898 Korean J. Chem. Eng., 37(5), 898-904 (2020) DOI: 10.1007/s11814-020-0506-5 INVITED REVIEW PAPER pISSN: 0256-1115 eISSN: 1975-7220 INVITED REVIEW PAPER † To whom correspondence should be addressed. E-mail: psj@gachon.ac.kr Copyright by The Korean Institute of Chemical Engineers. Composite of nanocrystalline cellulose with tin dioxide as Lightweight Substrates for high-performance Lithium-ion battery Quang Nhat Tran * , Il Tae Kim * , Jaehyun Hur * , Ji Hyeon Kim * , Hyung Wook Choi ** , and Sang Joon Park * ,† *Department of Chemical and Biological Engineering, Gachon University, Seongnam, Gyeonggi-do 13120, Korea **Department of Electrical Engineering, Gachon University, Seongnam, Gyeonggi-do 13120, Korea (Received 12 October 2019 • accepted 6 February 2020) AbstractNanocrystalline Cellulose (CNC) has smoother surfaces, better optical transparency and higher mechani- cal strength in comparison with various cellulose fibers. These properties combined with their low cost, light weight, and flexiblility indicate CNC’s great potential as an attractive candidate for preparation of carbon materials, which can be promising electrode for Lithium-ion batteries. However, CNC cannot be directly used in battery fabrication because of its electrically non-conductive property. Wherefore, using pyrolysis to convert CNC into conductive materials is extensively investigated. In our study, high temperature range is used to convert nanocrystalline cellulose into highly conductive carbon material and used in Lithium-ion batteries. The nanocellulose powder after pyrolysis from 800 o C and 1,600 o C is used as active material in Lithium-ion battery electrodes, and the results obtained show a good electro- chemical performance with stable cycling capacity. Following, the carbon network obtained through the pyrolysis (800 o C and 1,600 o C) of nanocrystalline cellulose incorporation with tin dioxide (SnO 2 ) was also used as electrode material in Lithium-ion batteries, resulting in stability, outstanding capacity and better performance in comparison with other carbon-based materials. Keywords: Lithium-ion Batteries, Nanocrystalline Cellulose, Pyrolysis, Carbon Based Conductive Materials, Tin Dioxide INTRODUCTION The sustainable development and environmental friendliness in energy storage technology has been receiving more attention recently. Based on different kinds of energy storage technologies, electro- chemical energy storage technology has been commonly used in various applications. Electrochemical energy storage devices can be divided into two groups, including battery and supercapactor based on its balance between energy and power density. Carbon is the commonest material used for electrodes in both commercial bat- teries and supercapacitors; moreover, carbon materials from renew- able natural sources, feedstocks, green synthesis route and environ- mentally friendly components, such as wood, biomass can be avail- able at low cost and be produced using simple pyrolysis and hydro- thermal carbonization [1-4]. In this respect, nanocellulose with most common types cellulose nanocrystals (CNC) is one of the cheapest, most abundant, biode- gradable, and sustainable nanomaterials that shows great potential as an attractive candidate for preparation of carbon materials. It can be a promising electrode for battery technology because of its excellent flexibility, large specific surface area, optical transparency, and outstanding mechanical strength for both films and aerogel forms. It also shows great potential when used as an additional sub- stance to improve the formation of flexible electrode materials. In addition, using nanocellulose from renewable sources can decrease the total electrode cost and can be more competitive for electricity storage on a large scale. However, nanocellulose is an insulating material, which reduces the conductivity of the electrode and may lead to more challenges when applied for high power application. To strengthen the properties and conductivity of CNC, many ap- proaches have been applied to convert nanocellulose to more con- ductive materials and used them in batteries [4-8]. Moreover, despite the abundance of sodium and calcium elements in the Earth’s crust, lithium ion batteries commonly have higher efficiency than calcium ion batteries and store more power than sodium ion batteries [9-11]. First, we studied the behavior of using high temperatures rang- ing (800 o C-1,600 o C) to convert nanocellulose into highly conduc- tive carbon materials and used them in Lithium-ion batteries. Fol- lowing, the combination of nanocellulose powder after pyrolysis as active material with Super P, PVDF and N-methyl pyrolidone served as electrodes on Cu foils used in Lithium-ion batteries. Tin dioxide (SnO 2 ) is popular among metal-oxide electrode mate- rials with its outstanding electrochemical performance. Moreover, owing to its non-toxic property, low cost synthesis and high theo- retical capacity make it more considered for use as electrode in Lithium-ion batteries [12-15]. Nano-size structure of SnO 2 is used to decrease the volume variation during charge and discharge pro- cess to improve the electrochemical performance of the electrode [16-18]. However, nanostructured SnO 2 is easy to agglomerate, which reduces the specific surface area of the active materials, leading to the decline of capacity and cell performance. To overcome this issue, a composite material of SnO 2 and pyrolyzed CNC has been cre- ated to utilize the area of electrode specific surface and combine the advantanges of both materials to enhance the electrical conductiv- ity of the composite material [19-21]. In this work, we synthesized a composite material of pyrolyzed