Carbon coated titanium dioxide (CC-TiO2) as an efficient anode material for sodium- ion batteries

Materials for Renewable and Sustainable Energy https://doi.org/10.1007/s40243-025-00298-7 (2025) 14:20 BRIEF COMMUNICATION Carbon coated titanium dioxide (CC-TiO2) as an efficient anode material for sodium- ion batteries Rahul Kumar1,2 · Anagha Pradeep1 · Parag Bhargava1 Received: 13 August 2024 / Accepted: 17 January 2025 © The Author(s) 2025 Abstract TiO2 has attracted a lot of attention as anode material for sodium-ion batteries due to its higher operating voltage, safely and low lost material, but TiO2 has two main issues, low electronic conductivity and slow solid-state ion diffusion. These issues have been successfully resolved by researchers using carbon coating on TiO2. In this work, carbon coated TiO2 (CC-TiO2) nanoparticles have been synthesized by using TiO2 and sucrose as soluble source of carbon. The carbon coating on TiO2 particles was formed after heat treatment in inert atmosphere. CC-TiO2 particles exhibited reversible capacity of 116 mAh g− 1 at 0.1 C after 50 cycles, and high capacity retention of 77% after 100 cycles in a sodium-ion battery cell. The impressive electrochemical performance of the TiO2 particles is due to several factors: the small size of the crystallites, the continuous electronic network created by the close contact of individual carbon-coated TiO2 particles, and the efficient penetration of the mesopores by the electrolyte. Keywords Titanium dioxide (TiO2) · Carbon based materials · Anode materials · Carbon coated titanium dioxide (CCTiO2), Sodium ion batteries Introduction Sodium-ion batteries (NIBs) with the great potential are one of the most promosing alternatives to replace lithium-ion batteries (LIBs) in various applications such as grid-level energy stroge, electric vehicles (EVs), stationary storage for residential and commercial use, integration with offgrid systems etc. due to sodium because sodium exhibits the similar battery chemistry to that of LIBs [1]. NIBs have been attractiving a lot of attention due to the natural abundance and low cost of sodium resources [2]. NIBs also have the potential for higher energy density and improved safety compared to lithium-ion batteries [3]. Rahul Kumar 1 Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Mumbai 400076, India 2 Department of Physics and Materials Science, Thapar Institute of Engineering and Technology, Patiala 147004, India NIBs share many similarities with lithium-ion batteries, but they use sodium ions instead of lithium ions for the electrochemical reactions that store and release energy. The basic structure of a sodium-ion battery is similar to that of a lithium-ion battery, consisting of two electrodes, a cathode and an anode, separated by an electrolyte. The cathode is typically made of a sodium-containing compound, such as sodium transition metal oxides (Na1 − xMO2, M-transition metal oxide), sodium layer oxides (Na[Ni1/3Fe1/3Mn1/3] O2, Na1 − x[Fe1 − yMny]O2 (x ≤ 0.3) and derivatives etc. ) or polyanionic compounds (NaFePO4, Na2FePO4F, Na3V2(PO4)3 and. Na3V2(PO4)3 etc.), prussian blue analogues (AxM1[M2(CN)6]y□1−y⋅zH2O, A shows a single alkaline earth metal or alkalimetal, or a mixture of these metals, while M1 and M2 shows transition metals bonded by CN − bonds to form a 3D open structure with the capabilityto host element(s) A inside the crystal structure. □ representsthe vacancy that is caused by the loss of an M2(CN)6 group andthe occupation by coordination water and interstitial water) sulfur-based cathodes (NaMSO4F, (M: Fe, Co, and Mn)) and organic cathode materials ((Na4DHTPA), Na2C8H2O etc.). It’s important to note that the choice of cathode material affects the overall performance of the sodium-ion 13 20 Page 2 of 9 battery, including its energy density, cycling stability, rate capability, and cost. Researchers continue to investigate and develop new cathode materials to improve the performance and commercial viability of sodium-ion batteries [4–6]. while there are many promosing anode materials like hard carbon, graphite, carbon nanotubes (CNTs), graphene, and carbon nanofibers, metallic sodium, alloys (tin (Sn), antimony (Sb), and bismuth (Bi), etc. based alloys), titanate spinel, alloy based compounds, metal oxides (titanium dioxide (TiO2), tin dioxide (SnO2), and iron oxide (Fe3O4) etc.,), transition metal dichalcogenides (e.g., MoS2, TiS2, etc. ) and layered metal oxides (Na2Ti3O7, Na0.44MnO2 etc.) and transition metal phosphide ( e.g. Sn4P3, FeP4, NiP3 etc.) [4–8].The electrolytes (aqueous electrolytes, non-aqueous electrolytes, solid electrolytes and ionic liquid electrolytes) allow the flow of sodium ions between the electrodes during charge and discharge cycles [9]. It has been seen that graphite, which is commonly used as anode material in LIBs while silicon also apperas the promising anode material for next generation LIBs, both of them do not exhibit very suitable electrochemical performance in SIBs [10–12] There are many promosing anode materials for SIBs as mentioned above but hard carbons are the most studied due to their abundance, low cost, extremely good sustainability, and performance characteristics [13]. Nevertheless, hard carbons endure because of safety issues related to the Na+-ion storage mechanism, which shows a long plateau at low voltages that are only slightly above the sodium metal plating potential. Sodium metal plating may happen easily, which increases safety concerns when used in conjunction with organic, volatile, and carbon-based electrolytes [14–16]. The titanium based materials, such as titanium oxides, titanates, and titanium phosphates, have been used as anodes for SIBs [17–18]. TiO2 has been attaining much attention as an anode material because of its higher operating voltage, despite its relatively low sodium storage capacity compared to hard carbons. TiO2 is low-cost and abundant, it does not suffer from sodium plating during cycling [18–20].TiO2 has various polymorphs such as amoprhous TiO2, rutile TiO2, anatase TiO2, TiO2(B) [21–25] and all of them have been used as anode materials in SIBs, lithium-ion batteries LIBs and photocatalyst for solar cell application. There are few main challenges with TiO2 as a anode material such as slow solidstate ion diffucion into TiO2 phase and it has low electrical conductity which result in poor rate performance and low reversible capacity. To solve these limitations, a lot methods have been proposed to enhance the electrochemical performance of TiO2, such as carbon materials coating on TiO2 surface, TiO2 depostion on graphene, reduction of particle size to decrease the ion diffuson length to enhance 13 Materials for Renewable and Sustainable Energy (2025) 14:20 the electronic conductivity, and facet control to facilitate ion diffusion [26–29]. The carbon coating on TiO2 provides several benefits, including improved electrochemical performance and stability, enhanced sodium-ion diffusion, and surf (...truncated)