Metal–organic frameworks (MOFs) have emerged as an important, yet highly challenging class of electrochemical energy storage materials. The chemical principles for electroactive MOFs remain, however, poorly explored because precise chemical and structural control is mandatory. For instance, no anionic MOF with a lithium cation reservoir and reversible redox (like a conventional Li-ion cathode) has been synthesized to date. Herein, we report on electrically conducting Li-ion MOF cathodes with the generic formula Li2-M-DOBDC (wherein M = Mg2+ or Mn2+; DOBDC4– = 2,5-dioxido-1,4-benzenedicarboxylate), by rational control of the ligand to transition metal stoichiometry and secondary building unit (SBU) topology in the archetypal CPO-27. The accurate chemical and structural changes not only enable reversible redox but also induce a million-fold electrical conductivity increase by virtue of efficient electronic self-exchange facilitated by mix-in redox: 10–7 S/cm for Li2-Mn-DOBDC vs 10–13 S/cm for the isoreticular H2-Mn-DOBDC and Li2-Mg-DOBDC, or the Mn-CPO-27 compositional analogues. This particular SBU topology also considerably augments the redox potential of the DOBDC4– linker (from 2.4 V up to 3.2 V, vs Li+/Li0), a highly practical feature for Li-ion battery assembly and energy evaluation. As a particular cathode material, Li2-Mn-DOBDC displays an average discharge potential of 3.2 V vs Li+/Li0, demonstrates excellent capacity retention over 100 cycles, while also handling fast cycling rates, inherent to the intrinsic electronic conductivity. The Li2-M-DOBDC material validates the concept of reversible redox activity and electronic conductivity in MOFs by accommodating the ligand’s noncoordinating redox center through composition and SBU design.

Raising the operating potential of the organic positive electrode materials is a crucial challenge if they are to compare with lithium-ion inorganic counterparts. Although many efforts have been directed on tuning through substituent electronic effect, the chemistries than can operate above 3 V vs Li + /Li 0 , and thus be air stable in the Li-reservoir form (alike the conventional inorganic Liion positive electrode materials) remain finger-counted. Herein, we report on a new n-type organic Li-ion positive electrode materialthe tetralithium 2,5dihydroxy-1,4-benzenediacetatewith a remarkably high redox potential of 3.35 V vs Li + /Li attained notably in the solid phase. The origin of the high-energy content in this quinone derivative is found in a stereoelectronic chameleonic effect with an intramolecular conformation change and charge modulation leading to a redox potential increase of 650 mV in the solid state as compared to the same chemistry tested in solution (2.70 V vs Li + /Li). The conformational dependent electroactivity rationale is supported by electrochemical and crystallography analysis, comparative infrared spectroscopy, and DFT calculation. We identify and make a linear correlation between the enolate vibrational modes and the redox potential, with general applicability for possibly other phenolate redox chemistries. Owing to these effects, this lithiated quinone is stable in ambient air and can be processed and handled alike the conventional inorganic Li-ion positive electrode materials. Whereas intrinsic to high voltage operation stability issues remain to be solved for practical implementation, our fundamental in nature and proof-of-concept study highlights the strong amplitude of through-space charge modulation effects in designing new organic Li-ion positive electrode chemistries with practical operating potential. 46For all these reasons, the organic battery field has 47

CsPbX3 perovskite quantum dots mechanochemically synthesized within an anionic MOF show intense luminescence and high solvent stability.

We report a one-step, solvent-free, green approach for the mechanochemical stabilization of hybrid organic–inorganic lead halide (MAPbBr3) perovskite quantum dots (PQDs) within perovskite metal–organic frameworks (MOFs) [MA-M­(HCOO)3] [M = Mn and Co; MA = methylammonium (CH3NH3 +)]. The perovskite MOF acts as a template and source of MA cations for growing and stabilizing hybrid PQDs. The synthesis of the composite has been carried out mechanochemically, without the use of any external reagents by simply grinding the perovskite MOF with PbBr2. MAPbBr3@MA-Mn­(HCOO)3 composite shows high chemical stability in several solvents. Its excellent processability has been demonstrated by using it as an electrode material which shows photoelectrochemical activity in the presence of light.