Sepion Technologies ($16M to develop lithium metal battery using innovative membrane)

Sepion Technologies, an American battery company founded in 2015, develops lithium metal batteries using its innovative separator of a hybrid polymer-ceramic composite membrane. The separator prevents the growth of lithium dendrites on the lithium metal anode of batteries and is only permeable to lithium ions and impermeable to electrolyte solvents.

Challenges: lithium battery

The majority of today's Li-ion batteries use graphite anodes to store charge. Unfortunately, graphite anodes fundamentally limit the energy density of the battery, as six space-Wasting carbon atoms are required for each electron and lithium ion stored in graphite after a battery charge. Without more energy-dense electrodes, the amount of energy that can be stored in each Li-ion battery will plateau below the level required to electrify transportation in a sustainable manner.

Using pure lithium metal as the anode can increase abode capacity by a factor of ten. However, the risk of catastrophic battery failure resulting from the growth of lithium dendrites at the lithium anode has proven to be an insurmountable obstacle. At the anode, Li metal electroplates during charging as undesirable needle-like dendrites rather than desirable smooth sheets. These dendrites propagate until the anode and cathode are connected by conductive lithium, causing short circuit and fires.

Sepion Technologies Technology

Sepion Technologies developed a separator with a hybrid polymer-ceramic composite membrane coating layer that prevents the growth of lithium dendrites on the lithium metal anode. This is made possible by the membrane’s permeability to lithium ions and impermeability to electrolyte solvents. The lithium metal batteries based on the membranes have twice the the gravimetric energy density of today's Li-ion batteries and can be produced by leveraging the current Li-ion manufacturing infrastructure.

Sepion Technologies battery

As depicted in the figure below, Sepion technologies’s lithium metal battery consists of a lithium metal anode, a NMC based cathode, a membrane coated separator, and a liquid electrolyte.