Planar Li Deposition and Dissolution Enable Practical Anode-Free Pouch Cells

Why It Matters

The breakthrough delivers ultra‑high energy density without an anode, lowering cost and weight for electric‑vehicle and grid storage applications. It proves that electrolyte‑engineered SEI can overcome mechanical instability that has limited anode‑free batteries.

Key Takeaways

• Crossover‑coupled electrolyte forms polymer‑rich SEI
• Achieves 508 Wh kg⁻¹ energy density in pouch cell
• Stable 100 cycles at full depth, 250 at 80 %
• Planar Li deposition up to 5.6 mAh cm⁻²
• High power output 2650 W kg⁻¹ at 96 Wh kg⁻¹

Pulse Analysis

Anode‑free lithium‑metal batteries (AFLMBs) have attracted intense interest because they eliminate the heavy copper current collector and excess lithium, promising unprecedented gravimetric energy. Yet, without a host material, the solid‑electrolyte interphase (SEI) becomes highly heterogeneous, leading to dendritic growth and rapid capacity fade. Overcoming this fragility has been the primary obstacle to scaling AFLMBs for electric‑vehicle and stationary storage markets, where safety, cycle life, and cost are non‑negotiable.

The Westlake team’s crossover‑coupled electrolyte triggers interfacial reactions that deposit a boron‑fluorine polymer‑rich SEI directly on the bare copper foil. This SEI exhibits sub‑nanometer uniformity, exceptional flexibility, and a self‑adaptive mesh‑film architecture that evenly distributes lithium‑ion flux. As a result, lithium plates and strips in a planar fashion at areal capacities of 5.6 mAh cm⁻², delivering 508 Wh kg⁻¹ (1668 Wh L⁻¹) and sustaining 100 full‑depth cycles plus 250 cycles at 80 % depth with 80 % capacity retention. The cell also achieves a power density of 2650 W kg⁻¹ at a usable energy of 96 Wh kg⁻¹, demonstrating that high‑energy and high‑power performance are compatible in anode‑free designs.

If the electrolyte chemistry can be transferred to large‑scale manufacturing, AFLMBs could dramatically reduce battery pack weight and cost, accelerating the adoption of long‑range electric vehicles and enabling more efficient grid‑scale storage. The study highlights the importance of interphase engineering over merely increasing cathode capacity, suggesting a new research direction focused on electrolyte‑driven SEI control. Future work will need to validate long‑term stability under varied temperatures and fast‑charging regimes, but the presented results mark a pivotal step toward practical, host‑free lithium‑metal batteries.