As EV wireless charging power advances to 11 kW, 22 kW and beyond, thermal management has become the core bottleneck limiting technology development. Traditional cooling struggles with surface overheating from skin effect. This article analyzes high-power wireless charging thermal challenges and proposes an innovative heat dissipation approach based on micron diamond composite conductor. By building efficient radial heat dissipation channels on copper conductor surface while maintaining excellent high-frequency electrical performance, this solution may achieve revolutionary thermal conductivity improvement, providing new thermal management for next-gen high-power wireless charging systems.
Wireless charging is seen as key to EV adoption. It removes traditional charging cable constraints, enabling automated, convenient charging—ideal for future autonomous vehicle energy replenishment. Major automakers and tech companies are investing; wireless charging is moving from lab to scale.
However, as power increases—from 3.7 kW home slow charge toward 11 kW, 22 kW and 100+ kW ultra-fast—heat has become the core bottleneck. Coils generate significant heat during energy transfer; without effective export, system efficiency drops, reliability decreases, safety risks arise. Solving heat dissipation is key to next-gen high-power wireless charging competitiveness.
Understanding requires two key physical phenomena.
2.1 Skin effect: Current "surface concentration"
When AC flows through a conductor, current concentrates near the surface rather than uniform distribution. At typical wireless charging frequency (85–150 kHz), copper skin depth is only 0.2–0.3 mm. Implications: interior material barely conducts; surface current density peaks; equivalent conductive area decreases; ACR far exceeds DCR.
2.2 Proximity effect: Adjacent conductor interaction
In tightly wound coils, adjacent wires' alternating magnetic fields distort current distribution, causing local density surge. Combined with skin effect, coil AC loss far exceeds single-wire theory.
2.3 Natural heat path dilemma
Traditional Litz wire splits conductor into insulated strands to mitigate skin effect, but circular cross-section and strand gaps limit packing, restricting heat paths. Enameled flat wire improves packing but outer insulation is thermally poor; tightly wound structure makes internal heat difficult to export radially,easily forming local hot spots. Studies show local coil temperature rise can exceed 100°C at high power, threatening safety and life. Traditional "add external heat sink" approach cannot meet extreme power density needs.
3.1 Air and liquid cooling: Air has very low thermal conductivity, only removes surface heat. Liquid cooling is more efficient but needs complex piping and pumps. In both cases, heat must first conduct from wire interior to surface—the weakest link.
3.2 Phase change materials: Use latent heat to absorb heat, smooth temperature. But low thermal conductivity and thermal lag make sustained high-power operation difficult.
3.3 New material exploration: Graphene, boron nitride coatings on wire surface. Lab potential but graphene CVD costly, large-area transfer difficult; BN coating has copper substrate adhesion issues. These focus on in-plane conduction; radial conduction (through wire surface outward)—the key for coil heat dissipation—receives insufficient attention.
Key insight: In tightly wound coils, heat conduction along wire is limited, cannot effectively transfer to distant areas. The urgent task is not "uniformize" heat inside the wire but let heat "escape" quickly—strengthen radial heat dissipation.
We propose building an ultra-high thermal conductivity "radial heat dissipation channel" on copper conductor surface. This channel acts like countless tiny heat fins, rapidly "sucking" heat from conductor interior and efficiently transferring to environment.
The key is material choice. Diamond—nature's highest thermal conductivity—enters our view. Diamond thermal conductivity 1000–2000 W/(m·K), 2.5–5× copper, with excellent electrical insulation. In diamond coating flows heat, not current.
5.1 Core concept: Let heat "take shortcut"
Build a composite layer of micron diamond particles on copper conductor surface. This layer: provides heat "highway"—diamond forms continuous thermal network; increases heat dissipation surface—particulate structure increases contact with coolant; does not affect current path—diamond insulation ensures current stays in copper.
5.2 Particle size: Finding optimal balance
Too large: surface roughness increases, distorts current path, ACR rises; rough surface makes insulation coating difficult. Too small: single particle defects increase, intrinsic thermal conductivity drops; huge interface area makes interface thermal resistance new bottleneck. We determined optimal balance for current conditions.
5.3 Interface design: "Bridge" connecting copper and diamond
Diamond and copper are very different. Our design: build "transition layer" on diamond surface. Coating titanium etc. reacts with diamond at high temperature to form carbide (TiC), which bonds firmly to diamond and wets copper well. Layer thickness controlled to micron/sub-micron, ensuring it doesn't become significant thermal resistance.
6.1 Fundamentally solving "heat generation-dissipation" paradox: Traditional cooling often introduces structures in skin effect zone that, if poor conductors, become new heat sources. In our solution, diamond is insulator, doesn't conduct; metal matrix in composite has good conductivity. Through rational design, "heat dissipation for heat dissipation, conduction for conduction".
6.2 Maintaining excellent high-frequency electrical performance: Micron diamond size, relatively smooth surface, won't significantly distort current path. Conductive matrix is pure copper or high-conductivity silver-copper, resistivity near pure copper. ACR controlled in acceptable range.
6.3 Achieving extreme radial heat dissipation: Continuous thermal network fundamentally transforms heat transfer path. Diamond particles become countless "thermal pumps", continuously "extracting" heat from copper and diffusing to surface.
6.4 Good process adaptability: Composite electroplating is mature industrial technology. Coating titanium, silver have mature supplier systems. Two process paths provide flexibility. Solution extensible to other high-frequency power devices—transformers, inductors.
7.1 Current challenges: Interface quality control—micron particle huge interface area demands very high process control; cost optimization—diamond and coating cost need optimization for scale; long-term reliability—composite structure stability under thermal cycling, mechanical vibration needs systematic validation.
7.2 Future outlook: With materials and manufacturing progress, we believe this solution will mature: material optimization—explore other high-thermal-conductivity materials; process upgrade—develop continuous production; system-level design—combine composite conductor with efficient cooling and smart thermal management.
High-power wireless charging breakthrough requires material, process and system co-innovation. Among many challenges, thermal management is the most urgent. Our micron diamond composite conductor solution, from fundamental physical understanding, shifts focus from traditional "external cooling" to "internal conduction", from "in-plane" to "radial"—providing new approach to break wireless charging thermal bottleneck.
We believe through sustained R&D and industry collaboration, this solution may achieve engineering application in 3–5 years, paving the way for EV wireless charging toward higher power. We look forward to exploring this promising direction with industry peers.