Organic materials (OMs) have great potential to accept alkaline ions and thus be used in energy storage systems. Owing to their low cost, easy synthesis, and wide applications, a green battery containing an OM without any considerable production of heavy pollutants such as graphite and transitionmetal oxides can be expected in the near future. In this study, two new OMs, chelidamic acid (CDA) and chelidonic acid (CDO), were prepared and investigated for energy storage. CDA and CDO have a similar molecular weight and structure but differ in the electronegative heteroatoms, the secondary amine, and the oxygen atom. This research demonstrates that the different heteroatom dramatically dominates the electrochemical behavior of these two materials. After cycling with Li + , composite electrodes containing CDA and CDO exhibited capacities of 740.2 and 562.8 mAh g −1 , respectively, for 250 cycles with no capacity decade. The specific surface area of CDA (2.46 m 2 g −1 ) is twice that of CDO (1.23 m 2 g −1 ), implying that the secondary amine changes the threedimensional structure and leads to an interesting electrochemical activity with Li + . The composite electrodes containing the two OMs, especially those containing CDA, exhibited rate performance (10 C) superior to that of graphite electrodes. Ex situ Fourier transform infrared and X-ray photoelectron spectroscopies were used to investigate the reaction mechanism of these two OMs. CDA and CDO not only provide outstanding capacity, rate performance, and cycle retention with Li + but also display great potential in applications with other alkaline ions.

Highly delithiated LiCoO 2 has high specific capacity (>200 mAh g −1 ); however, its degradation behavior causes it to have poor electrochemical performance and thermal instability. The degradation of highly delithiated LiCoO 2 is mainly induced by oxygen vacancy migration and weakening of oxygen-related interactions, which result in pitting corrosion and fault formation on the surface. In this research, a coupling agent, namely, 3-aminopropyltriethoxysilane (APTES), was grafted onto the surface of LiCoO 2 to form a cross-linking structure. Through the aza-Michael addition reaction, an oligomer formed from barbituric acid and bisphenol a diglycidyl ether diacrylate were reacted with the cross-linking APTES to form an artificial cathode electrolyte interphase (ACEI). The highly delithiated LiCoO 2 containing the ACEI had considerably less degradation on the surface of the bulk material caused by oxygen release. The formation of the O1 phase was prevented in high delithiation and high-temperature operations. This research revealed that the ACEI reinforced the Co−O bond, which is crucial in preventing gas evolution and O1 phase formation. In addition, the ACEI prevents direct contact between the electrolyte and highly active surface of LiCoO 2 , thereby preventing the formation of a thick and high impedance traditional cathode electrolyte interphase. According to the present results, highly delithiated LiCoO 2 containing the ACEI exhibited outstanding cycle retention and capacity at 55 °C as well as low heat capacity release in the fully delithiated state. The ACEI considerably protected and maintained the electrochemical performance of highly delithiated LiCoO 2 , which is suitable for high-energy-density applications, such as electric vehicles and power tools.

In this study we prepared potassium-ion batteries (KIBs) displaying high output voltage and, in turn, a high energy density, as replacements for lithium-ion batteries (LIBs). Organic electrode materials featuring void spaces and flexible structures can facilitate the mobility of K+ to enhance the performance of KIBs. We synthesized potassium maleamate (K-MA) from maleamic acid (MA) and applied as an anode material for KIBs and LIBs, with 1 M potassium bis(fluorosulfonyl)imide (KFSI) and 1 M lithium bis(fluorosulfonyl)imide (LiFSI) in a mixture of ethylene carbonate and ethyl methyl carbonate (1:2, v/v) as respective electrolytes. The K-MA_KFSI anode underwent charging/discharging with carbonyl groups at low voltage, due to the K···O bond interaction weaker than Li···O. The K-MA_KFSI and K-MA_LiFSI anode materials delivered a capacity of 172 and 485 mA h g−1 after 200 cycles at 0.1C rate, respectively. K-MA was capable of accepting one K+ in KIB, whereas it could accept two Li+ in a LIB. The superior recoveries performance of K-MA_LiFSI, K-MA_KFSI, and Super P_KFSI at rate of 0.1C were 320, 201, and 105 mA h g−1, respectively. This implies the larger size of K+ can reversibly cycling at high rate.