This study analyzes the energy density balancing mechanism of BYD Han EV's blade battery system:Adopting long strip-shaped cell design and module-free integration, volume utilization rate is significantly improved, with first-generation energy density of 140Wh/kg and second-generation reaching 190Wh/kg (lab data 210Wh/kg). Integrated with direct cooling thermal management and BMS active balancing, the temperature difference is controlled below 5℃ ,and cycle life exceeds 3000 times. Experimental data shows 92% range retention at -30℃ and 800V platform enabling 15-minute fast charging to 80%. The research reveals that through structural optimization with intelligent algorithms, the blade battery achieves balance between energy density, safety, and lifespan, providing references for high-energy-density battery design.