Self-assembled hydrated copper coordination compounds as ionic conductors for room temperature solid-state batteries

Abstract

As the core component of solid-state batteries, neither current inorganic solid-state electrolytes nor solid polymer electrolytes can simultaneously possess satisfactory ionic conductivity, electrode compatibility and processability. By incorporating efficient Li+ diffusion channels found in inorganic solid-state electrolytes and polar functional groups present in solid polymer electrolytes, it is conceivable to design inorganic-organic hybrid solid-state electrolytes to achieve true fusion and synergy in performance. Herein, we demonstrate that traditional metal coordination compounds can serve as exceptional Li+ ion conductors at room temperature through rational structural design. Specifically, we synthesize copper maleate hydrate nanoflakes via bottom-up self-assembly featuring highly-ordered 1D channels that are interconnected by Cu2+/Cu+ nodes and maleic acid ligands, alongside rich COO− groups and structural water within the channels. Benefiting from the combination of ion-hopping and coupling-dissociation mechanisms, Li+ ions can preferably transport through these channels rapidly. Thus, the Li+-implanted copper maleate hydrate solid-state electrolytes shows remarkable ionic conductivity (1.17 × 10−4 S cm−1 at room temperature), high Li+ transference number (0.77), and a 4.7 V-wide operating window. More impressively, Li+-implanted copper maleate hydrate solid-state electrolytes are demonstrated to have exceptional compatibility with both cathode and Li anode, enabling long-term stability of more than 800 cycles. This work brings new insight on exploring superior room-temperature ionic conductors based on metal coordination compounds.

High-Performance Anode Material Based on Zinc Naphthalocyanine/Graphene Composite

“…Metal coordination compounds have been proven to be used in battery systems through rational structural design . Metal naphthalocyanine is a large π-conjugated aromatic system that was originally used as pigment and is widely used in optical and electrical fields owing to its absorption characteristics in the near-infrared region. − Metal naphthalocyanine species comprise a central metal and ligand, which is obtained by adding four benzene rings to the phthalocyanine, and have a larger conjugated structure than those of phthalocyanines.…”

Polyacrylonitrile Based Triblock Copolymer Binder Enabling Excellent Performance toward LiNi0.5Mn1.5O4 and Sulfur Based Batteries

“…With the development of new energy industry, high energy density lithium batteries face new challenges, including expanding applications and extending lifetime. − Spinel LiNi 0.5 Mn 1.5 O 4 (LNMO) is the most promising cathode candidate for high power, high energy density lithium-ion batteries (LIBs) due to its high-voltage platform of 4.75 V (vs Li + /Li), and fast Li-ion diffusion. − However, conventional electrolytes inevitably exhibit instability at high voltages, which leads to further side reactions resulting in severe dissolution of metal ions and excessive growth of unstable solid electrolyte interfaces (SEIs), − resulting in poor cycling performance and inferior rate performance, preventing widespread use in high-voltage systems. Recently, significant efforts have been proposed to improve the performance of LNMO based LIBs from the binder perspective. − As inactive components in the electrode with less than 10 wt % weight, binders not only hold the conductive agent and active materials together and adhere them to the current collector, but also affect the electrode interface structure and show further influence on the prolonged cycle life. − Polyvinylidene fluoride (PVDF, 50% crystallinity) is the most commonly used binder in commercial LIBs due to its electrochemical stability and high adhesion properties. − However, the enormous Joule heat released by the reaction with Li and the excessive electrolyte absorption make PVDF a negative binder candidate for high energy density LIBs. , Based on these issues, the search for lower cost, higher efficiency alternatives has become a priority of great importance …”

Weakening Ionic Coordination for High Ionic Conductivity Composite Solid Electrolytes

“…However, the low ambient ionic conductivities (<10 –5 S cm –1 ) severely limit their application. Incorporating inorganic ceramic fillers such as Li 1+x Al x Ti 2‑x (PO 4 ) 3 , Li 7 La 3 Zr 2 O 12 , , Li 3 x La 2/3– x TiO 3 , and sulfides , into SPEs to form composite solid electrolytes (CSEs) can improve their ionic conductivities by (1) increasing amorphous regions and enhancing segmental motion of polymers, (2) promoting Li salt dissociation through the interaction between inorganic and Li salt anions, and (3) creating additional Li-ion pathways along polymer/inorganic interfaces and through bulk inorganic fillers. , In recent years, new types of single-component SSEs, such as copper-coordinated compounds, , have been developed. These compounds facilitate rapid Li + transport along 1D channels with oxygen-containing functional groups and structural water.…”