Nanoscale Borate Coating Network Stabilized Iron Oxide Anode for High‐Energy‐Density Bipolar Lithium‐Ion Batteries

Abstract

Advanced lithium-ion batteries (LIBs) for applications in electric vehicles, energy storage, and high-power devices call for novel designs of the electrochemical materials and the cell architecture. Among the candidates are bipolar LIBs which have an advanced stack configuration, simplify the cell components, and hold the promise to revolute the integrated cell design in the future. [1][2][3] In typical bipolar LIBs, cathode and anode slurries consisting of active materials, conductive carbon, and binders are separately coated on two sides of a current collector so that n (≥2) units of such can be serially connected to assemble a high-voltage cell. The design minimizes the internal resistive loss between neighboring cells in a stack, offers uniform current and field distributions, and allows high-power cell operations. It also minimizes the usage of inactive cell components such as those for housing and connecting, thus increases the gravimetric and volumetric energy density and lowers the cost compared to conventional LIB design. [3] Therefore, bipolar LIBs are more competitive in many applications, e.g., in electric vehicles which require high-voltage battery packs with 300-500 V working voltages. [4,5] As the preferred current collector in bipolar LIBs is aluminum foil (which has a lithiation voltage of ≈0.3 V vs Li/ Li + ), low-redox-voltage anodes such as graphite, carbon-silicon composite, and lithium metal cannot be used, and the conventional choice is lithium titanate Li 4 Ti 5 O 12 with a relatively low capacity (theoretical capacity: 175 mAh g −1 ). [3,5] It is therefore the goal of the present study to develop a cheap high-capacity anode with a suitable redox potential and stable cycling performance for high-energy-density bipolar LIBs. We chose conversion-type iron oxide FeO x because of its non-toxicity, earth abundance, low processing cost, high crystal density (5.24 g cm −3 for Fe 2 O 3 and 5.18 g cm −3 for Fe 3 O 4 , compared to 2.16 g cm −3 for graphite, 2.33 g cm −3 for Si, and 0.534 g cm −3 for Li), proper redox potential (lower cutoff voltage: 0.5 V vs Li/Li + , average delithiation voltage: 1.5 V vs Li/Li + ), and high capacity (the theoretical capacity is 1007 mAh g −1 for Fe 2 O 3 and 926 mAh g −1 for Fe 3 O 4 ). [6][7][8][9] Despite of the high capacity, FeO x like other conversion-type TM oxides, has poor cycling stability High-capacity metal oxides based on non-toxic earth-abundant elements offer unique opportunities as advanced anodes for lithium-ion batteries (LIBs).But they often suffer from large volumetric expansion, particle pulverization, extensive side reactions, and fast degradations during cycling. Here, an easy synthesis method is reported to construct amorphous borate coating network, which stabilizes conversion-type iron oxide anode for the highenergy-density semi-solid-state bipolar LIBs. The nano-borate coated iron oxide anode has high tap density (1.6 g cm −3 ), high capacity (710 mAh g −1 between 0.5 -3.0 V, vs Li/Li + ), good rate performance (200 mAh g −1 at 50 C), and...

Fast and Durable Lithium Storage Enabled by Tuning Entropy in Wadsley–Roth Phase Titanium Niobium Oxides

“…[ 3,53 ] Some other recently developed anodes with high tap density and volumetric capacity are also included for comparison. [ 54–57 ]…”

“…[3,53] Some other recently developed anodes with high tap density and volumetric capacity are also included for comparison. [54][55][56][57] The superior rate performance of FTNO-1000 is expected to be caused by the shortened Li + diffusion channel length as well as the smaller grain size, of which the effect on the specific Li + transfer kinetics within these three electrode materials will be discussed below. The long-term cycling stability of the electrodes was also investigated at 2 and 5 C. Initial 5 cycles are activation of the electrodes and calculation of the capacity retentions presented below are based on the discharge capacities at sixth cycle.…”

Quasi‐Topological Intercalation Mechanism of Bi0.67NbS2 Enabling 100 C Fast‐Charging for Sodium‐Ion Batteries

“…The degradation of electrochemical performance under high mass loading is possibly attributed to the poor contact of active materials with conductive agents when the coating thickness of electrode slurry increases, which can be mitigated by changing the conductive agents (e.g., multiwalled carbon nanotubes) or roll-pressing the electrode. [20,53,64] The cycling performance at 2 C demonstrates good stability of the electrode under 4.46 mg cm −2 (Figure S18b, Supporting Information). Overall, the Bi 0.67 NbS 2 anode exhibits impressive rate and cycling performance, even under high mass loadings.…”

Suppressing Side Reaction and Dendritic Growth via Interfacial Cyclization Molecule for Stable Zn Metal Anodes

“…Nowadays, under the background of carbon neutrality, with the continuous development of renewable energy industry and new energy vehicles, electrochemical energy storage has attracted great attention from the international community. − To cope with the challenges of high cost, research on a variety of new electrochemical energy storage systems and technologies has made continuous progress, especially Li-ion batteries (LIBs). − However, the typical energy storage systems based on LIBs have gradually exposed the safety and cost issues, forcing researchers to accelerate the exploration for safe, reliable, and cost-effective energy storage technologies. − Compared to LIBs, aqueous zinc ion batteries (ZIBs) are regarded as the most promising candidates for future energy storage systems because of features such as intrinsic safety, low redox potential (−0.76 V vs SHE), high natural abundance and chemical stability, being low cost, and so forth …”