Sluggish solid-state K⁺-migration kinetics and electrode material degradation represent two critical issues facing K-ion batteries. Here we report a new inorganic-open-framework (IOF) compound K_0.76V_0.55Nb_0.45OPO₄ (KVNP, synthesized through aliovalent substitution) which, as a bifunctional electrode material, simultaneously mitigates these issues on both anode and cathode sides. The distinctive IOF crystal structure enables a low K⁺-migration energy barrier (0.16 eV) even surpassing the Li⁺ counterpart in state-of-the-art LiCoO₂/LiFePO₄ (0.21/0.55 eV) and consequently achieves fast-charging capability and high energy efficiency. Equally important, KVNP undergoes exceptionally small lattice-volume changes upon cycling (7.1% on anode and 3.1% on cathode, versus 10% for graphite anode and 6.8% for LiFePO₄ cathode in commercial Li-ion batteries). This intrinsic low-strain feature ensures high structural stability against K⁺-ion (de)intercalation and ultralong cycle lives of > 18 months for both KVNP anode and cathode (versus < 3 months for previously reported IOFs). Aliovalent substitution in IOFs may pave a way for the exploration of fast-charging and long-lifespan K-ion batteries.

呆滞固体状态K ⁺ -migration动力学和电极材料降解代表面向K-离子电池的两个关键问题。在这里，我们报告了一种新的无机开放框架 (IOF) 化合物 K _0.76 V _0.55 Nb _0.45 OPO ₄（KVNP，通过异价取代合成），它作为一种双功能电极材料，同时缓解了阳极和阴极两侧的这些问题。独特的 IOF 晶体结构实现了低 K ⁺迁移能垒（0.16 eV），甚至超过了最先进的 LiCoO ₂ /LiFePO _{4 中}的 Li ⁺对应物(0.21/0.55 eV)，从而实现快速充电能力和高能效。同样重要的是，KVNP 在循环时经历了非常小的晶格体积变化（阳极为 7.1%，阴极为 3.1%，而商业锂离子电池中石墨阳极为 10%，LiFePO ₄阴极为 6.8% ）。这种固有的低应变特性确保了 K ⁺离子（脱）嵌入的高结构稳定性和 KVNP 阳极和阴极的超长循环寿命 > 18 个月（而之前报道的 IOF 的循环寿命小于 3 个月）。IOF 中的异价置换可能为探索快速充电和长寿命 K 离子电池铺平道路。