成果簡介

由于鉀元素地殼儲量豐富（~2.09%）、電勢較低（?2.93?V vs. SHE），鉀離子電池（KIBs）有望實現與鋰離子電池相當水平的能量密度與氧化還原電勢；且其相比于Na+與Li+具有較低的路易斯酸度，使得K+在液態與固態電解質中的電極/電解質界面上具有更高的轉移數和遷移率。得益于上述優勢，鉀離子電池備受關注。但由于鉀離子半徑較大（1.38??），很難找到具有大層間距和穩定骨架的主體材料來容納大半徑的K+，導致適用于KIBs的無機電極材料發展較慢。有機電極材料具有結構多樣性和可調性等優點，其電化學性能依賴于K+與活性官能團之間的轉化反應，不必受限于K+大半徑帶來的空間位阻效應。

近日，中國地質大學王圣平教授團隊在EcoMat發表了題為“Improving strategies for the molecular structure of organic anode/cathode materials in potassium-ion batteries“的綜述性文章，對有機KIBs的研究進展從有機正極材料、有機負極材料、電解液優化、全電池四個方面進行總結。介紹了具有各種官能團的有機材料的組成、結構、反應機理、電化學性能和開發策略。該論文可為研究人員開發高性能有機KIBs并實現有機KIBs的應用提供了指導和啟示。

內容詳情

FIGURE 1 Redox mechanisms of n-type, p-type and bipolar-type organic materials. X indicates anions present in the electrolyte, such as PF6?, bis(trifluoromethanesulfonyl)imide anion (TFSI?), and FSI?.

FIGURE 2 High-resolution (A) C1s and (B) O1s XPS spectra and (C) cycle performance of PTCDA@450°C (mass loading: 19.5 mg/cm2).

FIGURE 3 Photographs of separators in batteries with (A) an AQ cathode (1 cycle) and (D) an AQDS cathode (10 cycles). Scanning electron microscopy images of the AQ cathode (B) before and (C) after 1 cycle and the AQDS cathode (E) before and (F) after 10 cycles

FIGURE 4 ?(A) Charge and discharge curves and (B) long cycling behavior of PyAq in KIBs (100?mA/g). (C) Reaction mechanism of PyAq.

FIGURE 5 (A) Illustration of the PIM@KB synthetic process. (B) Discharge/charge mechanism of the P1 structural unit.

FIGURE 6 Elemental mapping of the (A) PTPAn cathode charged to 4.0 V and (B) discharged to 1.0 V in the first cycle. Elemental mapping of the (C) graphite anode charged to 4.0 V and (D) discharged to 1.0 V in the first cycle. The scale bars in A–D are 200, 300, 200, and 400?nm, respectively.

FIGURE 7 Reaction mechanism of the copper porphyrin complex in KIBs. (A) Schematic illustration of a K/KPF6/CuDEPP half-battery. (B) FTIR spectra and (C) XRD patterns of CuDEPP in the various charged states in the initial cycle.

FIGURE 8 (A) K+ intercalation/deintercalation mechanisms of K2TP and K2PC. (B) Galvanostatic discharge–charge curves of K2TP. Lattice structural calculations for (C) K2TP and (D) K2TP-K2.

FIGURE 9 (A) Reaction of ADAPTS in KIBs. Charge/discharge curves and cycling performance (B, D) at 1C and 50°C and (C, E) at 2C and 60°C.

FIGURE 10 (A) Structures and (E) cycling performance of COF-10@CNTs under 1000?mA/g. (B) Illustration of the formation of CTF-0 and CTF-1 with different pore sizes. Structures of (C) Bz-containing and (D) BT-containing CMPs.

FIGURE 11 Diagram of SEI formation during the initial cycle (1,2,3) and its growth (4) in the following cycles with (A) DME and (B) EC/DEC electrolytes.

FIGURE 12 SEM and digital pictures of the (A) nonwoven cellulose membrane and (B) PPCB-SPE. (C) Charge–discharge curves of PTCDA with PPCB-SPE under 10 mA/g. (D) Cycling performance of PTCDA with PPCB-SPE and an organic-liquid electrolyte at 20?mA/g. (E) Chemical structure of PMMA in the polymer-gel electrolyte. (F) Charge storage mechanism of a polyaniline cathode in KIBs.

FIGURE 13 (A) Ionic conductivity of different electrolytes. (B) Cycling performance of FKIBs (the numbers in the figure correspond to those in Table 2). (C) Voltage window, average discharge voltage and mass loading of electrodes for FKIBs. (D) Rate performance of various organic electrode materials. Voltage window and average discharge voltage of (E) organic cathode and (F) anode materials.

FIGURE 14 Schematic diagram of organic KIB improvement strategies.

審核編輯：劉清