Widespread electrification requires us to rethink battery technology

·6-min read

The global economy’s transition to widespread electrification has increased the demand for longer-lasting and faster-charging batteries across industries including transportation, consumer electronics, medical devices and residential energy storage. While the benefits of this transition are well understood, the reality is that battery innovation hasn’t kept pace with society’s ambitions.

With reports forecasting a 40% chance that the world’s temperature will rise over the next five years beyond the limit of 1.5 degrees Celsius laid out in the Paris climate agreement, it is clear that there’s little time to waste when it comes to creating next-generation batteries, which can easily take another 10 years to fully commercialize.

To meet the increasing pressures to electrify, a completely novel approach to building batteries is the only way to scale rechargeable batteries quickly enough to curb greenhouse-gas emissions globally and avoid the worst-case scenario for the climate crisis.

The challenges to battery innovation

Over the last few decades, battery experts, automakers, Tier 1 suppliers, investors and others looking to electrify have spent billions of dollars globally on creating next-generation batteries by focusing predominantly on battery chemistry. Yet the industry is still grappling with two major fundamental technical challenges that are stunting the proliferation of batteries:

  1. Energy/power tradeoff: All batteries manufactured today face an energy-to-power tradeoff. Batteries can store more energy or they can charge/discharge more quickly. In terms of electric vehicles, this means no single battery can provide both long range and fast charging.

  2. Anode-cathode mismatch: Today’s most promising battery technologies maximize the energy density of anodes, the negative electrode of the pair of electrodes that make up every lithium-ion battery cell. However, anodes already have greater energy density than their positive counterpart, the cathode. Cathode energy density needs to eventually match that of the anode in order to get the most energy storage capacity out of a certain battery size. Without breakthroughs in increasing cathode energy density, many of today’s most exciting battery technologies will not be able to deliver on their full potential. As it currently stands, the most commonly used lithium-ion battery cannot meet the needs of the wide-ranging applications of an all-electric future. Many companies have tried to address these demands through new battery chemistries to optimize the high-power-to-energy-density ratio to varying degrees of success, but very few are close to achieving the performance metrics required for mass scale and commercialization.

Ultimately, the winning technologies in the race toward total electrification will be the ones that have the most significant impact on performance, lowered costs and compatibility with existing manufacturing infrastructure.

Are solid-state batteries the holy grail?

Battery researchers have championed the solid-state battery as the holy grail of battery technology due to its ability to achieve high energy density and increased safety. However, until recently, the technology has fallen short in practice.

Solid-state batteries have significantly higher energy density and are potentially safer because they do not use flammable liquid electrolytes. However, the technology is still nascent and has a long way to go to achieve commercialization. The manufacturing process for solid-state batteries has to be improved to lower costs, especially for an automotive industry that aims to achieve aggressive cost reductions as low as $50/kWh in the coming years.

The other substantial challenge to implementing solid-state technology is the limitation of total energy density that can be stored in the cathodes per unit of volume. The obvious solution to this dilemma would be to have batteries with thicker cathodes. However, a thicker cathode would reduce the mechanical and thermal stability of the battery. That instability leads to delamination (a mode of failure where a material fractures into layers), cracks and separation -- all of which cause premature battery failure. In addition, thicker cathodes limit diffusion and decrease power. The result is that there is a practical limit to the thickness of cathodes, which restricts the power of anodes.

New takes on materials with silicon

In most cases, companies that are developing silicon-based batteries are mixing up to 30% silicon with graphite to boost energy density. The batteries made by Sila Nanotechnologies are an illustrative example of using a silicon mix to increase energy density. Another approach is to use 100% pure silicon anodes, which are limited by very thin electrodes and high production costs, to generate even higher energy density, like Amprius’ approach.

While silicon provides considerably greater energy density, there is a significant drawback that has limited its adoption until now: The material undergoes volume expansion and shrinkage while charging and discharging, limiting battery life and performance. This leads to degradation issues that manufacturers need to solve before commercial adoption. Despite those challenges, some silicon-based batteries are already being deployed commercially, including in the automotive sector, where Tesla leads in silicon adoption for EVs.

The imperative for electrification requires a new focus on battery design

Advances to battery architecture and cell design show significant promise for unlocking improvements with existing and emerging battery chemistries.

Probably the most notable from a mainstream perspective is Tesla’s “biscuit tin” battery cell that the company unveiled at its 2020 Battery Day. It's still using lithium-ion chemistry, but the company removed the tabs in the cell that act as the positive and negative connection points between the anode and cathode and the battery casing, and instead use a shingled design within the cell. This change in design helps reduce manufacturing costs while boosting driving range and removes many of the thermal barriers that a cell can encounter when fast-charging with DC electricity.

Transitioning away from a traditional 2D electrode structure to a 3D structure is another approach that is gaining traction in the industry. The 3D structure yields high energy and high power performance in both the anode and cathode for every battery chemistry.

Although still in the R&D and testing phases, 3D electrodes have achieved two times higher accessible capacity, 50% less charging time and 150% longer lifetime for high-performance products at market-competitive prices. Therefore, in order to advance battery capabilities to unlock the full potential of energy storage for a range of applications, it is critical to develop solutions that emphasize altering the physical structure of batteries.

Winning the battery race

It’s not just performance improvements that will win the battery race, but perfecting production and cost reduction as well. To capture a considerable share of the ballooning battery market that is projected to reach $279.7 billion by 2027, countries around the world must find ways to achieve low-cost battery manufacturing at scale. Prioritizing “drop-in” solutions and innovative production methods that can be incorporated with existing assembly lines and materials will be key.

The Biden administration’s American Jobs Plan highlights the importance of domestic battery production to the country’s goal of being a leader in electrification while meeting ambitious carbon reduction targets. Commitments like these will play a key role in establishing who can maintain a critical competitive edge in the battery space and take the largest share of the $162 billion global EV market.

Ultimately, the winning technologies in the race toward total electrification will be the ones that have the most significant impact on performance, lowered costs and compatibility with existing manufacturing infrastructure. By taking a holistic approach and focusing more on innovating cell design while also fine-tuning leading chemistries, we can achieve the next steps in battery performance and rapid commercialization that the world desperately needs.