Scientists develop the ‘holy grail’ of EV batteries

Scientists in the US claim to have developed the ‘holy grail’ of electric vehicle (EV) batteries using a design inspired by a BLT sandwich. 

The battery, developed by Harvard experts, is lithium metal, rather than lithium ion found in EVs that are already on the market.  

The BLT-inspired design overcomes the issue of dendrites – tiny, rigid tree-like structures that can grow inside a lithium battery and speed up battery failure.

Lithium-metal batteries have had great potential for their capacity to carry energy, but have been held back by an inability to be charged. 

With their intricate design, the researchers estimate that their battery can be charged and discharged at least 10,000 times. 

The technology could increase the lifetime of EVs to that of gasoline cars – 10 to 15 years – without the need to ever replace the battery during this time, and pave the way for EVs that can fully charge within just 10 to 20 minutes, they claim. 

Currently, EV batteries degrade over time and last up to seven or eight years, depending on how much they’re used – much like a smartphone battery.  

Long-lasting, quick-charging batteries are essential to the expansion of the electric vehicle market (stock image) 

EV batteries can be replaced, but they can cost thousands of pounds, meaning drivers are often better off buying a new EV altogether.  

The new technology has been created by a team at Harvard John A. Paulson School of Engineering and Applied Science (SEAS). 

‘A lithium-metal battery is considered the holy grail for battery chemistry because of its high capacity and energy density,’ said Xin Li, associate professor of materials science at SEAS. 

‘But the stability of these batteries has always been poor.

‘Our research shows that the solid-state battery could be fundamentally different from the commercial liquid electrolyte lithium-ion battery. 

Think of the battery like a BLT sandwich. First comes the bread (the lithium metal anode) followed by lettuce (a coating of graphite). Next, a layer of tomatoes (the first electrolyte) and a layer of bacon (the second electrolyte). Finish it off with another layer of tomatoes and the last piece of bread (the cathode)

Think of the battery like a BLT sandwich. First comes the bread (the lithium metal anode) followed by lettuce (a coating of graphite). Next, a layer of tomatoes (the first electrolyte) and a layer of bacon (the second electrolyte). Finish it off with another layer of tomatoes and the last piece of bread (the cathode)

LITHIUM-ION VS LITHIUM METAL  

Lithium metal batteries are generally non-rechargeable and contain metallic lithium. 

Lithium ion batteries contain lithium that’s only present in an ionic form in the electrolyte. 

Most lithium metal batteries are not rechargeable but lithium ion batteries are. 

A lithium metal battery should never be recharged while lithium-ion batteries are designed to be recharged hundreds of times. 

Source: IATA/Green Batteries 

‘By studying their fundamental thermodynamics, we can unlock superior performance and harness their abundant opportunities.’ 

Long-lasting, quick-charging batteries are essential to the expansion of the EV market, but today’s lithium-ion batteries fall short, because they’re too heavy and expensive and take too long to charge. 

Lithium-ion are currently powering EVs already on the market from Tesla and other companies, as well as laptops and smartphones.  

Researchers have therefore tried to harness the potential of solid-state, lithium-metal batteries, which hold substantially more energy in the same volume and charge in a fraction of the time compared to lithium-ion.  

A lithium metal battery uses lithium in its pure metallic form, rather than lithium compounds used in lithium ion batteries. 

While ‘solid-state’ just refers to the use of  solid electrodes and a solid electrolyte, instead of the liquid or polymer gel electrolytes found in lithium-ion. 

Batteries have three main components – the anode, cathode and electrolyte.

The electrolyte (typically a chemical) separates the anode and cathode and moves the flow of electrical charge between the two.  

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