Samsung has proposed a new type of solid-state battery smaller than a lithium-ion battery yet capable of storing more charge, and degrades more slowly than other iterations of this tech.
The prototype – based on research towards driving “the expansion of electric vehicles (EVs)" – uses a new kind of anode that could potentially offer a longer usable lifespan of more than 1000 full charges.
Solid-state batteries have been viewed as the next step in EV batteries for some time. They’re lighter and store more energy, and their solid electrolytes are a lower (thermal runaway) fire risk than liquid ones, but at least two obvious hurdles remain: cost, and longevity.
Samsung’s development focuses on the latter. It uses a silver-carbon (Ag-C) composite layer as the anode, in place of the typical lithium-metal anodes that are prone to trigger the growth of dendrites “which can produce undesirable side effects that reduce a battery’s lifespan and safety”.
Dendrites are crystals that form on a battery anode during charging.
According to Samsung, incorporating a 5µm (micrometers) thick Ag-C layer into a prototype pouch cell “enabled the battery to support a larger capacity, a longer cycle life, and enhanced its overall safety”.
“The ultrathin Ag-C nanocomposite layer allowed the team to reduce anode thickness and increase energy density up to 900Wh/L,” it said, adding that the prototype pouch cell featured a theoretical life cycle life of over 1000 charges. What level of degradation is present beyond this isn’t clear.
“We show that the thin Ag–C layer can effectively regulate Li [dendrite] deposition, which leads to a genuinely long electrochemical cyclability,” said an abstract for the study in the Nature Energy journal.
True to form, this prototype is also claimed to be 50 per cent smaller in volume than today’s typical lithium-ion EV battery packs (there is variance between suppliers), while being capable of driving a car for a range of up to 800km between charges.
Naturally, any EV’s driving range is contingent on a car’s weight and drag coefficient. The current range champion, Tesla’s Model S, tops out at just over 700km on the very lenient NEDC cycle. But its 100kWh li-ion battery is quite large and heavy, limiting its applications.
Using Samsung’s own sums, 1000 charges of a pack with an 800km range gives a life cycle of 800,000km, although practicalities around opportunistic DC ‘top ups’ raise some more questions.
“The product of this study could be a seed technology for safer, high-performance batteries of the future. Going forward, we will continue to develop and refine all-solid-state battery materials and manufacturing technologies to help take EV battery innovation to the next level,” said Master at SAIT’s Next Generation Battery Lab and the leader of the project, Dongmin Im.
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