It is impossible to use lithium batteries below 3 V. Due to electrochemical principles, the standard voltage between positive and negative electrodes is 3.6 V.
Thus, you can take it apart (if possible), and you can see that it is connected in series and parallel. Disassemble it and remove one to get 3.6V, or connect them. all in parallel, so that the capacity is greater.
Save energy. Lithium battery is a type of battery that uses lithium metal or lithium alloy as the negative electrode material and uses non-aqueous electrolyte solution. The power saving of lithium battery depends on the battery voltage and Rb value. Lithium batteries can be roughly divided into two categories: lithium metal batteries and lithium ion batteries do not contain lithium metal and are rechargeable.