Tailoring twisted WS2 structure with strain-self-relaxation for ultra-high capacity potassium ion batteries

The structural stress/strain induced by K-ion intercalation remains a critical challenge for K-ion batteries. To address this, a dopamine-intercalated WS2 hybrid (Dam-WS1.87) with a unique strain-self-relaxation architecture was fabricated. Interestingly, the WS2 matrix undergoes a structural transformation owing to the intense infiltration effect of dopamine molecules, expanding interlayer spacing (0.813 nm) and introducing 6.5% S-vacancies while preserving high compaction density (4.0874 g cm−3). The engineered structure demonstrates remarkable mechanical stability, exhibiting only 19.0% crystallite expansion upon full potassiation (vs. 101.3% for pristine WS2), demonstrating efficient strain alleviation through its strain-self-relaxation architecture. As a result, Dam-WS1.87 delivers reversible capacities of 312.6 mA h g−1/1277.7 mA h cm−3 at 0.125 C, along with superior rate capability (maintaining 210.4 mA h g−1 at 5 C) and unprecedented cycling stability (85.3% capacity retention after 1400 cycles at 1 C). This work provides new insights into designing strain-tolerant electrode materials for next-generation energy storage systems.