• Energy Research

AbstractMnOx‐surface‐modified Li1.2Ni0.4/3Co0.4/3Mn1.6/3O2 cathode materials have been prepared by solid‐state reaction with varying post‐annealing temperatures. The MnOx coating layers are homogeneous and crystalline with a thickness of 10 nm. Below a current rate of 0.1 C and in the voltage range of 2.0–4.8 V, the MnOx‐modified material, which has been post‐annealed at 300 °C, shows high discharge capacities of 308, 320, and 363 mAh g−1 at 20, 40, and 60 °C, respectively. Meanwhile, this sample shows good rate capability that can deliver discharge capacities of 278 and 178 mAh g−1, respectively, at 1 C and 10 C, both tested at 20 °C. However, the modified sample displays more serious capacity degradation compared to the pristine sample. The significantly higher extent of the transition metal dissolution from the modified sample is proved by compositional analysis. Cycling performance could be improved by replacing the conventional electrolyte with an ionic‐liquid‐based electrolyte.

The lithium metal battery with solid-state polymer electrolyte (SPE) is a promising candidate for solid-state batteries with high safety and high energy density. However, the low room temperature ionic conductivity and poor electrolyte/electrode interfacial stability of the SPEs seriously hinder the practical application. Herein, we adopt a polymer-in-salt electrolyte (PISE) strategy on the comb-like polycaprolactone (PCL) to circumvent the low ionic conductivity and poor interfacial stability of the conventional SPE, thus enabling the full function of room temperature lithium metal batteries. The all-solid-state PISE exhibits a high ionic conductivity of 3.9 × 10−4 S cm−1 at 30 °C, a superior lithium-ion transference number of 0.61 and an improved oxidative stability of ∼4.8 V vs Li/Li+. Due to the ultra-stable interface generated by the superconcentrated lithium salt, the all-solid-state LiFePO4∣∣Li cells exhibit prominent high cycling stability, with high capacity retention (92%) after 300 cycles at ambient temperature. The full function of the ambient temperature PISE offers a promising pathway towards high energy density and high safety room temperature LMBs.

Li6PS5Cl possesses high ionic conductivity and excellent interfacial stability to electrodes and is known as a promising solid-state electrolyte material for all-solid-state batteries (ASSBs). However, the optimal annealing process of Li6PS5Cl has not been studied systematically. Here, a Box–Behnken design is used to investigate the interactions of the heating rate, annealing temperature, and duration of annealing process for Li6PS5Cl to optimize the ionic conductivity. The response surface methodology with regression analysis is employed for simulating the data obtained, and the optimized parameters are verified in practice. As a consequence, Li6PS5Cl delivers a rather high conductivity of 4.45 mS/cm at 25 °C, and ASSB consisting of a LiNi0.6Co0.2Mn0.2O2 cathode and lithium anode shows a high initial discharge capacity of 151.7 mAh/g as well as excellent cycling performances for more than 350 cycles, highlighting the importance of the design of experiments.

The oxidation process of lattice oxygen in Li-rich cathodes is dynamically compatible with that of TMs. Fast delithiation at high current densities can lead to local structural transformation and limited Li+ diffusion rates.

The combination of novel operando neutron diffraction and 4D-STEM clearly reveals the defect-driven heterogeneous phase evolution in LIB full cells.

Solid-state batteries (SSBs) with projected high safety and high-energy density have been heavily pursued as the next generation of electrochemical storage devices, while their realization still faces challenges, including scalable fabrication process, high-loading electrode, and robust thin solid electrolyte. Dry electrode technology (DET) is an emerging battery preparation method that embodies with numerous advantages, including simplified production procedures, loading-enhanced electrode, as well as elimination of solvent sensitivity. Currently, the DET is of great interest for its potential capability in upgrading the slurry-based SSB system that we are experiencing. Herein, the issues encountered in the wet process and the corresponding remedies by DET are introduced, followed by a summarization of multiple DET methodologies. The latest developments of DET are analyzed separately in terms of its application in cathode, anode, and solid electrolytes with emphasis on manufacturing method and material science. Binder selection, which has a growing influence on the quality of the dry film, is discussed as well. Based on the insights acquired, future potential attempts at DET are proposed to meet the goal of SSB commercialization.

Phytate lithium plays multifunctional roles by coordinating with Co, scavenging free radicals, and flame-retardants, stabilizing LiCoO2 to 4.6 V.