Don't be quick to write off battery swapping

Flash charging dazzles, but physics bites back

BYD (比亚迪) last month rolled out its "megawatt flash charge 2.0", boasting that a battery can go from 10% to 97% in as little as nine minutes and still perform in extreme cold. It has been reported that BYD used 10%–97% as its test baseline — a headline-grabbing metric — and that the company is positioning the system as an answer to the slow-charging problem. NIO (蔚来), however, has doubled down on battery swapping, arguing that even the fastest flash charge cannot match the speed of a physical swap. Which is right? Both, depending on which problem you prioritise: time-in-site or battery longevity.

Chemistry limits — and why swapping still matters

Lithium-ion cells charge fast at first and then enter a slow trickle phase as they approach full capacity; that's basic electrochemistry. Rapid charging pushes many lithium ions to "pile up" on the graphite anode and can create metallic lithium deposits (lithium plating), accelerating capacity loss. Geotab’s analysis of over 20,000 vehicles reportedly shows average battery capacity decline of ~2.3% per year, with frequent fast-charging users losing capacity at roughly twice the rate of slow-charging drivers. Battery makers including CATL (宁德时代) and BYD have made material and BMS improvements to reduce damage from ultra-fast charging, but those advances mitigate rather than eliminate the physical trade-offs — so NIO’s claim that swapping (where station-side batteries can be charged more gently) better preserves pack health has a technical logic to it.

Business models and fleet realities

Swapping’s advantages aren’t just technical. NIO’s BaaS (Battery-as-a-Service) unbundles battery ownership, lowers upfront costs and turns batteries into networked assets that can be refurbished, reused as storage, or recycled — it has been reported that NIO limits battery degradation in its pool to below 15%. BYD’s flash-charge strategy, by contrast, appears aimed at raising the appeal of its higher-priced models that can carry 800V–1000V architectures needed to exploit megawatt charging; most cheaper BYD models currently can’t accept peak power, so the experience remains segmented by price tier. Practically, both flash-charging stations and swap stations are small grid-connected storage farms; deploy one way or the other and you’re building similar infrastructure, with different operational trade-offs.

Outlook: coexistence, not a knockout punch

A single technology is unlikely to win the market. Consumers don’t decide on a car solely by top-end charging speed: price, ownership model, infrastructure coverage and long‑term value matter too. Geopolitical factors complicate the picture as well — a decade ago many core chips and BMS algorithms were sourced abroad, and tightening export controls and supply-chain scrutiny have pushed Chinese firms to localise capabilities, accelerating iterative improvements in materials and power electronics. The result? Faster charging will keep getting better, and swapping will remain attractive where battery longevity, secondary-use value and ownership flexibility matter. So will swap stations become obsolete — or will the industry settle into a mix of options? That’s the real question consumers and policymakers should be watching.