Nallathamby Kalaiselvi is an Indian senior electrochemical scientist who became the first woman Director General of the Council of Scientific and Industrial Research (CISR) on 7 August 2022. On 22 February 2019, she was appointed as the Director of the CSIR-Central Electrochemical Research Institute (CSIR-CECRI) at Karaikudi in Tamil Nadu. Upon her appointment, an order of the Ministry of Personnel, Public Grievances, and Pensions stated, Kalaiselvi has been appointed for a period of two years with effect from the date of assumption of charge of the post or until further orders, whichever is earlier. Newly-appointed CSIR director general Dr N Kalaiselvi with MoS (Science and Tech) Jitendra Singh.Before joining CECRI in 1997, N Kalaiselvi was an organic chemist and did not have a background in electrochemistry. She was teaching as a professor at a private college for three years soon after completing her PhD from Annamalai University in Chidambaram.Reportedly, N Kalaiselvis father was a teacher who raised her like a boy. Another former colleague of N Kalaiselvi stated in a media interview that she enjoyed playing boys games in her childhood.According to some media sources, N Kalaiselvi did not have a background in electrochemistry when she joined CECRI. N Kalaiselvi received her entire education at government schools and colleges in Tamil Nadu. In a media conversation, she talked about her interest in the teaching field. She said, I loved teaching. But, I was also aching for research. CECRI provided me an opportunity to do both. Nallathamby Kalaiselvi while speaking at a college.N Kalaiselvi is known for her work in the field of lithium-ion batteries. She invented some new materials, which are used as electrodes in lithium-ion batteries for improving their storage capacities. In August 2022, she was also given an additional charge as secretary of the Department of Scientific and Industrial Research where she is involved in the development of practically viable Sodium-ion/Lithium-sulfur batteries and supercapacitors. In a media conversation, her former colleague, Dr T Prem Kumar stated that N Kalaiselvi had a great interest in electric mobility. Dr T Prem Kumar said, Electric mobility that is something very close to her heart, and that needs improved batteries. Also, wider utilisation of renewable energies like wind or solar..According to one of her former colleagues, N Kalaiselvi is a very powerful public speaker and used to participate in several public speaking platforms such as AIR. He said, Kalaiselvi was a very active participant, and participated in some of these at the local All India Radio station. This has made her a formidable public speaker. Nallathamby Kalaiselvi during a public speaking conference.From 2007-2009, 2011-2013, and 2013-2015, N Kalaiselvi served as the Board of Studies Member at Karunya University, PSG Institute of Technology, Sri Ramakrishna Engineering College, Coimbatore; Serfoji College of Arts and Science, Tanjore; and Sri. GVG Visalakshi College for Women, Udumalpet.In 2011, four of her research papers were selected under HIGHEST CITED TOP 25 HOTTEST ARTICLES by Elsevier. She was appointed as the editor of Ariga Ariviyal a Monthly Scientific Periodical issued in Tamil for popularising Science in Tamil to rural students.From 2012 to 2017, N Kalaiselvi served as the Nodal Scientist for Multifunctional Electrodes and Electrolytes for Futuristic Technologies (MULTIFUN), a Rs 68.54 crore twelfth five-year plan of CSIR.In 2019, N Kalaiselvi began working as a Theme Director of the Renewable and Non-renewable energy and devices of CSIR and the Chairperson and Member of the Administrative and Technical Committees of CSIR-CECRI. She was given the additional charge as the Chairperson of the SAC (Student Academic Committee) of CECRI.