The wide application of electric double layer capacitor (EDLC) is restricted by its low energy density. Such a bottleneck is hopefully tackled via engineering the carbon surface chemistry to kinetically inhibit the electrolyte decomposition and effectively extend the cell voltage of the EDLC. Here, we propose a facile carbon surface passivation strategy by rational functionalization with fluorine-containing functional groups. Evidenced by electrochemical measurements, the fluorinated activated carbon (F-AC) could tolerate a wider voltage window in commercially available organic electrolyte compared with the commercial activated carbon (AC). The theoretical simulation further verifies that the F-AC displays much increased activation energy for the formation of intermediate products, thereby dynamically hindering the electrolyte decomposition on the carbon surface. The F-AC based EDLC exhibits a remarkable voltage expansion from 2.7 V to 3.3 V and excellent cycling stability of 98.3% capacitance retention after 20000 cycles. A high energy density of 43.3 Wh kg⁻¹ is achieved at the power density of 135 W kg⁻¹, which is about 1.5-fold enhancement compared with the AC based counterpart, outperforming most of the reported organic EDLCs. These inspiring results bring fundamental insights into the regulation of voltage window, which will stimulate the design of high-performance energy storage devices.

双电层电容器（EDLC）的广泛应用受到其低能量密度的限制。这种瓶颈有望通过设计碳表面化学来解决，以在动力学上抑制电解质分解并有效延长 EDLC 的电池电压。在这里，我们通过含氟官能团的合理功能化提出了一种简便的碳表面钝化策略。电化学测量证明，与商业活性炭（AC）相比，氟化活性炭（F-AC）可以在市售有机电解质中耐受更宽的电压窗口。理论模拟进一步验证了 F-AC 显示出大大增加的中间产物形成活化能，从而动态地阻碍了碳表面上的电解质分解。基于 F-AC 的 EDLC 表现出从 2.7 V 到 3.3 V 的显着电压扩展和优异的循环稳定性，20000 次循环后电容保持率为 98.3%。43.3 Wh kg 的高能量密度^-1在 135 W kg ^-1的功率密度下实现，与基于 AC 的对应物相比提高了约 1.5 倍，优于大多数报道的有机 EDLC。这些鼓舞人心的结果为电压窗口的调节带来了基本的见解，这将刺激高性能储能设备的设计。