Dry electrode manufacturing for solid-state batteries

What Dry Electrode Manufacturing Is and Why It Matters for Solid-State Batteries

Dry electrode manufacturing is a solvent-free production process in which electrode powders and a fibrillizable binder are combined under mechanical shear — without any liquid carrier — to form a self-supporting film that is then laminated onto a current collector. Its defining advantage for solid-state batteries is the complete elimination of N-methylpyrrolidone (NMP) and other hazardous solvents that chemically degrade sulfide electrolytes, the class of solid electrolyte most widely pursued for high-energy-density cells. As documented across more than 50 patent filings spanning US, WO, EP, CN, JP, IN, and BR jurisdictions from 2012 to 2026, dry processing is increasingly recognised as a prerequisite for commercially viable solid-state battery production.

The motivation is twofold. First, NMP exposure leads to electrolyte decomposition and elevated boundary-layer resistance in sulfide-based solid-state cells — a failure mode explicitly documented in the prior art of LICAP Technologies’ foundational patents. Second, the wet-process infrastructure required for NMP recovery and recycling adds capital cost and environmental compliance burden that dry processing eliminates entirely. According to WIPO data, solid-state battery manufacturing patents have grown substantially since 2020, with process innovations — rather than materials alone — now forming the fastest-growing sub-category.

The broader industrial context is significant. Conventional lithium-ion battery electrode manufacture depends on slurry coating — dissolving binder in NMP, mixing with active material and conductive carbon, coating onto metal foil, and then evaporating the solvent in a long drying oven. For liquid-electrolyte cells this is an established, optimised process. For solid-state cells using sulfide electrolytes, it is fundamentally incompatible: the electrolyte reacts with NMP, degrading ionic conductivity before the cell is even assembled. Dry processing resolves this incompatibility at source. The U.S. Department of Energy has identified solvent-free electrode manufacturing as a key enabling technology for next-generation battery production.

Fibrillization, Calendering, and Electrolyte Film Formation: The Core Process Mechanisms

The defining step of dry electrode manufacturing is binder fibrillization under mechanical shear, which creates a three-dimensional fibrous network binding electrode powders together without solvent. As established in LICAP Technologies’ foundational US patent (2023), the process begins with a powder mixture in which dry electrolyte powder constitutes 80–97% of the total weight, with a fibrillizable binder as the minority component. The mixture is subjected to a controlled shear force — through jet milling, kneading, or high-shear mixing — to fibrillize the binder, after which it is pressed by calendering rolls into a free-standing film and laminated onto a current collector.

“The dry electrolyte powder constitutes 80–97% of the total weight of the mixture, with a fibrillizable binder as the minority component — a composition that eliminates NMP entirely while achieving sufficient mechanical cohesion for roll-to-roll processing.”

This same architecture is applied to the solid electrolyte layer itself. Rather than depositing an electrolyte by wet-coating with NMP, LICAP’s approach calls for dry electrolyte powder to be coated directly onto the second side of the electrode film — opposite the current collector — and then pressed to consolidate a solid electrolyte layer in situ. LICAP has protected this architecture globally, with counterpart filings in WO (2023), JP (2024 and 2026), and CN (2024, jointly with Lirong Technology), confirming a deliberate strategy of broad IP protection around this specific solvent-free stack architecture.

Binder fibrillization control is a critical sub-process in its own right. LG Energy Solution’s CN patent (2024) on dry electrode film manufacturing notes that the degree of binder microfibrillization can be tracked via the crystallinity of the binder resin, enabling feedback control over kneading and pulverization conditions. Without adequate crystallinity monitoring, particle agglomeration blocks process flow channels and compromises roll-to-roll scalability. The companion LG Energy Solution system patent (CN, 2024) adds that the dry electrode film’s edge geometry — prone to irregular, jagged profiles due to the anisotropic nature of the calendered dry mixture — must be actively controlled throughout continuous processing to prevent film cracking and width variation between production batches.

A distinct dry process variant using in-situ polymerization to construct a three-dimensional network electrode is disclosed by the Tianmu Lake Institute of Advanced Energy Storage Technologies (CN, 2021). Here, electrode active materials, unsaturated-bond small-molecule monomers, a conductive agent, and an initiator are mixed and coated onto a current collector, after which in-situ polymerization at a set temperature builds the 3D network structure. This approach avoids the PTFE fibrillization step entirely but introduces temperature sensitivity and initiator chemistry as new process variables. Research published by Nature on solid electrolyte interface formation underscores that any thermal step in solid-state electrode assembly carries risk of phase change in sulfide electrolytes — a constraint the in-situ polymerization route must carefully manage.

Interface Engineering: The Dominant Technical Challenge

Interface resistance between electrode and solid electrolyte is universally identified across the patent data as the central obstacle distinguishing solid-state batteries from liquid-electrolyte cells — and dry electrode manufacturing creates specific interface problems that wet processing does not. LG Chem’s US patent (2020) documents two canonical failure modes: in the dry-mix-then-press route, the absence of a binder prevents sustained electrode-electrolyte contact; in the wet-mix-then-dry route, solvent evaporation generates pores that elevate resistance. Both failure modes converge on the same outcome: high interfacial impedance that degrades cell performance.

For purely dry-process solid-state electrodes, residual porosity is the primary mechanism of interfacial resistance increase. Beijing Welion New Energy Technology’s EP patent (2024) directly addresses this: the PTFE binder expands during processing, leaving pores that increase impedance and reduce face-to-face contact between electrode and electrolyte. The solution proposed is a eutectic electrolyte incorporated into the dry electrode formulation. Upon heating to the eutectic phase-transition temperature, this material liquefies and wicks into inter-particle voids, then solidifies at room temperature to fill them, providing ionic conductivity pathways through previously resistive gaps. The parallel CN filing by Zhongke Chaoneng (Shenzhen) New Energy Technology (2024) notes that simple solvent injection into dense, low-porosity electrodes is inadequate because the liquid cannot penetrate the compressed structure — making the eutectic approach the only viable route for post-formation gap-filling.

LG Energy Solution quantifies the interface quality target precisely. Its US patent (2025) specifies that surface resistance of the negative electrode in contact with the solid electrolyte layer must be 3 mΩ/cm² or less in a properly manufactured unit cell — establishing a quantitative benchmark for interfacial process quality. The related EP filing (LG Energy Solution, 2024) identifies sulfide-based electrolytes as particularly problematic due to higher ionic and electronic resistance between electrodes compared with liquid-electrolyte cells, motivating further assembly optimisation.

Atomic-level surface treatment represents the most technically demanding approach to interface engineering. Jiyi Technology’s CN patent (2024) proposes atomic layer etching followed by atomic layer deposition of alumina (Al₂O₃) and silicon oxynitride or silicon nitride protective layers between the solid electrolyte layer and the cathode. This reduces short-circuit probability and extends battery life, demonstrating that the interface problem ultimately requires materials engineering solutions complementary to the mechanical process controls used in dry electrode formation. The U.S. Energy Information Administration has highlighted that interface resistance remains one of the primary barriers to solid-state battery commercialisation at scale.

Hyundai Motor addresses interlayer mixing at the electrode-electrolyte boundary in wet-assisted co-coating. Its US patent (2026) specifies that the electrode slurry must be partially dried to 20–50% dryness before the electrolyte slurry is coated over it. The viscosity ratio of the solid electrolyte slurry to the electrode slurry must fall between 0.2 and 1.0 — too high a ratio causes the electrolyte slurry to sink into the electrode layer and disrupt the N/P ratio; too low a ratio leaves the interface uneven. Drying both layers together at 60–120°C then yields a uniform interface. This “wet-on-partially-dry” technique represents a direct response to the delamination and N/P ratio drift problems documented in related Kia filings (CN, 2026).

Assembly, Compaction, and Roll-to-Roll Scalability Challenges

Translating laboratory-scale dry electrode films into high-volume production requires solving distinct engineering problems at three levels: edge geometry control during continuous calendering, multi-layer stack assembly, and current collector adhesion. Each represents an unresolved challenge documented across multiple independent patent families.

Edge Geometry and Film Width Control

Dry calendered films exhibit inherently irregular, jagged edge profiles due to the anisotropic nature of the calendered dry mixture. LG Energy Solution’s US and EP patents (both 2023) focus on forming a uniform insulating film on the uncoated edge portions of the dry electrode — a requirement that conventional dry processes fail to meet. The result is that an additional wet-coating step for the insulating layer is sometimes required, partially negating the benefits of the dry approach. The companion LG Energy Solution system patent (CN, 2024) adds that edge geometry must be actively controlled throughout continuous processing to prevent film cracking and width variation between production batches. Samsung SDI’s EP patent (2024) addresses a related problem: intermittent film deposition on the current collector, disclosing a process of supplying the dry electrode film at a primary speed for deposition and a reduced third speed for non-deposition intervals, enabling intermittent patterning of the film on the metal current collector.

Particle Dispersion and Thickness Uniformity

Samsung SDI’s companion device patent (EP, 2025) introduces a dispersing rod within a guide chute to actively adjust particle size distribution of the electrode powder before it reaches the rolling nip. Without this active dispersion step, inhomogeneous packing density causes thickness variation in the rolled sheet — a defect that propagates through the entire cell stack and degrades capacity uniformity. This equipment-level innovation reflects the broader trend in the 2024–2026 patent data toward process control systems and scalability engineering, rather than fundamental process definition.

Current Collector Adhesion

Dry electrode films lack the wetting-driven adhesion of slurry coatings, creating a persistent bonding challenge. Samsung SDI’s CN patent (2025) on dry electrode structure notes that conventional dry electrode processes require a separate primer coating layer between the current collector and the dry film to achieve adequate adhesion, adding cost and processing steps. The filing proposes a bond-enhancement structure that eliminates this separate primer layer. A second Samsung SDI CN patent (2025) takes a different approach: engineering deliberate surface topography (protrusions and recesses) on the current collector surface, onto which the self-supporting dry film is directly laminated, exploiting mechanical interlocking to replace chemical adhesion.

Stack Compaction and Edge Short-Circuit Prevention

Ford Global Technologies’ CN patent (2025) addresses contact resistance between electrode and solid electrolyte separator at the assembly level. Their approach positions a double-sided positive electrode assembly between two single-sided negative electrode assemblies, then applies a high-line-pressure roll-to-roll calendering step to compress the three-layer A-B-A stack simultaneously. This single calendering step replaces multiple sequential laminations, closing gaps and pores between electrode and electrolyte separator layers while reducing process complexity.

LG Energy Solution’s warm isostatic pressing (WIP) strategy, disclosed in its BR patent (2025), takes a different architectural approach: applying WIP to individual unit cells (mono-cells or bi-cells) before stacking, rather than pressing the full multi-layer stack. This prevents edge short circuits that occur when multiple uncompacted layers are stacked and pressed together — a failure mode that becomes more severe as stack layer count increases. Volkswagen’s CN patent (2024) decouples film formation from densification in a two-stage process: solvent-free electrode powder is deposited onto a substrate in a film-forming step, then compacted separately to reach target density, allowing independent optimisation of each stage. Standards bodies including IEC are actively developing quality benchmarks for solid-state battery manufacturing that will formalise many of these process control requirements.

Patent Landscape: Key Players and Innovation Trends from 2012 to 2026

The patent dataset — spanning more than 50 filings across seven jurisdictions from 2012 to 2026 — reveals a field dominated by Korean battery manufacturers and OEM-tier automotive companies, with a distinct cluster of Chinese independent innovators pursuing differentiated technical approaches.

LG Energy Solution / LG Chem dominate the dataset quantitatively, with filings across EP, US, JP, IN, BR, and CN jurisdictions covering: dry electrode edge insulation, binder fibrillization control and monitoring, all-solid-state battery assembly using warm isostatic pressing, interface surface resistance quantification, and electrode slurry concentration control. Their portfolio reflects a comprehensive, system-level approach to dry electrode integration into solid-state cell manufacturing.

LICAP Technologies is the focused specialist in pure dry-process electrode and electrolyte film manufacture. Their core US patent (2023) with PCT, JP, and CN counterparts establishes the foundational claims on fibrillizable-binder-based dry electrolyte film formation, with the electrolyte powder constituting the majority of the mixture by weight. LICAP’s global IP strategy — filing identical core claims in US, WO, JP, and CN — reflects the commercial significance of controlling this foundational process step.

Samsung SDI has filed aggressively on dry electrode manufacturing equipment and film structure, targeting particle dispersion control, intermittent film deposition, current-collector adhesion, and multi-active-material dry electrode composition. Hyundai Motor / Kia focus on electrode-electrolyte co-coating and assembly process control, with recent filings on partial-drying co-coating viscosity ratios, vacuum drying of unit cell stacks, and dry-process self-supporting electrode films. Volkswagen and Ford Global Technologies represent OEM-tier entrants, each contributing process equipment and cell assembly innovations. Beijing Welion New Energy Technology and Zhongke Chaoneng represent Chinese independent innovators targeting the residual porosity problem through eutectic electrolyte gap-filling — an approach distinct from the Western mainstream and potentially significant for Chinese domestic solid-state battery production.

The trend analysis across the dataset is clear: the period from 2020 to 2023 was dominated by process definition patents — establishing what dry electrode manufacturing is and how fibrillization works. From 2024 to 2026, the focus has shifted to equipment design, process control systems, and scalability, with growing attention to quantified interfacial resistance targets, roll-to-roll edge quality, and moisture management. The Hyundai Motor vacuum drying patent (JP, 2026) is emblematic: even in dry-process cells, residual moisture in solid electrolytes degrades electrochemical performance, requiring dedicated vacuum drying as a post-assembly step. This evolution from process definition to production engineering signals that the field is approaching manufacturing readiness — consistent with broader solid-state battery commercialisation timelines tracked by the International Energy Agency. PatSnap’s own innovation intelligence platform, covering more than 2 billion data points across 120+ countries, tracks this shift in real time.