Life after lithium: Future battery technologies

The surge in global demand for batteries, fuelled by the rapid electrification of vehicles and the demands to store renewable energy, has brought attention to the environmental drawbacks of lithium extraction methods. 

For instance, the evaporation ponds in Chile, where lithium-rich brine is concentrated, use 682 times more water than sodium extraction methods, leading to water contamination that affects local communities, and while hard rock lithium mining in Australia presents itself as an alternative, it emits a substantial 15 tonnes of CO2 per tonne of lithium extracted, contributing to greenhouse gas emissions.

Lithium batteries are renowned for their durability, power, energy storage capacity, safety, and affordability; however, the recycling of lithium batteries also poses a significant challenge due to their complexity and high cost. The process involves multiple steps to extract metals, consuming more energy compared to manufacturing new batteries, ultimately resulting in low recycling rates.

Motivated by the pursuit of alternatives, companies are now looking into various options to facilitate the transition to greener batteries, where factors such as lifespan, power, energy density, safety, and cost must all be considered.

Sodium-ion batteries

At a trial site in Australia’s Yarra Valley, cutting-edge battery technology developed by a company called Faradion is being employed to store renewable electricity and power buildings without the need for lithium. These batteries harness the power of sodium, a sustainable element with the potential to make a substantial impact in the quest for eco-friendly energy storage alternatives.

Sodium-ion batteries offer a promising alternative to lithium-ion, where sodium directly replaces lithium as the primary element. Similar to lithium-ion batteries, sodium batteries consist of four main components: the anode, the cathode, an electrolyte, and a separator, with the composition of the electrolyte varying depending on the manufacturer.

The abundance of sodium in the earth’s crust, with a sodium to lithium ratio of 23,600 parts per million (ppm) to 20ppm, positions sodium as a cost-effective choice for battery production, while switching would be relatively low-cost and straightforward, as existing battery factories would allow rapid scalability of production.

Notable advantages of sodium batteries include their ability to utilise other affordable materials, such as substituting copper foils for aluminium, enhancing cost efficiency, as well as their safety thanks to the ability to discharge sodium to zero volts for storage and transportation, thereby reducing flammability risks. 

Despite this, sodium batteries face significant drawbacks due to their lower energy density compared to lithium batteries, with sodium batteries offering an energy density range of 140–160Wh/kg, while lithium batteries typically range from 150–220Wh/kg.

This lower energy density specifically poses challenges for electric vehicle manufacturers, affecting the vehicle’s range between charges and potentially limiting the commercial scalability of sodium batteries for electric vehicles (EVs) that require longer ranges.

Another obstacle is the limited number of lifetime charging cycles that sodium batteries can endure, currently around 5000 cycles compared to 8000–10,000 cycles for lithium-ion batteries. Efforts are underway to improve the cycling performance of sodium batteries, with researchers making progress in enhancing durability. 

Undeterred by these challenges, advancements in sodium battery technology, such as the successful launch of a 100kWh energy storage power station by China’s HiNa, demonstrate the feasibility of sodium batteries for large-scale energy storage applications, including their Sehol E10X electric vehicle, which uses a 25kWh battery pack made from cylindrical sodium-ion cells, highlighting the growing interest and investment in this innovative technology.

Solid-state batteries

Solid-state batteries represent an innovative approach to energy storage technology by utilising solid rather than liquid electrolytes found in traditional batteries. The two primary types used are inorganic solid electrolytes (such as oxides and sulphides) and solid polymers (such as polymer salts or gel polymers).

One of the key advantages of solid-state batteries is their ability to reduce the risk of dendrite formation, which are tree-like structures that can lead to battery failure. Additionally, solid-state batteries offer lower flammability risks, higher energy density, and faster charging cycles compared to traditional batteries.

While currently available in a thin-film format for applications like wearable electronics and niche uses such as pacemakers, solid-state batteries face challenges due to their higher production costs compared to lithium-ion batteries, presenting a challenge in scaling up production for broader acceptance in mainstream markets.

However, to further advance solid-state battery technology, the development of durable solid-state electrolytes is considered crucial. Companies like QuantumScape and Factorial Energy have shown significant progress in designing sulphide electrolyte-based batteries with much higher energy density than modern lithium-ion batteries. Notably, Solid Power asserts that its version can provide a 50–100 per cent increase in energy density compared to modern lithium-ion batteries. The company aims to extend the application of its technology to meet the power requirements of 800,000 EVs annually by 2028, kickstarting with a demonstrator BMW next year.

Lithium-sulphur batteries

The availability of sulphur, a by-product of natural gas processing and oil refining, makes lithium-sulphur batteries – comprising lithium in the anode and sulphur in the cathode – an attractive and environmentally sustainable alternative to lithium-ion batteries, which rely on rare earth minerals such as nickel, manganese, and cobalt. In fact, lithium-sulphur batteries have a superior energy density compared to lithium-ion batteries, delivering up to nine times more power output thanks to the sulphur’s enhanced electron mobility.

LG Energy Solutions recently achieved a new record by conducting a successful 13-hour flight test of a solar-powered unmanned aerial vehicle (UAV) using a lithium-sulphur battery at an altitude of 22km. The flight demonstrated that the lithium-sulphur battery maintained stable charge and discharge functions in the stratosphere, enduring freezing temperatures as low as -70°C and atmospheric pressures equivalent to just 1/25 of those at ground level. With the ability to recharge during flight, these batteries offer increased energy density and stable performance in extreme conditions, helping to pave the way for mass production of this technology by 2025.

Despite their remarkable energy density, lithium-sulphur batteries face challenges. The formation of dendrites within the battery can lead to issues such as short-circuiting and battery failure, and current prototypes may only be reliable for about 50 charge cycles, and although currently used in certain commercial applications their lack of long-term durability hinders their adoption in EVs.

Diversification

As the world moves toward renewable energy sources it is predicted that improving diversity in battery technology will play a critical role in the replacement of lithium-ion batteries.

By strategically deploying a variety of battery alternatives and matching the most suitable technology to specific applications, the evolving demands of diverse industries will be effectively addressed.