Week 6 Session 13

Discuss two new trends in battery system field.

Answer:

New trends in battery technology:

Solid State Lithium Metal Batteries.

Sodium ion Batteries

Solid State Lithium metal Battery:

A solid-state battery is essentially battery technology that uses a solid electrolyte instead of liquid electrolytes.

The structure of a solid-state battery:

• A cathode (or positive electrode), which can be made with the same compounds as a lithium-ion battery (e.g. LFP, NMC, LMO, etc)
• A separator, generally ceramic or solid polymer, which also works as the electrolyte
• An anode made of lithium metal (pure lithium)

The grey central layer is the solid-state separator which, on its own, acts both as the separator between the anode and cathode and as the electrolyte. It, therefore, becomes the medium through which the ions move and also has electric insulating properties, and is a mechanical separator between the anode and cathode. The fact that there is this solid, resistant support allows the removal of the graphite structure on the anode part and ensures that lithium metal accumulates directly on the anode.

solid-state batteries promise many improvements over the current batteries on sale; in fact, solid electrolytes seem to offer greater energy density, a longer life and greater safety, all in a smaller size.

When the cell is charging, the lithium particles move from the cathode, through the structure of the atoms that form the separator, and then move in between the separator itself and the anode’s electrical contact, thus forming a solid layer of pure lithium. In this way, the anode will only be formed of lithium particles and will have a smaller volume than a lithium-ion technology anode, which contains the graphite structure.

Sodium-ion battery:

A sodium-ion battery is a type of rechargeable battery comparable to the ubiquitous lithium-ion battery, but it uses sodium ions (Na+) as the charge carriers rather than lithium ions (Li+). The working principles behind and cell construction of a sodium-ion battery are virtually identical to those of lithium-ion batteries, but sodium compounds are used instead of lithium compounds.

Sodium-ion batteries are currently emerging as a potential alternative to current lithium-ion battery technology due to their lower cost, higher availability, and reduced impact on the environment. Since sodium-ion batteries use cheap and abundant materials—sodium and aluminum rather than lithium and copper.

While a sodium-ion battery is discharging and providing a current, the anode releases sodium ions to the cathode, generating a flow of electrons from one side to the other. When plugging in the device, the opposite happens: Sodium ions are released by the cathode and received by the anode.

Applications:

Automotive

Power grids

Industrial mobility

the key differences between sodium-ion and lithium-ion battery technology:

	Sodium-ion	Lithium-ion
Cost/kWh of capacity	US$40 – 77	US$137 average
Volumetric energy density	250 – 375 W h/L	200 – 683 W h/L
Safety	Low risk for aqueous	High risk
Materials	Abundant and cheap	Scarce
Cycling stability	High	High
Temperature range	−20 °C to 60 °C	−20 °C to 60 °C (but 15 °C to 35 °C optimal)