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h i g h l i g h t sChemistry and electrochemistry in lithium-based microbatteries. Recent concept and cell design towards different applications. Future perspectives of microbattery development. a b s t r a c tBatteries employing lithium chemistry have been intensively investigated because of their high energy attributes which may be deployed for vehicle electrification and large-scale energy storage applications. Another important direction of battery research for micro-electronics, however, is relatively less discussed in the field but growing fast in recent years. This paper reviews chemistry and electrochemistry in different microbatteries along with their cell designs to meet the goals of their various applications. The state-of-the-art knowledge and recent progress of microbatteries for emerging micro-electronic devices may shed light on the future development of microbatteries towards high energy density and flexible design.

Some of the best thermoelectrics are complex materials with rattling guests inside oversized atomic cages. Understanding the chemical and structural origins of the rattling behavior is essential to the design of thermoelectric materials. In this work, a clear connection is established between the local bonding asymmetry and anharmonic rattling modes in tetrahedrite thermoelectrics, enabled by the chemically active electron lone pairs. The studies reveal a fi ve-atom atomic cage Sb[CuS 3 ]Sb in Cu 12 Sb 4 S 13 tetrahedrites that exhibits strong local bonding asymmetry: covalent bonding inside the CuS 3 trigonal plane and weak out-of-plane bonding induced by the lone-pair electrons of Sb. This bonding asymmetry leads to out-of-plane rattling modes that are quasilocalized and anharmonic with low frequency and large amplitude, and are likely the origin of low thermal conductivity in tetrahedrites. Such knowledge highlights the importance of local structure asymmetry and lonepair atoms in driving anharmonic rattling, providing a stepping stone to the discovery and design of next-generation thermoelectrics.

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Crystalline Li7P3S11 is a promising solid electrolyte for all solid-state lithium/lithium ion batteries. A controllable liquid phase synthesis of Li7P3S11 is more desirable than conventional mechanochemical synthesis, but recent attempts suffer from reduced ionic conductivities. Here we elucidate the mechanism of formation of crystalline Li7P3S11 synthesized in the liquid phase [acetonitrile (ACN)]. We conclude that crystalline Li7P3S11 forms through a two-step reaction: (1) formation of solid Li3PS4·ACN and amorphous “Li2S·P2S5” phases in the liquid phase and (2) solid-state conversion of the two phases. The implication of this two-step reaction mechanism for morphology control and the transport properties of liquid phase synthesized Li7P3S11 is identified and discussed.

We present magnetic-torque measurements of the organic superconductor κ-(BEDT-TTF) 2 Cu(NCS) 2 for inplane magnetic fields up to 32 T. In this layered two-dimensional compound the superconductivity can persist even in fields above the Pauli limit of about 21 T. There, a pronounced upturn of the upper-critical-field line occurs and the superconducting phase-transition line splits and forms an additional high-magnetic-field phase. κ-(BEDT-TTF) 2 Cu(NCS) 2 is a spin-singlet superconductor; therefore, such a superconducting high-field phase beyond the Pauli limit can originate only from Cooper pairing with finite center-of-mass momentum. The measurements are discussed in connection with a Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state, in accordance with earlier specific-heat observations. The torque experiments allow us to investigate the high-magnetic-field phase diagram and the FFLO state of κ-(BEDT-TTF) 2 Cu(NCS) 2 in great detail.

The specific heat due to line nodes in the superconducting gap of YBa 2 Cu 3 O 7 has been blurred up to now by magnetic terms of extrinsic origin, even for high quality crystals. We report the specific heat of a new single crystal grown in a non-corrosive BaZrO 3 crucible, for which paramagnetic terms are reduced to ≈ 0.006% spin-1/2 per Cu atom. The contribution of line nodes shows up directly in the difference C(B, T ) − C(0, T ) at fixed temperatures (T < 5 K) as a function of the magnetic field parallel to the c-axis (B ≤ 14 T). These data illustrate the smooth crossover from C ∝ T 2 at low fields to C ∝ T B 1/2 at high fields, and provide new values for gap parameters which are quantitatively consistent with tunneling spectroscopy and thermal conductivity in the framework of d x 2 −y 2 pairing symmetry. Data for B along the nodal and antinodal directions in the ab-plane are also provided. The in-plane anisotropy predicted in the clean limit is not observed.

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