A lithiophilic 3D copper substrate for anode-free lithium-metal cells

Why anode-free

A conventional lithium-ion cell stores lithium inside a graphite anode. The graphite does no electrochemical work of its own; it is a host, and it adds mass, volume, a slurry and drying line, and a supply chain that today runs almost entirely through one country. A lithium-metal cell removes the host and plates lithium directly. An anode-free cell goes one step further: it is built with no anode material at all. Every atom of lithium comes from the cathode and plates onto the copper current collector during the first charge. Removing the graphite anode can raise cell energy density substantially, which is why anode-free designs are the target of lithium-metal programmes worldwide.

The problem with plain copper

Planar copper foil is a poor surface for lithium. Lithium nucleates unevenly on it, plating kinetics are slow, and the first cycles lose lithium to side reactions and isolated deposits. The result is low coulombic efficiency early in life, uneven plating that can grow into dendrites, and cells that fade before they have shown what the chemistry can do. This is the problem that has kept anode-free cells in the laboratory.

What Alkalinth makes

Alkalinth makes negative-electrode substrates for anode-free lithium-metal batteries. Our proprietary, scalable roll-to-roll process turns standard copper foil into a lithiophilic, three-dimensional surface that lets lithium plate evenly. It replaces the anode in conventional cells and needs no excess lithium. The foil drops into existing cell manufacturing. Patent pending.

The functionalized surface lowers the barrier to lithium nucleation, so plating starts evenly across the foil instead of at a few points. The three-dimensional framework gives the lithium a structure to deposit into and accommodates the volume change of each cycle. In our testing the substrate gives improved nucleation and coulombic efficiency versus planar copper and promotes even, dendrite-resistant plating. We share the figures, with the test conditions behind them, under a non-disclosure agreement.

Fit with a cell line

The substrate is supplied in standard foil formats and is designed as a drop-in for existing cell lines. It is handled like planar foil and requires no special atmosphere. Because the cell is built anode-free, the anode slurry and drying steps disappear from the process. We have demonstrated the substrate in ether-based electrolytes; it is compatible with a wide range of electrolytes, and carbonate work is ongoing. The process is continuous and roll-to-roll, built for scale, and we are targeting a cost competitive with conventional anodes at scale. The substrate is made in Hudson, Massachusetts.

How to evaluate it

The useful test is simple: your cathode and electrolyte on our substrate against your current anode or thin lithium foil, at your conditions, on your cycler. We supply foil to your protocol for coin or pouch cells and compare notes under NDA. Write to info@alkalinth.com, or read about where the substrate matters most.