Solid State Batteries and Lithium Metal Anodes – The Holy Grail of Battery Technology

The breakthrough for xEVs (hybrid and electric vehicles) was using Ni-MH batteries, followed by Li-ion batteries, which have accelerated xEV adoption. And development has accelerated to overcome challenges and meet the ever-increasing performance demands.

The demands on battery technologies are primarily focused on energy density, safety, and cost, followed by cycle life and fast charging capacity. The often-cited range anxiety is a derivative of the above factors and the availability of a charging network. Enter solid-state battery technology, which addresses all of the above.

Solid State Batteries – the next stage of battery evolution          

The key differentiator in SSBs is the use of solid-state electrolytes, compared to the liquid electrolytes in conventional Li-ion batteries. These offer significant safety benefits while resulting in a compact package. At scale, the production costs are projected to be lower than Li-ion batteries, meeting the top 3 demands placed on battery technologies. Additionally, fast charging is also an aspect where SSBs have met the requisite performance.

The benefits of solid electrolytes, however, are not limited to the above factors, and their ability to bring together anode developments offers a true next-stage battery solution. New anode materials, such as alloys, silicon, and lithium-metal, are of great interest due to the high specific capacity on offer. Combining solid electrolytes and high-specific capacity anodes improves energy density via mechanical and electrochemical properties.

Lithium Metal Anodes – the holy grail for batteries

Where the SSB package offers benefits over Li-ion batteries, the solid electrolytes also enable the use of Lithium metal anodes (LMA). LMAs have the highest specific capacity, at more than 10 times the capacity of current graphite anodes, and are thus considered the holy grail of batteries. The use of LMA also promotes anode-less design and in-situ formation of the anode, bringing down production complexity and cost. 

LMA, though, brings its own challenges in terms of dendrite formation and cell expansion, affecting the battery’s overall life. Naturally, this has been the focus of cell developers and OEMs, and significant breakthroughs have been achieved via material and mechanical designs.

Competitive Landscape

The landscape for battery technologies is highly competitive, with sodium-ion batteries already available in the world’s largest BEV market, China. Even within SSBs, Silicon anodes are competing with LMAs by offering performance close to LMA SSBs. For its part, the use of Silicon brings its own challenges regarding volume changes and structural integrity. However, Silicon anodes are closer to the market and will co-exist with LMA SSBs.

Aside from SSB, Sodium-ion batteries’ cost competitiveness is its major strength, while it also has abundant resources combined with a good low-temperature performance. However, its limitations in terms of low energy density are negated by the lower cost, making it suitable for smaller vehicles targeting a limited range.