70.energy’s industrialisation solution for electromechanical prelithiation. It adds lithium and pre-forms the SEI before cell assembly in one continuous roll-to-roll step — from 70 seconds per process step.

The electrode is lithiated in a cell-like arrangement against a lithium source under controlled current and potential, then recovered and built into the final cell.

Because the charge passed is measured directly, this route offers the most direct handle on the dose, which makes it attractive for method development and for establishing a reference value. The cost is an additional assembly, cycling and disassembly step, and the need to transfer a lithiated electrode without losing that state.

The electrode is exposed to a solution containing a lithiating reagent, and lithium is transferred by chemical reaction rather than by an applied current.

This can treat larger electrode areas without cell assembly, and it scales more naturally to continuous handling. The dose is set indirectly — through reagent chemistry, concentration, temperature and exposure time — so it has to be calibrated, and solvent compatibility with binder and electrode structure has to be verified.

The electrode is brought into physical contact with a lithium source in the presence of an electrolyte, and lithium transfers along the short-circuited path formed by the contact.

The arrangement is mechanically simple and needs no external circuit, which makes it interesting for integration into an electrode handling line. Uniformity is the critical variable: contact pressure, wetting and time distribution determine whether the dose is even across the area, and the reaction is comparatively hard to stop precisely.

Protected lithium micro-particles are applied to the anode. After electrolyte filling, the protective shell dissolves and lithium transfers within the cell; powder safety and uniform distribution remain important constraints.

The delivered dose must be verified on the real electrode and in full cells. Assess powder handling, storage and distribution uniformity before transferring the approach to a coating workflow.

Physical vapour deposition places a thin lithium film on the anode in vacuum. It can produce uniform, precisely dosed films, but requires vacuum equipment and immediate inert handling after deposition.

The deposited film is not the same as a pre-formed SEI. Evaluate film stability, the transfer into cell assembly and whether vacuum-system cost is justified by the research or pilot objective.

Instead of treating the finished electrode, a lithium-donating material is introduced through the cathode formulation, releasing lithium during formation.

This is the least intrusive route for an existing production chain, because it changes a formulation rather than adding a process step. In exchange, the dose is coupled to the formulation and to formation conditions, and the additive and its reaction products have to be compatible with the rest of the cell.

The comparison that matters is not an abstract ranking but a match against project constraints. In practice the deciding factors are the electrode format and area, how tightly the dose has to be held, what solvents and atmospheres the process chain tolerates, and whether the target is laboratory-scale development or a route that can be scaled later.

For that reason method selection is normally done experimentally on the actual material system, comparing at least two candidate routes under otherwise identical electrode and formation conditions.