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A team in Germany and Hong Kong found a material that keeps solid-state batteries, which are batteries that use solid parts, lasting much longer than they believed was possible.
Their database-guided search checked more than 20,000 compounds, then narrowed the list to one clear winner.
The work was led by Prof. Dr. Francesco Ciucci at the University of Bayreuth in Germany. His group studies how electrodes behave when lithium ions move quickly and surfaces react together.
In solid-state designs, a hard electrolyte, the solid that carries lithium ions, presses against a lithium-metal electrode.
At the interface, the contact surface where two solids touch, atoms can swap partners and form new compounds.
Those reactions block lithium-ion flow and raise resistance, which makes the battery lose capacity and fail early.
Adding a thin interlayer
Engineers often add an interlayer, a thin protective layer placed between materials, to keep the two sides from reacting.
Higher energy density, more stored energy in a fixed size, matters for electric cars because every pound carries a cost.
The best interlayer lets lithium ions cross fast while blocking electrons, so side reactions slow down.
Even a good interlayer can fail if it does not bond well, because tiny gaps raise resistance and stress the cell.
Database that acts like a filter
Ciucci’s team built high-throughput screening, which is rapid testing across many options using shared rules, to compare thousands of possible interlayers.
They pulled candidates from the Materials Project, a public database of computed material properties.
The screen favored thermodynamic stability, a tendency to stay intact instead of decomposing, along with compatibility on both battery sides.
They also looked for self-limiting reactions, chemistry that stops once an insulating layer forms, so the interface stays stable.
The winner: Lithium oxychloride
From that search, lithium oxychloride, called Li3OCl, rose to the top as the best interlayer for this chemistry.
Li3OCl belongs to an antiperovskite, a crystal type that can conduct lithium well, and it resists runaway reactions.
In this study, it was paired with a halide electrolyte, a salt based on chlorine-like ions, called Li3InCl6.
“Our study presents a new approach to developing improved solid-state batteries,” said Prof. Dr. Ciucci.
Cells with the Li3OCl layer kept 76% capacity after 1,000 charge-discharge cycles, while unmodified cells kept 5%.
Under faster charging and discharging, the modified batteries still ran for more than 1,600 cycles without sudden failure.
Why does a thin layer matter so much for car owners who want quick charging and long battery life?
That kind of cycle life, the count of charges before big decline, matters for drivers who keep cars for years.
Protect battery life
A battery needs lithium ions to move, but trouble starts when electronic conductivity, which is easy electron flow through a material, stays high at interfaces.
The Li3OCl layer reacts at first, then leaves behind insulating solids such as lithium chloride and lithium oxide on both sides.
That passivation, the formation of a protective layer, can lock the interface into a steady state during long cycling.
Other interlayers can leave conductive byproducts, so resistance keeps rising and the cell loses power even when the layer looks intact.
Engineers keep coming back because lithium metal can raise energy density when everything else in the cell stays the same.
Lithium metal batteries face safety risks when dendrites form, needle-like deposits that can short-circuit a cell.
Solid electrolytes can lower fire risk because they do not leak, yet they still must stay stable at the electrode surface.
A stable interphase, a reaction layer that forms at contact, can protect lithium if it blocks electrons and stays thin.
New screening method
Researchers struggle to watch buried interfaces as they form, because these layers sit inside sealed cells and change quickly.
Teams often turn to density functional theory, which is a quantum calculation that estimates material energies, before they spend months on lab synthesis.
A well-known essay argues that solid-state batteries can be safer and denser, yet interfaces still hold them back.
By combining calculations with published conductivity data, the screen can highlight promising interlayers without endless trial-and-error testing.
Halide solid electrolytes matter
Halide electrolytes attract attention because they conduct lithium ions well at room temperature and tolerate high-voltage positive electrodes.
They can still react with lithium metal, so the same interface problem returns unless a protective layer steps in.
The same screen suggested interlayers for several other solid electrolytes, which shows that the method applies across different battery chemistries.
Many labs now build their own interface layers, because small chemistry changes can decide whether a solid-state cell survives.
What this means for battery makers
Some solid electrolytes are hygroscopic, they absorb moisture from air, so factories must keep materials very dry.
Lab cells often use stack pressure, force squeezing layers together during testing, and engineers must recreate contact without heavy hardware.
Companies will also ask whether the interlayer can be made cheaply, coated uniformly, and reused across different cell designs.
The next checkpoints include larger cells, wider temperature tests, and long calendar aging, not only repeated cycling.
A recipe, not a finished product
The real advance may be the screening framework, which gives researchers a repeatable set of rules for picking interlayers fast.
When computer screening rejects weak candidates early, labs can spend their time making and testing only the most promising materials.
Still, databases miss defects, contaminants, and processing steps, so experiments must confirm that the chosen layer behaves as predicted.
If teams keep improving interfaces, solid-state lithium-metal batteries may finally combine fast charging with long life and stronger safety.
The study is published in Nature Communications.
Image credit: Ciucci/Midjourney.
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