Polyvinylidene fluoride (pvdf)

The glass cathode material, cotinine black (Shanghai Macklin Biochemical Co., Shanghai, China, AR) and the polyvinylidene fluoride (PVDF, Shanghai Macklin Biochemical Co., Shanghai, China, AR) were weighed according to the mass ratio of 7:2:1, mixed well, and the mixed sample was then placed in a beaker with N-Methylpyrrolidone (NMP, Shanghai Aladdin Biochemical Co., Shanghai, China, AR) to be magnetically stirred for 7 h. The slurry was coated on 20 μm thick aluminum foil, fully dried at 80 °C, and finally cut into 15 mm diameter discs. 1 M LiPF6 dissolved in ethylene carbonate (EC) and dimethyl carbonate (DMC) as electrolyte (EC:DMC = 1:1 vol%). Polypropylene film (Celgard 2500, Celgard Inc., Charlotte, NC, USA) was used as a separator, and CR2032 half-cells were assembled in a glove box in an argon atmosphere. A Land CT2001A battery test system was used to measure the charge/discharge cycling performance and rate capability of the cathode material in the voltage range of 1.5–4.2 V (vs. Li/Li⁺). Cyclic voltammetry (CV) analysis of the cathode material was performed using an electrochemical workstation (CS350M, CORRTEST) with a voltage window of 1.5–4.2 V and a scan rate of 0.2 mV·s⁻¹.

All chemicals and reagents, such as zirconium
oxychloride octahydrate (ZrOCl₂·8H₂O, ≥99.0%,
Aladdin), 1,3,5-benzenetricarboxylic acid (H₃BTC, ≥96.0%,
Macklin), N,N-dimethylformamide (DMF, ≥99.5%,
Macklin), formic acid (CH₂O₂, ≥98.0%,
Macklin), poly(vinylidene fluoride) (PVDF, Macklin), poly(vinylpyrrolidone)
(PVP, Aladdin), imidazole (C₃H₄N₂, ≥99.0%, Macklin), titanium tetrachloride (TiCl₄, ≥99.0%, Macklin), 4-nitrophenol (C₆H₅NO₃, ≥99.5%, Macklin), dimethyl chlorophosphate
((CH₃O)₂P(O)Cl, 96.0%, Aladdin), triethylamine
(C₆H₁₅N, ≥99.0%, Aladdin), tetrahydrofuran
(C₄H₈O, ≥99.9%, Aladdin), ethyl acetate
(C₄H₈O₂, ≥99.5%, Aladdin), n-hexane (C₆H₁₄, ≥98.0%, Aladdin),
acetone (C₃H₆O, ≥99.8%, Merckmillipore),
magnesium sulfate anhydrous (MgSO₄, ≥99.9%, Macklin),
chloroform-d (CDCl₃, 99.8%, LaboTecc),
methyl sulfoxide-d₆ (DMSO-d₆, 99.9%, Macklin) and sulfuric acid-d₂ solution (D₂SO₄, 99.5%, Aladdin)
were obtained from available commercial sources and used without further
purification. DMNP was synthesized by following the reported procedure,^{38 (link)} and the details were described in the Supporting Information.

The hemicelluloses extracted from the dissolving pulp were supplied by a viscose fiber mill in Xinjiang, China. The preparation of the hemicelluloses can be found in our previous literature [30 (link)]. Potassium carbonate (K₂CO₃, 99%), potassium hydroxide (KOH, 95%), sodium carbonate (Na₂CO₃, 99.5%), Zinc chloride (ZnCl₂, 98%), Lithium sulfate (Li₂SO₄, 99%), polyvinylidene fluoride (PVDF), N-methyl pyrrolidone (NMP, 99%) were purchased from Shanghai Macklin Biochemical Co., Ltd., Shanghai, China. Acetylene black was obtained from Tianjin Ebory Chemical Co., Ltd., Tianjin, China. Hydrochloric acid (HCl, 37 wt%) and sulfuric acid (H₂SO₄, 95 wt%) were purchased from Shanghai Chemical Reagent Co., Ltd., Shanghai, China. HCl, H₂SO₄, KOH, K₂CO₃, Na₂CO₃, ZnCl₂, Li₂SO₄, PVDF, NMP, and acetylene black were all of analytical grade and used as received.

The electrode was prepared as follows: active material (Ti₃C₂, TiO₂/Ti₃C₂, or active carbon), acetylene black (Sinopharm Chemical Reagent Co., Ltd.), and polyvinylidene fluoride (Shanghai Macklin Biochemical Co., Ltd.) at a weight ratio of 80%:10%:10% were blended in a specified volume of N‐methyl‐2‐pyrrolidone (Aladdin Industrial) solvent under stirring for 12 h to obtain a homogenous slurry. Then, the as‐prepared slurry was uniformly dropped on graphite paper using a doctor‐blade method with a thickness of ≈75 µm. The thin film electrodes were vacuum‐dried at 60 °C for 12 h.