A team from Harvard University in the US has designed a lithium-metal solid-state battery that can be cycled at least 10,000 times.
The researchers paired a multilayer battery that sandwiches materials of varying stabilities between the anode and cathode with a commercial, high energy density cathode material.
This multilayer, multi-material battery prevents the penetration of lithium dendrites by controlling and containing them, say the team.
The team from the Harvard John A. Paulson School of Engineering and Applied Science (SEAS) published the findings in the journal Nature.
The first electrolyte (chemical name Li5.5PS4.5Cl1.5or LPSCI) was more stable with lithium, but prone to dendrite penetration; the second electrolyte, (Li10Ge1P2S12or LGPS), was less stable with lithium, but the researchers found it was immune to dendrites.
In the second design, dendrites were allowed to grow through the graphite and first electrolyte, but were stopped when they reached the second.
The cycling performance of the lithium metal anode paired with a LiNi0.8Mn0.1Co0.1 O2 cathode was found to be stable, with an 82% capacity retention after 10,000 cycles at a 20C rate (8.6 milliamps per centimetre squared) and 81.3% capacity retention after 2,000 cycles at a 1.5C rate (0.64 milliamps per centimetre squared).
The team’s battery recorded a specific power of 110.6kW/kg and specific energy up to 631.1Wh/kg watt at the micrometre-sized cathode material level.
Luhan Ye, co-author of the paper and graduate student at SEAS, said: “Our strategy of incorporating instability in order to stabilise the battery feels counterintuitive but just like an anchor can guide and control a screw going into a wall, so too can our multilayer design guide and control the growth of dendrites.”
The difference was the researchers’ anchor quickly becomes too tight for the dendrite to drill through, so the dendrite growth is stopped.
The battery is also self-healing; its chemistry allows it to backfill holes created by the dendrites.
Xin Li, associate professor of Materials Science at SEAS, said: “This proof-of-concept design shows that lithium-metal solid-state batteries could be competitive with commercial lithium-ion batteries.
“And the flexibility and versatility of our multilayer design makes it potentially compatible with mass production procedures in the battery industry. Scaling it up to the commercial battery wont’ be easy and there are still some practical challenges, but we believe they will be overcome.”
(Image courtesy of Second Bay Studios/Harvard SEAS)