by Jeff Desjardins | posted with permission of Visual Capitalist | February 23, 2017
The Battery Series presents five infographics exploring what investors need to know about modern battery technology, including raw material supply, demand and future applications.
This is the last instalment of the Battery Series. For a recap of what has been covered so far, see the evolution of battery technology, the energy problem in context, the reasons behind the surge in lithium-ion demand and the critical materials needed to make lithium-ion batteries.
There’s no doubt that the lithium-ion battery has been an important catalyst for the green revolution, but there is still much work to be done for a full switch to renewable energy.
The battery technology of the future could:
- Make electric cars a no-brainer choice for any driver
- Make grid-scale energy storage solutions cheap and efficient
- Make a full switch to renewable energy more feasible
Right now, scientists see many upcoming battery innovations that promise to do this. However, the road to commercialization is long, arduous and filled with many unexpected obstacles.
The near-term: Improving the Li-ion
For the foreseeable future, the improvement of battery technology relies on modifications being made to already-existing lithium-ion technology. In fact, experts estimate that lithium-ions will continue to increase capacity by 6% to 7% annually for a number of years.
Here’s what’s driving those advances:
Tesla has already made significant advances in battery design and production through its Gigafactory:
- Better engineering and manufacturing processes
- Wider and longer cell design allows more materials packaged into each cell
- New battery cooling system fits more cells into battery pack
Most of the recent advances in lithium-ion energy density have come from manipulating the relative quantities of cobalt, aluminum, manganese and nickel in the cathodes. By 2020, 75% of batteries are expected to contain cobalt in some capacity.
For scientists, it’s about finding the materials and crystal structures that can store the maximum amount of ions. The next generation of cathodes may be born from lithium-rich layered oxide materials (LLOs) or similar approaches, such as the nickel-rich variety.
While most lithium-ion progress to date has come from cathode tinkering, the biggest advances might happen in the anode.
Current graphite anodes can only store one lithium atom for every six carbon atoms—but silicon anodes could store 4.4 lithium atoms for every one silicon atom. That’s a theoretical tenfold increase in capacity!
However, the problem with this is well documented. When silicon houses these lithium-ions, it ends up bloating in size up to 400%. This volume change can cause irreversible damage to the anode, making the battery unusable.
To get around this, scientists are looking at a few different solutions.
1. Encasing silicon in a graphene “cage” to prevent cracking after expansion.
2. Using silicon nanowires, which can better handle the volume change.
3. Adding silicon in tiny amounts using existing manufacturing processes—Tesla is rumoured to be doing this already.
Lastly, a final improvement that is being worked on for the lithium-ion battery is to use a solid-state setup, rather than having liquid electrolytes enabling the ion transfer. This design could increase energy density in the future, but it still has some problems to resolve first, such as ions moving too slowly through the solid electrolyte.
The long term: Beyond the lithium-ion
Here are some new innovations in the pipeline that could help enable the future of battery technology:
Cathode: Porous carbon (oxygen)
Promise: 10 times greater energy density than Li-ion
Problems: Air is not pure enough and would need to be filtered. Lithium and oxygen form peroxide films that produce a barrier, ultimately killing storage capacity. Cycle life is only 50 cycles in lab tests
Variations: Scientists also trying aluminum-air and sodium-air batteries
Cathode: Sulphur, carbon
Promise: Lighter, cheaper and more powerful than Li-ion
Problems: Volume expansion up to 80%, causing mechanical stress. Unwanted reactions with electrolytes. Poor conductivity and poor stability at higher temperatures
Variations: Many different variations exist, including using graphite/graphene, and silicon in the chemistry
Vanadium flow batteries
Promise: Using vanadium ions in different oxidation states to store chemical potential energy at scale. Can be expanded simply by using larger electrolyte tanks
Problems: Poor energy-to-volume ratio. Very heavy, must be used in stationary applications
Variations: Scientists are experimenting with other flow battery chemistries as well, such as zinc-bromine
Battery series conclusion
While the future of battery technology is very exciting, for the near and medium terms scientists are mainly focused on improving the already-commercialized lithium-ion.
What does the battery market look like 15 to 20 years from now? It’s ultimately hard to say. However, it’s likely that some of the above new technologies will help in leading the charge to a 100% renewable future.
Thanks for taking a look at the Battery Series.
See Part 1, Part 2, Part 3 and Part 4.
Posted with permission of Visual Capitalist.