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Boranes for all solid-state batteries

Why do we need new battery materials?

To reduce carbon emissions, it is of critical importance to complete the transition to renewable energy sources. The downside of renewables, such as solar, wind and hydro, is that these are weather dependant and do not match with human consumption. This means that the energy production is too high and energy is wasted or vice versa. This has two major downsides. First, to stabilize the energy supply we are burning fossil fuel thereby emitting greenhouse gasses. Second, the price of renewable energy has fallen substantially in the last decade and energy gained from non-renewable sources there comes at a higher economic cost, especially in times of geopolitical uncertainty.   

A solution to the is efficient energy storage using batteries. By charging batteries during high production and discharging during low production, the energy gaps are closed. In that way, energy production will become both greener and more economical. Furthermore, it has the benefit of making countries more energy independent. Aside from bulk energy storage, batteries are used in everything from pacemakers to cars and better batteries could mean higher capacities, longer lifetimes, shorter charging times and increased safety.  

What are the challenges with current battery technology?

The most widely used battery technologies currently are Lead-acid, Nickel-Cadmium, Lithium-polymer and Lithium-ion, of which Lithium-ion is the most versatile, being used in everything from electric vehicles to smartphones. The challenge with the Lithium-ion battery, is that the technology is almost at the theoretical maximum energy density. We must therefore look towards new technologies that are compatible with better anode and cathode materials. Furthermore, the Lithium-ion batteries contains a highly flammable, posing a security risk if the cell short circuits. Finally, Lithium and Cobalt are materials that are unevenly distributed around the world, meaning battery production depends on global supply chains, which are unreliable during  geopolitical crisis.

Our research – Complex borohydrides and boranes

All solid-state batteries based on Li+ and other cations (Na+, Mg2+,Ca2+, etc.) can potentially resolve the issues seen in Lithium-ion batteries. These makes it possible to use metal anodes, thereby shrinking the anode and increasing energy density. Solid-state electrolytes can potentially work at higher voltages allowing for the use of a wider range of cathode materials. The challenge lays in finding materials with high cationic and low electronic conductivities that are stable towards both the anode and cathode. In recent years, the group has investigated various borohydrides, the chemistry of which is very diverse, in an attempt to reach a greater understanding of the effects responsible for high cationic conductivity. By introducing neutral ligands to the borohydride systems, different effects has been observed such as expansion of the otherwise closed structure, regions with flat energy landscapes and a catalytic ligand assisted transport. This has resulted in several publications. Currently the group is shifting focus towards the higher boranes, such as (B12H12)2- and (CB9H10)-, due to their high ionic conductivities and electrochemical stabilities. We hope to apply the knowledge gained from the borohydride systems to take the higher boranes to a new level. You can read more about our research in the publications listed below.

Battery related publications