Electric Vehicle Batteries

Based on my conversation with Euan McTurk, here are the answers to some commonly asked electric vehicle (EV) battery questions.

What is a battery? 

A battery is an energy source consisting of one or more electrochemical cells, where stored chemical energy can be converted into electrical energy when needed.  It has a negative electrode, an anode, a positive electrode, called a cathode, and an electrolyte, often consisting of soluble salts or acids, allowing the electric charge to pass between the electrodes.

How do batteries work?

Petrol and diesel cars employ a lead-acid battery, where two lead electrodes are submerged in a sulphuric acid electrolyte.  Hydrogen and oxygen ions bond to form water, producing electrical energy (battery discharging).  The reverse occurs during charging.  

The anode in electric vehicles typically consists of graphite (layers of carbon).  The cathode is made up of a lithium-oxide, in various combinations involving nickel, manganese and cobalt, or more recently, lithium-ion phosphate.  During charging, lithium ions interpolate within the anode from the cathode, and when discharging, the lithium ions move in the other direction.  It’s known apparently as rocking-horse chemistry! 

What makes a good battery? 

In terms of performance, people want their batteries to cover distances to suit their lifestyle and to know they will last.

Range

With an electric battery, capacity is favourable over power; this dictates the range of the car.  However, larger batteries inevitably require more raw materials.  So, if you don’t need to travel long-distance most of the time, then a smaller battery will probably do, particularly as charging facilities are ever-increasing.

Lifespan

Lifespan refers to how many times the battery can be charged and discharged before it ‘dies’.  The industry deems end-of-life as 70% of its original capacity.  For example, the range of the popular Kia e-Nero is 270 miles, so it will still travel 190 miles per charge at end-of-life.  If we consider the average UK commute round trip of 23 miles/day, the car will only need charging once a fortnight.  Batteries typically come with an 8-year, 100,000-mile warranty, but more than likely, the battery in your EV will outlast the car itself.  Even if you decide the depleted range does not suit you, it is probably sufficient for someone else.

Are there any issues sourcing raw materials?

Abundance

Lithium, the predominant metal component, is abundant, with about 14 million tonnes available on land; this equates to a billion 40Kw Nissan Leaf batteries.  Additionally, there are 230 billion tonnes in the sea.  In the UK, Cornwall has some of the richest lithium brines in the world, found within old mines.  The mica in the granite surrounding those brines also contains lithium. Numerous companies are trying to ethically access it through new techniques such as direct lithium extraction. 

Ethical Issues

Russia exports 13-20% of the world’s nickel supplies, which is problematic.  Also, the biggest exporter is Indonesia, where the grid primarily runs on coal.  The company, Britishvolt, is looking to establish nickel refining in Indonesia equipped with renewable energy.

The association of cobalt with child labour in a minority of artisanal mines within the Democratic Republic of Congo is unacceptable.  Consequently, EV battery manufacturers have sought ways to exclude it in battery production, resulting in a 90% reduction in usage.  As a consequence of this, lithium-ion phosphate batteries have become popular, particularly in shorter-range vehicles.  We should also remember that cobalt is used in refining petrol and diesel and is a component in electronic consumables such as phones and laptops.

Is EV manufacturing environmentally friendly?

As EVs are part of the decarbonisation of transport strategy through reduced emissions when in operation, it is crucial that manufacturing stands up to intense scrutiny.  It makes sense to have manufacturing plants operating in areas with plentiful renewable energy supplies.  In Norway, despite the very high standards of living and earnings, several battery gigafactories are being built because their energy supply is almost 100% hydro.  In China, CATL, the largest global EV battery manufacturer, has attained zero-carbon accreditation.

What happens to old EV batteries?

New lives

End-of-life batteries can find new purpose in domestic or grid-scale energy storage.  Multiple companies and organisations are utilising these batteries, such as the flagship charging hub at Dundee City Council, where a shipping container is home to 3 Zoe batteries.  

 Recycling

When batteries reach a point where they are no longer effective in service, recycling is needed.  It is still early days, as most EV batteries are still in use, but multiple organisations are looking at how best to recycle them.  One such project is ReLiB, is focusing research on the sustainable management of end-of-life lithium-ion batteries.  

Will the grid cope with charging all these new EVs?

The simple answer is yes, as EV charging will occur at different times.  Much charging will happen overnight when there is an oversupply of energy from renewables; currently wind turbines are regularly turned off at night.

What about air pollution?

Petrol and diesel cars have negative impacts on air quality, with pollutant particulate matter arising from: 

  1. Exhaust pipes – this is zero in EVs.  
  2. Brake dust – this is reduced in EVs by regenerative braking; brake lifespan is two and a half times longer. Some manufacturers are also switching from disc to drum brakes, as over-heating is not an issue and the enclosed drum captures the dust.  
  3. Tyre pollution – it seems it is pretty similar in EVs; more work needed here then.

Any more questions?

If you have any questions that remain unanswered, why not drop me a line and I’ll see if I can address them.

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