Solid State Ionics Lab | Dr. Sunil Kumar
The focus of our group is on designing, synthesis, and characterization of inorganic materials to discover technologically relevant novel materials and to understand and control the structure–property relationship. Of particular interest are materials for energy storage applications, lead-free piezoceramics, and magnetic oxides with perovskite and related structures. Primary research interests are (but not limited to) the following:

  • Solid Electrolytes for Lithium Batteries

  • Lead-free Piezoelectrics

  • Cathode Materials for Li/Na Batteries

  • Electrocaloric Effect and Energy Storage Phenomenon in Polar Materials

  • Polymer-Ceramic Composites

  • Solid State Ionics


1. Compositionally and Microstructurally Engineered Lead-Free Ceramics for Piezoelectric Applications

Ongoing (years: 2017-2020)

Piezoelectric materials are technologically relevant owing to their ability to convert the mechanical input into an electrical output and vice-versa. These materials have been in commercial use for several decades and in a wide range of devices, such as piezoelectric-operated actuators and motors, ultra-small-scale precision motion, sensors, transducers, fuel injectors used in automotive applications, micropumps, and piezo valves. The global market for piezoelectric operated devices is estimated to reach INR 1,252 billion by 2020, showing a compound annual growth of 7.7% per year. Lead-free piezoelectric materials are being extensively investigated as the viable replacement for the widely used but hazardous Pb(Zr,Ti)O3–based piezoceramics.

This project focuses on developing new materials and tailoring their properties by crystal structure modification for piezoelectric and electrical energy storage applications. The emphasis is on understanding the impact of dopants/defects on the crystal structure and domain pinning in perovskite structured (K0.5Na0.5NbO3 & A0.5Bi0.5TiO3) piezoceramics. Investigations on the extrinsic contribution to the electromechanical properties of the identified system are also carried out.

2. Development of Solid Electrolytes for All-Solid-State Rechargeable Lithium Batteries

Ongoing (years: 2015-2020)

One of the most critical challenges of the 21st century is the sustainable supply of energy from non-polluting sources, and the intermittent nature of renewable energy sources like solar and wind farms necessitates electrical energy storage devices such as batteries or electrochemical supercapacitors. While existing secondary Li-ion batteries have proven to be excellent power source for smaller electronic devices, these batteries have found only limited use as the primary power sources for automobile applications. This limitation is due to the insufficient energy & power capacities coupled with the prohibitively high cost of existing batteries technology. An attractive and seemingly simple way of improving the energy density of these batteries is to use high capacity metallic lithium (in place of commercially used graphite) as the anode along with high voltage cathodes. Unfortunately, the use of lithium anode in secondary batteries employing organic liquid electrolytes tends to result in dendrite formation, and eventually, in catastrophic battery failure.

In this regard, replacement of traditional liquid electrolytes with sufficiently fast lithium-ion conducting and mechanically robust solid electrolytes promises to deliver next-generation rechargeable lithium batteries that are safer, cheaper, and capable of faster charging and discharging than the existing batteries. We are exploring NASICON and Garnet structured ceramics as well as the PEO & PVDF based ceramic-polymer composite materials for the potential application in all-solid-state lithium batteries as the electrolyte.

We gratefully acknowledge the funding received from the following agencies for the research work being carried out in our lab:

  • Science and Engineering Research Board (SERB) under the Early Career Research Award Scheme
  • Department of Science & Technology (DST) under INSPIRE Faculty Scheme
  • Indian Institute of Technology Indore