There are many uses for energy storage batteries which range from excess energy storage, use as back-up energy, to peak energy costs reduction, and even shift the energy usage when prices are cheaper. When referring to “energy storage batteries”, this is typically in reference to storing energy for later usage rather than for usage in transport (e.g., electric vehicles). Energy storage batteries help, apart from its alleged sustainability issues, in meeting the energy demand during deficit of available energy and stores the energy where available energy is higher relative to the demand.

Basics of energy storage batteries

As far as batteries are concerned, the storing of excess energy is referred as charging whilst the reverse (energy supply) is called discharging.  Negative charges (electrons) are nullified with positive lithium ions passing from the anode (layered graphite) to the cathode (lithium metal oxide) during the discharging phase, utilizing electricity in the process.  Only lithium ions are allowed through the separator and forces the electrons through an external circuit.  The reverse is done during the charging phase, where the electrons and the lithium ions reverse direction of migration from the cathode to the anode.  The migration of lithium ions is facilitated by an electrolyte (commonly a lithium salt). What we’ve explained here is a battery cell, which could be connected in series as a module and multiple modules are assembled further in a pack.

Apart from the traditional lead-acid battery used in cars, nickel-cadmium batteries used in lightweight electrical appliances, Lithium-Ion batteries are front-runners in energy storage systems, mainly due to its high charging and discharging cycles with minimum losses and high energy density.  For example, your cell phone battery experiences some loss of power but it’s at an acceptable rate for energy storage batteries such as the Lithium-Ion battery, so that your cell phone doesn’t die within minutes, but rather hours, depending on your usage.

The common cathode materials currently being used are made of Lithium Iron Phosphate (LFP) due to rising energy demand, and Nickel Manganese Cobalt (NMC).  The latter possesses a high energy density while LFPs are cheaper amid its compromised performance, although stationary energy storage, e.g. harvested energy from photovoltaic cells for data center backup, storage for micro-grid backup power and discharge during peak pricing, may render the cost difference to be negligible, due to the LFPs higher installation cost.

Are Lithium-Ion batteries sustainable?

The batteries can be used to store harvested energy from renewable sources, such as solar and wind energy.  But there is the question of sustainability remaining.  Apart from the merits of Lithium-Ion batteries, there seems to be concerns that may arise in the minds of the consumer.  How safe is it?  How are they made?

The first question was particularly concerning in the past, with instances of Lithium-Ion batteries catching fire.  This concern, mainly due to thermal stress, seems to be under control with better choices of cathodes, where sudden release of heat is prevented and better sealing with state-of-the-art separators eliminates the chances of a short-circuit.  Overcharging is prevented with a by-pass circuit upon achieving the desired capacity (normally between 3 – 4 V for Lithium-Ion batteries) and in-built battery management systems, by cutting off the charging once overheating or overcharging is detected. The second question may concern environmentalist. 

Lithium is won by purification of lithium carbonate or lithium hydroxide, extracted from natural brine solutions or hard rocks by drying and precipitation through addition of sodium carbonate or sodium hydroxide.  This triggers further questions, such as the energy required for the extraction of these raw materials and the conditions of workers at the mines.  What are the environmental issues during the extraction of raw materials and does the Lithium-Ion battery prices fluctuate with time, rendering the storage of renewable energy to become unsustainable and financially weak?

Are Lithium-Ion Batteries Expensive?

The recent price of Lithium-Ion batteries stands at approximately $130/kWh, compared to $680/kWh in 2013.  Manufacturers apparently take a 20-30% profit, after considering the processing cost of mining and production of the Lithium-Ion battery itself.  However, with current prices of lithium carbonate soaring to nearly $75/kg, the profit margin is lost.  This renders the Lithium-Ion battery market to be ineffective and urges manufacturers and stakeholders alike to look for other alternatives such as flow batteries.  Experts are confident that the challenges causing the spike in prices will dissipate and return to a financially competitive stage.  The increase in energy density of lithium-ion batteries is definitely helping to reduce costs, owing to efforts by top researchers in electrochemistry.

How do Lithium-Ion Batteries cause Human Rights issues?

Human Rights issues are allegedly predominant in South American countries such as Argentina, Bolivia and Chile.  Chile holds about half of the lithium reserves in the world.  Inhalation of dust at mining areas may cause damage to respiratory tracts and the intense use of water for lithium production creates water scarcity in the region.  The consent of indigenous people in Argentina for mining purposes was of great concern as well.  The extraction of cobalt is reportedly attached to child labor and abuse.  Despite these issues, the extraction of raw materials for Lithium-Ion batteries is partly sustaining the livelihood in these regions.

Do Lithium-Ion Batteries Damage the Environment?

Apart from the alleged immense water consumption of lithium, water pollution during the extraction of lithium is a concern.  Apart from lithium, mining of cobalt and graphite damages the environmental landscape and animal habitats.  A climate study by MIT states that lithium mining emits 15 tons of carbon dioxide (CO₂) relative to each ton of lithium and producing an 80-kWh lithium-ion battery for an electric vehicle would emit between 3 to 16 tons of CO₂.  If fossil fuel-based electricity with an average conversion efficiency of 40 % is used to charge energy storage batteries, the sustainability of these systems, such as data centers with backup Lithium-Ion batteries, will remain in question.

Conclusion

Lithium-Ion batteries are a common commodity that has become essential for modern day life with smart phones, sensors, displays all running on such batteries. As common place as these batteries are, production of lithium-ion batteries are not simple at all with environmental challenges, safety challenges, and others. Research to increase the efficiency of lithium-ion batteries has been on an upward trend, indicating a probable interest in reducing raw material utilization. These efforts shall be of paramount interest for the sustainability of energy storage batteries. Recycling of Lithium-Ion batteries are encouraged to further reduce environmental impacts and labor issues.