Solid-State Electrolytes in Advanced Battery Technologies

Solid-state electrolytes (SSEs) represent a transformative advance for rechargeable batteries by replacing flammable liquid electrolytes with rigid or semi-rigid ionic conductors. These materials span oxide, sulfide, halide, polymeric and composite classes, each offering distinct trade-offs between ionic conductivity, chemical stability and mechanical compliance. Oxide garnets, such as Li7La3Zr2O12, deliver wide electrochemical windows and dendrite resistance, while sulfide electrolytes achieve record-high conductivities but face moisture sensitivity. Recent years have seen a surge of interest in halide frameworks, which combine high conductivity with enhanced oxidative stability and processability. Polymer-inorganic composites exploit the flexibility of polymers to mitigate interfacial contact issues. Key challenges remain in optimising grain boundaries, suppressing lithium dendrite growth, engineering stable electrode–electrolyte interfaces and scaling cost-effective synthesis routes. Interdisciplinary efforts in materials chemistry, advanced characterisation and computational design are accelerating progress towards safe, high-energy-density solid-state batteries for electric vehicles, grid storage and portable electronics.

Research from Nature Portfolio

Recent studies have introduced an oxychloride electrolyte, Li1.75ZrCl4.75O0.5, that achieves an ionic conductivity of 2.42 mS cm⁻¹ at room temperature, compressibility exceeding 94% density under 300 MPa and an estimated raw materials cost below $12 kg⁻¹. When paired with a LiNi0.8Mn0.1Co0.1O2 cathode and a Li6PS5Cl-coated Li-In anode, the resulting all-solid-state cell retains over 70% capacity after more than 2000 cycles, demonstrating the practical viability of low-cost halide electrolytes in high-performance cells.

Advances in garnet-type oxides have focused on tailoring Li7-xLa3-aZr2-bO12 (LLZO) through dopant regulation and surface treatments to improve lithium-metal compatibility. Bulk dopant strategies combined with protonation or etching at the interface have yielded cells with areal capacities above 5 mAh cm⁻² and cumulative capacity plating of over 4000 mAh cm⁻² at currents of 3 mA cm⁻², fulfilling commercial lifespan criteria and showcasing the importance of coupled bulk and interface engineering.

Research from all publishers

A comprehensive review of emerging halide superionic conductors highlights design strategies such as element substitution, crystal-structure modification and defect engineering to optimise ionic pathways. Attention is drawn to moisture and solvent compatibility, in situ/operando techniques for probing interface evolution and scalable processing challenges, with recommendations for guiding future halide-based solid-state battery development.

Mechanochemical synthesis has been exploited to tune cation site disorder in Li3MCl6 (M = Y, Er) superionic conductors. By adjusting milling and crystallisation protocols, researchers induced controlled site disorder that lowers activation energies for Li⁺ transport. This approach elucidates the link between local structural motifs and macroscopic conductivity, offering a roadmap for improving halide-based SSEs via synthetic design.

Solid-State Electrolytes in Advanced Battery Technologies publication trend

The graph below shows the total number of articles in solid-state electrolytes in advanced battery technologies across all publications each year (not limited to Nature Index journals).

Technical terms

Solid-state electrolyte (SSE): A non-liquid ionic conductor used in place of conventional electrolytes, spanning oxides, sulfides, halides and polymers.

Ionic conductivity: A measure of an electrolyte’s ability to transport ions, typically expressed in siemens per centimetre (S cm⁻¹).

Garnet-type oxide: A crystalline framework (e.g. Li7La3Zr2O12) with high electrochemical stability and dendrite resistance.

Halide superionic conductor: A class of SSEs composed of halogen-containing compounds, offering high conductivity and oxidative stability.

Dendrite: Needle-like lithium metal deposits that can grow through solid electrolytes, causing short-circuits.

Interface impedance: The resistance to ion flow across electrode–electrolyte boundaries, critical to cell performance and stability.

References

1. A cost-effective, ionically conductive and compressible oxychloride solid-state electrolyte for stable all-solid-state lithium-based batteries. Nature Communications (2023).
2. High-energy and durable lithium metal batteries using garnet-type solid electrolytes with tailored lithium-metal compatibility. Nature Communications (2022).
3. Recent Progress in and Perspectives on Emerging Halide Superionic Conductors for All-Solid-State Batteries. Electrochemical Energy Reviews (2023).
4. Mechanochemical Synthesis: A Tool to Tune Cation Site Disorder and Ionic Transport Properties of Li3MCl6 (M = Y, Er) Superionic Conductors. Advanced Energy Materials (2019).